--- /dev/null
+// foster btree version a
+// 16 DEC 2013
+
+// author: karl malbrain, malbrain@cal.berkeley.edu
+
+/*
+This work, including the source code, documentation
+and related data, is placed into the public domain.
+
+The orginal author is Karl Malbrain.
+
+THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
+OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
+MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
+ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
+RESULTING FROM THE USE, MODIFICATION, OR
+REDISTRIBUTION OF THIS SOFTWARE.
+*/
+
+// Please see the project home page for documentation
+// code.google.com/p/high-concurrency-btree
+
+#define _FILE_OFFSET_BITS 64
+#define _LARGEFILE64_SOURCE
+
+#ifdef linux
+#define _GNU_SOURCE
+#endif
+
+#ifdef unix
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/time.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <pthread.h>
+#else
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <fcntl.h>
+#include <process.h>
+#endif
+
+#include <memory.h>
+#include <string.h>
+
+typedef unsigned long long uid;
+
+#ifndef unix
+typedef unsigned long long off64_t;
+typedef unsigned short ushort;
+typedef unsigned int uint;
+#endif
+
+#define BT_ro 0x6f72 // ro
+#define BT_rw 0x7772 // rw
+
+#define BT_maxbits 24 // maximum page size in bits
+#define BT_minbits 9 // minimum page size in bits
+#define BT_minpage (1 << BT_minbits) // minimum page size
+#define BT_maxpage (1 << BT_maxbits) // maximum page size
+
+/*
+There are five lock types for each node in three independent sets:
+1. (set 1) AccessIntent: Sharable. Going to Read the node. Incompatible with NodeDelete.
+2. (set 1) NodeDelete: Exclusive. About to release the node. Incompatible with AccessIntent.
+3. (set 2) ReadLock: Sharable. Read the node. Incompatible with WriteLock.
+4. (set 2) WriteLock: Exclusive. Modify the node. Incompatible with ReadLock and other WriteLocks.
+5. (set 3) ParentLock: Exclusive. Have parent adopt/delete maximum foster child from the node.
+*/
+
+typedef enum{
+ BtLockAccess,
+ BtLockDelete,
+ BtLockRead,
+ BtLockWrite,
+ BtLockParent
+}BtLock;
+
+// Define the length of the page and key pointers
+
+#define BtId 6
+
+// Page key slot definition.
+
+// If BT_maxbits is 15 or less, you can save 4 bytes
+// for each key stored by making the first two uints
+// into ushorts. You can also save 4 bytes by removing
+// the tod field from the key.
+
+// Keys are marked dead, but remain on the page until
+// it cleanup is called. The fence key (highest key) for
+// the page is always present, even after cleanup.
+
+typedef struct {
+ uint off:BT_maxbits; // page offset for key start
+ uint dead:1; // set for deleted key
+ uint tod; // time-stamp for key
+ unsigned char id[BtId]; // id associated with key
+} BtSlot;
+
+// The key structure occupies space at the upper end of
+// each page. It's a length byte followed by the value
+// bytes.
+
+typedef struct {
+ unsigned char len;
+ unsigned char key[1];
+} *BtKey;
+
+// The first part of an index page.
+// It is immediately followed
+// by the BtSlot array of keys.
+
+typedef struct Page {
+ uint cnt; // count of keys in page
+ uint act; // count of active keys
+ uint min; // next key offset
+ uint foster; // count of foster children
+ unsigned char bits:6; // page size in bits
+ unsigned char dirty:1; // page needs to be cleaned
+ unsigned char kill:1; // page is being deleted
+ unsigned char lvl; // level of page
+ unsigned char right[BtId]; // page number to right
+} *BtPage;
+
+// mode & definition for latch table implementation
+
+enum {
+ Write = 1,
+ Share = 2
+} LockMode;
+
+// latch table lock structure
+
+// mode is set for write access
+// share is count of read accessors
+// grant write lock when share == 0
+
+typedef struct {
+ int mode:1;
+ int share:31;
+} BtLatch;
+
+typedef struct {
+ BtLatch readwr[1]; // read/write page lock
+ BtLatch access[1]; // Access Intent/Page delete
+ BtLatch parent[1]; // adoption of foster children
+} BtLatchSet;
+
+// The memory mapping hash table buffer manager entry
+
+typedef struct {
+ unsigned long long int lru; // number of times accessed
+ uid basepage; // mapped base page number
+ char *map; // mapped memory pointer
+ uint pin; // mapped page pin counter
+ uint slot; // slot index in this array
+ void *hashprev; // previous cache block for the same hash idx
+ void *hashnext; // next cache block for the same hash idx
+#ifndef unix
+ HANDLE hmap;
+#endif
+// array of page latch sets, one for each page in map segment
+ BtLatchSet pagelatch[0];
+} BtHash;
+
+// The object structure for Btree access
+
+typedef struct {
+ uint page_size; // page size
+ uint page_bits; // page size in bits
+ uint seg_bits; // seg size in pages in bits
+ uint mode; // read-write mode
+#ifdef unix
+ int idx;
+#else
+ HANDLE idx;
+#endif
+ uint nodecnt; // highest page cache node in use
+ uint nodemax; // highest page cache node allocated
+ uint hashmask; // number of pages in mmap segment
+ uint hashsize; // size of Hash Table
+ uint evicted; // last evicted hash slot
+ ushort *cache; // hash index for memory pool
+ BtLatch *latch; // latches for hash table slots
+ char *nodes; // memory pool page hash nodes
+} BtMgr;
+
+typedef struct {
+ BtMgr *mgr; // buffer manager for thread
+ BtPage temp; // temporary frame buffer (memory mapped/file IO)
+ BtPage alloc; // frame buffer for alloc page ( page 0 )
+ BtPage cursor; // cached frame for start/next (never mapped)
+ BtPage frame; // spare frame for the page split (never mapped)
+ BtPage zero; // page frame for zeroes at end of file
+ BtPage page; // current page
+ uid page_no; // current page number
+ uid cursor_page; // current cursor page number
+ unsigned char *mem; // frame, cursor, page memory buffer
+ int err; // last error
+} BtDb;
+
+typedef enum {
+ BTERR_ok = 0,
+ BTERR_again,
+ BTERR_struct,
+ BTERR_ovflw,
+ BTERR_lock,
+ BTERR_map,
+ BTERR_wrt,
+ BTERR_hash
+} BTERR;
+
+// B-Tree functions
+extern void bt_close (BtDb *bt);
+extern BtDb *bt_open (BtMgr *mgr);
+extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod);
+extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl);
+extern uid bt_findkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_startkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_nextkey (BtDb *bt, uint slot);
+
+// manager functions
+extern BtMgr *bt_mgr (char *name, uint mode, uint bits, uint cacheblk, uint segsize, uint hashsize);
+void bt_mgrclose (BtMgr *mgr);
+
+// Helper functions to return cursor slot values
+
+extern BtKey bt_key (BtDb *bt, uint slot);
+extern uid bt_uid (BtDb *bt, uint slot);
+extern uint bt_tod (BtDb *bt, uint slot);
+
+// BTree page number constants
+#define ALLOC_page 0
+#define ROOT_page 1
+
+// Number of levels to create in a new BTree
+
+#define MIN_lvl 2
+
+// The page is allocated from low and hi ends.
+// The key offsets and row-id's are allocated
+// from the bottom, while the text of the key
+// is allocated from the top. When the two
+// areas meet, the page is split into two.
+
+// A key consists of a length byte, two bytes of
+// index number (0 - 65534), and up to 253 bytes
+// of key value. Duplicate keys are discarded.
+// Associated with each key is a 48 bit row-id.
+
+// The b-tree root is always located at page 1.
+// The first leaf page of level zero is always
+// located on page 2.
+
+// When to root page fills, it is split in two and
+// the tree height is raised by a new root at page
+// one with two keys.
+
+// Deleted keys are marked with a dead bit until
+// page cleanup The fence key for a node is always
+// present, even after deletion and cleanup.
+
+// Groups of pages called segments from the btree are
+// cached with memory mapping. A hash table is used to keep
+// track of the cached segments. This behaviour is controlled
+// by the cache block size parameter to bt_open.
+
+// To achieve maximum concurrency one page is locked at a time
+// as the tree is traversed to find leaf key in question.
+
+// An adoption traversal leaves the parent node locked as the
+// tree is traversed to the level in quesiton.
+
+// Page 0 is dedicated to lock for new page extensions,
+// and chains empty pages together for reuse.
+
+// Empty pages are chained together through the ALLOC page and reused.
+
+// Access macros to address slot and key values from the page
+
+#define slotptr(page, slot) (((BtSlot *)(page+1)) + (slot-1))
+#define keyptr(page, slot) ((BtKey)((unsigned char*)(page) + slotptr(page, slot)->off))
+
+void bt_putid(unsigned char *dest, uid id)
+{
+int i = BtId;
+
+ while( i-- )
+ dest[i] = (unsigned char)id, id >>= 8;
+}
+
+uid bt_getid(unsigned char *src)
+{
+uid id = 0;
+int i;
+
+ for( i = 0; i < BtId; i++ )
+ id <<= 8, id |= *src++;
+
+ return id;
+}
+
+void bt_mgrclose (BtMgr *mgr)
+{
+BtHash *hash;
+uint slot;
+
+ // release mapped pages
+
+ for( slot = 0; slot < mgr->nodemax; slot++ ) {
+ hash = (BtHash *)(mgr->nodes + slot * (sizeof(BtHash) + (mgr->hashmask + 1) * sizeof(BtLatchSet)));
+ if( hash->slot )
+#ifdef unix
+ munmap (hash->map, (mgr->hashmask+1) << mgr->page_bits);
+#else
+ {
+ FlushViewOfFile(hash->map, 0);
+ UnmapViewOfFile(hash->map);
+ CloseHandle(hash->hmap);
+ }
+#endif
+ }
+
+#ifdef unix
+ close (mgr->idx);
+ free (mgr->nodes);
+ free (mgr->cache);
+ free (mgr->latch);
+#else
+ FlushFileBuffers(mgr->idx);
+ CloseHandle(mgr->idx);
+ GlobalFree (mgr->nodes);
+ GlobalFree (mgr->cache);
+ GlobalFree (mgr->latch);
+#endif
+}
+
+// close and release memory
+
+void bt_close (BtDb *bt)
+{
+#ifdef unix
+ if ( bt->mem )
+ free (bt->mem);
+ free (bt);
+#else
+ if ( bt->mem)
+ VirtualFree (bt->mem, 0, MEM_RELEASE);
+ GlobalFree (bt);
+#endif
+}
+
+// open/create new btree buffer manager
+
+// call with file_name, BT_openmode, bits in page size (e.g. 16),
+// size of mapped page cache (e.g. 8192)
+
+BtMgr *bt_mgr (char *name, uint mode, uint bits, uint nodemax, uint segsize, uint hashsize)
+{
+uint lvl, attr, cacheblk, last;
+BtPage alloc;
+int lockmode;
+off64_t size;
+uint amt[1];
+BtMgr* mgr;
+BtKey key;
+
+#ifndef unix
+SYSTEM_INFO sysinfo[1];
+#endif
+
+ // determine sanity of page size and buffer pool
+
+ if( bits > BT_maxbits )
+ bits = BT_maxbits;
+ else if( bits < BT_minbits )
+ bits = BT_minbits;
+
+ if( !nodemax )
+ return NULL; // must have buffer pool
+
+#ifdef unix
+ mgr = calloc (1, sizeof(BtMgr));
+
+ switch (mode & 0x7fff)
+ {
+ case BT_rw:
+ mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
+ lockmode = 1;
+ break;
+
+ case BT_ro:
+ default:
+ mgr->idx = open ((char*)name, O_RDONLY);
+ lockmode = 0;
+ break;
+ }
+ if( mgr->idx == -1 )
+ return free(mgr), NULL;
+
+ cacheblk = 4096; // minimum mmap segment size for unix
+
+#else
+ mgr = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtMgr));
+ attr = FILE_ATTRIBUTE_NORMAL;
+ switch (mode & 0x7fff)
+ {
+ case BT_rw:
+ mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
+ lockmode = 1;
+ break;
+
+ case BT_ro:
+ default:
+ mgr->idx = CreateFile(name, GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, attr, NULL);
+ lockmode = 0;
+ break;
+ }
+ if( mgr->idx == INVALID_HANDLE_VALUE )
+ return GlobalFree(mgr), NULL;
+
+ // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity
+ GetSystemInfo(sysinfo);
+ cacheblk = sysinfo->dwAllocationGranularity;
+#endif
+
+#ifdef unix
+ alloc = malloc (BT_maxpage);
+ *amt = 0;
+
+ // read minimum page size to get root info
+
+ if( size = lseek (mgr->idx, 0L, 2) ) {
+ if( pread(mgr->idx, alloc, BT_minpage, 0) == BT_minpage )
+ bits = alloc->bits;
+ else
+ return free(mgr), free(alloc), NULL;
+ } else if( mode == BT_ro )
+ return bt_mgrclose (mgr), NULL;
+#else
+ alloc = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE);
+ size = GetFileSize(mgr->idx, amt);
+
+ if( size || *amt ) {
+ if( !ReadFile(mgr->idx, (char *)alloc, BT_minpage, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ bits = alloc->bits;
+ } else if( mode == BT_ro )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ mgr->page_size = 1 << bits;
+ mgr->page_bits = bits;
+
+ mgr->nodemax = nodemax;
+ mgr->mode = mode;
+
+ if( cacheblk < mgr->page_size )
+ cacheblk = mgr->page_size;
+
+ // mask for partial memmaps
+
+ mgr->hashmask = (cacheblk >> bits) - 1;
+
+ // see if requested number of pages per memmap is greater
+
+ if( (1 << segsize) > mgr->hashmask )
+ mgr->hashmask = (1 << segsize) - 1;
+
+ mgr->seg_bits = 0;
+
+ while( (1 << mgr->seg_bits) <= mgr->hashmask )
+ mgr->seg_bits++;
+
+ mgr->hashsize = hashsize;
+
+#ifdef unix
+ mgr->nodes = calloc (nodemax, (sizeof(BtHash) + (mgr->hashmask + 1) * sizeof(BtLatchSet)));
+ mgr->cache = calloc (hashsize, sizeof(ushort));
+ mgr->latch = calloc (hashsize, sizeof(BtLatch));
+#else
+ mgr->nodes = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, cacheblk * (sizeof(BtHash) + (mgr->hashmask + 1) * sizeof(BtLatchSet)));
+ mgr->cache = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(ushort));
+ mgr->latch = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(BtLatch));
+#endif
+
+ if( size || *amt )
+ goto mgrxit;
+
+ // initializes an empty b-tree with root page and page of leaves
+
+ memset (alloc, 0, 1 << bits);
+ bt_putid(slotptr(alloc, 2)->id, MIN_lvl+1);
+ alloc->bits = mgr->page_bits;
+
+#ifdef unix
+ if( write (mgr->idx, alloc, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ memset (alloc, 0, 1 << bits);
+ alloc->bits = mgr->page_bits;
+
+ for( lvl=MIN_lvl; lvl--; ) {
+ slotptr(alloc, 1)->off = mgr->page_size - 3;
+ bt_putid(slotptr(alloc, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number
+ key = keyptr(alloc, 1);
+ key->len = 2; // create stopper key
+ key->key[0] = 0xff;
+ key->key[1] = 0xff;
+ alloc->min = mgr->page_size - 3;
+ alloc->lvl = lvl;
+ alloc->cnt = 1;
+ alloc->act = 1;
+#ifdef unix
+ if( write (mgr->idx, alloc, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ }
+
+ // create empty page area by writing last page of first
+ // cache area (other pages are zeroed by O/S)
+
+ if( mgr->hashmask ) {
+ memset(alloc, 0, mgr->page_size);
+ last = mgr->hashmask;
+
+ while( last < MIN_lvl + 1 )
+ last += mgr->hashmask + 1;
+
+#ifdef unix
+ pwrite(mgr->idx, alloc, mgr->page_size, last << mgr->page_bits);
+#else
+ SetFilePointer (mgr->idx, last << mgr->page_bits, NULL, FILE_BEGIN);
+ if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ }
+
+mgrxit:
+#ifdef unix
+ free (alloc);
+#else
+ VirtualFree (alloc, 0, MEM_RELEASE);
+#endif
+ return mgr;
+}
+
+// open BTree access method
+// based on buffer manager
+
+BtDb *bt_open (BtMgr *mgr)
+{
+BtDb *bt = malloc (sizeof(*bt));
+
+ memset (bt, 0, sizeof(*bt));
+ bt->mgr = mgr;
+#ifdef unix
+ bt->mem = malloc (3 *mgr->page_size);
+#else
+ bt->mem = VirtualAlloc(NULL, 3 * mgr->page_size, MEM_COMMIT, PAGE_READWRITE);
+#endif
+ bt->frame = (BtPage)bt->mem;
+ bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size);
+ bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size);
+ return bt;
+}
+
+// compare two keys, returning > 0, = 0, or < 0
+// as the comparison value
+
+int keycmp (BtKey key1, unsigned char *key2, uint len2)
+{
+uint len1 = key1->len;
+int ans;
+
+ if( ans = memcmp (key1->key, key2, len1 > len2 ? len2 : len1) )
+ return ans;
+
+ if( len1 > len2 )
+ return 1;
+ if( len1 < len2 )
+ return -1;
+
+ return 0;
+}
+
+// Latch Manager
+
+// wait until write lock mode is clear
+// and add 1 to the share count
+
+void bt_readlock(BtLatch *latch)
+{
+ do {
+ // add one to counter, check write bit
+
+#ifdef unix
+ if( ~__sync_fetch_and_add((int *)latch, Share) & Write )
+ return;
+#else
+ if( ~InterlockedAdd((int *)latch, Share) & Write )
+ return;
+#endif
+ // didn't get latch, reset counter by one
+
+#ifdef unix
+ __sync_fetch_and_add((int *)latch, -Share);
+#else
+ InterlockedAdd ((int *)latch, -Share);
+#endif
+
+ // and yield
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ } while( 1 );
+}
+
+// wait for other read and write latches to relinquish
+
+void bt_writelock(BtLatch *latch)
+{
+int prev, ours = 0;
+
+ do {
+ // see if we can get write access
+ // with no readers
+#ifdef unix
+ prev = __sync_fetch_and_or((int *)latch, Write);
+#else
+ prev = InterlockedOr((int *)latch, Write);
+#endif
+
+ if( ~prev & 1 )
+ ours++; // it's ours
+
+ if( !(prev >> 1) && ours )
+ return;
+
+ // otherwise yield
+
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ } while( 1 );
+}
+
+// try to obtain write lock
+
+// return 1 if obtained,
+// 0 if already write locked
+
+int bt_writetry(BtLatch *latch)
+{
+int prev, ours = 0;
+
+ do {
+ // see if we can get write access
+ // with no readers
+#ifdef unix
+ prev = __sync_fetch_and_or((int *)latch, Write);
+#else
+ prev = InterlockedOr((int *)latch, Write);
+#endif
+
+ if( ~prev & 1 )
+ ours++; // it's ours
+
+ if( !ours )
+ return 0;
+
+ if( !(prev >> 1) && ours )
+ return 1;
+
+ // otherwise yield
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ } while( 1 );
+}
+
+// clear write mode
+
+void bt_releasewrite(BtLatch *latch)
+{
+#ifdef unix
+ __sync_fetch_and_and((int *)latch, ~Write);
+#else
+ InterlockedAnd ((int *)latch, ~Write);
+#endif
+}
+
+// decrement reader count
+
+void bt_releaseread(BtLatch *latch)
+{
+#ifdef unix
+ __sync_fetch_and_add((int *)latch, -Share);
+#else
+ InterlockedAdd((int *)latch, -Share);
+#endif
+}
+
+// Buffer Pool mgr
+
+// find segment in cache
+// return NULL if not there
+// otherwise return node
+
+BtHash *bt_findhash(BtDb *bt, uid page_no, uint idx)
+{
+BtHash *hash;
+uint slot;
+
+ // compute cache block first page and hash idx
+
+ if( slot = bt->mgr->cache[idx] )
+ hash = (BtHash *)(bt->mgr->nodes + slot * (sizeof(BtHash) + (bt->mgr->hashmask + 1) * sizeof(BtLatchSet)));
+ else
+ return NULL;
+
+ page_no &= ~bt->mgr->hashmask;
+
+ while( hash->basepage != page_no )
+ if( hash = hash->hashnext )
+ continue;
+ else
+ return NULL;
+
+ return hash;
+}
+
+// add segment to hash table
+
+void bt_linkhash(BtDb *bt, BtHash *hash, uid page_no, int idx)
+{
+BtHash *node;
+uint slot;
+
+ hash->hashprev = hash->hashnext = NULL;
+ hash->basepage = page_no & ~bt->mgr->hashmask;
+ hash->pin = 1;
+ hash->lru = 1;
+
+ if( slot = bt->mgr->cache[idx] ) {
+ node = (BtHash *)(bt->mgr->nodes + slot * (sizeof(BtHash) + (bt->mgr->hashmask + 1) * sizeof(BtLatchSet)));
+ hash->hashnext = node;
+ node->hashprev = hash;
+ }
+
+ bt->mgr->cache[idx] = hash->slot;
+}
+
+// find best segment to evict from buffer pool
+
+BtHash *bt_findlru (BtDb *bt, uint slot)
+{
+unsigned long long int target = ~0LL;
+BtHash *hash = NULL, *node;
+
+ if( !slot )
+ return NULL;
+
+ node = (BtHash *)(bt->mgr->nodes + slot * (sizeof(BtHash) + (bt->mgr->hashmask + 1) * sizeof(BtLatchSet)));
+
+ do {
+ if( node->pin )
+ continue;
+ if( node->lru > target )
+ continue;
+ target = node->lru;
+ hash = node;
+ } while( node = node->hashnext );
+
+ return hash;
+}
+
+// map new segment to virtual memory
+
+BTERR bt_mapsegment(BtDb *bt, BtHash *hash, uid page_no)
+{
+off64_t off = (page_no & ~bt->mgr->hashmask) << bt->mgr->page_bits;
+off64_t limit = off + ((bt->mgr->hashmask+1) << bt->mgr->page_bits);
+int flag;
+
+#ifdef unix
+ flag = PROT_READ | ( bt->mgr->mode == BT_ro ? 0 : PROT_WRITE );
+ hash->map = mmap (0, (bt->mgr->hashmask+1) << bt->mgr->page_bits, flag, MAP_SHARED, bt->mgr->idx, off);
+ if( hash->map == MAP_FAILED )
+ return bt->err = BTERR_map;
+#else
+ flag = ( bt->mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE );
+ hash->hmap = CreateFileMapping(bt->mgr->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL);
+ if( !hash->hmap )
+ return bt->err = BTERR_map;
+
+ flag = ( bt->mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE );
+ hash->map = MapViewOfFile(hash->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->mgr->hashmask+1) << bt->mgr->page_bits);
+ if( !hash->map )
+ return bt->err = BTERR_map;
+#endif
+ return bt->err = 0;
+}
+
+// find or place requested page in segment-cache
+// return hash table entry
+
+BtHash *bt_hashpage(BtDb *bt, uid page_no)
+{
+BtHash *hash, *node, *next;
+uint slot, idx, victim;
+BtLatchSet *set;
+
+ // lock hash table chain
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_readlock (&bt->mgr->latch[idx]);
+
+ // look up in hash table
+
+ if( hash = bt_findhash(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&hash->pin, 1);
+#else
+ InterlockedIncrement (&hash->pin);
+#endif
+ bt_releaseread (&bt->mgr->latch[idx]);
+ hash->lru++;
+ return hash;
+ }
+
+ // upgrade to write lock
+
+ bt_releaseread (&bt->mgr->latch[idx]);
+ bt_writelock (&bt->mgr->latch[idx]);
+
+ // try to find page in cache with write lock
+
+ if( hash = bt_findhash(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&hash->pin, 1);
+#else
+ InterlockedIncrement (&hash->pin);
+#endif
+ bt_releasewrite (&bt->mgr->latch[idx]);
+ hash->lru++;
+ return hash;
+ }
+
+ // allocate a new hash node
+ // and add to hash table
+
+#ifdef unix
+ slot = __sync_fetch_and_add(&bt->mgr->nodecnt, 1);
+#else
+ slot = InterlockedIncrement (&bt->mgr->nodecnt) - 1;
+#endif
+
+ if( ++slot < bt->mgr->nodemax ) {
+ hash = (BtHash *)(bt->mgr->nodes + slot * (sizeof(BtHash) + (bt->mgr->hashmask + 1) * sizeof(BtLatchSet)));
+ hash->slot = slot;
+
+ if( bt_mapsegment(bt, hash, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, hash, page_no, idx);
+ bt_releasewrite (&bt->mgr->latch[idx]);
+ return hash;
+ }
+
+ // hash table is full
+ // find best cache entry to evict
+
+#ifdef unix
+ __sync_fetch_and_add(&bt->mgr->nodecnt, -1);
+#else
+ InterlockedDecrement (&bt->mgr->nodecnt);
+#endif
+
+ while( 1 ) {
+#ifdef unix
+ victim = __sync_fetch_and_add(&bt->mgr->evicted, 1);
+#else
+ victim = InterlockedIncrement (&bt->mgr->evicted) - 1;
+#endif
+ victim %= bt->mgr->hashsize;
+
+ // try to get write lock
+ // skip entry if not obtained
+
+ if( !bt_writetry (&bt->mgr->latch[victim]) )
+ continue;
+
+ // if cache entry is empty
+ // or no slots are unpinned
+ // skip this entry
+
+ if( !(hash = bt_findlru(bt, bt->mgr->cache[victim])) ) {
+ bt_releasewrite (&bt->mgr->latch[victim]);
+ continue;
+ }
+
+ // unlink victim hash node from hash table
+
+ if( node = hash->hashprev )
+ node->hashnext = hash->hashnext;
+ else if( node = hash->hashnext )
+ bt->mgr->cache[victim] = node->slot;
+ else
+ bt->mgr->cache[victim] = 0;
+
+ if( node = hash->hashnext )
+ node->hashprev = hash->hashprev;
+
+ // remove old file mapping
+#ifdef unix
+ munmap (hash->map, (bt->mgr->hashmask+1) << bt->mgr->page_bits);
+#else
+ FlushViewOfFile(hash->map, 0);
+ UnmapViewOfFile(hash->map);
+ CloseHandle(hash->hmap);
+#endif
+ hash->map = NULL;
+ bt_releasewrite (&bt->mgr->latch[victim]);
+
+ // create new file mapping
+ // and link into hash table
+
+ if( bt_mapsegment(bt, hash, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, hash, page_no, idx);
+ bt_releasewrite (&bt->mgr->latch[idx]);
+ return hash;
+ }
+}
+
+// place write, read, or parent lock on requested page_no.
+// pin to buffer pool
+
+BTERR bt_lockpage(BtDb *bt, uid page_no, BtLock mode, BtPage *page)
+{
+BtLatchSet *set;
+BtHash *hash;
+uint subpage;
+
+ // find/create maping in hash table
+
+ if( hash = bt_hashpage(bt, page_no) )
+ subpage = (uint)(page_no & bt->mgr->hashmask); // page within mapping
+ else
+ return bt->err;
+
+ set = hash->pagelatch + subpage;
+
+ switch( mode ) {
+ case BtLockRead:
+ bt_readlock (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_writelock (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_readlock (set->access);
+ break;
+ case BtLockDelete:
+ bt_writelock (set->access);
+ break;
+ case BtLockParent:
+ bt_writelock (set->parent);
+ break;
+ default:
+ return bt->err = BTERR_lock;
+ }
+
+ if( page )
+ *page = (BtPage)(hash->map + (subpage << bt->mgr->page_bits));
+
+ return bt->err = 0;
+}
+
+// remove write, read, or parent lock on requested page_no.
+
+BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode)
+{
+uint subpage, idx;
+BtLatchSet *set;
+BtHash *hash;
+
+ // since page is pinned
+ // it should still be in the buffer pool
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_readlock (&bt->mgr->latch[idx]);
+
+ if( hash = bt_findhash(bt, page_no, idx) )
+ subpage = (uint)(page_no & bt->mgr->hashmask);
+ else
+ return bt->err = BTERR_hash;
+
+ bt_releaseread (&bt->mgr->latch[idx]);
+ set = hash->pagelatch + subpage;
+
+ switch( mode ) {
+ case BtLockRead:
+ bt_releaseread (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_releasewrite (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_releaseread (set->access);
+ break;
+ case BtLockDelete:
+ bt_releasewrite (set->access);
+ break;
+ case BtLockParent:
+ bt_releasewrite (set->parent);
+ break;
+ default:
+ return bt->err = BTERR_lock;
+ }
+
+#ifdef unix
+ __sync_fetch_and_add(&hash->pin, -1);
+#else
+ InterlockedDecrement (&hash->pin);
+#endif
+ return bt->err = 0;
+}
+
+// deallocate a deleted page that has no tree pointers
+// place on free chain out of allocator page
+
+BTERR bt_freepage(BtDb *bt, uid page_no)
+{
+ // obtain delete lock on deleted page
+
+ if( bt_lockpage(bt, page_no, BtLockDelete, NULL) )
+ return bt->err;
+
+ // obtain write lock on deleted page
+
+ if( bt_lockpage(bt, page_no, BtLockWrite, &bt->temp) )
+ return bt->err;
+
+ // lock allocation page
+
+ if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) )
+ return bt->err;
+
+ // store chain in first key
+ bt_putid(slotptr(bt->temp, 1)->id, bt_getid(slotptr(bt->alloc, 1)->id));
+ bt_putid(slotptr(bt->alloc, 1)->id, page_no);
+
+ // unlock page zero
+
+ if( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
+ return bt->err;
+
+ // remove write lock on deleted node
+
+ if( bt_unlockpage(bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ // remove delete lock on deleted node
+
+ if( bt_unlockpage(bt, page_no, BtLockDelete) )
+ return bt->err;
+
+ return 0;
+}
+
+// allocate a new page and write page into it
+
+uid bt_newpage(BtDb *bt, BtPage page)
+{
+uid new_page;
+BtPage pmap;
+int reuse;
+
+ // lock page zero
+
+ if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) )
+ return 0;
+
+ // use empty chain first
+ // else allocate empty page
+
+ if( new_page = bt_getid(slotptr(bt->alloc, 1)->id) ) {
+ if( bt_lockpage (bt, new_page, BtLockWrite, &bt->temp) )
+ return 0;
+ bt_putid(slotptr(bt->alloc, 1)->id, bt_getid(slotptr(bt->temp, 1)->id));
+ if( bt_unlockpage (bt, new_page, BtLockWrite) )
+ return 0;
+ reuse = 1;
+ } else {
+ new_page = bt_getid(slotptr(bt->alloc, 2)->id);
+ bt_putid(slotptr(bt->alloc, 2)->id, new_page+1);
+ reuse = 0;
+ }
+#ifdef unix
+ if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+
+ // if writing first page of hash block, zero last page in the block
+
+ if ( !reuse && bt->mgr->hashmask > 0 && (new_page & bt->mgr->hashmask) == 0 )
+ {
+ // use zero buffer to write zeros
+ memset(bt->zero, 0, bt->mgr->page_size);
+ if ( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->hashmask) << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+ }
+#else
+ // bring new page into page-cache and copy page.
+ // this will extend the file into the new pages.
+
+ if( bt_lockpage(bt, new_page, BtLockWrite, &pmap) )
+ return 0;
+
+ memcpy(pmap, page, bt->mgr->page_size);
+
+ if( bt_unlockpage (bt, new_page, BtLockWrite) )
+ return 0;
+#endif
+ // unlock page zero
+
+ if ( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
+ return 0;
+
+ return new_page;
+}
+
+// find slot in page for given key at a given level
+
+int bt_findslot (BtDb *bt, unsigned char *key, uint len)
+{
+uint diff, higher = bt->page->cnt, low = 1, slot;
+
+ // low is the lowest candidate, higher is already
+ // tested as .ge. the given key, loop ends when they meet
+
+ while( diff = higher - low ) {
+ slot = low + ( diff >> 1 );
+ if( keycmp (keyptr(bt->page, slot), key, len) < 0 )
+ low = slot + 1;
+ else
+ higher = slot;
+ }
+
+ return higher;
+}
+
+// find and load page at given level for given key
+// leave page rd or wr locked as requested
+
+int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, uint lock)
+{
+uid page_no = ROOT_page, prevpage = 0;
+uint drill = 0xff, slot;
+uint mode, prevmode;
+
+ // start at root of btree and drill down
+
+ do {
+ // determine lock mode of drill level
+ mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead;
+
+ bt->page_no = page_no;
+
+ // obtain access lock using lock chaining with Access mode
+
+ if( page_no > ROOT_page )
+ if( bt_lockpage(bt, page_no, BtLockAccess, NULL) )
+ return 0;
+
+ if( prevpage )
+ if( bt_unlockpage(bt, prevpage, prevmode) )
+ return 0;
+
+ // obtain read lock using lock chaining
+ // and pin page contents
+
+ if( bt_lockpage(bt, page_no, mode, &bt->page) )
+ return 0;
+
+ if( page_no > ROOT_page )
+ if( bt_unlockpage(bt, page_no, BtLockAccess) )
+ return 0;
+
+ // re-read and re-lock root after determining actual level of root
+
+ if( bt->page_no == ROOT_page )
+ if( bt->page->lvl != drill) {
+ drill = bt->page->lvl;
+
+ if( lock == BtLockWrite && drill == lvl )
+ if( bt_unlockpage(bt, page_no, mode) )
+ return 0;
+ else
+ continue;
+ }
+
+ // if page is being deleted,
+ // move back to preceeding page
+
+ if( bt->page->kill ) {
+ page_no = bt_getid (bt->page->right);
+ continue;
+ }
+
+ // find key on page at this level
+ // and descend to requested level
+
+ slot = bt_findslot (bt, key, len);
+
+ // is this slot a foster child?
+
+ if( slot <= bt->page->cnt - bt->page->foster )
+ if( drill == lvl )
+ return slot;
+ else
+ drill--;
+
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ return bt->err = BTERR_struct, 0;
+
+ // continue down / right using overlapping locks
+ // to protect pages being killed or split.
+
+ prevmode = mode;
+ prevpage = bt->page_no;
+ page_no = bt_getid(slotptr(bt->page, slot)->id);
+ } while( page_no );
+
+ // return error on end of chain
+
+ bt->err = BTERR_struct;
+ return 0; // return error
+}
+
+// find and delete key on page by marking delete flag bit
+// when page becomes empty, delete it from the btree
+
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl)
+{
+unsigned char leftkey[256], rightkey[256];
+uid page_no, right;
+uint slot, tod;
+BtKey ptr;
+
+ if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // if key is found delete it, otherwise ignore request
+
+ if( !keycmp (ptr, key, len) )
+ if( slotptr(bt->page, slot)->dead == 0 ) {
+ slotptr(bt->page,slot)->dead = 1;
+ if( slot < bt->page->cnt )
+ bt->page->dirty = 1;
+ bt->page->act--;
+ }
+
+ // return if page is not empty, or it has no right sibling
+
+ right = bt_getid(bt->page->right);
+ page_no = bt->page_no;
+
+ if( !right || bt->page->act )
+ return bt_unlockpage(bt, page_no, BtLockWrite);
+
+ // obtain Parent lock over write lock
+
+ if( bt_lockpage(bt, page_no, BtLockParent, NULL) )
+ return bt->err;
+
+ // cache copy of key to delete
+
+ ptr = keyptr(bt->page, bt->page->cnt);
+ memcpy(leftkey, ptr, ptr->len + 1);
+
+ // lock and map right page
+
+ if ( bt_lockpage(bt, right, BtLockWrite, &bt->temp) )
+ return bt->err;
+
+ // pull contents of next page into current empty page
+ memcpy (bt->page, bt->temp, bt->mgr->page_size);
+
+ // cache copy of key to update
+ ptr = keyptr(bt->temp, bt->temp->cnt);
+ memcpy(rightkey, ptr, ptr->len + 1);
+
+ // Mark right page as deleted and point it to left page
+ // until we can post updates at higher level.
+
+ bt_putid(bt->temp->right, page_no);
+ bt->temp->kill = 1;
+ bt->temp->cnt = 0;
+
+ if( bt_unlockpage(bt, right, BtLockWrite) )
+ return bt->err;
+ if( bt_unlockpage(bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ // delete old lower key to consolidated node
+
+ if( bt_deletekey (bt, leftkey + 1, *leftkey, lvl + 1) )
+ return bt->err;
+
+ // redirect higher key directly to consolidated node
+
+ if( slot = bt_loadpage (bt, rightkey+1, *rightkey, lvl+1, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // since key already exists, update id
+
+ if( keycmp (ptr, rightkey+1, *rightkey) )
+ return bt->err = BTERR_struct;
+
+ slotptr(bt->page, slot)->dead = 0;
+ bt_putid(slotptr(bt->page,slot)->id, page_no);
+ bt_unlockpage(bt, bt->page_no, BtLockWrite);
+
+ // obtain write lock and
+ // add right block to free chain
+
+ if( bt_freepage (bt, right) )
+ return bt->err;
+
+ // remove ParentModify lock
+
+ if( bt_unlockpage(bt, page_no, BtLockParent) )
+ return bt->err;
+
+ return 0;
+}
+
+// find key in leaf level and return row-id
+
+uid bt_findkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+BtKey ptr;
+uid id;
+
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return 0;
+
+ // if key exists, return row-id
+ // otherwise return 0
+
+ if( ptr->len == len && !memcmp (ptr->key, key, len) )
+ id = bt_getid(slotptr(bt->page,slot)->id);
+ else
+ id = 0;
+
+ if ( bt_unlockpage(bt, bt->page_no, BtLockRead) )
+ return 0;
+
+ return id;
+}
+
+// check page for space available,
+// clean if necessary and return
+// 0 - page needs splitting
+// 1 - go ahead
+
+uint bt_cleanpage(BtDb *bt, uint amt)
+{
+uint nxt = bt->mgr->page_size;
+BtPage page = bt->page;
+uint cnt = 0, idx = 0;
+uint max = page->cnt;
+BtKey key;
+
+ if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return 1;
+
+ // skip cleanup if nothing to reclaim
+
+ if( !page->dirty )
+ return 0;
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+
+ // skip page info and set rest of page to zero
+
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ page->dirty = 0;
+ page->act = 0;
+
+ // try cleaning up page first
+
+ while( cnt++ < max ) {
+ // always leave fence key in list
+ if( cnt < max && slotptr(bt->frame,cnt)->dead )
+ continue;
+
+ // copy key
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+
+ // copy slot
+ memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId);
+ if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
+ page->act++;
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ }
+ page->min = nxt;
+ page->cnt = idx;
+
+ if( page->min >= (idx+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return 1;
+
+ return 0;
+}
+
+// add key to page
+// return with page unlocked
+
+BTERR bt_addkeytopage (BtDb *bt, uint slot, unsigned char *key, uint len, uid id, uint tod)
+{
+BtPage page = bt->page;
+uint idx;
+
+ // calculate next available slot and copy key into page
+
+ page->min -= len + 1;
+ ((unsigned char *)page)[page->min] = len;
+ memcpy ((unsigned char *)page + page->min +1, key, len );
+
+ for( idx = slot; idx < page->cnt; idx++ )
+ if( slotptr(page, idx)->dead )
+ break;
+
+ // now insert key into array before slot
+ // preserving the fence slot
+
+ if( idx == page->cnt )
+ idx++, page->cnt++;
+
+ page->act++;
+
+ while( idx > slot )
+ *slotptr(page, idx) = *slotptr(page, idx -1), idx--;
+
+ bt_putid(slotptr(page,slot)->id, id);
+ slotptr(page, slot)->off = page->min;
+ slotptr(page, slot)->tod = tod;
+ slotptr(page, slot)->dead = 0;
+
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+}
+
+// split the root and raise the height of the btree
+
+BTERR bt_splitroot(BtDb *bt, uid right)
+{
+uint nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+BtPage root = bt->page;
+uid new_page;
+BtKey key;
+
+ // Obtain an empty page to use, and copy the left page
+ // contents into it. Strip foster child key.
+ // Save left fence key.
+
+ bt->page->act--;
+ bt->page->cnt--;
+ bt->page->foster--;
+ key = keyptr(bt->page, bt->page->cnt);
+ memcpy (fencekey, key, key->len + 1);
+
+ if( !(new_page = bt_newpage(bt, bt->page)) )
+ return bt->err;
+
+ // preserve the page info at the bottom
+ // and set rest to zero
+
+ memset (root+1, 0, bt->mgr->page_size - sizeof(*root));
+
+ // insert left fence key on newroot page
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 1)->id, new_page);
+ slotptr(root, 1)->off = nxt;
+
+ // insert stopper key on newroot page
+ // and increase the root height
+
+ nxt -= 3;
+ fencekey[0] = 2;
+ fencekey[1] = 0xff;
+ fencekey[2] = 0xff;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 2)->id, right);
+ slotptr(root, 2)->off = nxt;
+
+ bt_putid(root->right, 0);
+ root->min = nxt; // reset lowest used offset and key count
+ root->cnt = 2;
+ root->act = 2;
+ root->lvl++;
+
+ // release root (bt->page)
+
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+}
+
+// split already locked full node
+// return unlocked.
+
+BTERR bt_splitpage (BtDb *bt)
+{
+uint slot, cnt, idx, max, nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+uid page_no = bt->page_no;
+BtPage page = bt->page;
+uint tod = time(NULL);
+uint lvl = page->lvl;
+uid new_page, right;
+BtKey key;
+
+ // initialize frame buffer
+
+ memset (bt->frame, 0, bt->mgr->page_size);
+ max = page->cnt - page->foster;
+ tod = (uint)time(NULL);
+ cnt = max / 2;
+ idx = 0;
+
+ // split higher half of keys to bt->frame
+ // leaving foster children in the left node.
+
+ while( cnt++ < max ) {
+ key = keyptr(page, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1);
+ memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId);
+ slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod;
+ slotptr(bt->frame, idx)->off = nxt;
+ bt->frame->act++;
+ }
+
+ // transfer right link node
+
+ if( page_no > ROOT_page ) {
+ right = bt_getid (page->right);
+ bt_putid(bt->frame->right, right);
+ }
+
+ bt->frame->bits = bt->mgr->page_bits;
+ bt->frame->min = nxt;
+ bt->frame->cnt = idx;
+ bt->frame->lvl = lvl;
+
+ // get new free page and write frame to it.
+
+ if( !(new_page = bt_newpage(bt, bt->frame)) )
+ return bt->err;
+
+ // update lower keys and foster children to continue in old page
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ nxt = bt->mgr->page_size;
+ page->act = 0;
+ cnt = 0;
+ idx = 0;
+
+ // assemble page of smaller keys
+ // to remain in the old page
+
+ while( cnt++ < max / 2 ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ page->act++;
+ }
+
+ // assemble old foster child keys
+ // add new foster child fence
+
+ cnt = bt->frame->cnt - bt->frame->foster - 1;
+
+ while( cnt++ < bt->frame->cnt ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ page->act++;
+ }
+
+ // link new right page
+
+ bt_putid (page->right, new_page);
+
+ // put new page as smallest foster child key
+
+ page->min = nxt;
+ page->cnt = idx;
+ cnt = page->cnt - page->foster++;
+ bt_putid (slotptr(page,cnt)->id, new_page);
+
+ // if current page is the root page, split it
+
+ if( page_no == ROOT_page )
+ return bt_splitroot (bt, new_page);
+
+ // release wr lock on page
+
+ if( bt_unlockpage (bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ // obtain ParentModification lock for current page
+ // to fix highest foster child on page
+
+ if( bt_lockpage (bt, page_no, BtLockParent, NULL) )
+ return bt->err;
+
+ if( bt_lockpage (bt, page_no, BtLockRead, &page) )
+ return bt->err;
+
+ // get our old fence key
+
+ key = keyptr(page, page->cnt);
+ memcpy (fencekey, key, key->len+1);
+
+ if( bt_unlockpage (bt, page_no, BtLockRead) )
+ return bt->err;
+
+ do {
+ slot = bt_loadpage (bt, fencekey + 1, *fencekey, lvl + 1, BtLockWrite);
+
+ if( !slot )
+ return bt->err;
+
+ // check if parent page has enough space for largest possible key
+
+ if( bt_cleanpage (bt, 256) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ } while( 1 );
+
+ // wait until readers from parent get their locks
+
+ if( bt_lockpage (bt, page_no, BtLockDelete, NULL) )
+ return bt->err;
+
+ if( bt_lockpage (bt, page_no, BtLockWrite, &page) )
+ return bt->err;
+
+ // switch parent fence key to foster child
+
+ if( slotptr(page, page->cnt)->dead )
+ slotptr(bt->page, slot)->dead = 1;
+ else
+ bt_putid (slotptr(bt->page, slot)->id, bt_getid(slotptr(page, page->cnt)->id));
+
+ // remove foster child from our page
+ // add our new fence key to parent
+
+ page->cnt--;
+ page->act--;
+ page->foster--;
+ page->dirty = 1;
+ key = keyptr(page, page->cnt);
+
+ if( bt_addkeytopage (bt, slot, key->key, key->len, page_no, tod) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockDelete) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockParent) )
+ return bt->err;
+
+ return bt_unlockpage (bt, page_no, BtLockWrite);
+}
+
+// Insert new key into the btree at leaf level.
+
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod)
+{
+uint slot, idx;
+BtPage page;
+BtKey ptr;
+
+ while( 1 ) {
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ {
+ if ( !bt->err )
+ bt->err = BTERR_ovflw;
+ return bt->err;
+ }
+
+ // if key already exists, update id and return
+
+ page = bt->page;
+
+ if( !keycmp (ptr, key, len) ) {
+ slotptr(page, slot)->dead = 0;
+ slotptr(page, slot)->tod = tod;
+ bt_putid(slotptr(page,slot)->id, id);
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+ }
+
+ // check if page has enough space
+
+ if( bt_cleanpage (bt, len) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ }
+
+ return bt_addkeytopage (bt, slot, key, len, id, tod);
+}
+
+// cache page of keys into cursor and return starting slot for given key
+
+uint bt_startkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+
+ // cache page for retrieval
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ memcpy (bt->cursor, bt->page, bt->mgr->page_size);
+ bt->cursor_page = bt->page_no;
+ if ( bt_unlockpage(bt, bt->page_no, BtLockRead) )
+ return 0;
+
+ return slot;
+}
+
+// return next slot for cursor page
+// or slide cursor right into next page
+
+uint bt_nextkey (BtDb *bt, uint slot)
+{
+BtPage page;
+uid right;
+
+ do {
+ right = bt_getid(bt->cursor->right);
+ while( slot++ < bt->cursor->cnt - bt->cursor->foster )
+ if( slotptr(bt->cursor,slot)->dead )
+ continue;
+ else if( right || (slot < bt->cursor->cnt - bt->cursor->foster) )
+ return slot;
+ else
+ break;
+
+ if( !right )
+ break;
+
+ bt->cursor_page = right;
+
+ if( bt_lockpage(bt, right, BtLockRead, &page) )
+ return 0;
+
+ memcpy (bt->cursor, page, bt->mgr->page_size);
+
+ if ( bt_unlockpage(bt, right, BtLockRead) )
+ return 0;
+
+ slot = 0;
+ } while( 1 );
+
+ return bt->err = 0;
+}
+
+BtKey bt_key(BtDb *bt, uint slot)
+{
+ return keyptr(bt->cursor, slot);
+}
+
+uid bt_uid(BtDb *bt, uint slot)
+{
+ return bt_getid(slotptr(bt->cursor,slot)->id);
+}
+
+uint bt_tod(BtDb *bt, uint slot)
+{
+ return slotptr(bt->cursor,slot)->tod;
+}
+
+
+#ifdef STANDALONE
+
+typedef struct {
+ char type, num;
+ char *infile;
+ BtMgr *mgr;
+} ThreadArg;
+
+// standalone program to index file of keys
+// then list them onto std-out
+
+#ifdef unix
+void *index_file (void *arg)
+#else
+uint __stdcall index_file (void *arg)
+#endif
+{
+int line = 0, found = 0;
+unsigned char key[256];
+ThreadArg *args = arg;
+int ch, len = 0, slot;
+time_t tod[1];
+BtKey ptr;
+BtDb *bt;
+FILE *in;
+
+ bt = bt_open (args->mgr);
+ time (tod);
+
+ switch(args->type | 0x20)
+ {
+ case 'w':
+ fprintf(stderr, "started indexing for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+
+ if( args->num )
+ sprintf((char *)key+len, "%.9d", line), len += 9;
+
+ if( bt_insertkey (bt, key, len, line, *tod) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys\n", args->infile, line);
+ break;
+
+ case 'd':
+ fprintf(stderr, "started deleting keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( bt_deletekey (bt, key, len, 0) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for keys, %d \n", args->infile, line);
+ break;
+
+ case 'f':
+ fprintf(stderr, "started finding keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( bt_findkey (bt, key, len) )
+ found++;
+ else if( bt->err )
+ fprintf(stderr, "Error %d Syserr %d Line: %d\n", bt->err, errno, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys, found %d\n", args->infile, line, found);
+ break;
+
+ case 's':
+ len = key[0] = 0;
+
+ fprintf(stderr, "started reading\n");
+
+ if( slot = bt_startkey (bt, key, len) )
+ slot--;
+ else
+ fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0);
+
+ while( slot = bt_nextkey (bt, slot) ) {
+ ptr = bt_key(bt, slot);
+ fwrite (ptr->key, ptr->len, 1, stdout);
+ fputc ('\n', stdout);
+ }
+ }
+
+ bt_close (bt);
+#ifdef unix
+ return NULL;
+#else
+ return 0;
+#endif
+}
+
+typedef struct timeval timer;
+
+int main (int argc, char **argv)
+{
+int idx, cnt, len, slot, err;
+int segsize, bits = 16;
+#ifdef unix
+pthread_t *threads;
+timer start, stop;
+#else
+time_t start[1], stop[1];
+HANDLE *threads;
+#endif
+double real_time;
+ThreadArg *args;
+uint map = 0;
+int num = 0;
+char key[1];
+BtMgr *mgr;
+BtKey ptr;
+BtDb *bt;
+
+ if( argc < 3 ) {
+ fprintf (stderr, "Usage: %s idx_file Read/Write/Scan/Delete/Find [page_bits mapped_segments seg_bits line_numbers src_file1 src_file2 ... ]\n", argv[0]);
+ fprintf (stderr, " where page_bits is the page size in bits\n");
+ fprintf (stderr, " mapped_segments is the number of mmap segments in buffer pool\n");
+ fprintf (stderr, " seg_bits is the size of individual segments in buffer pool in pages in bits\n");
+ fprintf (stderr, " line_numbers = 1 to append line numbers to keys\n");
+ fprintf (stderr, " src_file1 thru src_filen are files of keys separated by newline\n");
+ exit(0);
+ }
+
+#ifdef unix
+ gettimeofday(&start, NULL);
+#else
+ time(start);
+#endif
+
+ if( argc > 3 )
+ bits = atoi(argv[3]);
+
+ if( argc > 4 )
+ map = atoi(argv[4]);
+
+ if( map > 65536 )
+ fprintf (stderr, "Warning: mapped_pool > 65536 segments\n");
+
+ if( argc > 5 )
+ segsize = atoi(argv[5]);
+ else
+ segsize = 4; // 16 pages per mmap segment
+
+ if( argc > 6 )
+ num = atoi(argv[6]);
+
+ cnt = argc - 7;
+#ifdef unix
+ threads = malloc (cnt * sizeof(pthread_t));
+#else
+ threads = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, cnt * sizeof(HANDLE));
+#endif
+ args = malloc (cnt * sizeof(ThreadArg));
+
+ mgr = bt_mgr ((argv[1]), BT_rw, bits, map, segsize, map / 8);
+
+ if( !mgr ) {
+ fprintf(stderr, "Index Open Error %s\n", argv[1]);
+ exit (1);
+ }
+
+ // fire off threads
+
+ for( idx = 0; idx < cnt; idx++ ) {
+ args[idx].infile = argv[idx + 7];
+ args[idx].type = argv[2][0];
+ args[idx].mgr = mgr;
+ args[idx].num = num;
+#ifdef unix
+ if( err = pthread_create (threads + idx, NULL, index_file, args + idx) )
+ fprintf(stderr, "Error creating thread %d\n", err);
+#else
+ threads[idx] = (HANDLE)_beginthreadex(NULL, 65536, index_file, args + idx, 0, NULL);
+#endif
+ }
+
+ // wait for termination
+
+#ifdef unix
+ for( idx = 0; idx < cnt; idx++ )
+ pthread_join (threads[idx], NULL);
+ gettimeofday(&stop, NULL);
+ real_time = 1000.0 * ( stop.tv_sec - start.tv_sec ) + 0.001 * (stop.tv_usec - start.tv_usec );
+#else
+ WaitForMultipleObjects (cnt, threads, TRUE, INFINITE);
+
+ for( idx = 0; idx < cnt; idx++ )
+ CloseHandle(threads[idx]);
+
+ time (stop);
+ real_time = 1000 * (*stop - *start);
+#endif
+ fprintf(stderr, " Time to complete: %.2f seconds\n", real_time/1000);
+
+ cnt = 0;
+ len = key[0] = 0;
+ bt = bt_open (mgr);
+
+ fprintf(stderr, "started reading\n");
+
+ if( slot = bt_startkey (bt, key, len) )
+ slot--;
+ else
+ fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0);
+
+ while( slot = bt_nextkey (bt, slot) )
+ cnt++;
+
+ fprintf(stderr, " Total keys read %d\n", cnt);
+
+ bt_close (bt);
+ bt_mgrclose (mgr);
+}
+
+#endif //STANDALONE
--- /dev/null
+// foster btree version b
+// 22 DEC 2013
+
+// author: karl malbrain, malbrain@cal.berkeley.edu
+
+/*
+This work, including the source code, documentation
+and related data, is placed into the public domain.
+
+The orginal author is Karl Malbrain.
+
+THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
+OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
+MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
+ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
+RESULTING FROM THE USE, MODIFICATION, OR
+REDISTRIBUTION OF THIS SOFTWARE.
+*/
+
+// Please see the project home page for documentation
+// code.google.com/p/high-concurrency-btree
+
+#define _FILE_OFFSET_BITS 64
+#define _LARGEFILE64_SOURCE
+
+#ifdef linux
+#define _GNU_SOURCE
+#endif
+
+#ifdef unix
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/time.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <pthread.h>
+#else
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <fcntl.h>
+#include <process.h>
+#include <intrin.h>
+#endif
+
+#include <memory.h>
+#include <string.h>
+
+typedef unsigned long long uid;
+
+#ifndef unix
+typedef unsigned long long off64_t;
+typedef unsigned short ushort;
+typedef unsigned int uint;
+#endif
+
+#define BT_ro 0x6f72 // ro
+#define BT_rw 0x7772 // rw
+
+#define BT_maxbits 24 // maximum page size in bits
+#define BT_minbits 9 // minimum page size in bits
+#define BT_minpage (1 << BT_minbits) // minimum page size
+#define BT_maxpage (1 << BT_maxbits) // maximum page size
+
+/*
+There are five lock types for each node in three independent sets:
+1. (set 1) AccessIntent: Sharable. Going to Read the node. Incompatible with NodeDelete.
+2. (set 1) NodeDelete: Exclusive. About to release the node. Incompatible with AccessIntent.
+3. (set 2) ReadLock: Sharable. Read the node. Incompatible with WriteLock.
+4. (set 2) WriteLock: Exclusive. Modify the node. Incompatible with ReadLock and other WriteLocks.
+5. (set 3) ParentLock: Exclusive. Have parent adopt/delete maximum foster child from the node.
+*/
+
+typedef enum{
+ BtLockAccess,
+ BtLockDelete,
+ BtLockRead,
+ BtLockWrite,
+ BtLockParent
+}BtLock;
+
+// Define the length of the page and key pointers
+
+#define BtId 6
+
+// Page key slot definition.
+
+// If BT_maxbits is 15 or less, you can save 4 bytes
+// for each key stored by making the first two uints
+// into ushorts. You can also save 4 bytes by removing
+// the tod field from the key.
+
+// Keys are marked dead, but remain on the page until
+// it cleanup is called. The fence key (highest key) for
+// the page is always present, even after cleanup.
+
+typedef struct {
+ uint off:BT_maxbits; // page offset for key start
+ uint dead:1; // set for deleted key
+ uint tod; // time-stamp for key
+ unsigned char id[BtId]; // id associated with key
+} BtSlot;
+
+// The key structure occupies space at the upper end of
+// each page. It's a length byte followed by the value
+// bytes.
+
+typedef struct {
+ unsigned char len;
+ unsigned char key[1];
+} *BtKey;
+
+// The first part of an index page.
+// It is immediately followed
+// by the BtSlot array of keys.
+
+typedef struct Page {
+ uint cnt; // count of keys in page
+ uint act; // count of active keys
+ uint min; // next key offset
+ uint foster; // count of foster children
+ unsigned char bits; // page size in bits
+ unsigned char lvl:6; // level of page
+ unsigned char kill:1; // page is being deleted
+ unsigned char dirty:1; // page needs to be cleaned
+ unsigned char right[BtId]; // page number to right
+} *BtPage;
+
+// mode & definition for latch table implementation
+
+enum {
+ Write = 1,
+ Pending = 2,
+ Share = 4
+} LockMode;
+
+// latch table lock structure
+
+// exclusive is set for write access
+// share is count of read accessors
+// grant write lock when share == 0
+
+typedef struct {
+ volatile uint exclusive:1;
+ volatile uint request:1;
+ volatile uint share:30;
+} BtLatch;
+
+typedef struct {
+ BtLatch readwr[1]; // read/write page lock
+ BtLatch access[1]; // Access Intent/Page delete
+ BtLatch parent[1]; // adoption of foster children
+} BtLatchSet;
+
+// The memory mapping pool table buffer manager entry
+
+typedef struct {
+ unsigned long long int lru; // number of times accessed
+ uid basepage; // mapped base page number
+ char *map; // mapped memory pointer
+ uint pin; // mapped page pin counter
+ uint slot; // slot index in this array
+ void *hashprev; // previous pool entry for the same hash idx
+ void *hashnext; // next pool entry for the same hash idx
+#ifndef unix
+ HANDLE hmap;
+#endif
+// array of page latch sets, one for each page in map segment
+ BtLatchSet pagelatch[0];
+} BtPool;
+
+// The object structure for Btree access
+
+typedef struct {
+ uint page_size; // page size
+ uint page_bits; // page size in bits
+ uint seg_bits; // seg size in pages in bits
+ uint mode; // read-write mode
+#ifdef unix
+ int idx;
+ char *pooladvise; // bit maps for pool page advisements
+#else
+ HANDLE idx;
+#endif
+ uint poolcnt; // highest page pool node in use
+ uint poolmax; // highest page pool node allocated
+ uint poolmask; // total size of pages in mmap segment - 1
+ uint hashsize; // size of Hash Table for pool entries
+ volatile uint evicted; // last evicted hash table slot
+ ushort *hash; // hash table of pool entries
+ BtLatch *latch; // latches for hash table slots
+ char *nodes; // memory pool page segments
+} BtMgr;
+
+typedef struct {
+ BtMgr *mgr; // buffer manager for thread
+ BtPage temp; // temporary frame buffer (memory mapped/file IO)
+ BtPage alloc; // frame buffer for alloc page ( page 0 )
+ BtPage cursor; // cached frame for start/next (never mapped)
+ BtPage frame; // spare frame for the page split (never mapped)
+ BtPage zero; // page frame for zeroes at end of file
+ BtPage page; // current page
+ uid page_no; // current page number
+ uid cursor_page; // current cursor page number
+ unsigned char *mem; // frame, cursor, page memory buffer
+ int err; // last error
+} BtDb;
+
+typedef enum {
+ BTERR_ok = 0,
+ BTERR_struct,
+ BTERR_ovflw,
+ BTERR_lock,
+ BTERR_map,
+ BTERR_wrt,
+ BTERR_hash
+} BTERR;
+
+// B-Tree functions
+extern void bt_close (BtDb *bt);
+extern BtDb *bt_open (BtMgr *mgr);
+extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod);
+extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl);
+extern uid bt_findkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_startkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_nextkey (BtDb *bt, uint slot);
+
+// manager functions
+bt_mgr (char *name, uint mode, uint bits, uint poolsize, uint segsize, uint hashsize);
+void bt_mgrclose (BtMgr *mgr);
+
+// Helper functions to return cursor slot values
+
+extern BtKey bt_key (BtDb *bt, uint slot);
+extern uid bt_uid (BtDb *bt, uint slot);
+extern uint bt_tod (BtDb *bt, uint slot);
+
+// BTree page number constants
+#define ALLOC_page 0
+#define ROOT_page 1
+#define LEAF_page 2
+
+// Number of levels to create in a new BTree
+
+#define MIN_lvl 2
+
+// The page is allocated from low and hi ends.
+// The key offsets and row-id's are allocated
+// from the bottom, while the text of the key
+// is allocated from the top. When the two
+// areas meet, the page is split into two.
+
+// A key consists of a length byte, two bytes of
+// index number (0 - 65534), and up to 253 bytes
+// of key value. Duplicate keys are discarded.
+// Associated with each key is a 48 bit row-id.
+
+// The b-tree root is always located at page 1.
+// The first leaf page of level zero is always
+// located on page 2.
+
+// When to root page fills, it is split in two and
+// the tree height is raised by a new root at page
+// one with two keys.
+
+// Deleted keys are marked with a dead bit until
+// page cleanup The fence key for a node is always
+// present, even after deletion and cleanup.
+
+// Groups of pages called segments from the btree are
+// cached with memory mapping. A hash table is used to keep
+// track of the cached segments. This behaviour is controlled
+// by the cache block size parameter to bt_open.
+
+// To achieve maximum concurrency one page is locked at a time
+// as the tree is traversed to find leaf key in question.
+
+// An adoption traversal leaves the parent node locked as the
+// tree is traversed to the level in quesiton.
+
+// Page 0 is dedicated to lock for new page extensions,
+// and chains empty pages together for reuse.
+
+// Empty pages are chained together through the ALLOC page and reused.
+
+// Access macros to address slot and key values from the page
+
+#define slotptr(page, slot) (((BtSlot *)(page+1)) + (slot-1))
+#define keyptr(page, slot) ((BtKey)((unsigned char*)(page) + slotptr(page, slot)->off))
+
+void bt_putid(unsigned char *dest, uid id)
+{
+int i = BtId;
+
+ while( i-- )
+ dest[i] = (unsigned char)id, id >>= 8;
+}
+
+uid bt_getid(unsigned char *src)
+{
+uid id = 0;
+int i;
+
+ for( i = 0; i < BtId; i++ )
+ id <<= 8, id |= *src++;
+
+ return id;
+}
+
+void bt_mgrclose (BtMgr *mgr)
+{
+BtPool *pool;
+uint slot;
+
+ // release mapped pages
+ // note that slot zero is never used
+
+ for( slot = 1; slot < mgr->poolmax; slot++ ) {
+ pool = (BtPool *)(mgr->nodes + slot * (sizeof(BtPool) + (mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ if( pool->slot )
+#ifdef unix
+ munmap (pool->map, (mgr->poolmask+1) << mgr->page_bits);
+#else
+ {
+ FlushViewOfFile(pool->map, 0);
+ UnmapViewOfFile(pool->map);
+ CloseHandle(pool->hmap);
+ }
+#endif
+ }
+
+#ifdef unix
+ close (mgr->idx);
+ free (mgr->nodes);
+ free (mgr->hash);
+ free (mgr->latch);
+ free (mgr->pooladvise);
+ free (mgr);
+#else
+ FlushFileBuffers(mgr->idx);
+ CloseHandle(mgr->idx);
+ GlobalFree (mgr->nodes);
+ GlobalFree (mgr->hash);
+ GlobalFree (mgr->latch);
+ GlobalFree (mgr);
+#endif
+}
+
+// close and release memory
+
+void bt_close (BtDb *bt)
+{
+#ifdef unix
+ if ( bt->mem )
+ free (bt->mem);
+#else
+ if ( bt->mem)
+ VirtualFree (bt->mem, 0, MEM_RELEASE);
+#endif
+ free (bt);
+}
+
+// open/create new btree buffer manager
+
+// call with file_name, BT_openmode, bits in page size (e.g. 16),
+// size of mapped page pool (e.g. 8192)
+
+BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolmax, uint segsize, uint hashsize)
+{
+uint lvl, attr, cacheblk, last;
+BtPage alloc;
+int lockmode;
+off64_t size;
+uint amt[1];
+BtMgr* mgr;
+BtKey key;
+
+#ifndef unix
+SYSTEM_INFO sysinfo[1];
+#endif
+
+ // determine sanity of page size and buffer pool
+
+ if( bits > BT_maxbits )
+ bits = BT_maxbits;
+ else if( bits < BT_minbits )
+ bits = BT_minbits;
+
+ if( !poolmax )
+ return NULL; // must have buffer pool
+
+#ifdef unix
+ mgr = calloc (1, sizeof(BtMgr));
+
+ switch (mode & 0x7fff)
+ {
+ case BT_rw:
+ mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
+ lockmode = 1;
+ break;
+
+ case BT_ro:
+ default:
+ mgr->idx = open ((char*)name, O_RDONLY);
+ lockmode = 0;
+ break;
+ }
+ if( mgr->idx == -1 )
+ return free(mgr), NULL;
+
+ cacheblk = 4096; // minimum mmap segment size for unix
+
+#else
+ mgr = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtMgr));
+ attr = FILE_ATTRIBUTE_NORMAL;
+ switch (mode & 0x7fff)
+ {
+ case BT_rw:
+ mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
+ lockmode = 1;
+ break;
+
+ case BT_ro:
+ default:
+ mgr->idx = CreateFile(name, GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, attr, NULL);
+ lockmode = 0;
+ break;
+ }
+ if( mgr->idx == INVALID_HANDLE_VALUE )
+ return GlobalFree(mgr), NULL;
+
+ // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity
+ GetSystemInfo(sysinfo);
+ cacheblk = sysinfo->dwAllocationGranularity;
+#endif
+
+#ifdef unix
+ alloc = malloc (BT_maxpage);
+ *amt = 0;
+
+ // read minimum page size to get root info
+
+ if( size = lseek (mgr->idx, 0L, 2) ) {
+ if( pread(mgr->idx, alloc, BT_minpage, 0) == BT_minpage )
+ bits = alloc->bits;
+ else
+ return free(mgr), free(alloc), NULL;
+ } else if( mode == BT_ro )
+ return bt_mgrclose (mgr), NULL;
+#else
+ alloc = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE);
+ size = GetFileSize(mgr->idx, amt);
+
+ if( size || *amt ) {
+ if( !ReadFile(mgr->idx, (char *)alloc, BT_minpage, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ bits = alloc->bits;
+ } else if( mode == BT_ro )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ mgr->page_size = 1 << bits;
+ mgr->page_bits = bits;
+
+ mgr->poolmax = poolmax;
+ mgr->mode = mode;
+
+ if( cacheblk < mgr->page_size )
+ cacheblk = mgr->page_size;
+
+ // mask for partial memmaps
+
+ mgr->poolmask = (cacheblk >> bits) - 1;
+
+ // see if requested size of pages per memmap is greater
+
+ if( (1 << segsize) > mgr->poolmask )
+ mgr->poolmask = (1 << segsize) - 1;
+
+ mgr->seg_bits = 0;
+
+ while( (1 << mgr->seg_bits) <= mgr->poolmask )
+ mgr->seg_bits++;
+
+ mgr->hashsize = hashsize;
+
+#ifdef unix
+ mgr->nodes = calloc (poolmax, (sizeof(BtPool) + (mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ mgr->hash = calloc (hashsize, sizeof(ushort));
+ mgr->latch = calloc (hashsize, sizeof(BtLatch));
+ mgr->pooladvise = calloc (poolmax, (mgr->poolmask + 1) / 8);
+#else
+ mgr->nodes = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, poolmax * (sizeof(BtPool) + (mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ mgr->hash = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(ushort));
+ mgr->latch = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(BtLatch));
+#endif
+
+ if( size || *amt )
+ goto mgrxit;
+
+ // initializes an empty b-tree with root page and page of leaves
+
+ memset (alloc, 0, 1 << bits);
+ bt_putid(alloc->right, MIN_lvl+1);
+ alloc->bits = mgr->page_bits;
+
+#ifdef unix
+ if( write (mgr->idx, alloc, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ memset (alloc, 0, 1 << bits);
+ alloc->bits = mgr->page_bits;
+
+ for( lvl=MIN_lvl; lvl--; ) {
+ slotptr(alloc, 1)->off = mgr->page_size - 3;
+ bt_putid(slotptr(alloc, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number
+ key = keyptr(alloc, 1);
+ key->len = 2; // create stopper key
+ key->key[0] = 0xff;
+ key->key[1] = 0xff;
+ alloc->min = mgr->page_size - 3;
+ alloc->lvl = lvl;
+ alloc->cnt = 1;
+ alloc->act = 1;
+#ifdef unix
+ if( write (mgr->idx, alloc, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ }
+
+ // create empty page area by writing last page of first
+ // segment area (other pages are zeroed by O/S)
+
+ if( mgr->poolmask ) {
+ memset(alloc, 0, mgr->page_size);
+ last = mgr->poolmask;
+
+ while( last < MIN_lvl + 1 )
+ last += mgr->poolmask + 1;
+
+#ifdef unix
+ pwrite(mgr->idx, alloc, mgr->page_size, last << mgr->page_bits);
+#else
+ SetFilePointer (mgr->idx, last << mgr->page_bits, NULL, FILE_BEGIN);
+ if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ }
+
+mgrxit:
+#ifdef unix
+ free (alloc);
+#else
+ VirtualFree (alloc, 0, MEM_RELEASE);
+#endif
+ return mgr;
+}
+
+// open BTree access method
+// based on buffer manager
+
+BtDb *bt_open (BtMgr *mgr)
+{
+BtDb *bt = malloc (sizeof(*bt));
+
+ memset (bt, 0, sizeof(*bt));
+ bt->mgr = mgr;
+#ifdef unix
+ bt->mem = malloc (3 *mgr->page_size);
+#else
+ bt->mem = VirtualAlloc(NULL, 3 * mgr->page_size, MEM_COMMIT, PAGE_READWRITE);
+#endif
+ bt->frame = (BtPage)bt->mem;
+ bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size);
+ bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size);
+ return bt;
+}
+
+// compare two keys, returning > 0, = 0, or < 0
+// as the comparison value
+
+int keycmp (BtKey key1, unsigned char *key2, uint len2)
+{
+uint len1 = key1->len;
+int ans;
+
+ if( ans = memcmp (key1->key, key2, len1 > len2 ? len2 : len1) )
+ return ans;
+
+ if( len1 > len2 )
+ return 1;
+ if( len1 < len2 )
+ return -1;
+
+ return 0;
+}
+
+// Latch Manager
+
+// wait until write lock mode is clear
+// and add 1 to the share count
+
+void bt_readlock(BtLatch *latch)
+{
+ do {
+ // see if exclusive request is pending, or granted
+
+ if( !(volatile int)latch->request && !(volatile int)latch->exclusive ) {
+ // add one to counter, check write bit
+#ifdef unix
+ if( ~__sync_fetch_and_add((volatile int *)latch, Share) & Write )
+ return;
+#else
+ if( ~_InterlockedExchangeAdd((volatile int *)latch, Share) & Write )
+ return;
+#endif
+ // didn't get latch, reduce counter by one
+
+#ifdef unix
+ __sync_fetch_and_add((volatile int *)latch, -Share);
+#else
+ _InterlockedExchangeAdd ((volatile int *)latch, -Share);
+#endif
+ }
+
+ // and yield
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ } while( 1 );
+}
+
+// wait for other read and write latches to relinquish
+
+void bt_writelock(BtLatch *latch)
+{
+int prev;
+
+ do {
+ // set exclusive access pending
+
+#ifdef unix
+ __sync_fetch_and_or((int *)latch, Pending);
+#else
+ _InterlockedOr((int *)latch, Pending);
+#endif
+
+ // see if we can get write access
+ // with no readers
+#ifdef unix
+ prev = __sync_fetch_and_or((volatile int *)latch, Write);
+#else
+ prev = _InterlockedOr((volatile int *)latch, Write);
+#endif
+
+ // did we get exclusive access?
+ // if so, clear write pending
+
+ if( !(prev & ~Pending) ) {
+#ifdef unix
+ __sync_fetch_and_and((volatile int *)latch, ~Pending);
+#else
+ _InterlockedAnd((volatile int *)latch, ~Pending);
+#endif
+ return;
+ }
+
+ // reset our Write mode if it was clear before
+
+ if( !(prev & Write) ) {
+#ifdef unix
+ __sync_fetch_and_and((volatile int *)latch, ~Write);
+#else
+ _InterlockedAnd((volatile int *)latch, ~Write);
+#endif
+ }
+
+ // otherwise yield
+
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ } while( 1 );
+}
+
+// try to obtain write lock
+
+// return 1 if obtained,
+// 0 if already write locked
+
+int bt_writetry(BtLatch *latch)
+{
+int prev;
+
+ // see if we can get write access
+ // with no readers
+#ifdef unix
+ prev = __sync_fetch_and_or((volatile int *)latch, Write);
+#else
+ prev = _InterlockedOr((volatile int *)latch, Write);
+#endif
+
+ // did we get exclusive access?
+ // if so, return OK
+
+ if( !(prev & ~Pending) )
+ return 1;
+
+ // reset our Write mode if it was clear before
+
+ if( !(prev & Write) ) {
+#ifdef unix
+ __sync_fetch_and_and((volatile int *)latch, ~Write);
+#else
+ _InterlockedAnd((volatile int *)latch, ~Write);
+#endif
+ }
+ return 0;
+}
+
+// clear write mode
+
+void bt_releasewrite(BtLatch *latch)
+{
+#ifdef unix
+ __sync_fetch_and_and((int *)latch, ~Write);
+#else
+ _InterlockedAnd ((int *)latch, ~Write);
+#endif
+}
+
+// decrement reader count
+
+void bt_releaseread(BtLatch *latch)
+{
+#ifdef unix
+ __sync_fetch_and_add((int *)latch, -Share);
+#else
+ _InterlockedExchangeAdd((int *)latch, -Share);
+#endif
+}
+
+// Buffer Pool mgr
+
+// find segment in pool
+// must be called with hashslot idx locked
+// return NULL if not there
+// otherwise return node
+
+BtPool *bt_findpool(BtDb *bt, uid page_no, uint idx)
+{
+BtPool *pool;
+uint slot;
+
+ // compute start of hash chain in pool
+
+ if( slot = bt->mgr->hash[idx] )
+ pool = (BtPool *)(bt->mgr->nodes + slot * (sizeof(BtPool) + (bt->mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ else
+ return NULL;
+
+ page_no &= ~bt->mgr->poolmask;
+
+ while( pool->basepage != page_no )
+ if( pool = pool->hashnext )
+ continue;
+ else
+ return NULL;
+
+ return pool;
+}
+
+// add segment to hash table
+
+void bt_linkhash(BtDb *bt, BtPool *pool, uid page_no, int idx)
+{
+BtPool *node;
+uint slot;
+
+ pool->hashprev = pool->hashnext = NULL;
+ pool->basepage = page_no & ~bt->mgr->poolmask;
+ pool->lru = 1;
+
+ if( slot = bt->mgr->hash[idx] ) {
+ node = (BtPool *)(bt->mgr->nodes + slot * (sizeof(BtPool) + (bt->mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ pool->hashnext = node;
+ node->hashprev = pool;
+ }
+
+ bt->mgr->hash[idx] = pool->slot;
+}
+
+// find best segment to evict from buffer pool
+
+BtPool *bt_findlru (BtDb *bt, uint hashslot)
+{
+unsigned long long int target = ~0LL;
+BtPool *pool = NULL, *node;
+
+ if( !hashslot )
+ return NULL;
+
+ node = (BtPool *)(bt->mgr->nodes + hashslot * (sizeof(BtPool) + (bt->mgr->poolmask + 1) * sizeof(BtLatchSet)));
+
+ // scan pool entries under hash table slot
+
+ do {
+ if( node->pin )
+ continue;
+ if( node->lru > target )
+ continue;
+ target = node->lru;
+ pool = node;
+ } while( node = node->hashnext );
+
+ return pool;
+}
+
+// map new buffer pool segment to virtual memory
+
+BTERR bt_mapsegment(BtDb *bt, BtPool *pool, uid page_no)
+{
+off64_t off = (page_no & ~bt->mgr->poolmask) << bt->mgr->page_bits;
+off64_t limit = off + ((bt->mgr->poolmask+1) << bt->mgr->page_bits);
+int flag;
+
+#ifdef unix
+ flag = PROT_READ | ( bt->mgr->mode == BT_ro ? 0 : PROT_WRITE );
+ pool->map = mmap (0, (bt->mgr->poolmask+1) << bt->mgr->page_bits, flag, MAP_SHARED, bt->mgr->idx, off);
+ if( pool->map == MAP_FAILED )
+ return bt->err = BTERR_map;
+ // clear out madvise issued bits
+ memset (bt->mgr->pooladvise + pool->slot * (bt->mgr->poolmask + 1) / 8, 0, (bt->mgr->poolmask + 1)/8);
+#else
+ flag = ( bt->mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE );
+ pool->hmap = CreateFileMapping(bt->mgr->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL);
+ if( !pool->hmap )
+ return bt->err = BTERR_map;
+
+ flag = ( bt->mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE );
+ pool->map = MapViewOfFile(pool->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->mgr->poolmask+1) << bt->mgr->page_bits);
+ if( !pool->map )
+ return bt->err = BTERR_map;
+#endif
+ return bt->err = 0;
+}
+
+// find or place requested page in segment-pool
+// return pool table entry, incrementing pin
+
+BtPool *bt_pinpage(BtDb *bt, uid page_no)
+{
+BtPool *pool, *node, *next;
+uint slot, idx, victim;
+BtLatchSet *set;
+
+ // lock hash table chain
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_readlock (&bt->mgr->latch[idx]);
+
+ // look up in hash table
+
+ if( pool = bt_findpool(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement (&pool->pin);
+#endif
+ bt_releaseread (&bt->mgr->latch[idx]);
+ pool->lru++;
+ return pool;
+ }
+
+ // upgrade to write lock
+
+ bt_releaseread (&bt->mgr->latch[idx]);
+ bt_writelock (&bt->mgr->latch[idx]);
+
+ // try to find page in pool with write lock
+
+ if( pool = bt_findpool(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement (&pool->pin);
+#endif
+ bt_releasewrite (&bt->mgr->latch[idx]);
+ pool->lru++;
+ return pool;
+ }
+
+ // allocate a new pool node
+ // and add to hash table
+
+#ifdef unix
+ slot = __sync_fetch_and_add(&bt->mgr->poolcnt, 1);
+#else
+ slot = _InterlockedIncrement (&bt->mgr->poolcnt) - 1;
+#endif
+
+ if( ++slot < bt->mgr->poolmax ) {
+ pool = (BtPool *)(bt->mgr->nodes + slot * (sizeof(BtPool) + (bt->mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ pool->slot = slot;
+
+ if( bt_mapsegment(bt, pool, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, pool, page_no, idx);
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement (&pool->pin);
+#endif
+ bt_releasewrite (&bt->mgr->latch[idx]);
+ return pool;
+ }
+
+ // pool table is full
+ // find best pool entry to evict
+
+#ifdef unix
+ __sync_fetch_and_add(&bt->mgr->poolcnt, -1);
+#else
+ _InterlockedDecrement (&bt->mgr->poolcnt);
+#endif
+
+ while( 1 ) {
+#ifdef unix
+ victim = __sync_fetch_and_add(&bt->mgr->evicted, 1);
+#else
+ victim = _InterlockedIncrement (&bt->mgr->evicted) - 1;
+#endif
+ victim %= bt->mgr->hashsize;
+
+ // try to get write lock
+ // skip entry if not obtained
+
+ if( !bt_writetry (&bt->mgr->latch[victim]) )
+ continue;
+
+ // if cache entry is empty
+ // or no slots are unpinned
+ // skip this entry
+
+ if( !(pool = bt_findlru(bt, bt->mgr->hash[victim])) ) {
+ bt_releasewrite (&bt->mgr->latch[victim]);
+ continue;
+ }
+
+ // unlink victim pool node from hash table
+
+ if( node = pool->hashprev )
+ node->hashnext = pool->hashnext;
+ else if( node = pool->hashnext )
+ bt->mgr->hash[victim] = node->slot;
+ else
+ bt->mgr->hash[victim] = 0;
+
+ if( node = pool->hashnext )
+ node->hashprev = pool->hashprev;
+
+ bt_releasewrite (&bt->mgr->latch[victim]);
+
+ // remove old file mapping
+#ifdef unix
+ munmap (pool->map, (bt->mgr->poolmask+1) << bt->mgr->page_bits);
+#else
+ FlushViewOfFile(pool->map, 0);
+ UnmapViewOfFile(pool->map);
+ CloseHandle(pool->hmap);
+#endif
+ pool->map = NULL;
+
+ // create new pool mapping
+ // and link into hash table
+
+ if( bt_mapsegment(bt, pool, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, pool, page_no, idx);
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement (&pool->pin);
+#endif
+ bt_releasewrite (&bt->mgr->latch[idx]);
+ return pool;
+ }
+}
+
+// place write, read, or parent lock on requested page_no.
+// pin to buffer pool and return page pointer
+
+BTERR bt_lockpage(BtDb *bt, uid page_no, BtLock mode, BtPage *pageptr)
+{
+BtLatchSet *set;
+BtPool *pool;
+uint subpage;
+BtPage page;
+
+ // find/create maping in pool table
+ // and pin our pool slot
+
+ if( pool = bt_pinpage(bt, page_no) )
+ subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
+ else
+ return bt->err;
+
+ set = pool->pagelatch + subpage;
+ page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
+#ifdef unix
+ {
+ uint idx = subpage / 8;
+ uint bit = subpage % 8;
+
+ if( !((bt->mgr->pooladvise + pool->slot * (bt->mgr->poolmask + 1)/8)[idx] >> bit) & 1 ) {
+ madvise (page, bt->mgr->page_size, MADV_WILLNEED);
+ (bt->mgr->pooladvise + pool->slot * (bt->mgr->poolmask + 1)/8)[idx] |= 1 << bit;
+ }
+ }
+#endif
+
+ switch( mode ) {
+ case BtLockRead:
+ bt_readlock (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_writelock (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_readlock (set->access);
+ break;
+ case BtLockDelete:
+ bt_writelock (set->access);
+ break;
+ case BtLockParent:
+ bt_writelock (set->parent);
+ break;
+ default:
+ return bt->err = BTERR_lock;
+ }
+
+ if( pageptr )
+ *pageptr = page;
+
+ return bt->err = 0;
+}
+
+// remove write, read, or parent lock on requested page_no.
+
+BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode)
+{
+uint subpage, idx;
+BtLatchSet *set;
+BtPool *pool;
+
+ // since page is pinned
+ // it should still be in the buffer pool
+ // and is in no danger of being a victim for reuse
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_readlock (&bt->mgr->latch[idx]);
+
+ if( pool = bt_findpool(bt, page_no, idx) )
+ subpage = (uint)(page_no & bt->mgr->poolmask);
+ else
+ return bt->err = BTERR_hash;
+
+ bt_releaseread (&bt->mgr->latch[idx]);
+ set = pool->pagelatch + subpage;
+
+ switch( mode ) {
+ case BtLockRead:
+ bt_releaseread (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_releasewrite (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_releaseread (set->access);
+ break;
+ case BtLockDelete:
+ bt_releasewrite (set->access);
+ break;
+ case BtLockParent:
+ bt_releasewrite (set->parent);
+ break;
+ default:
+ return bt->err = BTERR_lock;
+ }
+
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, -1);
+#else
+ _InterlockedDecrement (&pool->pin);
+#endif
+ return bt->err = 0;
+}
+
+// deallocate a deleted page
+// place on free chain out of allocator page
+
+BTERR bt_freepage(BtDb *bt, uid page_no)
+{
+ // obtain delete lock on deleted page
+
+ if( bt_lockpage(bt, page_no, BtLockDelete, NULL) )
+ return bt->err;
+
+ // obtain write lock on deleted page
+
+ if( bt_lockpage(bt, page_no, BtLockWrite, &bt->temp) )
+ return bt->err;
+
+ // lock allocation page
+
+ if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) )
+ return bt->err;
+
+ // store chain in second right
+ bt_putid(bt->temp->right, bt_getid(bt->alloc[1].right));
+ bt_putid(bt->alloc[1].right, page_no);
+
+ // unlock page zero
+
+ if( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
+ return bt->err;
+
+ // remove write lock on deleted node
+
+ if( bt_unlockpage(bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ // remove delete lock on deleted node
+
+ if( bt_unlockpage(bt, page_no, BtLockDelete) )
+ return bt->err;
+
+ return 0;
+}
+
+// allocate a new page and write page into it
+
+uid bt_newpage(BtDb *bt, BtPage page)
+{
+uid new_page;
+BtPage pmap;
+int reuse;
+
+ // lock page zero
+
+ if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) )
+ return 0;
+
+ // use empty chain first
+ // else allocate empty page
+
+ if( new_page = bt_getid(bt->alloc[1].right) ) {
+ if( bt_lockpage (bt, new_page, BtLockWrite, &bt->temp) )
+ return 0;
+ bt_putid(bt->alloc[1].right, bt_getid(bt->temp->right));
+ if( bt_unlockpage (bt, new_page, BtLockWrite) )
+ return 0;
+ reuse = 1;
+ } else {
+ new_page = bt_getid(bt->alloc->right);
+ bt_putid(bt->alloc->right, new_page+1);
+ reuse = 0;
+ }
+#ifdef unix
+ if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+
+ // if writing first page of pool block, zero last page in the block
+
+ if ( !reuse && bt->mgr->poolmask > 0 && (new_page & bt->mgr->poolmask) == 0 )
+ {
+ // use zero buffer to write zeros
+ memset(bt->zero, 0, bt->mgr->page_size);
+ if ( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->poolmask) << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+ }
+#else
+ // bring new page into pool and copy page.
+ // this will extend the file into the new pages.
+
+ if( bt_lockpage(bt, new_page, BtLockWrite, &pmap) )
+ return 0;
+
+ memcpy(pmap, page, bt->mgr->page_size);
+
+ if( bt_unlockpage (bt, new_page, BtLockWrite) )
+ return 0;
+#endif
+ // unlock page zero
+
+ if ( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
+ return 0;
+
+ return new_page;
+}
+
+// find slot in page for given key at a given level
+
+int bt_findslot (BtDb *bt, unsigned char *key, uint len)
+{
+uint diff, higher = bt->page->cnt, low = 1, slot;
+
+ // low is the lowest candidate, higher is already
+ // tested as .ge. the given key, loop ends when they meet
+
+ while( diff = higher - low ) {
+ slot = low + ( diff >> 1 );
+ if( keycmp (keyptr(bt->page, slot), key, len) < 0 )
+ low = slot + 1;
+ else
+ higher = slot;
+ }
+
+ return higher;
+}
+
+// find and load page at given level for given key
+// leave page rd or wr locked as requested
+
+int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, uint lock)
+{
+uid page_no = ROOT_page, prevpage = 0;
+uint drill = 0xff, slot;
+uint mode, prevmode;
+
+ // start at root of btree and drill down
+
+ do {
+ // determine lock mode of drill level
+ mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead;
+
+ bt->page_no = page_no;
+
+ // obtain access lock using lock chaining with Access mode
+
+ if( page_no > ROOT_page )
+ if( bt_lockpage(bt, page_no, BtLockAccess, NULL) )
+ return 0;
+
+ if( prevpage )
+ if( bt_unlockpage(bt, prevpage, prevmode) )
+ return 0;
+
+ // obtain read lock using lock chaining
+ // and pin page contents
+
+ if( bt_lockpage(bt, page_no, mode, &bt->page) )
+ return 0;
+
+ if( page_no > ROOT_page )
+ if( bt_unlockpage(bt, page_no, BtLockAccess) )
+ return 0;
+
+ // re-read and re-lock root after determining actual level of root
+
+ if( bt->page_no == ROOT_page )
+ if( bt->page->lvl != drill) {
+ drill = bt->page->lvl;
+
+ if( lock == BtLockWrite && drill == lvl )
+ if( bt_unlockpage(bt, page_no, mode) )
+ return 0;
+ else
+ continue;
+ }
+
+ // if page is being deleted,
+ // move back to preceeding page
+
+ if( bt->page->kill ) {
+ page_no = bt_getid (bt->page->right);
+ continue;
+ }
+
+ // find key on page at this level
+ // and descend to requested level
+
+ slot = bt_findslot (bt, key, len);
+
+ // is this slot a foster child?
+
+ if( slot <= bt->page->cnt - bt->page->foster )
+ if( drill == lvl )
+ return slot;
+ else
+ drill--;
+
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ return bt->err = BTERR_struct, 0;
+
+ // continue down / right using overlapping locks
+ // to protect pages being killed or split.
+
+ prevmode = mode;
+ prevpage = bt->page_no;
+ page_no = bt_getid(slotptr(bt->page, slot)->id);
+ } while( page_no );
+
+ // return error on end of chain
+
+ bt->err = BTERR_struct;
+ return 0; // return error
+}
+
+// find and delete key on page by marking delete flag bit
+// when page becomes empty, delete it from the btree
+
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl)
+{
+unsigned char leftkey[256], rightkey[256];
+uid page_no, right;
+uint slot, tod;
+BtKey ptr;
+
+ if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // if key is found delete it, otherwise ignore request
+
+ if( !keycmp (ptr, key, len) )
+ if( slotptr(bt->page, slot)->dead == 0 ) {
+ slotptr(bt->page,slot)->dead = 1;
+ if( slot < bt->page->cnt )
+ bt->page->dirty = 1;
+ bt->page->act--;
+ }
+
+ // return if page is not empty, or it has no right sibling
+
+ right = bt_getid(bt->page->right);
+ page_no = bt->page_no;
+
+ if( !right || bt->page->act )
+ return bt_unlockpage(bt, page_no, BtLockWrite);
+
+ // obtain Parent lock over write lock
+
+ if( bt_lockpage(bt, page_no, BtLockParent, NULL) )
+ return bt->err;
+
+ // cache copy of key to delete
+
+ ptr = keyptr(bt->page, bt->page->cnt);
+ memcpy(leftkey, ptr, ptr->len + 1);
+
+ // lock and map right page
+
+ if ( bt_lockpage(bt, right, BtLockWrite, &bt->temp) )
+ return bt->err;
+
+ // pull contents of next page into current empty page
+ memcpy (bt->page, bt->temp, bt->mgr->page_size);
+
+ // cache copy of key to update
+ ptr = keyptr(bt->temp, bt->temp->cnt);
+ memcpy(rightkey, ptr, ptr->len + 1);
+
+ // Mark right page as deleted and point it to left page
+ // until we can post updates at higher level.
+
+ bt_putid(bt->temp->right, page_no);
+ bt->temp->kill = 1;
+ bt->temp->cnt = 0;
+
+ if( bt_unlockpage(bt, right, BtLockWrite) )
+ return bt->err;
+ if( bt_unlockpage(bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ // delete old lower key to consolidated node
+
+ if( bt_deletekey (bt, leftkey + 1, *leftkey, lvl + 1) )
+ return bt->err;
+
+ // redirect higher key directly to consolidated node
+
+ if( slot = bt_loadpage (bt, rightkey+1, *rightkey, lvl+1, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // since key already exists, update id
+
+ if( keycmp (ptr, rightkey+1, *rightkey) )
+ return bt->err = BTERR_struct;
+
+ slotptr(bt->page, slot)->dead = 0;
+ bt_putid(slotptr(bt->page,slot)->id, page_no);
+ bt_unlockpage(bt, bt->page_no, BtLockWrite);
+
+ // obtain write lock and
+ // add right block to free chain
+
+ if( bt_freepage (bt, right) )
+ return bt->err;
+
+ // remove ParentModify lock
+
+ if( bt_unlockpage(bt, page_no, BtLockParent) )
+ return bt->err;
+
+ return 0;
+}
+
+// find key in leaf level and return row-id
+
+uid bt_findkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+BtKey ptr;
+uid id;
+
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return 0;
+
+ // if key exists, return row-id
+ // otherwise return 0
+
+ if( ptr->len == len && !memcmp (ptr->key, key, len) )
+ id = bt_getid(slotptr(bt->page,slot)->id);
+ else
+ id = 0;
+
+ if ( bt_unlockpage(bt, bt->page_no, BtLockRead) )
+ return 0;
+
+ return id;
+}
+
+// check page for space available,
+// clean if necessary and return
+// 0 - page needs splitting
+// 1 - go ahead
+
+uint bt_cleanpage(BtDb *bt, uint amt)
+{
+uint nxt = bt->mgr->page_size;
+BtPage page = bt->page;
+uint cnt = 0, idx = 0;
+uint max = page->cnt;
+BtKey key;
+
+ if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return 1;
+
+ // skip cleanup if nothing to reclaim
+
+ if( !page->dirty )
+ return 0;
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+
+ // skip page info and set rest of page to zero
+
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ page->dirty = 0;
+ page->act = 0;
+
+ // try cleaning up page first
+
+ while( cnt++ < max ) {
+ // always leave fence key and foster children in list
+ if( cnt < max - page->foster && slotptr(bt->frame,cnt)->dead )
+ continue;
+
+ // copy key
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+
+ // copy slot
+ memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId);
+ if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
+ page->act++;
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ // see if page has enough space now, or does it need splitting?
+
+ if( page->min >= (idx+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return 1;
+
+ return 0;
+}
+
+// add key to page
+// return with page unlocked
+
+BTERR bt_addkeytopage (BtDb *bt, uint slot, unsigned char *key, uint len, uid id, uint tod)
+{
+BtPage page = bt->page;
+uint idx;
+
+ // calculate next available slot and copy key into page
+
+ page->min -= len + 1;
+ ((unsigned char *)page)[page->min] = len;
+ memcpy ((unsigned char *)page + page->min +1, key, len );
+
+ for( idx = slot; idx < page->cnt; idx++ )
+ if( slotptr(page, idx)->dead )
+ break;
+
+ // now insert key into array before slot
+ // preserving the fence slot
+
+ if( idx == page->cnt )
+ idx++, page->cnt++;
+
+ page->act++;
+
+ while( idx > slot )
+ *slotptr(page, idx) = *slotptr(page, idx -1), idx--;
+
+ bt_putid(slotptr(page,slot)->id, id);
+ slotptr(page, slot)->off = page->min;
+ slotptr(page, slot)->tod = tod;
+ slotptr(page, slot)->dead = 0;
+
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+}
+
+// split the root and raise the height of the btree
+
+BTERR bt_splitroot(BtDb *bt, uid right)
+{
+uint nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+BtPage root = bt->page;
+uid new_page;
+BtKey key;
+
+ // Obtain an empty page to use, and copy the left page
+ // contents into it from the root. Strip foster child key.
+ // (it's the stopper key)
+
+ root->act--;
+ root->cnt--;
+ root->foster--;
+
+ // Save left fence key.
+
+ key = keyptr(root, root->cnt);
+ memcpy (fencekey, key, key->len + 1);
+
+ // copy the lower keys into a new left page
+
+ if( !(new_page = bt_newpage(bt, root)) )
+ return bt->err;
+
+ // preserve the page info at the bottom
+ // and set rest of the root to zero
+
+ memset (root+1, 0, bt->mgr->page_size - sizeof(*root));
+
+ // insert left fence key on empty newroot page
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 1)->id, new_page);
+ slotptr(root, 1)->off = nxt;
+
+ // insert stopper key on newroot page
+ // and increase the root height
+
+ nxt -= 3;
+ fencekey[0] = 2;
+ fencekey[1] = 0xff;
+ fencekey[2] = 0xff;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 2)->id, right);
+ slotptr(root, 2)->off = nxt;
+
+ bt_putid(root->right, 0);
+ root->min = nxt; // reset lowest used offset and key count
+ root->cnt = 2;
+ root->act = 2;
+ root->lvl++;
+
+ // release root (bt->page)
+
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+}
+
+// split already locked full node
+// return unlocked.
+
+BTERR bt_splitpage (BtDb *bt)
+{
+uint slot, cnt, idx, max, nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+uid page_no = bt->page_no;
+BtPage page = bt->page;
+uint tod = time(NULL);
+uint lvl = page->lvl;
+uid new_page, right;
+BtKey key;
+
+ // initialize frame buffer
+
+ memset (bt->frame, 0, bt->mgr->page_size);
+ max = page->cnt - page->foster;
+ tod = (uint)time(NULL);
+ cnt = max / 2;
+ idx = 0;
+
+ // split higher half of keys to bt->frame
+ // leaving foster children in the left node.
+
+ while( cnt++ < max ) {
+ key = keyptr(page, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1);
+ memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId);
+ slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod;
+ slotptr(bt->frame, idx)->off = nxt;
+ bt->frame->act++;
+ }
+
+ // transfer right link node
+
+ if( page_no > ROOT_page ) {
+ right = bt_getid (page->right);
+ bt_putid(bt->frame->right, right);
+ }
+
+ bt->frame->bits = bt->mgr->page_bits;
+ bt->frame->min = nxt;
+ bt->frame->cnt = idx;
+ bt->frame->lvl = lvl;
+
+ // get new free page and write frame to it.
+
+ if( !(new_page = bt_newpage(bt, bt->frame)) )
+ return bt->err;
+
+ // remember fence key for new page to add
+ // as foster child
+
+ key = keyptr(bt->frame, idx);
+ memcpy (fencekey, key, key->len + 1);
+
+ // update lower keys and foster children to continue in old page
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ nxt = bt->mgr->page_size;
+ page->act = 0;
+ cnt = 0;
+ idx = 0;
+
+ // assemble page of smaller keys
+ // to remain in the old page
+
+ while( cnt++ < max / 2 ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ page->act++;
+ }
+
+ // insert new foster child at beginning of the current foster children
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)page + nxt, fencekey, *fencekey + 1);
+ bt_putid (slotptr(page,++idx)->id, new_page);
+ slotptr(page, idx)->tod = tod;
+ slotptr(page, idx)->off = nxt;
+ page->foster++;
+ page->act++;
+
+ // continue with old foster child keys if any
+
+ cnt = bt->frame->cnt - bt->frame->foster;
+
+ while( cnt++ < bt->frame->cnt ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ page->act++;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ // link new right page
+
+ bt_putid (page->right, new_page);
+
+ // if current page is the root page, split it
+
+ if( page_no == ROOT_page )
+ return bt_splitroot (bt, new_page);
+
+ // release wr lock on page
+
+ if( bt_unlockpage (bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ // obtain ParentModification lock for current page
+ // to fix fence key and highest foster child on page
+
+ if( bt_lockpage (bt, page_no, BtLockParent, NULL) )
+ return bt->err;
+
+ // get our highest foster child key to find in parent node
+
+ if( bt_lockpage (bt, page_no, BtLockRead, &page) )
+ return bt->err;
+
+ key = keyptr(page, page->cnt);
+ memcpy (fencekey, key, key->len+1);
+
+ if( bt_unlockpage (bt, page_no, BtLockRead) )
+ return bt->err;
+
+try_again:
+
+ do {
+ slot = bt_loadpage (bt, fencekey + 1, *fencekey, lvl + 1, BtLockWrite);
+
+ if( !slot )
+ return bt->err;
+
+ // check if parent page has enough space for any possible key
+
+ if( bt_cleanpage (bt, 256) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ } while( 1 );
+
+ // see if we are still a foster child from another node
+
+ if( bt_getid (slotptr(bt->page, slot)->id) != page_no ) {
+ bt_unlockpage (bt, bt->page_no, BtLockWrite);
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ goto try_again;
+ }
+
+ // wait until readers from parent get their locks
+
+ if( bt_lockpage (bt, page_no, BtLockDelete, NULL) )
+ return bt->err;
+
+ if( bt_lockpage (bt, page_no, BtLockWrite, &page) )
+ return bt->err;
+
+ // switch parent fence key to foster child
+
+ if( slotptr(page, page->cnt)->dead )
+ slotptr(bt->page, slot)->dead = 1;
+ else
+ bt_putid (slotptr(bt->page, slot)->id, bt_getid(slotptr(page, page->cnt)->id));
+
+ // remove highest foster child from our page
+ // add our new fence key to parent
+
+ page->cnt--;
+ page->act--;
+ page->foster--;
+ page->dirty = 1;
+ key = keyptr(page, page->cnt);
+
+ if( bt_addkeytopage (bt, slot, key->key, key->len, page_no, tod) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockDelete) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ return bt_unlockpage (bt, page_no, BtLockParent);
+}
+
+// Insert new key into the btree at leaf level.
+
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod)
+{
+uint slot, idx;
+BtPage page;
+BtKey ptr;
+
+ while( 1 ) {
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ {
+ if ( !bt->err )
+ bt->err = BTERR_ovflw;
+ return bt->err;
+ }
+
+ // if key already exists, update id and return
+
+ page = bt->page;
+
+ if( !keycmp (ptr, key, len) ) {
+ slotptr(page, slot)->dead = 0;
+ slotptr(page, slot)->tod = tod;
+ bt_putid(slotptr(page,slot)->id, id);
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+ }
+
+ // check if page has enough space
+
+ if( bt_cleanpage (bt, len) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ }
+
+ return bt_addkeytopage (bt, slot, key, len, id, tod);
+}
+
+// cache page of keys into cursor and return starting slot for given key
+
+uint bt_startkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+
+ // cache page for retrieval
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ memcpy (bt->cursor, bt->page, bt->mgr->page_size);
+ bt->cursor_page = bt->page_no;
+ if ( bt_unlockpage(bt, bt->page_no, BtLockRead) )
+ return 0;
+
+ return slot;
+}
+
+// return next slot for cursor page
+// or slide cursor right into next page
+
+uint bt_nextkey (BtDb *bt, uint slot)
+{
+BtPage page;
+uid right;
+
+ do {
+ right = bt_getid(bt->cursor->right);
+ while( slot++ < bt->cursor->cnt - bt->cursor->foster )
+ if( slotptr(bt->cursor,slot)->dead )
+ continue;
+ else if( right || (slot < bt->cursor->cnt - bt->cursor->foster) )
+ return slot;
+ else
+ break;
+
+ if( !right )
+ break;
+
+ bt->cursor_page = right;
+
+ if( bt_lockpage(bt, right, BtLockRead, &page) )
+ return 0;
+
+ memcpy (bt->cursor, page, bt->mgr->page_size);
+
+ if ( bt_unlockpage(bt, right, BtLockRead) )
+ return 0;
+
+ slot = 0;
+ } while( 1 );
+
+ return bt->err = 0;
+}
+
+BtKey bt_key(BtDb *bt, uint slot)
+{
+ return keyptr(bt->cursor, slot);
+}
+
+uid bt_uid(BtDb *bt, uint slot)
+{
+ return bt_getid(slotptr(bt->cursor,slot)->id);
+}
+
+uint bt_tod(BtDb *bt, uint slot)
+{
+ return slotptr(bt->cursor,slot)->tod;
+}
+
+
+#ifdef STANDALONE
+
+typedef struct {
+ char type, idx;
+ char *infile;
+ BtMgr *mgr;
+ int num;
+} ThreadArg;
+
+// standalone program to index file of keys
+// then list them onto std-out
+
+#ifdef unix
+void *index_file (void *arg)
+#else
+uint __stdcall index_file (void *arg)
+#endif
+{
+int line = 0, found = 0, cnt = 0;
+uid next, page_no = LEAF_page; // start on first page of leaves
+unsigned char key[256];
+ThreadArg *args = arg;
+int ch, len = 0, slot;
+time_t tod[1];
+BtPage page;
+BtKey ptr;
+BtDb *bt;
+FILE *in;
+
+ bt = bt_open (args->mgr);
+ time (tod);
+
+ switch(args->type | 0x20)
+ {
+ case 'w':
+ fprintf(stderr, "started indexing for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_insertkey (bt, key, len, line, *tod) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys\n", args->infile, line);
+ break;
+
+ case 'd':
+ fprintf(stderr, "started deleting keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_deletekey (bt, key, len, 0) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for keys, %d \n", args->infile, line);
+ break;
+
+ case 'f':
+ fprintf(stderr, "started finding keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_findkey (bt, key, len) )
+ found++;
+ else if( bt->err )
+ fprintf(stderr, "Error %d Syserr %d Line: %d\n", bt->err, errno, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys, found %d\n", args->infile, line, found);
+ break;
+
+ case 's':
+ len = key[0] = 0;
+
+ fprintf(stderr, "started reading\n");
+
+ if( slot = bt_startkey (bt, key, len) )
+ slot--;
+ else
+ fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0);
+
+ while( slot = bt_nextkey (bt, slot) ) {
+ ptr = bt_key(bt, slot);
+ fwrite (ptr->key, ptr->len, 1, stdout);
+ fputc ('\n', stdout);
+ }
+
+ break;
+
+ case 'c':
+ fprintf(stderr, "started reading\n");
+
+ do {
+ bt_lockpage (bt, page_no, BtLockRead, &page);
+ cnt += page->act;
+ next = bt_getid (page->right);
+ bt_unlockpage (bt, page_no, BtLockRead);
+ } while( page_no = next );
+
+ cnt--; // remove stopper key
+ fprintf(stderr, " Total keys read %d\n", cnt);
+ break;
+ }
+
+ bt_close (bt);
+#ifdef unix
+ return NULL;
+#else
+ return 0;
+#endif
+}
+
+typedef struct timeval timer;
+
+int main (int argc, char **argv)
+{
+int idx, cnt, len, slot, err;
+int segsize, bits = 16;
+#ifdef unix
+pthread_t *threads;
+timer start, stop;
+#else
+time_t start[1], stop[1];
+HANDLE *threads;
+#endif
+double real_time;
+ThreadArg *args;
+uint poolsize = 0;
+int num = 0;
+char key[1];
+BtMgr *mgr;
+BtKey ptr;
+BtDb *bt;
+
+ if( argc < 3 ) {
+ fprintf (stderr, "Usage: %s idx_file Read/Write/Scan/Delete/Find [page_bits mapped_segments seg_bits line_numbers src_file1 src_file2 ... ]\n", argv[0]);
+ fprintf (stderr, " where page_bits is the page size in bits\n");
+ fprintf (stderr, " mapped_segments is the number of mmap segments in buffer pool\n");
+ fprintf (stderr, " seg_bits is the size of individual segments in buffer pool in pages in bits\n");
+ fprintf (stderr, " line_numbers = 1 to append line numbers to keys\n");
+ fprintf (stderr, " src_file1 thru src_filen are files of keys separated by newline\n");
+ exit(0);
+ }
+
+#ifdef unix
+ gettimeofday(&start, NULL);
+#else
+ time(start);
+#endif
+
+ if( argc > 3 )
+ bits = atoi(argv[3]);
+
+ if( argc > 4 )
+ poolsize = atoi(argv[4]);
+
+ if( !poolsize )
+ fprintf (stderr, "Warning: no mapped_pool\n");
+
+ if( poolsize > 65535 )
+ fprintf (stderr, "Warning: mapped_pool > 65535 segments\n");
+
+ if( argc > 5 )
+ segsize = atoi(argv[5]);
+ else
+ segsize = 4; // 16 pages per mmap segment
+
+ if( argc > 6 )
+ num = atoi(argv[6]);
+
+ cnt = argc - 7;
+#ifdef unix
+ threads = malloc (cnt * sizeof(pthread_t));
+#else
+ threads = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, cnt * sizeof(HANDLE));
+#endif
+ args = malloc (cnt * sizeof(ThreadArg));
+
+ mgr = bt_mgr ((argv[1]), BT_rw, bits, poolsize, segsize, poolsize / 8);
+
+ if( !mgr ) {
+ fprintf(stderr, "Index Open Error %s\n", argv[1]);
+ exit (1);
+ }
+
+ // fire off threads
+
+ for( idx = 0; idx < cnt; idx++ ) {
+ args[idx].infile = argv[idx + 7];
+ args[idx].type = argv[2][0];
+ args[idx].mgr = mgr;
+ args[idx].num = num;
+ args[idx].idx = idx;
+#ifdef unix
+ if( err = pthread_create (threads + idx, NULL, index_file, args + idx) )
+ fprintf(stderr, "Error creating thread %d\n", err);
+#else
+ threads[idx] = (HANDLE)_beginthreadex(NULL, 65536, index_file, args + idx, 0, NULL);
+#endif
+ }
+
+ // wait for termination
+
+#ifdef unix
+ for( idx = 0; idx < cnt; idx++ )
+ pthread_join (threads[idx], NULL);
+ gettimeofday(&stop, NULL);
+ real_time = 1000.0 * ( stop.tv_sec - start.tv_sec ) + 0.001 * (stop.tv_usec - start.tv_usec );
+#else
+ WaitForMultipleObjects (cnt, threads, TRUE, INFINITE);
+
+ for( idx = 0; idx < cnt; idx++ )
+ CloseHandle(threads[idx]);
+
+ time (stop);
+ real_time = 1000 * (*stop - *start);
+#endif
+ fprintf(stderr, " Time to complete: %.2f seconds\n", real_time/1000);
+ bt_mgrclose (mgr);
+}
+
+#endif //STANDALONE
--- /dev/null
+// foster btree version d
+// 26 DEC 2013
+
+// author: karl malbrain, malbrain@cal.berkeley.edu
+
+/*
+This work, including the source code, documentation
+and related data, is placed into the public domain.
+
+The orginal author is Karl Malbrain.
+
+THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
+OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
+MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
+ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
+RESULTING FROM THE USE, MODIFICATION, OR
+REDISTRIBUTION OF THIS SOFTWARE.
+*/
+
+// Please see the project home page for documentation
+// code.google.com/p/high-concurrency-btree
+
+#define _FILE_OFFSET_BITS 64
+#define _LARGEFILE64_SOURCE
+
+#ifdef linux
+#define _GNU_SOURCE
+#endif
+
+#ifdef unix
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/time.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <pthread.h>
+#else
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <fcntl.h>
+#include <process.h>
+#include <intrin.h>
+#endif
+
+#include <memory.h>
+#include <string.h>
+
+typedef unsigned long long uid;
+
+#ifndef unix
+typedef unsigned long long off64_t;
+typedef unsigned short ushort;
+typedef unsigned int uint;
+#endif
+
+#define BT_ro 0x6f72 // ro
+#define BT_rw 0x7772 // rw
+
+#define BT_maxbits 24 // maximum page size in bits
+#define BT_minbits 9 // minimum page size in bits
+#define BT_minpage (1 << BT_minbits) // minimum page size
+#define BT_maxpage (1 << BT_maxbits) // maximum page size
+
+/*
+There are five lock types for each node in three independent sets:
+1. (set 1) AccessIntent: Sharable. Going to Read the node. Incompatible with NodeDelete.
+2. (set 1) NodeDelete: Exclusive. About to release the node. Incompatible with AccessIntent.
+3. (set 2) ReadLock: Sharable. Read the node. Incompatible with WriteLock.
+4. (set 2) WriteLock: Exclusive. Modify the node. Incompatible with ReadLock and other WriteLocks.
+5. (set 3) ParentLock: Exclusive. Have parent adopt/delete maximum foster child from the node.
+*/
+
+typedef enum{
+ BtLockAccess,
+ BtLockDelete,
+ BtLockRead,
+ BtLockWrite,
+ BtLockParent
+}BtLock;
+
+// Define the length of the page and key pointers
+
+#define BtId 6
+
+// Page key slot definition.
+
+// If BT_maxbits is 15 or less, you can save 4 bytes
+// for each key stored by making the first two uints
+// into ushorts. You can also save 4 bytes by removing
+// the tod field from the key.
+
+// Keys are marked dead, but remain on the page until
+// it cleanup is called. The fence key (highest key) for
+// the page is always present, even after cleanup.
+
+typedef struct {
+ uint off:BT_maxbits; // page offset for key start
+ uint dead:1; // set for deleted key
+ uint tod; // time-stamp for key
+ unsigned char id[BtId]; // id associated with key
+} BtSlot;
+
+// The key structure occupies space at the upper end of
+// each page. It's a length byte followed by the value
+// bytes.
+
+typedef struct {
+ unsigned char len;
+ unsigned char key[1];
+} *BtKey;
+
+// The first part of an index page.
+// It is immediately followed
+// by the BtSlot array of keys.
+
+typedef struct Page {
+ uint cnt; // count of keys in page
+ uint act; // count of active keys
+ uint min; // next key offset
+ uint foster; // count of foster children
+ unsigned char bits; // page size in bits
+ unsigned char lvl:6; // level of page
+ unsigned char kill:1; // page is being deleted
+ unsigned char dirty:1; // page needs to be cleaned
+ unsigned char right[BtId]; // page number to right
+} *BtPage;
+
+// latch table lock structure
+
+// exclusive is set for write access
+// share is count of read accessors
+// pending is count of waiting writers
+// grant write lock when share == 0
+
+typedef struct {
+#ifdef unix
+ volatile uint exclusive:1;
+ volatile uint pending:15;
+ volatile uint share:16;
+ pthread_mutex_t mut[1];
+ pthread_cond_t cond[1];
+#else
+ SRWLOCK srw[1];
+#endif
+} BtLatch;
+
+typedef struct {
+ BtLatch readwr[1]; // read/write page lock
+ BtLatch access[1]; // Access Intent/Page delete
+ BtLatch parent[1]; // adoption of foster children
+} BtLatchSet;
+
+// The memory mapping pool table buffer manager entry
+
+typedef struct {
+ unsigned long long int lru; // number of times accessed
+ uid basepage; // mapped base page number
+ char *map; // mapped memory pointer
+ uint pin; // mapped page pin counter
+ uint slot; // slot index in this array
+ void *hashprev; // previous pool entry for the same hash idx
+ void *hashnext; // next pool entry for the same hash idx
+#ifndef unix
+ HANDLE hmap;
+#endif
+// array of page latch sets, one for each page in map segment
+ BtLatchSet pagelatch[0];
+} BtPool;
+
+// The object structure for Btree access
+
+typedef struct {
+ uint page_size; // page size
+ uint page_bits; // page size in bits
+ uint seg_bits; // seg size in pages in bits
+ uint mode; // read-write mode
+#ifdef unix
+ int idx;
+ char *pooladvise; // bit maps for pool page advisements
+#else
+ HANDLE idx;
+#endif
+ uint poolcnt; // highest page pool node in use
+ uint poolmax; // highest page pool node allocated
+ uint poolmask; // total size of pages in mmap segment - 1
+ uint hashsize; // size of Hash Table for pool entries
+ volatile uint evicted; // last evicted hash table slot
+ ushort *hash; // hash table of pool entries
+ BtLatch *latch; // latches for hash table slots
+ char *nodes; // memory pool page segments
+} BtMgr;
+
+typedef struct {
+ BtMgr *mgr; // buffer manager for thread
+ BtPage temp; // temporary frame buffer (memory mapped/file IO)
+ BtPage alloc; // frame buffer for alloc page ( page 0 )
+ BtPage cursor; // cached frame for start/next (never mapped)
+ BtPage frame; // spare frame for the page split (never mapped)
+ BtPage zero; // page frame for zeroes at end of file
+ BtPage page; // current page
+ uid page_no; // current page number
+ uid cursor_page; // current cursor page number
+ unsigned char *mem; // frame, cursor, page memory buffer
+ int err; // last error
+} BtDb;
+
+typedef enum {
+ BTERR_ok = 0,
+ BTERR_struct,
+ BTERR_ovflw,
+ BTERR_lock,
+ BTERR_map,
+ BTERR_wrt,
+ BTERR_hash
+} BTERR;
+
+// B-Tree functions
+extern void bt_close (BtDb *bt);
+extern BtDb *bt_open (BtMgr *mgr);
+extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod);
+extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl);
+extern uid bt_findkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_startkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_nextkey (BtDb *bt, uint slot);
+
+// manager functions
+extern BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolsize, uint segsize, uint hashsize);
+void bt_mgrclose (BtMgr *mgr);
+
+// Helper functions to return cursor slot values
+
+extern BtKey bt_key (BtDb *bt, uint slot);
+extern uid bt_uid (BtDb *bt, uint slot);
+extern uint bt_tod (BtDb *bt, uint slot);
+
+// BTree page number constants
+#define ALLOC_page 0
+#define ROOT_page 1
+#define LEAF_page 2
+
+// Number of levels to create in a new BTree
+
+#define MIN_lvl 2
+
+// The page is allocated from low and hi ends.
+// The key offsets and row-id's are allocated
+// from the bottom, while the text of the key
+// is allocated from the top. When the two
+// areas meet, the page is split into two.
+
+// A key consists of a length byte, two bytes of
+// index number (0 - 65534), and up to 253 bytes
+// of key value. Duplicate keys are discarded.
+// Associated with each key is a 48 bit row-id.
+
+// The b-tree root is always located at page 1.
+// The first leaf page of level zero is always
+// located on page 2.
+
+// When to root page fills, it is split in two and
+// the tree height is raised by a new root at page
+// one with two keys.
+
+// Deleted keys are marked with a dead bit until
+// page cleanup The fence key for a node is always
+// present, even after deletion and cleanup.
+
+// Groups of pages called segments from the btree are
+// cached with memory mapping. A hash table is used to keep
+// track of the cached segments. This behaviour is controlled
+// by the cache block size parameter to bt_open.
+
+// To achieve maximum concurrency one page is locked at a time
+// as the tree is traversed to find leaf key in question.
+
+// An adoption traversal leaves the parent node locked as the
+// tree is traversed to the level in quesiton.
+
+// Page 0 is dedicated to lock for new page extensions,
+// and chains empty pages together for reuse.
+
+// Empty pages are chained together through the ALLOC page and reused.
+
+// Access macros to address slot and key values from the page
+
+#define slotptr(page, slot) (((BtSlot *)(page+1)) + (slot-1))
+#define keyptr(page, slot) ((BtKey)((unsigned char*)(page) + slotptr(page, slot)->off))
+
+void bt_putid(unsigned char *dest, uid id)
+{
+int i = BtId;
+
+ while( i-- )
+ dest[i] = (unsigned char)id, id >>= 8;
+}
+
+uid bt_getid(unsigned char *src)
+{
+uid id = 0;
+int i;
+
+ for( i = 0; i < BtId; i++ )
+ id <<= 8, id |= *src++;
+
+ return id;
+}
+
+void bt_mgrclose (BtMgr *mgr)
+{
+BtPool *pool;
+uint slot;
+
+ // release mapped pages
+ // note that slot zero is never used
+
+ for( slot = 1; slot < mgr->poolmax; slot++ ) {
+ pool = (BtPool *)(mgr->nodes + slot * (sizeof(BtPool) + (mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ if( pool->slot )
+#ifdef unix
+ munmap (pool->map, (mgr->poolmask+1) << mgr->page_bits);
+#else
+ {
+ FlushViewOfFile(pool->map, 0);
+ UnmapViewOfFile(pool->map);
+ CloseHandle(pool->hmap);
+ }
+#endif
+ }
+
+#ifdef unix
+ close (mgr->idx);
+ free (mgr->nodes);
+ free (mgr->hash);
+ free (mgr->latch);
+ free (mgr->pooladvise);
+ free (mgr);
+#else
+ FlushFileBuffers(mgr->idx);
+ CloseHandle(mgr->idx);
+ GlobalFree (mgr->nodes);
+ GlobalFree (mgr->hash);
+ GlobalFree (mgr->latch);
+ GlobalFree (mgr);
+#endif
+}
+
+// close and release memory
+
+void bt_close (BtDb *bt)
+{
+#ifdef unix
+ if ( bt->mem )
+ free (bt->mem);
+#else
+ if ( bt->mem)
+ VirtualFree (bt->mem, 0, MEM_RELEASE);
+#endif
+ free (bt);
+}
+
+// open/create new btree buffer manager
+
+// call with file_name, BT_openmode, bits in page size (e.g. 16),
+// size of mapped page pool (e.g. 8192)
+
+BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolmax, uint segsize, uint hashsize)
+{
+uint lvl, attr, cacheblk, last, slot, idx;
+BtPage alloc;
+int lockmode;
+off64_t size;
+uint amt[1];
+BtMgr* mgr;
+BtKey key;
+
+#ifndef unix
+SYSTEM_INFO sysinfo[1];
+#endif
+
+ // determine sanity of page size and buffer pool
+
+ if( bits > BT_maxbits )
+ bits = BT_maxbits;
+ else if( bits < BT_minbits )
+ bits = BT_minbits;
+
+ if( !poolmax )
+ return NULL; // must have buffer pool
+
+#ifdef unix
+ mgr = calloc (1, sizeof(BtMgr));
+
+ switch (mode & 0x7fff)
+ {
+ case BT_rw:
+ mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
+ lockmode = 1;
+ break;
+
+ case BT_ro:
+ default:
+ mgr->idx = open ((char*)name, O_RDONLY);
+ lockmode = 0;
+ break;
+ }
+ if( mgr->idx == -1 )
+ return free(mgr), NULL;
+
+ cacheblk = 4096; // minimum mmap segment size for unix
+
+#else
+ mgr = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtMgr));
+ attr = FILE_ATTRIBUTE_NORMAL;
+ switch (mode & 0x7fff)
+ {
+ case BT_rw:
+ mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
+ lockmode = 1;
+ break;
+
+ case BT_ro:
+ default:
+ mgr->idx = CreateFile(name, GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, attr, NULL);
+ lockmode = 0;
+ break;
+ }
+ if( mgr->idx == INVALID_HANDLE_VALUE )
+ return GlobalFree(mgr), NULL;
+
+ // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity
+ GetSystemInfo(sysinfo);
+ cacheblk = sysinfo->dwAllocationGranularity;
+#endif
+
+#ifdef unix
+ alloc = malloc (BT_maxpage);
+ *amt = 0;
+
+ // read minimum page size to get root info
+
+ if( size = lseek (mgr->idx, 0L, 2) ) {
+ if( pread(mgr->idx, alloc, BT_minpage, 0) == BT_minpage )
+ bits = alloc->bits;
+ else
+ return free(mgr), free(alloc), NULL;
+ } else if( mode == BT_ro )
+ return bt_mgrclose (mgr), NULL;
+#else
+ alloc = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE);
+ size = GetFileSize(mgr->idx, amt);
+
+ if( size || *amt ) {
+ if( !ReadFile(mgr->idx, (char *)alloc, BT_minpage, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ bits = alloc->bits;
+ } else if( mode == BT_ro )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ mgr->page_size = 1 << bits;
+ mgr->page_bits = bits;
+
+ mgr->poolmax = poolmax;
+ mgr->mode = mode;
+
+ if( cacheblk < mgr->page_size )
+ cacheblk = mgr->page_size;
+
+ // mask for partial memmaps
+
+ mgr->poolmask = (cacheblk >> bits) - 1;
+
+ // see if requested size of pages per memmap is greater
+
+ if( (1 << segsize) > mgr->poolmask )
+ mgr->poolmask = (1 << segsize) - 1;
+
+ mgr->seg_bits = 0;
+
+ while( (1 << mgr->seg_bits) <= mgr->poolmask )
+ mgr->seg_bits++;
+
+ mgr->hashsize = hashsize;
+
+#ifdef unix
+ mgr->nodes = calloc (poolmax, (sizeof(BtPool) + (mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ mgr->hash = calloc (hashsize, sizeof(ushort));
+ mgr->latch = calloc (hashsize, sizeof(BtLatch));
+ mgr->pooladvise = calloc (poolmax, (mgr->poolmask + 1) / 8);
+#else
+ mgr->nodes = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, poolmax * (sizeof(BtPool) + (mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ mgr->hash = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(ushort));
+ mgr->latch = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(BtLatch));
+#endif
+
+ // initialize buffer pool page latches
+
+ for( slot = 1; slot < poolmax; slot++ ) {
+ BtLatchSet *latchset = (BtLatchSet *)(mgr->nodes + slot * (sizeof(BtPool) + (mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ for( idx = 0; idx < mgr->poolmask + 1; idx++ ) {
+#ifdef unix
+ pthread_mutex_init (latchset[idx].readwr->mut, NULL);
+ pthread_cond_init (latchset[idx].readwr->cond, NULL);
+ pthread_mutex_init (latchset[idx].access->mut, NULL);
+ pthread_cond_init (latchset[idx].access->cond, NULL);
+ pthread_mutex_init (latchset[idx].parent->mut, NULL);
+ pthread_cond_init (latchset[idx].parent->cond, NULL);
+#else
+ InitializeSRWLock (latchset[idx].readwr->srw);
+ InitializeSRWLock (latchset[idx].access->srw);
+ InitializeSRWLock (latchset[idx].parent->srw);
+#endif
+ }
+ }
+
+ // initialize buffer pool mgr latches
+
+ for( slot = 0; slot < hashsize; slot++ ) {
+#ifdef unix
+ pthread_mutex_init (mgr->latch[slot].mut, NULL);
+ pthread_cond_init (mgr->latch[slot].cond, NULL);
+#else
+ InitializeSRWLock (mgr->latch[slot].srw);
+#endif
+ }
+
+ if( size || *amt )
+ goto mgrxit;
+
+ // initializes an empty b-tree with root page and page of leaves
+
+ memset (alloc, 0, 1 << bits);
+ bt_putid(alloc->right, MIN_lvl+1);
+ alloc->bits = mgr->page_bits;
+
+#ifdef unix
+ if( write (mgr->idx, alloc, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ memset (alloc, 0, 1 << bits);
+ alloc->bits = mgr->page_bits;
+
+ for( lvl=MIN_lvl; lvl--; ) {
+ slotptr(alloc, 1)->off = mgr->page_size - 3;
+ bt_putid(slotptr(alloc, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number
+ key = keyptr(alloc, 1);
+ key->len = 2; // create stopper key
+ key->key[0] = 0xff;
+ key->key[1] = 0xff;
+ alloc->min = mgr->page_size - 3;
+ alloc->lvl = lvl;
+ alloc->cnt = 1;
+ alloc->act = 1;
+#ifdef unix
+ if( write (mgr->idx, alloc, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ }
+
+ // create empty page area by writing last page of first
+ // segment area (other pages are zeroed by O/S)
+
+ if( mgr->poolmask ) {
+ memset(alloc, 0, mgr->page_size);
+ last = mgr->poolmask;
+
+ while( last < MIN_lvl + 1 )
+ last += mgr->poolmask + 1;
+
+#ifdef unix
+ pwrite(mgr->idx, alloc, mgr->page_size, last << mgr->page_bits);
+#else
+ SetFilePointer (mgr->idx, last << mgr->page_bits, NULL, FILE_BEGIN);
+ if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ }
+
+mgrxit:
+#ifdef unix
+ free (alloc);
+#else
+ VirtualFree (alloc, 0, MEM_RELEASE);
+#endif
+ return mgr;
+}
+
+// open BTree access method
+// based on buffer manager
+
+BtDb *bt_open (BtMgr *mgr)
+{
+BtDb *bt = malloc (sizeof(*bt));
+
+ memset (bt, 0, sizeof(*bt));
+ bt->mgr = mgr;
+#ifdef unix
+ bt->mem = malloc (3 *mgr->page_size);
+#else
+ bt->mem = VirtualAlloc(NULL, 3 * mgr->page_size, MEM_COMMIT, PAGE_READWRITE);
+#endif
+ bt->frame = (BtPage)bt->mem;
+ bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size);
+ bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size);
+ return bt;
+}
+
+// compare two keys, returning > 0, = 0, or < 0
+// as the comparison value
+
+int keycmp (BtKey key1, unsigned char *key2, uint len2)
+{
+uint len1 = key1->len;
+int ans;
+
+ if( ans = memcmp (key1->key, key2, len1 > len2 ? len2 : len1) )
+ return ans;
+
+ if( len1 > len2 )
+ return 1;
+ if( len1 < len2 )
+ return -1;
+
+ return 0;
+}
+
+// Latch Manager
+
+// wait if exclusive request is pending, or granted
+// and add 1 to the share count
+
+void bt_readlock(BtLatch *latch)
+{
+#ifdef unix
+ pthread_mutex_lock (latch->mut);
+
+ while( latch->pending || latch->exclusive )
+ pthread_cond_wait (latch->cond, latch->mut);
+
+ // add one to readers counter
+
+ latch->share++;
+ pthread_mutex_unlock (latch->mut);
+#else
+ AcquireSRWLockShared (latch->srw);
+#endif
+}
+
+// wait for other read and write latches to relinquish
+
+void bt_writelock(BtLatch *latch)
+{
+#ifdef unix
+ pthread_mutex_lock (latch->mut);
+ latch->pending++;
+
+ while( latch->share || latch->exclusive )
+ pthread_cond_wait (latch->cond, latch->mut);
+
+ latch->exclusive = 1;
+ latch->pending--;
+ pthread_mutex_unlock (latch->mut);
+#else
+ AcquireSRWLockExclusive (latch->srw);
+#endif
+}
+
+// try to obtain write lock
+
+// return 1 if obtained,
+// 0 if already write or read locked
+
+int bt_writetry(BtLatch *latch)
+{
+int result = 0;
+
+#ifdef unix
+ pthread_mutex_lock (latch->mut);
+
+ if( !latch->share && !latch->exclusive )
+ result = latch->exclusive = 1;
+
+ pthread_mutex_unlock (latch->mut);
+#else
+ result = TryAcquireSRWLockExclusive (latch->srw);
+#endif
+ return result;
+}
+
+// clear write mode
+
+void bt_releasewrite(BtLatch *latch)
+{
+#ifdef unix
+ pthread_mutex_lock (latch->mut);
+ latch->exclusive = 0;
+ pthread_cond_broadcast (latch->cond);
+ pthread_mutex_unlock (latch->mut);
+#else
+ ReleaseSRWLockExclusive (latch->srw);
+#endif
+}
+
+// decrement reader count
+
+void bt_releaseread(BtLatch *latch)
+{
+#ifdef unix
+ pthread_mutex_lock (latch->mut);
+
+ if( !--latch->share && latch->pending )
+ pthread_cond_broadcast (latch->cond);
+
+ pthread_mutex_unlock (latch->mut);
+#else
+ ReleaseSRWLockShared (latch->srw);
+#endif
+}
+
+// Buffer Pool mgr
+
+// find segment in pool
+// must be called with hashslot idx locked
+// return NULL if not there
+// otherwise return node
+
+BtPool *bt_findpool(BtDb *bt, uid page_no, uint idx)
+{
+BtPool *pool;
+uint slot;
+
+ // compute start of hash chain in pool
+
+ if( slot = bt->mgr->hash[idx] )
+ pool = (BtPool *)(bt->mgr->nodes + slot * (sizeof(BtPool) + (bt->mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ else
+ return NULL;
+
+ page_no &= ~bt->mgr->poolmask;
+
+ while( pool->basepage != page_no )
+ if( pool = pool->hashnext )
+ continue;
+ else
+ return NULL;
+
+ return pool;
+}
+
+// add segment to hash table
+
+void bt_linkhash(BtDb *bt, BtPool *pool, uid page_no, int idx)
+{
+BtPool *node;
+uint slot;
+
+ pool->hashprev = pool->hashnext = NULL;
+ pool->basepage = page_no & ~bt->mgr->poolmask;
+ pool->lru = 1;
+
+ if( slot = bt->mgr->hash[idx] ) {
+ node = (BtPool *)(bt->mgr->nodes + slot * (sizeof(BtPool) + (bt->mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ pool->hashnext = node;
+ node->hashprev = pool;
+ }
+
+ bt->mgr->hash[idx] = pool->slot;
+}
+
+// find best segment to evict from buffer pool
+
+BtPool *bt_findlru (BtDb *bt, uint hashslot)
+{
+unsigned long long int target = ~0LL;
+BtPool *pool = NULL, *node;
+
+ if( !hashslot )
+ return NULL;
+
+ node = (BtPool *)(bt->mgr->nodes + hashslot * (sizeof(BtPool) + (bt->mgr->poolmask + 1) * sizeof(BtLatchSet)));
+
+ // scan pool entries under hash table slot
+
+ do {
+ if( node->pin )
+ continue;
+ if( node->lru > target )
+ continue;
+ target = node->lru;
+ pool = node;
+ } while( node = node->hashnext );
+
+ return pool;
+}
+
+// map new buffer pool segment to virtual memory
+
+BTERR bt_mapsegment(BtDb *bt, BtPool *pool, uid page_no)
+{
+off64_t off = (page_no & ~bt->mgr->poolmask) << bt->mgr->page_bits;
+off64_t limit = off + ((bt->mgr->poolmask+1) << bt->mgr->page_bits);
+int flag;
+
+#ifdef unix
+ flag = PROT_READ | ( bt->mgr->mode == BT_ro ? 0 : PROT_WRITE );
+ pool->map = mmap (0, (bt->mgr->poolmask+1) << bt->mgr->page_bits, flag, MAP_SHARED, bt->mgr->idx, off);
+ if( pool->map == MAP_FAILED )
+ return bt->err = BTERR_map;
+ // clear out madvise issued bits
+ memset (bt->mgr->pooladvise + pool->slot * (bt->mgr->poolmask + 1) / 8, 0, (bt->mgr->poolmask + 1)/8);
+#else
+ flag = ( bt->mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE );
+ pool->hmap = CreateFileMapping(bt->mgr->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL);
+ if( !pool->hmap )
+ return bt->err = BTERR_map;
+
+ flag = ( bt->mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE );
+ pool->map = MapViewOfFile(pool->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->mgr->poolmask+1) << bt->mgr->page_bits);
+ if( !pool->map )
+ return bt->err = BTERR_map;
+#endif
+ return bt->err = 0;
+}
+
+// find or place requested page in segment-pool
+// return pool table entry, incrementing pin
+
+BtPool *bt_pinpage(BtDb *bt, uid page_no)
+{
+BtPool *pool, *node, *next;
+uint slot, idx, victim;
+BtLatchSet *set;
+
+ // lock hash table chain
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_readlock (&bt->mgr->latch[idx]);
+
+ // look up in hash table
+
+ if( pool = bt_findpool(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement (&pool->pin);
+#endif
+ bt_releaseread (&bt->mgr->latch[idx]);
+ pool->lru++;
+ return pool;
+ }
+
+ // upgrade to write lock
+
+ bt_releaseread (&bt->mgr->latch[idx]);
+ bt_writelock (&bt->mgr->latch[idx]);
+
+ // try to find page in pool with write lock
+
+ if( pool = bt_findpool(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement (&pool->pin);
+#endif
+ bt_releasewrite (&bt->mgr->latch[idx]);
+ pool->lru++;
+ return pool;
+ }
+
+ // allocate a new pool node
+ // and add to hash table
+
+#ifdef unix
+ slot = __sync_fetch_and_add(&bt->mgr->poolcnt, 1);
+#else
+ slot = _InterlockedIncrement (&bt->mgr->poolcnt) - 1;
+#endif
+
+ if( ++slot < bt->mgr->poolmax ) {
+ pool = (BtPool *)(bt->mgr->nodes + slot * (sizeof(BtPool) + (bt->mgr->poolmask + 1) * sizeof(BtLatchSet)));
+ pool->slot = slot;
+
+ if( bt_mapsegment(bt, pool, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, pool, page_no, idx);
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement (&pool->pin);
+#endif
+ bt_releasewrite (&bt->mgr->latch[idx]);
+ return pool;
+ }
+
+ // pool table is full
+ // find best pool entry to evict
+
+#ifdef unix
+ __sync_fetch_and_add(&bt->mgr->poolcnt, -1);
+#else
+ _InterlockedDecrement (&bt->mgr->poolcnt);
+#endif
+
+ while( 1 ) {
+#ifdef unix
+ victim = __sync_fetch_and_add(&bt->mgr->evicted, 1);
+#else
+ victim = _InterlockedIncrement (&bt->mgr->evicted) - 1;
+#endif
+ victim %= bt->mgr->hashsize;
+
+ // try to get write lock
+ // skip entry if not obtained
+
+ if( !bt_writetry (&bt->mgr->latch[victim]) )
+ continue;
+
+ // if cache entry is empty
+ // or no slots are unpinned
+ // skip this entry
+
+ if( !(pool = bt_findlru(bt, bt->mgr->hash[victim])) ) {
+ bt_releasewrite (&bt->mgr->latch[victim]);
+ continue;
+ }
+
+ // unlink victim pool node from hash table
+
+ if( node = pool->hashprev )
+ node->hashnext = pool->hashnext;
+ else if( node = pool->hashnext )
+ bt->mgr->hash[victim] = node->slot;
+ else
+ bt->mgr->hash[victim] = 0;
+
+ if( node = pool->hashnext )
+ node->hashprev = pool->hashprev;
+
+ bt_releasewrite (&bt->mgr->latch[victim]);
+
+ // remove old file mapping
+#ifdef unix
+ munmap (pool->map, (bt->mgr->poolmask+1) << bt->mgr->page_bits);
+#else
+ FlushViewOfFile(pool->map, 0);
+ UnmapViewOfFile(pool->map);
+ CloseHandle(pool->hmap);
+#endif
+ pool->map = NULL;
+
+ // create new pool mapping
+ // and link into hash table
+
+ if( bt_mapsegment(bt, pool, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, pool, page_no, idx);
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement (&pool->pin);
+#endif
+ bt_releasewrite (&bt->mgr->latch[idx]);
+ return pool;
+ }
+}
+
+// place write, read, or parent lock on requested page_no.
+// pin to buffer pool and return page pointer
+
+BTERR bt_lockpage(BtDb *bt, uid page_no, BtLock mode, BtPage *pageptr)
+{
+BtLatchSet *set;
+BtPool *pool;
+uint subpage;
+BtPage page;
+
+ // find/create maping in pool table
+ // and pin our pool slot
+
+ if( pool = bt_pinpage(bt, page_no) )
+ subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
+ else
+ return bt->err;
+
+ set = pool->pagelatch + subpage;
+ page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
+#ifdef unix
+ {
+ uint idx = subpage / 8;
+ uint bit = subpage % 8;
+
+ if( !((bt->mgr->pooladvise + pool->slot * (bt->mgr->poolmask + 1)/8)[idx] >> bit) & 1 ) {
+ madvise (page, bt->mgr->page_size, MADV_WILLNEED);
+ (bt->mgr->pooladvise + pool->slot * (bt->mgr->poolmask + 1)/8)[idx] |= 1 << bit;
+ }
+ }
+#endif
+
+ switch( mode ) {
+ case BtLockRead:
+ bt_readlock (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_writelock (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_readlock (set->access);
+ break;
+ case BtLockDelete:
+ bt_writelock (set->access);
+ break;
+ case BtLockParent:
+ bt_writelock (set->parent);
+ break;
+ default:
+ return bt->err = BTERR_lock;
+ }
+
+ if( pageptr )
+ *pageptr = page;
+
+ return bt->err = 0;
+}
+
+// remove write, read, or parent lock on requested page_no.
+
+BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode)
+{
+uint subpage, idx;
+BtLatchSet *set;
+BtPool *pool;
+
+ // since page is pinned
+ // it should still be in the buffer pool
+ // and is in no danger of being a victim for reuse
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_readlock (&bt->mgr->latch[idx]);
+
+ if( pool = bt_findpool(bt, page_no, idx) )
+ subpage = (uint)(page_no & bt->mgr->poolmask);
+ else
+ return bt->err = BTERR_hash;
+
+ bt_releaseread (&bt->mgr->latch[idx]);
+ set = pool->pagelatch + subpage;
+
+ switch( mode ) {
+ case BtLockRead:
+ bt_releaseread (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_releasewrite (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_releaseread (set->access);
+ break;
+ case BtLockDelete:
+ bt_releasewrite (set->access);
+ break;
+ case BtLockParent:
+ bt_releasewrite (set->parent);
+ break;
+ default:
+ return bt->err = BTERR_lock;
+ }
+
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, -1);
+#else
+ _InterlockedDecrement (&pool->pin);
+#endif
+ return bt->err = 0;
+}
+
+// deallocate a deleted page
+// place on free chain out of allocator page
+
+BTERR bt_freepage(BtDb *bt, uid page_no)
+{
+ // obtain delete lock on deleted page
+
+ if( bt_lockpage(bt, page_no, BtLockDelete, NULL) )
+ return bt->err;
+
+ // obtain write lock on deleted page
+
+ if( bt_lockpage(bt, page_no, BtLockWrite, &bt->temp) )
+ return bt->err;
+
+ // lock allocation page
+
+ if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) )
+ return bt->err;
+
+ // store chain in second right
+ bt_putid(bt->temp->right, bt_getid(bt->alloc[1].right));
+ bt_putid(bt->alloc[1].right, page_no);
+
+ // unlock page zero
+
+ if( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
+ return bt->err;
+
+ // remove write lock on deleted node
+
+ if( bt_unlockpage(bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ // remove delete lock on deleted node
+
+ if( bt_unlockpage(bt, page_no, BtLockDelete) )
+ return bt->err;
+
+ return 0;
+}
+
+// allocate a new page and write page into it
+
+uid bt_newpage(BtDb *bt, BtPage page)
+{
+uid new_page;
+BtPage pmap;
+int reuse;
+
+ // lock page zero
+
+ if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) )
+ return 0;
+
+ // use empty chain first
+ // else allocate empty page
+
+ if( new_page = bt_getid(bt->alloc[1].right) ) {
+ if( bt_lockpage (bt, new_page, BtLockWrite, &bt->temp) )
+ return 0;
+ bt_putid(bt->alloc[1].right, bt_getid(bt->temp->right));
+ if( bt_unlockpage (bt, new_page, BtLockWrite) )
+ return 0;
+ reuse = 1;
+ } else {
+ new_page = bt_getid(bt->alloc->right);
+ bt_putid(bt->alloc->right, new_page+1);
+ reuse = 0;
+ }
+#ifdef unix
+ if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+
+ // if writing first page of pool block, zero last page in the block
+
+ if ( !reuse && bt->mgr->poolmask > 0 && (new_page & bt->mgr->poolmask) == 0 )
+ {
+ // use zero buffer to write zeros
+ memset(bt->zero, 0, bt->mgr->page_size);
+ if ( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->poolmask) << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+ }
+#else
+ // bring new page into pool and copy page.
+ // this will extend the file into the new pages.
+
+ if( bt_lockpage(bt, new_page, BtLockWrite, &pmap) )
+ return 0;
+
+ memcpy(pmap, page, bt->mgr->page_size);
+
+ if( bt_unlockpage (bt, new_page, BtLockWrite) )
+ return 0;
+#endif
+ // unlock page zero
+
+ if ( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
+ return 0;
+
+ return new_page;
+}
+
+// find slot in page for given key at a given level
+
+int bt_findslot (BtDb *bt, unsigned char *key, uint len)
+{
+uint diff, higher = bt->page->cnt, low = 1, slot;
+
+ // low is the lowest candidate, higher is already
+ // tested as .ge. the given key, loop ends when they meet
+
+ while( diff = higher - low ) {
+ slot = low + ( diff >> 1 );
+ if( keycmp (keyptr(bt->page, slot), key, len) < 0 )
+ low = slot + 1;
+ else
+ higher = slot;
+ }
+
+ return higher;
+}
+
+// find and load page at given level for given key
+// leave page rd or wr locked as requested
+
+int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, uint lock)
+{
+uid page_no = ROOT_page, prevpage = 0;
+uint drill = 0xff, slot;
+uint mode, prevmode;
+
+ // start at root of btree and drill down
+
+ do {
+ // determine lock mode of drill level
+ mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead;
+
+ bt->page_no = page_no;
+
+ // obtain access lock using lock chaining with Access mode
+
+ if( page_no > ROOT_page )
+ if( bt_lockpage(bt, page_no, BtLockAccess, NULL) )
+ return 0;
+
+ if( prevpage )
+ if( bt_unlockpage(bt, prevpage, prevmode) )
+ return 0;
+
+ // obtain read lock using lock chaining
+ // and pin page contents
+
+ if( bt_lockpage(bt, page_no, mode, &bt->page) )
+ return 0;
+
+ if( page_no > ROOT_page )
+ if( bt_unlockpage(bt, page_no, BtLockAccess) )
+ return 0;
+
+ // re-read and re-lock root after determining actual level of root
+
+ if( bt->page_no == ROOT_page )
+ if( bt->page->lvl != drill) {
+ drill = bt->page->lvl;
+
+ if( lock == BtLockWrite && drill == lvl )
+ if( bt_unlockpage(bt, page_no, mode) )
+ return 0;
+ else
+ continue;
+ }
+
+ // if page is being deleted,
+ // move back to preceeding page
+
+ if( bt->page->kill ) {
+ page_no = bt_getid (bt->page->right);
+ continue;
+ }
+
+ // find key on page at this level
+ // and descend to requested level
+
+ slot = bt_findslot (bt, key, len);
+
+ // is this slot a foster child?
+
+ if( slot <= bt->page->cnt - bt->page->foster )
+ if( drill == lvl )
+ return slot;
+ else
+ drill--;
+
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ return bt->err = BTERR_struct, 0;
+
+ // continue down / right using overlapping locks
+ // to protect pages being killed or split.
+
+ prevmode = mode;
+ prevpage = bt->page_no;
+ page_no = bt_getid(slotptr(bt->page, slot)->id);
+ } while( page_no );
+
+ // return error on end of chain
+
+ bt->err = BTERR_struct;
+ return 0; // return error
+}
+
+// find and delete key on page by marking delete flag bit
+// when page becomes empty, delete it from the btree
+
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl)
+{
+unsigned char leftkey[256], rightkey[256];
+uid page_no, right;
+uint slot, tod;
+BtKey ptr;
+
+ if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // if key is found delete it, otherwise ignore request
+
+ if( !keycmp (ptr, key, len) )
+ if( slotptr(bt->page, slot)->dead == 0 ) {
+ slotptr(bt->page,slot)->dead = 1;
+ if( slot < bt->page->cnt )
+ bt->page->dirty = 1;
+ bt->page->act--;
+ }
+
+ // return if page is not empty, or it has no right sibling
+
+ right = bt_getid(bt->page->right);
+ page_no = bt->page_no;
+
+ if( !right || bt->page->act )
+ return bt_unlockpage(bt, page_no, BtLockWrite);
+
+ // obtain Parent lock over write lock
+
+ if( bt_lockpage(bt, page_no, BtLockParent, NULL) )
+ return bt->err;
+
+ // cache copy of key to delete
+
+ ptr = keyptr(bt->page, bt->page->cnt);
+ memcpy(leftkey, ptr, ptr->len + 1);
+
+ // lock and map right page
+
+ if ( bt_lockpage(bt, right, BtLockWrite, &bt->temp) )
+ return bt->err;
+
+ // pull contents of next page into current empty page
+ memcpy (bt->page, bt->temp, bt->mgr->page_size);
+
+ // cache copy of key to update
+ ptr = keyptr(bt->temp, bt->temp->cnt);
+ memcpy(rightkey, ptr, ptr->len + 1);
+
+ // Mark right page as deleted and point it to left page
+ // until we can post updates at higher level.
+
+ bt_putid(bt->temp->right, page_no);
+ bt->temp->kill = 1;
+ bt->temp->cnt = 0;
+
+ if( bt_unlockpage(bt, right, BtLockWrite) )
+ return bt->err;
+ if( bt_unlockpage(bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ // delete old lower key to consolidated node
+
+ if( bt_deletekey (bt, leftkey + 1, *leftkey, lvl + 1) )
+ return bt->err;
+
+ // redirect higher key directly to consolidated node
+
+ if( slot = bt_loadpage (bt, rightkey+1, *rightkey, lvl+1, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // since key already exists, update id
+
+ if( keycmp (ptr, rightkey+1, *rightkey) )
+ return bt->err = BTERR_struct;
+
+ slotptr(bt->page, slot)->dead = 0;
+ bt_putid(slotptr(bt->page,slot)->id, page_no);
+ bt_unlockpage(bt, bt->page_no, BtLockWrite);
+
+ // obtain write lock and
+ // add right block to free chain
+
+ if( bt_freepage (bt, right) )
+ return bt->err;
+
+ // remove ParentModify lock
+
+ if( bt_unlockpage(bt, page_no, BtLockParent) )
+ return bt->err;
+
+ return 0;
+}
+
+// find key in leaf level and return row-id
+
+uid bt_findkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+BtKey ptr;
+uid id;
+
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return 0;
+
+ // if key exists, return row-id
+ // otherwise return 0
+
+ if( ptr->len == len && !memcmp (ptr->key, key, len) )
+ id = bt_getid(slotptr(bt->page,slot)->id);
+ else
+ id = 0;
+
+ if ( bt_unlockpage(bt, bt->page_no, BtLockRead) )
+ return 0;
+
+ return id;
+}
+
+// check page for space available,
+// clean if necessary and return
+// 0 - page needs splitting
+// 1 - go ahead
+
+uint bt_cleanpage(BtDb *bt, uint amt)
+{
+uint nxt = bt->mgr->page_size;
+BtPage page = bt->page;
+uint cnt = 0, idx = 0;
+uint max = page->cnt;
+BtKey key;
+
+ if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return 1;
+
+ // skip cleanup if nothing to reclaim
+
+ if( !page->dirty )
+ return 0;
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+
+ // skip page info and set rest of page to zero
+
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ page->dirty = 0;
+ page->act = 0;
+
+ // try cleaning up page first
+
+ while( cnt++ < max ) {
+ // always leave fence key and foster children in list
+ if( cnt < max - page->foster && slotptr(bt->frame,cnt)->dead )
+ continue;
+
+ // copy key
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+
+ // copy slot
+ memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId);
+ if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
+ page->act++;
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ // see if page has enough space now, or does it need splitting?
+
+ if( page->min >= (idx+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return 1;
+
+ return 0;
+}
+
+// add key to page
+// return with page unlocked
+
+BTERR bt_addkeytopage (BtDb *bt, uint slot, unsigned char *key, uint len, uid id, uint tod)
+{
+BtPage page = bt->page;
+uint idx;
+
+ // calculate next available slot and copy key into page
+
+ page->min -= len + 1;
+ ((unsigned char *)page)[page->min] = len;
+ memcpy ((unsigned char *)page + page->min +1, key, len );
+
+ for( idx = slot; idx < page->cnt; idx++ )
+ if( slotptr(page, idx)->dead )
+ break;
+
+ // now insert key into array before slot
+ // preserving the fence slot
+
+ if( idx == page->cnt )
+ idx++, page->cnt++;
+
+ page->act++;
+
+ while( idx > slot )
+ *slotptr(page, idx) = *slotptr(page, idx -1), idx--;
+
+ bt_putid(slotptr(page,slot)->id, id);
+ slotptr(page, slot)->off = page->min;
+ slotptr(page, slot)->tod = tod;
+ slotptr(page, slot)->dead = 0;
+
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+}
+
+// split the root and raise the height of the btree
+
+BTERR bt_splitroot(BtDb *bt, uid right)
+{
+uint nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+BtPage root = bt->page;
+uid new_page;
+BtKey key;
+
+ // Obtain an empty page to use, and copy the left page
+ // contents into it from the root. Strip foster child key.
+ // (it's the stopper key)
+
+ root->act--;
+ root->cnt--;
+ root->foster--;
+
+ // Save left fence key.
+
+ key = keyptr(root, root->cnt);
+ memcpy (fencekey, key, key->len + 1);
+
+ // copy the lower keys into a new left page
+
+ if( !(new_page = bt_newpage(bt, root)) )
+ return bt->err;
+
+ // preserve the page info at the bottom
+ // and set rest of the root to zero
+
+ memset (root+1, 0, bt->mgr->page_size - sizeof(*root));
+
+ // insert left fence key on empty newroot page
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 1)->id, new_page);
+ slotptr(root, 1)->off = nxt;
+
+ // insert stopper key on newroot page
+ // and increase the root height
+
+ nxt -= 3;
+ fencekey[0] = 2;
+ fencekey[1] = 0xff;
+ fencekey[2] = 0xff;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 2)->id, right);
+ slotptr(root, 2)->off = nxt;
+
+ bt_putid(root->right, 0);
+ root->min = nxt; // reset lowest used offset and key count
+ root->cnt = 2;
+ root->act = 2;
+ root->lvl++;
+
+ // release root (bt->page)
+
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+}
+
+// split already locked full node
+// return unlocked.
+
+BTERR bt_splitpage (BtDb *bt)
+{
+uint slot, cnt, idx, max, nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+uid page_no = bt->page_no;
+BtPage page = bt->page;
+uint tod = time(NULL);
+uint lvl = page->lvl;
+uid new_page, right;
+BtKey key;
+
+ // initialize frame buffer
+
+ memset (bt->frame, 0, bt->mgr->page_size);
+ max = page->cnt - page->foster;
+ tod = (uint)time(NULL);
+ cnt = max / 2;
+ idx = 0;
+
+ // split higher half of keys to bt->frame
+ // leaving foster children in the left node.
+
+ while( cnt++ < max ) {
+ key = keyptr(page, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1);
+ memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId);
+ slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod;
+ slotptr(bt->frame, idx)->off = nxt;
+ bt->frame->act++;
+ }
+
+ // transfer right link node
+
+ if( page_no > ROOT_page ) {
+ right = bt_getid (page->right);
+ bt_putid(bt->frame->right, right);
+ }
+
+ bt->frame->bits = bt->mgr->page_bits;
+ bt->frame->min = nxt;
+ bt->frame->cnt = idx;
+ bt->frame->lvl = lvl;
+
+ // get new free page and write frame to it.
+
+ if( !(new_page = bt_newpage(bt, bt->frame)) )
+ return bt->err;
+
+ // remember fence key for new page to add
+ // as foster child
+
+ key = keyptr(bt->frame, idx);
+ memcpy (fencekey, key, key->len + 1);
+
+ // update lower keys and foster children to continue in old page
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ nxt = bt->mgr->page_size;
+ page->act = 0;
+ cnt = 0;
+ idx = 0;
+
+ // assemble page of smaller keys
+ // to remain in the old page
+
+ while( cnt++ < max / 2 ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ page->act++;
+ }
+
+ // insert new foster child at beginning of the current foster children
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)page + nxt, fencekey, *fencekey + 1);
+ bt_putid (slotptr(page,++idx)->id, new_page);
+ slotptr(page, idx)->tod = tod;
+ slotptr(page, idx)->off = nxt;
+ page->foster++;
+ page->act++;
+
+ // continue with old foster child keys if any
+
+ cnt = bt->frame->cnt - bt->frame->foster;
+
+ while( cnt++ < bt->frame->cnt ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ page->act++;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ // link new right page
+
+ bt_putid (page->right, new_page);
+
+ // if current page is the root page, split it
+
+ if( page_no == ROOT_page )
+ return bt_splitroot (bt, new_page);
+
+ // release wr lock on page
+
+ if( bt_unlockpage (bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ // obtain ParentModification lock for current page
+ // to fix fence key and highest foster child on page
+
+ if( bt_lockpage (bt, page_no, BtLockParent, NULL) )
+ return bt->err;
+
+ // get our highest foster child key to find in parent node
+
+ if( bt_lockpage (bt, page_no, BtLockRead, &page) )
+ return bt->err;
+
+ key = keyptr(page, page->cnt);
+ memcpy (fencekey, key, key->len+1);
+
+ if( bt_unlockpage (bt, page_no, BtLockRead) )
+ return bt->err;
+
+try_again:
+
+ do {
+ slot = bt_loadpage (bt, fencekey + 1, *fencekey, lvl + 1, BtLockWrite);
+
+ if( !slot )
+ return bt->err;
+
+ // check if parent page has enough space for any possible key
+
+ if( bt_cleanpage (bt, 256) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ } while( 1 );
+
+ // see if we are still a foster child from another node
+
+ if( bt_getid (slotptr(bt->page, slot)->id) != page_no ) {
+ bt_unlockpage (bt, bt->page_no, BtLockWrite);
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ goto try_again;
+ }
+
+ // wait until readers from parent get their locks
+
+ if( bt_lockpage (bt, page_no, BtLockDelete, NULL) )
+ return bt->err;
+
+ if( bt_lockpage (bt, page_no, BtLockWrite, &page) )
+ return bt->err;
+
+ // switch parent fence key to foster child
+
+ if( slotptr(page, page->cnt)->dead )
+ slotptr(bt->page, slot)->dead = 1;
+ else
+ bt_putid (slotptr(bt->page, slot)->id, bt_getid(slotptr(page, page->cnt)->id));
+
+ // remove highest foster child from our page
+ // add our new fence key to parent
+
+ page->cnt--;
+ page->act--;
+ page->foster--;
+ page->dirty = 1;
+ key = keyptr(page, page->cnt);
+
+ if( bt_addkeytopage (bt, slot, key->key, key->len, page_no, tod) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockDelete) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ return bt_unlockpage (bt, page_no, BtLockParent);
+}
+
+// Insert new key into the btree at leaf level.
+
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod)
+{
+uint slot, idx;
+BtPage page;
+BtKey ptr;
+
+ while( 1 ) {
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ {
+ if ( !bt->err )
+ bt->err = BTERR_ovflw;
+ return bt->err;
+ }
+
+ // if key already exists, update id and return
+
+ page = bt->page;
+
+ if( !keycmp (ptr, key, len) ) {
+ slotptr(page, slot)->dead = 0;
+ slotptr(page, slot)->tod = tod;
+ bt_putid(slotptr(page,slot)->id, id);
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+ }
+
+ // check if page has enough space
+
+ if( bt_cleanpage (bt, len) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ }
+
+ return bt_addkeytopage (bt, slot, key, len, id, tod);
+}
+
+// cache page of keys into cursor and return starting slot for given key
+
+uint bt_startkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+
+ // cache page for retrieval
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ memcpy (bt->cursor, bt->page, bt->mgr->page_size);
+ bt->cursor_page = bt->page_no;
+ if ( bt_unlockpage(bt, bt->page_no, BtLockRead) )
+ return 0;
+
+ return slot;
+}
+
+// return next slot for cursor page
+// or slide cursor right into next page
+
+uint bt_nextkey (BtDb *bt, uint slot)
+{
+BtPage page;
+uid right;
+
+ do {
+ right = bt_getid(bt->cursor->right);
+ while( slot++ < bt->cursor->cnt - bt->cursor->foster )
+ if( slotptr(bt->cursor,slot)->dead )
+ continue;
+ else if( right || (slot < bt->cursor->cnt - bt->cursor->foster) )
+ return slot;
+ else
+ break;
+
+ if( !right )
+ break;
+
+ bt->cursor_page = right;
+
+ if( bt_lockpage(bt, right, BtLockRead, &page) )
+ return 0;
+
+ memcpy (bt->cursor, page, bt->mgr->page_size);
+
+ if ( bt_unlockpage(bt, right, BtLockRead) )
+ return 0;
+
+ slot = 0;
+ } while( 1 );
+
+ return bt->err = 0;
+}
+
+BtKey bt_key(BtDb *bt, uint slot)
+{
+ return keyptr(bt->cursor, slot);
+}
+
+uid bt_uid(BtDb *bt, uint slot)
+{
+ return bt_getid(slotptr(bt->cursor,slot)->id);
+}
+
+uint bt_tod(BtDb *bt, uint slot)
+{
+ return slotptr(bt->cursor,slot)->tod;
+}
+
+
+#ifdef STANDALONE
+
+typedef struct {
+ char type, idx;
+ char *infile;
+ BtMgr *mgr;
+ int num;
+} ThreadArg;
+
+// standalone program to index file of keys
+// then list them onto std-out
+
+#ifdef unix
+void *index_file (void *arg)
+#else
+uint __stdcall index_file (void *arg)
+#endif
+{
+int line = 0, found = 0, cnt = 0;
+uid next, page_no = LEAF_page; // start on first page of leaves
+unsigned char key[256];
+ThreadArg *args = arg;
+int ch, len = 0, slot;
+time_t tod[1];
+BtPage page;
+BtKey ptr;
+BtDb *bt;
+FILE *in;
+
+ bt = bt_open (args->mgr);
+ time (tod);
+
+ switch(args->type | 0x20)
+ {
+ case 'w':
+ fprintf(stderr, "started indexing for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_insertkey (bt, key, len, line, *tod) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys\n", args->infile, line);
+ break;
+
+ case 'd':
+ fprintf(stderr, "started deleting keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_deletekey (bt, key, len, 0) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for keys, %d \n", args->infile, line);
+ break;
+
+ case 'f':
+ fprintf(stderr, "started finding keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_findkey (bt, key, len) )
+ found++;
+ else if( bt->err )
+ fprintf(stderr, "Error %d Syserr %d Line: %d\n", bt->err, errno, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys, found %d\n", args->infile, line, found);
+ break;
+
+ case 's':
+ len = key[0] = 0;
+
+ fprintf(stderr, "started reading\n");
+
+ if( slot = bt_startkey (bt, key, len) )
+ slot--;
+ else
+ fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0);
+
+ while( slot = bt_nextkey (bt, slot) ) {
+ ptr = bt_key(bt, slot);
+ fwrite (ptr->key, ptr->len, 1, stdout);
+ fputc ('\n', stdout);
+ }
+
+ break;
+
+ case 'c':
+ fprintf(stderr, "started reading\n");
+
+ do {
+ bt_lockpage (bt, page_no, BtLockRead, &page);
+ cnt += page->act;
+ next = bt_getid (page->right);
+ bt_unlockpage (bt, page_no, BtLockRead);
+ } while( page_no = next );
+
+ cnt--; // remove stopper key
+ fprintf(stderr, " Total keys read %d\n", cnt);
+ break;
+ }
+
+ bt_close (bt);
+#ifdef unix
+ return NULL;
+#else
+ return 0;
+#endif
+}
+
+typedef struct timeval timer;
+
+int main (int argc, char **argv)
+{
+int idx, cnt, len, slot, err;
+int segsize, bits = 16;
+#ifdef unix
+pthread_t *threads;
+timer start, stop;
+#else
+time_t start[1], stop[1];
+HANDLE *threads;
+#endif
+double real_time;
+ThreadArg *args;
+uint poolsize = 0;
+int num = 0;
+char key[1];
+BtMgr *mgr;
+BtKey ptr;
+BtDb *bt;
+
+ if( argc < 3 ) {
+ fprintf (stderr, "Usage: %s idx_file Read/Write/Scan/Delete/Find [page_bits mapped_segments seg_bits line_numbers src_file1 src_file2 ... ]\n", argv[0]);
+ fprintf (stderr, " where page_bits is the page size in bits\n");
+ fprintf (stderr, " mapped_segments is the number of mmap segments in buffer pool\n");
+ fprintf (stderr, " seg_bits is the size of individual segments in buffer pool in pages in bits\n");
+ fprintf (stderr, " line_numbers = 1 to append line numbers to keys\n");
+ fprintf (stderr, " src_file1 thru src_filen are files of keys separated by newline\n");
+ exit(0);
+ }
+
+#ifdef unix
+ gettimeofday(&start, NULL);
+#else
+ time(start);
+#endif
+
+ if( argc > 3 )
+ bits = atoi(argv[3]);
+
+ if( argc > 4 )
+ poolsize = atoi(argv[4]);
+
+ if( !poolsize )
+ fprintf (stderr, "Warning: no mapped_pool\n");
+
+ if( poolsize > 65535 )
+ fprintf (stderr, "Warning: mapped_pool > 65535 segments\n");
+
+ if( argc > 5 )
+ segsize = atoi(argv[5]);
+ else
+ segsize = 4; // 16 pages per mmap segment
+
+ if( argc > 6 )
+ num = atoi(argv[6]);
+
+ cnt = argc - 7;
+#ifdef unix
+ threads = malloc (cnt * sizeof(pthread_t));
+#else
+ threads = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, cnt * sizeof(HANDLE));
+#endif
+ args = malloc (cnt * sizeof(ThreadArg));
+
+ mgr = bt_mgr ((argv[1]), BT_rw, bits, poolsize, segsize, poolsize / 8);
+
+ if( !mgr ) {
+ fprintf(stderr, "Index Open Error %s\n", argv[1]);
+ exit (1);
+ }
+
+ // fire off threads
+
+ for( idx = 0; idx < cnt; idx++ ) {
+ args[idx].infile = argv[idx + 7];
+ args[idx].type = argv[2][0];
+ args[idx].mgr = mgr;
+ args[idx].num = num;
+ args[idx].idx = idx;
+#ifdef unix
+ if( err = pthread_create (threads + idx, NULL, index_file, args + idx) )
+ fprintf(stderr, "Error creating thread %d\n", err);
+#else
+ threads[idx] = (HANDLE)_beginthreadex(NULL, 65536, index_file, args + idx, 0, NULL);
+#endif
+ }
+
+ // wait for termination
+
+#ifdef unix
+ for( idx = 0; idx < cnt; idx++ )
+ pthread_join (threads[idx], NULL);
+ gettimeofday(&stop, NULL);
+ real_time = 1000.0 * ( stop.tv_sec - start.tv_sec ) + 0.001 * (stop.tv_usec - start.tv_usec );
+#else
+ WaitForMultipleObjects (cnt, threads, TRUE, INFINITE);
+
+ for( idx = 0; idx < cnt; idx++ )
+ CloseHandle(threads[idx]);
+
+ time (stop);
+ real_time = 1000 * (*stop - *start);
+#endif
+ fprintf(stderr, " Time to complete: %.2f seconds\n", real_time/1000);
+ bt_mgrclose (mgr);
+}
+
+#endif //STANDALONE
-// foster btree version e
-// 30 DEC 2013
+// foster btree version e2
+// 18 JAN 2014
// author: karl malbrain, malbrain@cal.berkeley.edu
// the tod field from the key.
// Keys are marked dead, but remain on the page until
-// it cleanup is called. The fence key (highest key) for
+// cleanup is called. The fence key (highest key) for
// the page is always present, even after cleanup.
typedef struct {
// by the BtSlot array of keys.
typedef struct Page {
- uint cnt; // count of keys in page
- uint act; // count of active keys
- uint min; // next key offset
- uint foster; // count of foster children
+ volatile uint cnt; // count of keys in page
+ volatile uint act; // count of active keys
+ volatile uint min; // next key offset
+ volatile uint foster; // count of foster children
unsigned char bits; // page size in bits
- unsigned char lvl:6; // level of page
- unsigned char kill:1; // page is being deleted
+ unsigned char lvl:7; // level of page
unsigned char dirty:1; // page needs to be cleaned
unsigned char right[BtId]; // page number to right
} *BtPage;
volatile ushort slot; // Latch table entry at head of chain
} BtHashEntry;
-// latch table lock structure
-// implements a fair read-write lock
+// latch manager table structure
typedef struct {
#ifdef unix
#endif
ushort poolcnt; // highest page pool node in use
ushort poolmax; // highest page pool node allocated
- ushort poolmask; // total size of pages in mmap segment - 1
+ ushort poolmask; // total number of pages in mmap segment - 1
ushort hashsize; // size of Hash Table for pool entries
ushort evicted; // last evicted hash table slot
ushort *hash; // hash table of pool entries
BtPool *pool; // memory pool page segments
BtSpinLatch *latch; // latches for pool hash slots
BtLatchMgr *latchmgr; // mapped latch page from allocation page
- BtLatchSet *latchset; // first mapped latch set from latch pages
+ BtLatchSet *latchsets; // mapped latch set from latch pages
#ifndef unix
HANDLE halloc; // allocation and latch table handle
#endif
typedef struct {
BtMgr *mgr; // buffer manager for thread
- BtPage temp; // temporary frame buffer (memory mapped/file IO)
BtPage cursor; // cached frame for start/next (never mapped)
BtPage frame; // spare frame for the page split (never mapped)
BtPage zero; // page frame for zeroes at end of file
BtPage page; // current page
uid page_no; // current page number
uid cursor_page; // current cursor page number
+ BtLatchSet *set; // current page latch set
+ BtPool *pool; // current page pool
unsigned char *mem; // frame, cursor, page memory buffer
+ int found; // last delete was found
int err; // last error
} BtDb;
// B-Tree functions
extern void bt_close (BtDb *bt);
extern BtDb *bt_open (BtMgr *mgr);
-extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod);
-extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl);
+extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod, uint lvl);
+extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len);
extern uid bt_findkey (BtDb *bt, unsigned char *key, uint len);
extern uint bt_startkey (BtDb *bt, unsigned char *key, uint len);
extern uint bt_nextkey (BtDb *bt, uint slot);
void bt_spinwritelock(BtSpinLatch *latch)
{
-ushort prev;
-
do {
-#ifdef unix
+#ifdef unix
while( __sync_fetch_and_or((ushort *)latch, Mutex | Pending) & Mutex )
sched_yield();
#else
while( _InterlockedOr16((ushort *)latch, Mutex | Pending) & Mutex )
SwitchToThread();
#endif
- if( prev = !(latch->share | latch->exclusive) )
+ if( !(latch->share | latch->exclusive) ) {
#ifdef unix
__sync_fetch_and_or((ushort *)latch, Write);
+ __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending));
#else
_InterlockedOr16((ushort *)latch, Write);
+ _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending));
#endif
+ return;
+ }
#ifdef unix
- __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending));
+ __sync_fetch_and_and ((ushort *)latch, ~Mutex);
#else
- _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending));
+ _InterlockedAnd16((ushort *)latch, ~Mutex);
#endif
- if( prev )
- return;
#ifdef unix
sched_yield();
#else
#endif
}
-void bt_initlockset (BtLatchSet *set)
+void bt_initlockset (BtLatchSet *set, int reuse)
{
#ifdef unix
pthread_rwlockattr_t rwattr[1];
+ if( reuse ) {
+ pthread_rwlock_destroy (set->readwr->lock);
+ pthread_rwlock_destroy (set->access->lock);
+ pthread_rwlock_destroy (set->parent->lock);
+ }
+
pthread_rwlockattr_init (rwattr);
pthread_rwlockattr_setkind_np (rwattr, PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
pthread_rwlockattr_setpshared (rwattr, PTHREAD_PROCESS_SHARED);
void bt_latchlink (BtDb *bt, ushort hashidx, ushort victim, uid page_no)
{
-BtLatchSet *set = bt->mgr->latchset + victim;
+BtLatchSet *set = bt->mgr->latchsets + victim;
if( set->next = bt->mgr->latchmgr->table[hashidx].slot )
- bt->mgr->latchset[set->next].prev = victim;
+ bt->mgr->latchsets[set->next].prev = victim;
bt->mgr->latchmgr->table[hashidx].slot = victim;
set->page_no = page_no;
set->prev = 0;
}
+void bt_unpinlatch (BtLatchSet *set)
+{
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, -1);
+#else
+ _InterlockedDecrement16 (&set->pin);
+#endif
+}
+
// find existing latchset or inspire new one
// return with latchset pinned
-BtLatchSet *bt_bindlatch (BtDb *bt, uid page_no, int incr)
+BtLatchSet *bt_pinlatch (BtDb *bt, uid page_no)
{
ushort hashidx = page_no % bt->mgr->latchmgr->latchhash;
ushort slot, avail = 0, victim, idx;
if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
{
- set = bt->mgr->latchset + slot;
+ set = bt->mgr->latchsets + slot;
if( page_no == set->page_no )
break;
} while( slot = set->next );
- if( slot && incr ) {
+ if( slot ) {
#ifdef unix
__sync_fetch_and_add(&set->pin, 1);
#else
if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
{
- set = bt->mgr->latchset + slot;
+ set = bt->mgr->latchsets + slot;
if( page_no == set->page_no )
break;
if( !set->pin && !avail )
// found our entry, or take over an unpinned one
if( slot || (slot = avail) ) {
- set = bt->mgr->latchset + slot;
- if( incr )
+ set = bt->mgr->latchsets + slot;
#ifdef unix
- __sync_fetch_and_add(&set->pin, 1);
+ __sync_fetch_and_add(&set->pin, 1);
#else
- _InterlockedIncrement16 (&set->pin);
+ _InterlockedIncrement16 (&set->pin);
#endif
set->page_no = page_no;
bt_spinreleasewrite(bt->mgr->latchmgr->table[hashidx].latch);
#endif
if( victim < bt->mgr->latchmgr->latchtotal ) {
- set = bt->mgr->latchset + victim;
- if( incr )
+ set = bt->mgr->latchsets + victim;
#ifdef unix
- __sync_fetch_and_add(&set->pin, 1);
+ __sync_fetch_and_add(&set->pin, 1);
#else
- _InterlockedIncrement16 (&set->pin);
+ _InterlockedIncrement16 (&set->pin);
#endif
- bt_initlockset (set);
+ bt_initlockset (set, 0);
bt_latchlink (bt, hashidx, victim, page_no);
bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch);
return set;
// we don't use slot zero
if( victim %= bt->mgr->latchmgr->latchtotal )
- set = bt->mgr->latchset + victim;
+ set = bt->mgr->latchsets + victim;
else
continue;
// unlink our available victim from its hash chain
if( set->prev )
- bt->mgr->latchset[set->prev].next = set->next;
+ bt->mgr->latchsets[set->prev].next = set->next;
else
bt->mgr->latchmgr->table[idx].slot = set->next;
if( set->next )
- bt->mgr->latchset[set->next].prev = set->prev;
+ bt->mgr->latchsets[set->next].prev = set->prev;
bt_spinreleasewrite (bt->mgr->latchmgr->table[idx].latch);
-
- if( incr )
#ifdef unix
- __sync_fetch_and_add(&set->pin, 1);
+ __sync_fetch_and_add(&set->pin, 1);
#else
- _InterlockedIncrement16 (&set->pin);
+ _InterlockedIncrement16 (&set->pin);
#endif
-
+ bt_initlockset (set, 1);
bt_latchlink (bt, hashidx, victim, page_no);
bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch);
bt_spinreleasewrite (set->busy);
#endif
}
+#ifdef unix
+ munmap (mgr->latchsets, mgr->latchmgr->nlatchpage * mgr->page_size);
+ munmap (mgr->latchmgr, mgr->page_size);
+#else
+ FlushViewOfFile(mgr->latchmgr, 0);
+ UnmapViewOfFile(mgr->latchmgr);
+ CloseHandle(mgr->halloc);
+#endif
#ifdef unix
close (mgr->idx);
free (mgr->pool);
uint lvl, attr, cacheblk, last, slot, idx;
uint nlatchpage, latchhash;
BtLatchMgr *latchmgr;
-int lockmode;
off64_t size;
uint amt[1];
BtMgr* mgr;
#ifdef unix
mgr = calloc (1, sizeof(BtMgr));
- switch (mode & 0x7fff)
- {
- case BT_rw:
- mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
- lockmode = 1;
- break;
+ mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
- case BT_ro:
- default:
- mgr->idx = open ((char*)name, O_RDONLY);
- lockmode = 0;
- break;
- }
if( mgr->idx == -1 )
return free(mgr), NULL;
#else
mgr = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtMgr));
attr = FILE_ATTRIBUTE_NORMAL;
- switch (mode & 0x7fff)
- {
- case BT_rw:
- mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
- lockmode = 1;
- break;
+ mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
- case BT_ro:
- default:
- mgr->idx = CreateFile(name, GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, attr, NULL);
- lockmode = 0;
- break;
- }
if( mgr->idx == INVALID_HANDLE_VALUE )
return GlobalFree(mgr), NULL;
else
return free(mgr), free(latchmgr), NULL;
} else if( mode == BT_ro )
- return bt_mgrclose (mgr), NULL;
+ return free(latchmgr), free (mgr), NULL;
#else
latchmgr = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE);
size = GetFileSize(mgr->idx, amt);
#ifdef unix
if( write (mgr->idx, latchmgr, mgr->page_size) < mgr->page_size )
- return bt_mgrclose (mgr), NULL;
+ return free(latchmgr), bt_mgrclose (mgr), NULL;
#else
if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
return bt_mgrclose (mgr), NULL;
mgrlatch:
#ifdef unix
- flag = PROT_READ | ( mgr->mode == BT_ro ? 0 : PROT_WRITE );
+ flag = PROT_READ | PROT_WRITE;
mgr->latchmgr = mmap (0, mgr->page_size, flag, MAP_SHARED, mgr->idx, ALLOC_page * mgr->page_size);
if( mgr->latchmgr == MAP_FAILED )
return bt_mgrclose (mgr), NULL;
- mgr->latchset = (BtLatchSet *)mmap (0, mgr->latchmgr->nlatchpage * mgr->page_size, flag, MAP_SHARED, mgr->idx, LATCH_page * mgr->page_size);
- if( mgr->latchset == MAP_FAILED )
+ mgr->latchsets = (BtLatchSet *)mmap (0, mgr->latchmgr->nlatchpage * mgr->page_size, flag, MAP_SHARED, mgr->idx, LATCH_page * mgr->page_size);
+ if( mgr->latchsets == MAP_FAILED )
return bt_mgrclose (mgr), NULL;
#else
- flag = ( mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE );
+ flag = PAGE_READWRITE;
mgr->halloc = CreateFileMapping(mgr->idx, NULL, flag, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size, NULL);
if( !mgr->halloc )
return bt_mgrclose (mgr), NULL;
- flag = ( mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE );
+ flag = FILE_MAP_WRITE;
mgr->latchmgr = MapViewOfFile(mgr->halloc, flag, 0, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size);
if( !mgr->latchmgr )
return GetLastError(), bt_mgrclose (mgr), NULL;
- mgr->latchset = (void *)((char *)mgr->latchmgr + LATCH_page * mgr->page_size);
+ mgr->latchsets = (void *)((char *)mgr->latchmgr + LATCH_page * mgr->page_size);
#endif
#ifdef unix
bt->frame = (BtPage)bt->mem;
bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size);
bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size);
+
+ memset(bt->zero, 0, mgr->page_size);
return bt;
}
return bt->err = 0;
}
+// calculate page within pool
+
+BtPage bt_page (BtDb *bt, BtPool *pool, uid page_no)
+{
+uint subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
+BtPage page;
+
+ page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
+#ifdef unix
+ {
+ uint idx = subpage / 8;
+ uint bit = subpage % 8;
+
+ if( ~((bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] >> bit) & 1 ) {
+ madvise (page, bt->mgr->page_size, MADV_WILLNEED);
+ (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] |= 1 << bit;
+ }
+ }
+#endif
+ return page;
+}
+
+// release pool pin
+
+void bt_unpinpool (BtPool *pool)
+{
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, -1);
+#else
+ _InterlockedDecrement16 (&pool->pin);
+#endif
+}
+
// find or place requested page in segment-pool
// return pool table entry, incrementing pin
-BtPool *bt_pinpage(BtDb *bt, uid page_no)
+BtPool *bt_pinpool(BtDb *bt, uid page_no)
{
BtPool *pool, *node, *next;
uint slot, idx, victim;
}
// place write, read, or parent lock on requested page_no.
-// pin to buffer pool and return page pointer
+// pin to buffer pool and return latchset pointer
-BTERR bt_lockpage(BtDb *bt, uid page_no, BtLock mode, BtPage *pageptr)
+void bt_lockpage(BtLock mode, BtLatchSet *set)
{
-BtLatchSet *set;
-BtPool *pool;
-uint subpage;
-BtPage page;
-
- // find/create maping in pool table
- // and pin our pool slot
-
- if( pool = bt_pinpage(bt, page_no) )
- subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
- else
- return bt->err;
-
- if( !(set = bt_bindlatch (bt, page_no, 1)) )
- return bt->err;
-
- page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
-
-#ifdef unix
- {
- uint idx = subpage / 8;
- uint bit = subpage % 8;
-
- if( mode == BtLockRead || mode == BtLockWrite )
- if( ~((bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] >> bit) & 1 ) {
- madvise (page, bt->mgr->page_size, MADV_WILLNEED);
- (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] |= 1 << bit;
- }
- }
-#endif
-
switch( mode ) {
case BtLockRead:
bt_readlock (set->readwr);
case BtLockParent:
bt_writelock (set->parent);
break;
- default:
- return bt->err = BTERR_lock;
}
-
- if( pageptr )
- *pageptr = page;
-
- return bt->err = 0;
}
// remove write, read, or parent lock on requested page_no.
-BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode)
+void bt_unlockpage(BtLock mode, BtLatchSet *set)
{
-BtLatchSet *set;
-BtPool *pool;
-uint idx;
-
- // since page is pinned
- // it should still be in the buffer pool
- // and is in no danger of being a victim for reuse
-
- if( !(set = bt_bindlatch (bt, page_no, 0)) )
- return bt->err = BTERR_latch;
-
- idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
- bt_spinreadlock (&bt->mgr->latch[idx]);
-
- if( !(pool = bt_findpool(bt, page_no, idx)) )
- return bt->err = BTERR_hash;
-
- bt_spinreleaseread (&bt->mgr->latch[idx]);
-
switch( mode ) {
case BtLockRead:
bt_releaseread (set->readwr);
case BtLockParent:
bt_releasewrite (set->parent);
break;
- default:
- return bt->err = BTERR_lock;
}
-
-#ifdef unix
- __sync_fetch_and_add(&pool->pin, -1);
- __sync_fetch_and_add (&set->pin, -1);
-#else
- _InterlockedDecrement16 (&pool->pin);
- _InterlockedDecrement16 (&set->pin);
-#endif
- return bt->err = 0;
-}
-
-// deallocate a deleted page
-// place on free chain out of allocator page
-// fence key must already be removed from parent
-
-BTERR bt_freepage(BtDb *bt, uid page_no)
-{
- // obtain delete lock on deleted page
-
- if( bt_lockpage(bt, page_no, BtLockDelete, NULL) )
- return bt->err;
-
- // obtain write lock on deleted page
-
- if( bt_lockpage(bt, page_no, BtLockWrite, &bt->temp) )
- return bt->err;
-
- // lock allocation page
-
- bt_spinwritelock(bt->mgr->latchmgr->lock);
-
- // store free chain in allocation page second right
- bt_putid(bt->temp->right, bt_getid(bt->mgr->latchmgr->alloc[1].right));
- bt_putid(bt->mgr->latchmgr->alloc[1].right, page_no);
-
- // unlock page zero
-
- bt_spinreleasewrite(bt->mgr->latchmgr->lock);
-
- // remove write lock on deleted node
-
- if( bt_unlockpage(bt, page_no, BtLockWrite) )
- return bt->err;
-
- // remove delete lock on deleted node
-
- if( bt_unlockpage(bt, page_no, BtLockDelete) )
- return bt->err;
-
- return 0;
}
// allocate a new page and write page into it
uid bt_newpage(BtDb *bt, BtPage page)
{
+BtLatchSet *set;
+BtPool *pool;
uid new_page;
BtPage pmap;
int reuse;
// else allocate empty page
if( new_page = bt_getid(bt->mgr->latchmgr->alloc[1].right) ) {
- if( bt_lockpage (bt, new_page, BtLockWrite, &bt->temp) )
- return 0;
- bt_putid(bt->mgr->latchmgr->alloc[1].right, bt_getid(bt->temp->right));
- if( bt_unlockpage (bt, new_page, BtLockWrite) )
+ if( pool = bt_pinpool (bt, new_page) )
+ pmap = bt_page (bt, pool, new_page);
+ else
return 0;
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, bt_getid(pmap->right));
+ bt_unpinpool (pool);
reuse = 1;
} else {
new_page = bt_getid(bt->mgr->latchmgr->alloc->right);
reuse = 0;
}
#ifdef unix
- if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
- return bt->err = BTERR_wrt, 0;
-
// if writing first page of pool block, zero last page in the block
if ( !reuse && bt->mgr->poolmask > 0 && (new_page & bt->mgr->poolmask) == 0 )
{
// use zero buffer to write zeros
- memset(bt->zero, 0, bt->mgr->page_size);
if ( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->poolmask) << bt->mgr->page_bits) < bt->mgr->page_size )
return bt->err = BTERR_wrt, 0;
}
+
+ // unlock allocation latch
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
+ if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+
#else
+ // unlock allocation latch
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
// bring new page into pool and copy page.
// this will extend the file into the new pages.
+ // NB -- no latch required
- if( bt_lockpage(bt, new_page, BtLockWrite, &pmap) )
+ if( pool = bt_pinpool (bt, new_page) )
+ pmap = bt_page (bt, pool, new_page);
+ else
return 0;
memcpy(pmap, page, bt->mgr->page_size);
-
- if( bt_unlockpage (bt, new_page, BtLockWrite) )
- return 0;
+ bt_unpinpool (pool);
#endif
- // unlock allocation latch and return new page no
-
- bt_spinreleasewrite(bt->mgr->latchmgr->lock);
return new_page;
}
// find and load page at given level for given key
// leave page rd or wr locked as requested
-int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, uint lock)
+int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, BtLock lock)
{
uid page_no = ROOT_page, prevpage = 0;
+BtLatchSet *set, *prevset;
uint drill = 0xff, slot;
uint mode, prevmode;
+BtPool *prevpool;
// start at root of btree and drill down
// determine lock mode of drill level
mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead;
+ // obtain latch set for this page
+
+ bt->set = bt_pinlatch (bt, page_no);
bt->page_no = page_no;
+ // pin page contents
+
+ if( bt->pool = bt_pinpool (bt, page_no) )
+ bt->page = bt_page (bt, bt->pool, page_no);
+ else
+ return 0;
+
// obtain access lock using lock chaining with Access mode
if( page_no > ROOT_page )
- if( bt_lockpage(bt, page_no, BtLockAccess, NULL) )
- return 0;
+ bt_lockpage(BtLockAccess, bt->set);
- // now unlock our (possibly foster) parent
+ // now unlock and unpin our (possibly foster) parent
- if( prevpage )
- if( bt_unlockpage(bt, prevpage, prevmode) )
- return 0;
- else
- prevpage = 0;
+ if( prevpage ) {
+ bt_unlockpage(prevmode, prevset);
+ bt_unpinlatch (prevset);
+ bt_unpinpool (prevpool);
+ prevpage = 0;
+ }
// obtain read lock using lock chaining
- // and pin page contents
- if( bt_lockpage(bt, page_no, mode, &bt->page) )
- return 0;
+ bt_lockpage(mode, bt->set);
if( page_no > ROOT_page )
- if( bt_unlockpage(bt, page_no, BtLockAccess) )
- return 0;
+ bt_unlockpage(BtLockAccess, bt->set);
// re-read and re-lock root after determining actual level of root
- if( bt->page_no == ROOT_page )
+ if( page_no == ROOT_page )
if( bt->page->lvl != drill) {
drill = bt->page->lvl;
- if( lock == BtLockWrite && drill == lvl )
- if( bt_unlockpage(bt, page_no, mode) )
- return 0;
- else
- continue;
+ if( lock == BtLockWrite && drill == lvl ) {
+ bt_unlockpage(mode, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ continue;
+ }
}
prevpage = bt->page_no;
+ prevpool = bt->pool;
+ prevset = bt->set;
prevmode = mode;
- // if page is being deleted,
- // move back to preceeding page
-
- if( bt->page->kill ) {
- page_no = bt_getid (bt->page->right);
- continue;
- }
-
// find key on page at this level
- // and descend to requested level
+ // and either descend to requested level
+ // or return key slot
slot = bt_findslot (bt, key, len);
- // is this slot a foster child?
+ // is this slot < foster child area
+ // on the requested level?
+
+ // if so, return actual slot even if dead
if( slot <= bt->page->cnt - bt->page->foster )
if( drill == lvl )
return slot;
+ // find next active slot
+
+ // note: foster children are never dead
+ // nor fence keys for interiour nodes
+
while( slotptr(bt->page, slot)->dead )
if( slot++ < bt->page->cnt )
continue;
else
- goto slideright;
+ return bt->err = BTERR_struct, 0; // last key shouldn't be deleted
+
+ // is this slot < foster child area
+ // if so, drill to next level
if( slot <= bt->page->cnt - bt->page->foster )
drill--;
- // continue down / right using overlapping locks
- // to protect pages being killed or split.
+ // continue right onto foster child
+ // or down to next level.
page_no = bt_getid(slotptr(bt->page, slot)->id);
- continue;
-
-slideright:
- page_no = bt_getid(bt->page->right);
} while( page_no );
}
// find and delete key on page by marking delete flag bit
-// when page becomes empty, delete it from the btree
+// when leaf page becomes empty, delete it from the btree
-BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl)
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len)
{
-unsigned char leftkey[256], rightkey[256];
+unsigned char leftkey[256];
+BtLatchSet *rset, *set;
+BtPool *pool, *rpool;
+BtPage rpage, page;
uid page_no, right;
uint slot, tod;
BtKey ptr;
- if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
ptr = keyptr(bt->page, slot);
else
return bt->err;
// if key is found delete it, otherwise ignore request
+ // note that fence keys of interiour nodes are not deleted.
- if( !keycmp (ptr, key, len) )
- if( slotptr(bt->page, slot)->dead == 0 ) {
+ if( bt->found = !keycmp (ptr, key, len) )
+ if( bt->found = slotptr(bt->page, slot)->dead == 0 ) {
slotptr(bt->page,slot)->dead = 1;
if( slot < bt->page->cnt )
bt->page->dirty = 1;
bt->page->act--;
}
- // return if page is not empty, or it has no right sibling
-
- right = bt_getid(bt->page->right);
page_no = bt->page_no;
+ pool = bt->pool;
+ page = bt->page;
+ set = bt->set;
- if( !right || bt->page->act )
- return bt_unlockpage(bt, page_no, BtLockWrite);
-
- // obtain Parent lock over write lock
+ // return if page is not empty or not found
- if( bt_lockpage(bt, page_no, BtLockParent, NULL) )
+ if( page->act || !bt->found ) {
+ bt_unlockpage(BtLockWrite, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
return bt->err;
+ }
- // cache copy of key to delete
+ // cache copy of fence key of empty node
- ptr = keyptr(bt->page, bt->page->cnt);
+ ptr = keyptr(page, page->cnt);
memcpy(leftkey, ptr, ptr->len + 1);
- // lock and map right page
+ // release write lock on empty node
+ // obtain Parent lock
- if( bt_lockpage(bt, right, BtLockWrite, &bt->temp) )
- return bt->err;
+ bt_unlockpage(BtLockWrite, set);
+ bt_lockpage(BtLockParent, set);
- // pull contents of next page into current empty page
- memcpy (bt->page, bt->temp, bt->mgr->page_size);
+ // load and lock parent to see
+ // if delete of empty node is OK
+ // ie, not a fence key of parent
- // cache copy of key to update
- ptr = keyptr(bt->temp, bt->temp->cnt);
- memcpy(rightkey, ptr, ptr->len + 1);
+ while( 1 ) {
+ if( slot = bt_loadpage (bt, leftkey+1, *leftkey, 1, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
- // Mark right page as deleted and point it to left page
- // until we can post updates at higher level.
+ // does parent level contain our fence key yet?
+ // and is it free of foster children?
- bt_putid(bt->temp->right, page_no);
- bt->temp->kill = 1;
- bt->temp->cnt = 0;
+ if( !bt->page->foster )
+ if( !keycmp (ptr, leftkey+1, *leftkey) )
+ break;
- if( bt_unlockpage(bt, right, BtLockWrite) )
- return bt->err;
- if( bt_unlockpage(bt, page_no, BtLockWrite) )
- return bt->err;
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ }
- // delete old lower key to consolidated node
+ // find our left fence key
- if( bt_deletekey (bt, leftkey + 1, *leftkey, lvl + 1) )
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ return bt->err = BTERR_struct; // last key shouldn't be deleted
+
+ // now we have both parent and child
+
+ bt_lockpage(BtLockDelete, set);
+ bt_lockpage(BtLockWrite, set);
+
+ // return if page has no right sibling within parent
+ // or if empty node is no longer empty
+
+ if( page->act || slot == bt->page->cnt ) {
+ // unpin parent
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ // unpin empty node
+ bt_unlockpage(BtLockParent, set);
+ bt_unlockpage(BtLockDelete, set);
+ bt_unlockpage(BtLockWrite, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
return bt->err;
+ }
- // redirect higher key directly to consolidated node
+ // lock and map our right page
+ // note that it cannot be our foster child
+ // since the our node is empty
- if( slot = bt_loadpage (bt, rightkey+1, *rightkey, lvl+1, BtLockWrite) )
- ptr = keyptr(bt->page, slot);
+ right = bt_getid(page->right);
+
+ if( rpool = bt_pinpool (bt, right) )
+ rpage = bt_page (bt, rpool, right);
else
return bt->err;
- // since key already exists, update id
+ rset = bt_pinlatch (bt, right);
+ bt_lockpage(BtLockWrite, rset);
+ bt_lockpage(BtLockDelete, rset);
+
+ // pull contents of right page into empty page
+
+ memcpy (page, rpage, bt->mgr->page_size);
- if( keycmp (ptr, rightkey+1, *rightkey) )
- return bt->err = BTERR_struct;
+ // delete left parent slot for old empty page
+ // and redirect right parent slot to it
+
+ bt->page->act--;
+ bt->page->dirty = 1;
+ slotptr(bt->page, slot)->dead = 1;
+
+ while( slot++ < bt->page->cnt )
+ if( !slotptr(bt->page, slot)->dead )
+ break;
- slotptr(bt->page, slot)->dead = 0;
bt_putid(slotptr(bt->page,slot)->id, page_no);
- if( bt_unlockpage(bt, bt->page_no, BtLockWrite) )
- return bt->err;
+ // release parent level lock
+ // and our empty node lock
- // obtain write lock and
- // add right block to free chain
+ bt_unlockpage(BtLockWrite, set);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
- if( bt_freepage (bt, right) )
- return bt->err;
+ // add killed right block to free chain
+ // lock latch mgr
+
+ bt_spinwritelock(bt->mgr->latchmgr->lock);
+
+ // store free chain in allocation page second right
+ bt_putid(rpage->right, bt_getid(bt->mgr->latchmgr->alloc[1].right));
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, right);
+
+ // unlock latch mgr and right page
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
+ bt_unlockpage(BtLockWrite, rset);
+ bt_unlockpage(BtLockDelete, rset);
+ bt_unpinlatch (rset);
+ bt_unpinpool (rpool);
// remove ParentModify lock
- if( bt_unlockpage(bt, page_no, BtLockParent) )
- return bt->err;
-
+ bt_unlockpage(BtLockParent, set);
+ bt_unlockpage(BtLockDelete, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
return 0;
-}
+}
// find key in leaf level and return row-id
// if key exists, return row-id
// otherwise return 0
- if( ptr->len == len && !memcmp (ptr->key, key, len) )
+ if( slot <= bt->page->cnt && !keycmp (ptr, key, len) )
id = bt_getid(slotptr(bt->page,slot)->id);
else
id = 0;
- if( bt_unlockpage (bt, bt->page_no, BtLockRead) )
- return 0;
-
+ bt_unlockpage (BtLockRead, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
return id;
}
// check page for space available,
// clean if necessary and return
// 0 - page needs splitting
-// 1 - go ahead
+// >0 new slot value
-uint bt_cleanpage(BtDb *bt, uint amt)
+uint bt_cleanpage(BtDb *bt, uint amt, uint slot)
{
uint nxt = bt->mgr->page_size;
BtPage page = bt->page;
uint cnt = 0, idx = 0;
uint max = page->cnt;
+uint newslot;
BtKey key;
if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
- return 1;
+ return slot;
// skip cleanup if nothing to reclaim
// try cleaning up page first
+ // always leave fence key in the array
+ // otherwise, remove deleted key
+
+ // note: foster children are never dead
+ // nor are fence keys for interiour nodes
+
while( cnt++ < max ) {
- // always leave fence key and foster children in list
- if( cnt < max - page->foster && slotptr(bt->frame,cnt)->dead )
+ if( cnt == slot )
+ newslot = idx + 1;
+ else if( cnt < max && slotptr(bt->frame,cnt)->dead )
continue;
// copy key
+
key = keyptr(bt->frame, cnt);
nxt -= key->len + 1;
memcpy ((unsigned char *)page + nxt, key, key->len + 1);
// see if page has enough space now, or does it need splitting?
if( page->min >= (idx+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
- return 1;
+ return newslot;
return 0;
}
BtPage page = bt->page;
uint idx;
- // calculate next available slot and copy key into page
+ // find next available dead slot and copy key onto page
+ // note that foster children on the page are never dead
- page->min -= len + 1;
- ((unsigned char *)page)[page->min] = len;
- memcpy ((unsigned char *)page + page->min +1, key, len );
+ // look for next hole, but stay back from the fence key
for( idx = slot; idx < page->cnt; idx++ )
if( slotptr(page, idx)->dead )
break;
- // now insert key into array before slot
- // preserving the fence slot
-
if( idx == page->cnt )
idx++, page->cnt++;
page->act++;
+ // now insert key into array before slot
+
while( idx > slot )
*slotptr(page, idx) = *slotptr(page, idx -1), idx--;
+ page->min -= len + 1;
+ ((unsigned char *)page)[page->min] = len;
+ memcpy ((unsigned char *)page + page->min +1, key, len );
+
bt_putid(slotptr(page,slot)->id, id);
slotptr(page, slot)->off = page->min;
slotptr(page, slot)->tod = tod;
// contents into it from the root. Strip foster child key.
// (it's the stopper key)
+ memset (slotptr(root, root->cnt), 0, sizeof(BtSlot));
+ root->dirty = 1;
+ root->foster--;
root->act--;
root->cnt--;
- root->foster--;
// Save left fence key.
root->act = 2;
root->lvl++;
- // release root (bt->page)
+ // release and unpin root (bt->page)
- return bt_unlockpage(bt, ROOT_page, BtLockWrite);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return 0;
}
// split already locked full node
// in current page variables
-// return unlocked.
+// return unlocked and unpinned.
BTERR bt_splitpage (BtDb *bt)
{
uint slot, cnt, idx, max, nxt = bt->mgr->page_size;
unsigned char fencekey[256];
uid page_no = bt->page_no;
+BtLatchSet *set = bt->set;
+BtPool *pool = bt->pool;
BtPage page = bt->page;
uint tod = time(NULL);
uint lvl = page->lvl;
uid new_page, right;
BtKey key;
- // initialize frame buffer
+ // initialize frame buffer for right node
memset (bt->frame, 0, bt->mgr->page_size);
max = page->cnt - page->foster;
idx = 0;
// split higher half of keys to bt->frame
- // leaving foster children in the left node.
+ // leaving old foster children in the left node,
+ // and adding a new foster child there.
while( cnt++ < max ) {
key = keyptr(page, cnt);
nxt -= key->len + 1;
memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1);
memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId);
+ if( !(slotptr(bt->frame, idx)->dead = slotptr(page, cnt)->dead) )
+ bt->frame->act++;
slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod;
slotptr(bt->frame, idx)->off = nxt;
- bt->frame->act++;
}
- // transfer right link node
+ // transfer right link node to new right node
if( page_no > ROOT_page ) {
right = bt_getid (page->right);
bt->frame->cnt = idx;
bt->frame->lvl = lvl;
- // get new free page and write frame to it.
+ // get new free page and write right frame to it.
if( !(new_page = bt_newpage(bt, bt->frame)) )
return bt->err;
- // remember fence key for new page to add
- // as foster child
+ // remember fence key for new right page to add
+ // as foster child to the left node
key = keyptr(bt->frame, idx);
memcpy (fencekey, key, key->len + 1);
memcpy (bt->frame, page, bt->mgr->page_size);
memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
nxt = bt->mgr->page_size;
+ page->dirty = 0;
page->act = 0;
cnt = 0;
idx = 0;
nxt -= key->len + 1;
memcpy ((unsigned char *)page + nxt, key, key->len + 1);
memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
+ page->act++;
slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
slotptr(page, idx)->off = nxt;
- page->act++;
}
- // insert new foster child at beginning of the current foster children
+ // insert new foster child for right page in queue
+ // before any of the current foster children
nxt -= *fencekey + 1;
memcpy ((unsigned char *)page + nxt, fencekey, *fencekey + 1);
+
bt_putid (slotptr(page,++idx)->id, new_page);
slotptr(page, idx)->tod = tod;
slotptr(page, idx)->off = nxt;
page->foster++;
page->act++;
- // continue with old foster child keys if any
+ // continue with old foster child keys
+ // note that none will be dead
cnt = bt->frame->cnt - bt->frame->foster;
// release wr lock on our page
- if( bt_unlockpage (bt, page_no, BtLockWrite) )
- return bt->err;
+ bt_unlockpage (BtLockWrite, set);
// obtain ParentModification lock for current page
- // to fix fence key and highest foster child on page
+ // to fix new fence key and oldest foster child on page
- if( bt_lockpage (bt, page_no, BtLockParent, NULL) )
- return bt->err;
+ bt_lockpage (BtLockParent, set);
- // get our highest foster child key to find in parent node
+ // get our new fence key to insert in parent node
- if( bt_lockpage (bt, page_no, BtLockRead, &page) )
- return bt->err;
+ bt_lockpage (BtLockRead, set);
- key = keyptr(page, page->cnt);
+ key = keyptr(page, page->cnt-1);
memcpy (fencekey, key, key->len+1);
- if( bt_unlockpage (bt, page_no, BtLockRead) )
- return bt->err;
-
- // update our parent
-try_again:
-
- do {
- slot = bt_loadpage (bt, fencekey + 1, *fencekey, lvl + 1, BtLockWrite);
+ bt_unlockpage (BtLockRead, set);
- if( !slot )
+ if( bt_insertkey (bt, fencekey + 1, *fencekey, page_no, tod, lvl + 1) )
return bt->err;
- // check if parent page has enough space for any possible key
+ // lock our page for writing
- if( bt_cleanpage (bt, 256) )
- break;
+ bt_lockpage (BtLockRead, set);
- if( bt_splitpage (bt) )
- return bt->err;
- } while( 1 );
+ // switch old parent key from us to our oldest foster child
- // see if we are still a foster child from another node
-
- if( bt_getid (slotptr(bt->page, slot)->id) != page_no ) {
- if( bt_unlockpage (bt, bt->page_no, BtLockWrite) )
- return bt->err;
-#ifdef unix
- sched_yield();
-#else
- SwitchToThread();
-#endif
- goto try_again;
- }
-
- // wait until readers from parent get their locks
- // on our page
-
- if( bt_lockpage (bt, page_no, BtLockDelete, NULL) )
- return bt->err;
+ key = keyptr(page, page->cnt);
+ memcpy (fencekey, key, key->len+1);
- // lock our page for writing
+ new_page = bt_getid (slotptr(page, page->cnt)->id);
+ bt_unlockpage (BtLockRead, set);
- if( bt_lockpage (bt, page_no, BtLockWrite, &page) )
+ if( bt_insertkey (bt, fencekey + 1, *fencekey, new_page, tod, lvl + 1) )
return bt->err;
- // switch parent fence key to foster child
-
- if( slotptr(page, page->cnt)->dead )
- slotptr(bt->page, slot)->dead = 1;
- else
- bt_putid (slotptr(bt->page, slot)->id, bt_getid(slotptr(page, page->cnt)->id));
-
- // remove highest foster child from our page
+ // now that it has its own parent pointer,
+ // remove oldest foster child from our page
+ bt_lockpage (BtLockWrite, set);
+ memset (slotptr(page, page->cnt), 0, sizeof(BtSlot));
+ page->dirty = 1;
+ page->foster--;
page->cnt--;
page->act--;
- page->foster--;
- page->dirty = 1;
- key = keyptr(page, page->cnt);
-
- // add our new fence key for foster child to our parent
- bt_addkeytopage (bt, slot, key->key, key->len, page_no, tod);
-
- if( bt_unlockpage (bt, bt->page_no, BtLockWrite) )
- return bt->err;
+ // unlock and unpin
- if( bt_unlockpage (bt, page_no, BtLockDelete) )
- return bt->err;
-
- if( bt_unlockpage (bt, page_no, BtLockWrite) )
- return bt->err;
-
- return bt_unlockpage (bt, page_no, BtLockParent);
+ bt_unlockpage (BtLockWrite, set);
+ bt_unlockpage (BtLockParent, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ return 0;
}
// Insert new key into the btree at leaf level.
-BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod)
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod, uint lvl)
{
uint slot, idx;
BtPage page;
BtKey ptr;
while( 1 ) {
- if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
+ if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
ptr = keyptr(bt->page, slot);
else
{
page = bt->page;
if( !keycmp (ptr, key, len) ) {
+ if( slotptr(page, slot)->dead )
+ page->act++;
slotptr(page, slot)->dead = 0;
slotptr(page, slot)->tod = tod;
bt_putid(slotptr(page,slot)->id, id);
- return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return bt->err;
}
// check if page has enough space
- if( bt_cleanpage (bt, len) )
+ if( slot = bt_cleanpage (bt, len, slot) )
break;
if( bt_splitpage (bt) )
bt_addkeytopage (bt, slot, key, len, id, tod);
- return bt_unlockpage (bt, bt->page_no, BtLockWrite);
+ bt_unlockpage (BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return 0;
}
// cache page of keys into cursor and return starting slot for given key
// cache page for retrieval
if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
memcpy (bt->cursor, bt->page, bt->mgr->page_size);
+
bt->cursor_page = bt->page_no;
- if ( bt_unlockpage(bt, bt->page_no, BtLockRead) )
- return 0;
+ bt_unlockpage(BtLockRead, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
return slot;
}
uint bt_nextkey (BtDb *bt, uint slot)
{
+BtLatchSet *set;
+BtPool *pool;
BtPage page;
uid right;
break;
bt->cursor_page = right;
-
- if( bt_lockpage(bt, right, BtLockRead, &page) )
+ if( pool = bt_pinpool (bt, right) )
+ page = bt_page (bt, pool, right);
+ else
return 0;
- memcpy (bt->cursor, page, bt->mgr->page_size);
+ set = bt_pinlatch (bt, right);
+ bt_lockpage(BtLockRead, set);
- if ( bt_unlockpage(bt, right, BtLockRead) )
- return 0;
+ memcpy (bt->cursor, page, bt->mgr->page_size);
+ bt_unlockpage(BtLockRead, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
slot = 0;
} while( 1 );
unsigned char key[256];
ThreadArg *args = arg;
int ch, len = 0, slot;
+BtLatchSet *set;
time_t tod[1];
+BtPool *pool;
BtPage page;
BtKey ptr;
BtDb *bt;
else if( args->num )
sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
- if( bt_insertkey (bt, key, len, line, *tod) )
+ if( bt_insertkey (bt, key, len, line, *tod, 0) )
fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
len = 0;
}
else if( args->num )
sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
- if( bt_deletekey (bt, key, len, 0) )
+ if( bt_deletekey (bt, key, len) )
fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
len = 0;
}
fprintf(stderr, "started reading\n");
do {
- bt_lockpage (bt, page_no, BtLockRead, &page);
+ if( pool = bt_pinpool (bt, page_no) )
+ page = bt_page (bt, pool, page_no);
+ else
+ break;
+ set = bt_pinlatch (bt, page_no);
+ bt_lockpage (BtLockRead, set);
cnt += page->act;
next = bt_getid (page->right);
- bt_unlockpage (bt, page_no, BtLockRead);
+ bt_unlockpage (BtLockRead, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
} while( page_no = next );
cnt--; // remove stopper key
--- /dev/null
+// foster btree version e
+// 17 JAN 2014
+
+// author: karl malbrain, malbrain@cal.berkeley.edu
+
+/*
+This work, including the source code, documentation
+and related data, is placed into the public domain.
+
+The orginal author is Karl Malbrain.
+
+THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
+OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
+MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
+ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
+RESULTING FROM THE USE, MODIFICATION, OR
+REDISTRIBUTION OF THIS SOFTWARE.
+*/
+
+// Please see the project home page for documentation
+// code.google.com/p/high-concurrency-btree
+
+#define _FILE_OFFSET_BITS 64
+#define _LARGEFILE64_SOURCE
+
+#ifdef linux
+#define _GNU_SOURCE
+#endif
+
+#ifdef unix
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/time.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <pthread.h>
+#else
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <fcntl.h>
+#include <process.h>
+#include <intrin.h>
+#endif
+
+#include <memory.h>
+#include <string.h>
+
+typedef unsigned long long uid;
+
+#ifndef unix
+typedef unsigned long long off64_t;
+typedef unsigned short ushort;
+typedef unsigned int uint;
+#endif
+
+#define BT_ro 0x6f72 // ro
+#define BT_rw 0x7772 // rw
+
+#define BT_latchtable 128 // number of latch manager slots
+
+#define BT_maxbits 24 // maximum page size in bits
+#define BT_minbits 9 // minimum page size in bits
+#define BT_minpage (1 << BT_minbits) // minimum page size
+#define BT_maxpage (1 << BT_maxbits) // maximum page size
+
+/*
+There are five lock types for each node in three independent sets:
+1. (set 1) AccessIntent: Sharable. Going to Read the node. Incompatible with NodeDelete.
+2. (set 1) NodeDelete: Exclusive. About to release the node. Incompatible with AccessIntent.
+3. (set 2) ReadLock: Sharable. Read the node. Incompatible with WriteLock.
+4. (set 2) WriteLock: Exclusive. Modify the node. Incompatible with ReadLock and other WriteLocks.
+5. (set 3) ParentLock: Exclusive. Have parent adopt/delete maximum foster child from the node.
+*/
+
+typedef enum{
+ BtLockAccess,
+ BtLockDelete,
+ BtLockRead,
+ BtLockWrite,
+ BtLockParent,
+ BtLockPin
+}BtLock;
+
+// Define the length of the page and key pointers
+
+#define BtId 6
+
+// Page key slot definition.
+
+// If BT_maxbits is 15 or less, you can save 4 bytes
+// for each key stored by making the first two uints
+// into ushorts. You can also save 4 bytes by removing
+// the tod field from the key.
+
+// Keys are marked dead, but remain on the page until
+// it cleanup is called. The fence key (highest key) for
+// the page is always present, even after cleanup.
+
+typedef struct {
+ uint off:BT_maxbits; // page offset for key start
+ uint dead:1; // set for deleted key
+ uint tod; // time-stamp for key
+ unsigned char id[BtId]; // id associated with key
+} BtSlot;
+
+// The key structure occupies space at the upper end of
+// each page. It's a length byte followed by the value
+// bytes.
+
+typedef struct {
+ unsigned char len;
+ unsigned char key[1];
+} *BtKey;
+
+// The first part of an index page.
+// It is immediately followed
+// by the BtSlot array of keys.
+
+typedef struct Page {
+ uint cnt; // count of keys in page
+ uint act; // count of active keys
+ uint min; // next key offset
+ uint foster; // count of foster children
+ unsigned char bits; // page size in bits
+ unsigned char lvl:6; // level of page
+ unsigned char kill:1; // page is being deleted
+ unsigned char dirty:1; // page needs to be cleaned
+ unsigned char right[BtId]; // page number to right
+} *BtPage;
+
+// mode & definition for hash latch implementation
+
+enum {
+ Mutex = 1,
+ Write = 2,
+ Pending = 4,
+ Share = 8
+} LockMode;
+
+// mutex locks the other fields
+// exclusive is set for write access
+// share is count of read accessors
+
+typedef struct {
+ volatile ushort mutex:1;
+ volatile ushort exclusive:1;
+ volatile ushort pending:1;
+ volatile ushort share:13;
+} BtSpinLatch;
+
+// hash table entries
+
+typedef struct {
+ BtSpinLatch latch[1];
+ volatile ushort slot; // Latch table entry at head of chain
+} BtHashEntry;
+
+// latch table lock structure
+// implements a fair read-write lock
+
+typedef struct {
+#ifdef unix
+ pthread_rwlock_t lock[1];
+#else
+ SRWLOCK srw[1];
+#endif
+} BtLatch;
+
+typedef struct {
+ BtLatch readwr[1]; // read/write page lock
+ BtLatch access[1]; // Access Intent/Page delete
+ BtLatch parent[1]; // adoption of foster children
+ BtSpinLatch busy[1]; // slot is being moved between chains
+ volatile ushort next; // next entry in hash table chain
+ volatile ushort prev; // prev entry in hash table chain
+ volatile ushort pin; // number of outstanding locks
+ volatile ushort hash; // hash slot entry is under
+ volatile uid page_no; // latch set page number
+} BtLatchSet;
+
+// The memory mapping pool table buffer manager entry
+
+typedef struct {
+ unsigned long long int lru; // number of times accessed
+ uid basepage; // mapped base page number
+ char *map; // mapped memory pointer
+ ushort pin; // mapped page pin counter
+ ushort slot; // slot index in this array
+ void *hashprev; // previous pool entry for the same hash idx
+ void *hashnext; // next pool entry for the same hash idx
+#ifndef unix
+ HANDLE hmap; // Windows memory mapping handle
+#endif
+} BtPool;
+
+// structure for latch manager on ALLOC_page
+
+typedef struct {
+ struct Page alloc[2]; // next & free page_nos in right ptr
+ BtSpinLatch lock[1]; // allocation area lite latch
+ ushort latchdeployed; // highest number of latch entries deployed
+ ushort nlatchpage; // number of latch pages at BT_latch
+ ushort latchtotal; // number of page latch entries
+ ushort latchhash; // number of latch hash table slots
+ ushort latchvictim; // next latch entry to examine
+ BtHashEntry table[0]; // the hash table
+} BtLatchMgr;
+
+// The object structure for Btree access
+
+typedef struct {
+ uint page_size; // page size
+ uint page_bits; // page size in bits
+ uint seg_bits; // seg size in pages in bits
+ uint mode; // read-write mode
+#ifdef unix
+ int idx;
+ char *pooladvise; // bit maps for pool page advisements
+#else
+ HANDLE idx;
+#endif
+ ushort poolcnt; // highest page pool node in use
+ ushort poolmax; // highest page pool node allocated
+ ushort poolmask; // total size of pages in mmap segment - 1
+ ushort hashsize; // size of Hash Table for pool entries
+ ushort evicted; // last evicted hash table slot
+ ushort *hash; // hash table of pool entries
+ BtPool *pool; // memory pool page segments
+ BtSpinLatch *latch; // latches for pool hash slots
+ BtLatchMgr *latchmgr; // mapped latch page from allocation page
+ BtLatchSet *latchsets; // mapped latch set from latch pages
+#ifndef unix
+ HANDLE halloc; // allocation and latch table handle
+#endif
+} BtMgr;
+
+typedef struct {
+ BtMgr *mgr; // buffer manager for thread
+ BtPage temp; // temporary frame buffer (memory mapped/file IO)
+ BtPage cursor; // cached frame for start/next (never mapped)
+ BtPage frame; // spare frame for the page split (never mapped)
+ BtPage zero; // page frame for zeroes at end of file
+ BtPage page; // current page
+ uid page_no; // current page number
+ uid cursor_page; // current cursor page number
+ BtLatchSet *set; // current page latch set
+ unsigned char *mem; // frame, cursor, page memory buffer
+ int err; // last error
+} BtDb;
+
+typedef enum {
+ BTERR_ok = 0,
+ BTERR_struct,
+ BTERR_ovflw,
+ BTERR_lock,
+ BTERR_map,
+ BTERR_wrt,
+ BTERR_hash,
+ BTERR_latch
+} BTERR;
+
+// B-Tree functions
+extern void bt_close (BtDb *bt);
+extern BtDb *bt_open (BtMgr *mgr);
+extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod);
+extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl);
+extern uid bt_findkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_startkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_nextkey (BtDb *bt, uint slot);
+
+// manager functions
+extern BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolsize, uint segsize, uint hashsize);
+void bt_mgrclose (BtMgr *mgr);
+
+// Helper functions to return cursor slot values
+
+extern BtKey bt_key (BtDb *bt, uint slot);
+extern uid bt_uid (BtDb *bt, uint slot);
+extern uint bt_tod (BtDb *bt, uint slot);
+
+// BTree page number constants
+#define ALLOC_page 0 // allocation & lock manager hash table
+#define ROOT_page 1 // root of the btree
+#define LEAF_page 2 // first page of leaves
+#define LATCH_page 3 // pages for lock manager
+
+// Number of levels to create in a new BTree
+
+#define MIN_lvl 2
+
+// The page is allocated from low and hi ends.
+// The key offsets and row-id's are allocated
+// from the bottom, while the text of the key
+// is allocated from the top. When the two
+// areas meet, the page is split into two.
+
+// A key consists of a length byte, two bytes of
+// index number (0 - 65534), and up to 253 bytes
+// of key value. Duplicate keys are discarded.
+// Associated with each key is a 48 bit row-id.
+
+// The b-tree root is always located at page 1.
+// The first leaf page of level zero is always
+// located on page 2.
+
+// When to root page fills, it is split in two and
+// the tree height is raised by a new root at page
+// one with two keys.
+
+// Deleted keys are marked with a dead bit until
+// page cleanup The fence key for a node is always
+// present, even after deletion and cleanup.
+
+// Groups of pages called segments from the btree are
+// cached with memory mapping. A hash table is used to keep
+// track of the cached segments. This behaviour is controlled
+// by the cache block size parameter to bt_open.
+
+// To achieve maximum concurrency one page is locked at a time
+// as the tree is traversed to find leaf key in question.
+
+// An adoption traversal leaves the parent node locked as the
+// tree is traversed to the level in quesiton.
+
+// Page 0 is dedicated to lock for new page extensions,
+// and chains empty pages together for reuse.
+
+// Empty pages are chained together through the ALLOC page and reused.
+
+// Access macros to address slot and key values from the page
+
+#define slotptr(page, slot) (((BtSlot *)(page+1)) + (slot-1))
+#define keyptr(page, slot) ((BtKey)((unsigned char*)(page) + slotptr(page, slot)->off))
+
+void bt_putid(unsigned char *dest, uid id)
+{
+int i = BtId;
+
+ while( i-- )
+ dest[i] = (unsigned char)id, id >>= 8;
+}
+
+uid bt_getid(unsigned char *src)
+{
+uid id = 0;
+int i;
+
+ for( i = 0; i < BtId; i++ )
+ id <<= 8, id |= *src++;
+
+ return id;
+}
+
+// wait until write lock mode is clear
+// and add 1 to the share count
+
+void bt_spinreadlock(BtSpinLatch *latch)
+{
+ushort prev;
+
+ do {
+#ifdef unix
+ while( __sync_fetch_and_or((ushort *)latch, Mutex) & Mutex )
+ sched_yield();
+#else
+ while( _InterlockedOr16((ushort *)latch, Mutex) & Mutex )
+ SwitchToThread();
+#endif
+
+ // see if exclusive request is granted or pending
+
+ if( prev = !(latch->exclusive | latch->pending) )
+#ifdef unix
+ __sync_fetch_and_add((ushort *)latch, Share);
+#else
+ _InterlockedExchangeAdd16 ((ushort *)latch, Share);
+#endif
+
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Mutex);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Mutex);
+#endif
+ if( prev )
+ return;
+#ifdef unix
+ } while( sched_yield(), 1 );
+#else
+ } while( SwitchToThread(), 1 );
+#endif
+}
+
+// wait for other read and write latches to relinquish
+
+void bt_spinwritelock(BtSpinLatch *latch)
+{
+ushort prev;
+
+ do {
+#ifdef unix
+ while( __sync_fetch_and_or((ushort *)latch, Mutex | Pending) & Mutex )
+ sched_yield();
+#else
+ while( _InterlockedOr16((ushort *)latch, Mutex | Pending) & Mutex )
+ SwitchToThread();
+#endif
+ if( prev = !(latch->share | latch->exclusive) )
+#ifdef unix
+ __sync_fetch_and_or((ushort *)latch, Write);
+#else
+ _InterlockedOr16((ushort *)latch, Write);
+#endif
+
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending));
+#else
+ _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending));
+#endif
+ if( prev )
+ return;
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ } while( 1 );
+}
+
+// try to obtain write lock
+
+// return 1 if obtained,
+// 0 otherwise
+
+int bt_spinwritetry(BtSpinLatch *latch)
+{
+ushort prev;
+
+#ifdef unix
+ if( prev = __sync_fetch_and_or((ushort *)latch, Mutex), prev & Mutex )
+ return 0;
+#else
+ if( prev = _InterlockedOr16((ushort *)latch, Mutex), prev & Mutex )
+ return 0;
+#endif
+ // take write access if all bits are clear
+
+ if( !prev )
+#ifdef unix
+ __sync_fetch_and_or ((ushort *)latch, Write);
+#else
+ _InterlockedOr16((ushort *)latch, Write);
+#endif
+
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Mutex);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Mutex);
+#endif
+ return !prev;
+}
+
+// clear write mode
+
+void bt_spinreleasewrite(BtSpinLatch *latch)
+{
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Write);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Write);
+#endif
+}
+
+// decrement reader count
+
+void bt_spinreleaseread(BtSpinLatch *latch)
+{
+#ifdef unix
+ __sync_fetch_and_add((ushort *)latch, -Share);
+#else
+ _InterlockedExchangeAdd16 ((ushort *)latch, -Share);
+#endif
+}
+
+void bt_initlockset (BtLatchSet *set)
+{
+#ifdef unix
+pthread_rwlockattr_t rwattr[1];
+
+ pthread_rwlockattr_init (rwattr);
+ pthread_rwlockattr_setkind_np (rwattr, PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
+ pthread_rwlockattr_setpshared (rwattr, PTHREAD_PROCESS_SHARED);
+
+ pthread_rwlock_init (set->readwr->lock, rwattr);
+ pthread_rwlock_init (set->access->lock, rwattr);
+ pthread_rwlock_init (set->parent->lock, rwattr);
+ pthread_rwlockattr_destroy (rwattr);
+#else
+ InitializeSRWLock (set->readwr->srw);
+ InitializeSRWLock (set->access->srw);
+ InitializeSRWLock (set->parent->srw);
+#endif
+}
+
+// link latch table entry into latch hash table
+
+void bt_latchlink (BtDb *bt, ushort hashidx, ushort victim, uid page_no)
+{
+BtLatchSet *set = bt->mgr->latchsets + victim;
+
+ if( set->next = bt->mgr->latchmgr->table[hashidx].slot )
+ bt->mgr->latchsets[set->next].prev = victim;
+
+ bt->mgr->latchmgr->table[hashidx].slot = victim;
+ set->page_no = page_no;
+ set->hash = hashidx;
+ set->prev = 0;
+}
+
+// find existing latchset or inspire new one
+// return with latchset pinned
+
+BtLatchSet *bt_bindlatch (BtDb *bt, uid page_no, int incr)
+{
+ushort hashidx = page_no % bt->mgr->latchmgr->latchhash;
+ushort slot, avail = 0, victim, idx;
+BtLatchSet *set;
+
+ // obtain read lock on hash table entry
+
+ bt_spinreadlock(bt->mgr->latchmgr->table[hashidx].latch);
+
+ if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
+ {
+ set = bt->mgr->latchsets + slot;
+ if( page_no == set->page_no )
+ break;
+ } while( slot = set->next );
+
+ if( slot && incr ) {
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ }
+
+ bt_spinreleaseread (bt->mgr->latchmgr->table[hashidx].latch);
+
+ if( slot )
+ return set;
+
+ // try again, this time with write lock
+
+ bt_spinwritelock(bt->mgr->latchmgr->table[hashidx].latch);
+
+ if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
+ {
+ set = bt->mgr->latchsets + slot;
+ if( page_no == set->page_no )
+ break;
+ if( !set->pin && !avail )
+ avail = slot;
+ } while( slot = set->next );
+
+ // found our entry, or take over an unpinned one
+
+ if( slot || (slot = avail) ) {
+ set = bt->mgr->latchsets + slot;
+ if( incr )
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ set->page_no = page_no;
+ bt_spinreleasewrite(bt->mgr->latchmgr->table[hashidx].latch);
+ return set;
+ }
+
+ // see if there are any unused entries
+#ifdef unix
+ victim = __sync_fetch_and_add (&bt->mgr->latchmgr->latchdeployed, 1) + 1;
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->latchmgr->latchdeployed);
+#endif
+
+ if( victim < bt->mgr->latchmgr->latchtotal ) {
+ set = bt->mgr->latchsets + victim;
+ if( incr )
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ bt_initlockset (set);
+ bt_latchlink (bt, hashidx, victim, page_no);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch);
+ return set;
+ }
+
+#ifdef unix
+ victim = __sync_fetch_and_add (&bt->mgr->latchmgr->latchdeployed, -1);
+#else
+ victim = _InterlockedDecrement16 (&bt->mgr->latchmgr->latchdeployed);
+#endif
+ // find and reuse previous lock entry
+
+ while( 1 ) {
+#ifdef unix
+ victim = __sync_fetch_and_add(&bt->mgr->latchmgr->latchvictim, 1);
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->latchmgr->latchvictim) - 1;
+#endif
+ // we don't use slot zero
+
+ if( victim %= bt->mgr->latchmgr->latchtotal )
+ set = bt->mgr->latchsets + victim;
+ else
+ continue;
+
+ // take control of our slot
+ // from other threads
+
+ if( set->pin || !bt_spinwritetry (set->busy) )
+ continue;
+
+ idx = set->hash;
+
+ // try to get write lock on hash chain
+ // skip entry if not obtained
+ // or has outstanding locks
+
+ if( !bt_spinwritetry (bt->mgr->latchmgr->table[idx].latch) ) {
+ bt_spinreleasewrite (set->busy);
+ continue;
+ }
+
+ if( set->pin ) {
+ bt_spinreleasewrite (set->busy);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[idx].latch);
+ continue;
+ }
+
+ // unlink our available victim from its hash chain
+
+ if( set->prev )
+ bt->mgr->latchsets[set->prev].next = set->next;
+ else
+ bt->mgr->latchmgr->table[idx].slot = set->next;
+
+ if( set->next )
+ bt->mgr->latchsets[set->next].prev = set->prev;
+
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[idx].latch);
+
+ if( incr )
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+
+ bt_latchlink (bt, hashidx, victim, page_no);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch);
+ bt_spinreleasewrite (set->busy);
+ return set;
+ }
+}
+
+void bt_mgrclose (BtMgr *mgr)
+{
+BtPool *pool;
+uint slot;
+
+ // release mapped pages
+ // note that slot zero is never used
+
+ for( slot = 1; slot < mgr->poolmax; slot++ ) {
+ pool = mgr->pool + slot;
+ if( pool->slot )
+#ifdef unix
+ munmap (pool->map, (mgr->poolmask+1) << mgr->page_bits);
+#else
+ {
+ FlushViewOfFile(pool->map, 0);
+ UnmapViewOfFile(pool->map);
+ CloseHandle(pool->hmap);
+ }
+#endif
+ }
+
+#ifdef unix
+ close (mgr->idx);
+ free (mgr->pool);
+ free (mgr->hash);
+ free (mgr->latch);
+ free (mgr->pooladvise);
+ free (mgr);
+#else
+ FlushFileBuffers(mgr->idx);
+ CloseHandle(mgr->idx);
+ GlobalFree (mgr->pool);
+ GlobalFree (mgr->hash);
+ GlobalFree (mgr->latch);
+ GlobalFree (mgr);
+#endif
+}
+
+// close and release memory
+
+void bt_close (BtDb *bt)
+{
+#ifdef unix
+ if ( bt->mem )
+ free (bt->mem);
+#else
+ if ( bt->mem)
+ VirtualFree (bt->mem, 0, MEM_RELEASE);
+#endif
+ free (bt);
+}
+
+// open/create new btree buffer manager
+
+// call with file_name, BT_openmode, bits in page size (e.g. 16),
+// size of mapped page pool (e.g. 8192)
+
+BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolmax, uint segsize, uint hashsize)
+{
+uint lvl, attr, cacheblk, last, slot, idx;
+uint nlatchpage, latchhash;
+BtLatchMgr *latchmgr;
+off64_t size;
+uint amt[1];
+BtMgr* mgr;
+BtKey key;
+int flag;
+
+#ifndef unix
+SYSTEM_INFO sysinfo[1];
+#endif
+
+ // determine sanity of page size and buffer pool
+
+ if( bits > BT_maxbits )
+ bits = BT_maxbits;
+ else if( bits < BT_minbits )
+ bits = BT_minbits;
+
+ if( !poolmax )
+ return NULL; // must have buffer pool
+
+#ifdef unix
+ mgr = calloc (1, sizeof(BtMgr));
+
+ mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
+
+ if( mgr->idx == -1 )
+ return free(mgr), NULL;
+
+ cacheblk = 4096; // minimum mmap segment size for unix
+
+#else
+ mgr = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtMgr));
+ attr = FILE_ATTRIBUTE_NORMAL;
+ mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
+
+ if( mgr->idx == INVALID_HANDLE_VALUE )
+ return GlobalFree(mgr), NULL;
+
+ // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity
+ GetSystemInfo(sysinfo);
+ cacheblk = sysinfo->dwAllocationGranularity;
+#endif
+
+#ifdef unix
+ latchmgr = malloc (BT_maxpage);
+ *amt = 0;
+
+ // read minimum page size to get root info
+
+ if( size = lseek (mgr->idx, 0L, 2) ) {
+ if( pread(mgr->idx, latchmgr, BT_minpage, 0) == BT_minpage )
+ bits = latchmgr->alloc->bits;
+ else
+ return free(mgr), free(latchmgr), NULL;
+ } else if( mode == BT_ro )
+ return bt_mgrclose (mgr), NULL;
+#else
+ latchmgr = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE);
+ size = GetFileSize(mgr->idx, amt);
+
+ if( size || *amt ) {
+ if( !ReadFile(mgr->idx, (char *)latchmgr, BT_minpage, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ bits = latchmgr->alloc->bits;
+ } else if( mode == BT_ro )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ mgr->page_size = 1 << bits;
+ mgr->page_bits = bits;
+
+ mgr->poolmax = poolmax;
+ mgr->mode = mode;
+
+ if( cacheblk < mgr->page_size )
+ cacheblk = mgr->page_size;
+
+ // mask for partial memmaps
+
+ mgr->poolmask = (cacheblk >> bits) - 1;
+
+ // see if requested size of pages per memmap is greater
+
+ if( (1 << segsize) > mgr->poolmask )
+ mgr->poolmask = (1 << segsize) - 1;
+
+ mgr->seg_bits = 0;
+
+ while( (1 << mgr->seg_bits) <= mgr->poolmask )
+ mgr->seg_bits++;
+
+ mgr->hashsize = hashsize;
+
+#ifdef unix
+ mgr->pool = calloc (poolmax, sizeof(BtPool));
+ mgr->hash = calloc (hashsize, sizeof(ushort));
+ mgr->latch = calloc (hashsize, sizeof(BtSpinLatch));
+ mgr->pooladvise = calloc (poolmax, (mgr->poolmask + 8) / 8);
+#else
+ mgr->pool = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, poolmax * sizeof(BtPool));
+ mgr->hash = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(ushort));
+ mgr->latch = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(BtSpinLatch));
+#endif
+
+ if( size || *amt )
+ goto mgrlatch;
+
+ // initialize an empty b-tree with latch page, root page, page of leaves
+ // and page(s) of latches
+
+ memset (latchmgr, 0, 1 << bits);
+ nlatchpage = BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1;
+ bt_putid(latchmgr->alloc->right, MIN_lvl+1+nlatchpage);
+ latchmgr->alloc->bits = mgr->page_bits;
+
+ latchmgr->nlatchpage = nlatchpage;
+ latchmgr->latchtotal = nlatchpage * (mgr->page_size / sizeof(BtLatchSet));
+
+ // initialize latch manager
+
+ latchhash = (mgr->page_size - sizeof(BtLatchMgr)) / sizeof(BtHashEntry);
+
+ // size of hash table = total number of latchsets
+
+ if( latchhash > latchmgr->latchtotal )
+ latchhash = latchmgr->latchtotal;
+
+ latchmgr->latchhash = latchhash;
+
+#ifdef unix
+ if( write (mgr->idx, latchmgr, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ memset (latchmgr, 0, 1 << bits);
+ latchmgr->alloc->bits = mgr->page_bits;
+
+ for( lvl=MIN_lvl; lvl--; ) {
+ slotptr(latchmgr->alloc, 1)->off = mgr->page_size - 3;
+ bt_putid(slotptr(latchmgr->alloc, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number
+ key = keyptr(latchmgr->alloc, 1);
+ key->len = 2; // create stopper key
+ key->key[0] = 0xff;
+ key->key[1] = 0xff;
+ latchmgr->alloc->min = mgr->page_size - 3;
+ latchmgr->alloc->lvl = lvl;
+ latchmgr->alloc->cnt = 1;
+ latchmgr->alloc->act = 1;
+#ifdef unix
+ if( write (mgr->idx, latchmgr, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ }
+
+ // clear out latch manager locks
+ // and rest of pages to round out segment
+
+ memset(latchmgr, 0, mgr->page_size);
+ last = MIN_lvl + 1;
+
+ while( last <= ((MIN_lvl + 1 + nlatchpage) | mgr->poolmask) ) {
+#ifdef unix
+ pwrite(mgr->idx, latchmgr, mgr->page_size, last << mgr->page_bits);
+#else
+ SetFilePointer (mgr->idx, last << mgr->page_bits, NULL, FILE_BEGIN);
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ last++;
+ }
+
+mgrlatch:
+#ifdef unix
+ flag = PROT_READ | PROT_WRITE;
+ mgr->latchmgr = mmap (0, mgr->page_size, flag, MAP_SHARED, mgr->idx, ALLOC_page * mgr->page_size);
+ if( mgr->latchmgr == MAP_FAILED )
+ return bt_mgrclose (mgr), NULL;
+ mgr->latchsets = (BtLatchSet *)mmap (0, mgr->latchmgr->nlatchpage * mgr->page_size, flag, MAP_SHARED, mgr->idx, LATCH_page * mgr->page_size);
+ if( mgr->latchsets == MAP_FAILED )
+ return bt_mgrclose (mgr), NULL;
+#else
+ flag = PAGE_READWRITE;
+ mgr->halloc = CreateFileMapping(mgr->idx, NULL, flag, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size, NULL);
+ if( !mgr->halloc )
+ return bt_mgrclose (mgr), NULL;
+
+ flag = FILE_MAP_WRITE;
+ mgr->latchmgr = MapViewOfFile(mgr->halloc, flag, 0, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size);
+ if( !mgr->latchmgr )
+ return GetLastError(), bt_mgrclose (mgr), NULL;
+
+ mgr->latchsets = (void *)((char *)mgr->latchmgr + LATCH_page * mgr->page_size);
+#endif
+
+#ifdef unix
+ free (latchmgr);
+#else
+ VirtualFree (latchmgr, 0, MEM_RELEASE);
+#endif
+ return mgr;
+}
+
+// open BTree access method
+// based on buffer manager
+
+BtDb *bt_open (BtMgr *mgr)
+{
+BtDb *bt = malloc (sizeof(*bt));
+
+ memset (bt, 0, sizeof(*bt));
+ bt->mgr = mgr;
+#ifdef unix
+ bt->mem = malloc (3 *mgr->page_size);
+#else
+ bt->mem = VirtualAlloc(NULL, 3 * mgr->page_size, MEM_COMMIT, PAGE_READWRITE);
+#endif
+ bt->frame = (BtPage)bt->mem;
+ bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size);
+ bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size);
+ return bt;
+}
+
+// compare two keys, returning > 0, = 0, or < 0
+// as the comparison value
+
+int keycmp (BtKey key1, unsigned char *key2, uint len2)
+{
+uint len1 = key1->len;
+int ans;
+
+ if( ans = memcmp (key1->key, key2, len1 > len2 ? len2 : len1) )
+ return ans;
+
+ if( len1 > len2 )
+ return 1;
+ if( len1 < len2 )
+ return -1;
+
+ return 0;
+}
+
+// Latch Manager
+
+void bt_readlock(BtLatch *latch)
+{
+#ifdef unix
+ pthread_rwlock_rdlock (latch->lock);
+#else
+ AcquireSRWLockShared (latch->srw);
+#endif
+}
+
+// wait for other read and write latches to relinquish
+
+void bt_writelock(BtLatch *latch)
+{
+#ifdef unix
+ pthread_rwlock_wrlock (latch->lock);
+#else
+ AcquireSRWLockExclusive (latch->srw);
+#endif
+}
+
+// try to obtain write lock
+
+// return 1 if obtained,
+// 0 if already write or read locked
+
+int bt_writetry(BtLatch *latch)
+{
+int result = 0;
+
+#ifdef unix
+ result = !pthread_rwlock_trywrlock (latch->lock);
+#else
+ result = TryAcquireSRWLockExclusive (latch->srw);
+#endif
+ return result;
+}
+
+// clear write mode
+
+void bt_releasewrite(BtLatch *latch)
+{
+#ifdef unix
+ pthread_rwlock_unlock (latch->lock);
+#else
+ ReleaseSRWLockExclusive (latch->srw);
+#endif
+}
+
+// decrement reader count
+
+void bt_releaseread(BtLatch *latch)
+{
+#ifdef unix
+ pthread_rwlock_unlock (latch->lock);
+#else
+ ReleaseSRWLockShared (latch->srw);
+#endif
+}
+
+// Buffer Pool mgr
+
+// find segment in pool
+// must be called with hashslot idx locked
+// return NULL if not there
+// otherwise return node
+
+BtPool *bt_findpool(BtDb *bt, uid page_no, uint idx)
+{
+BtPool *pool;
+uint slot;
+
+ // compute start of hash chain in pool
+
+ if( slot = bt->mgr->hash[idx] )
+ pool = bt->mgr->pool + slot;
+ else
+ return NULL;
+
+ page_no &= ~bt->mgr->poolmask;
+
+ while( pool->basepage != page_no )
+ if( pool = pool->hashnext )
+ continue;
+ else
+ return NULL;
+
+ return pool;
+}
+
+// add segment to hash table
+
+void bt_linkhash(BtDb *bt, BtPool *pool, uid page_no, int idx)
+{
+BtPool *node;
+uint slot;
+
+ pool->hashprev = pool->hashnext = NULL;
+ pool->basepage = page_no & ~bt->mgr->poolmask;
+ pool->lru = 1;
+
+ if( slot = bt->mgr->hash[idx] ) {
+ node = bt->mgr->pool + slot;
+ pool->hashnext = node;
+ node->hashprev = pool;
+ }
+
+ bt->mgr->hash[idx] = pool->slot;
+}
+
+// find best segment to evict from buffer pool
+
+BtPool *bt_findlru (BtDb *bt, uint hashslot)
+{
+unsigned long long int target = ~0LL;
+BtPool *pool = NULL, *node;
+
+ if( !hashslot )
+ return NULL;
+
+ node = bt->mgr->pool + hashslot;
+
+ // scan pool entries under hash table slot
+
+ do {
+ if( node->pin )
+ continue;
+ if( node->lru > target )
+ continue;
+ target = node->lru;
+ pool = node;
+ } while( node = node->hashnext );
+
+ return pool;
+}
+
+// map new buffer pool segment to virtual memory
+
+BTERR bt_mapsegment(BtDb *bt, BtPool *pool, uid page_no)
+{
+off64_t off = (page_no & ~bt->mgr->poolmask) << bt->mgr->page_bits;
+off64_t limit = off + ((bt->mgr->poolmask+1) << bt->mgr->page_bits);
+int flag;
+
+#ifdef unix
+ flag = PROT_READ | ( bt->mgr->mode == BT_ro ? 0 : PROT_WRITE );
+ pool->map = mmap (0, (bt->mgr->poolmask+1) << bt->mgr->page_bits, flag, MAP_SHARED, bt->mgr->idx, off);
+ if( pool->map == MAP_FAILED )
+ return bt->err = BTERR_map;
+ // clear out madvise issued bits
+ memset (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8) / 8), 0, (bt->mgr->poolmask + 8)/8);
+#else
+ flag = ( bt->mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE );
+ pool->hmap = CreateFileMapping(bt->mgr->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL);
+ if( !pool->hmap )
+ return bt->err = BTERR_map;
+
+ flag = ( bt->mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE );
+ pool->map = MapViewOfFile(pool->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->mgr->poolmask+1) << bt->mgr->page_bits);
+ if( !pool->map )
+ return bt->err = BTERR_map;
+#endif
+ return bt->err = 0;
+}
+
+// find or place requested page in segment-pool
+// return pool table entry, incrementing pin
+
+BtPool *bt_pinpage(BtDb *bt, uid page_no)
+{
+BtPool *pool, *node, *next;
+uint slot, idx, victim;
+BtLatchSet *set;
+
+ // lock hash table chain
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_spinreadlock (&bt->mgr->latch[idx]);
+
+ // look up in hash table
+
+ if( pool = bt_findpool(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleaseread (&bt->mgr->latch[idx]);
+ pool->lru++;
+ return pool;
+ }
+
+ // upgrade to write lock
+
+ bt_spinreleaseread (&bt->mgr->latch[idx]);
+ bt_spinwritelock (&bt->mgr->latch[idx]);
+
+ // try to find page in pool with write lock
+
+ if( pool = bt_findpool(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ pool->lru++;
+ return pool;
+ }
+
+ // allocate a new pool node
+ // and add to hash table
+
+#ifdef unix
+ slot = __sync_fetch_and_add(&bt->mgr->poolcnt, 1);
+#else
+ slot = _InterlockedIncrement16 (&bt->mgr->poolcnt) - 1;
+#endif
+
+ if( ++slot < bt->mgr->poolmax ) {
+ pool = bt->mgr->pool + slot;
+ pool->slot = slot;
+
+ if( bt_mapsegment(bt, pool, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, pool, page_no, idx);
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ return pool;
+ }
+
+ // pool table is full
+ // find best pool entry to evict
+
+#ifdef unix
+ __sync_fetch_and_add(&bt->mgr->poolcnt, -1);
+#else
+ _InterlockedDecrement16 (&bt->mgr->poolcnt);
+#endif
+
+ while( 1 ) {
+#ifdef unix
+ victim = __sync_fetch_and_add(&bt->mgr->evicted, 1);
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->evicted) - 1;
+#endif
+ victim %= bt->mgr->hashsize;
+
+ // try to get write lock
+ // skip entry if not obtained
+
+ if( !bt_spinwritetry (&bt->mgr->latch[victim]) )
+ continue;
+
+ // if cache entry is empty
+ // or no slots are unpinned
+ // skip this entry
+
+ if( !(pool = bt_findlru(bt, bt->mgr->hash[victim])) ) {
+ bt_spinreleasewrite (&bt->mgr->latch[victim]);
+ continue;
+ }
+
+ // unlink victim pool node from hash table
+
+ if( node = pool->hashprev )
+ node->hashnext = pool->hashnext;
+ else if( node = pool->hashnext )
+ bt->mgr->hash[victim] = node->slot;
+ else
+ bt->mgr->hash[victim] = 0;
+
+ if( node = pool->hashnext )
+ node->hashprev = pool->hashprev;
+
+ bt_spinreleasewrite (&bt->mgr->latch[victim]);
+
+ // remove old file mapping
+#ifdef unix
+ munmap (pool->map, (bt->mgr->poolmask+1) << bt->mgr->page_bits);
+#else
+ FlushViewOfFile(pool->map, 0);
+ UnmapViewOfFile(pool->map);
+ CloseHandle(pool->hmap);
+#endif
+ pool->map = NULL;
+
+ // create new pool mapping
+ // and link into hash table
+
+ if( bt_mapsegment(bt, pool, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, pool, page_no, idx);
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ return pool;
+ }
+}
+
+// place write, read, or parent lock on requested page_no.
+// pin to buffer pool and return latchset pointer
+
+BtLatchSet *bt_lockpage(BtDb *bt, uid page_no, BtLock mode, BtPage *pageptr, BtLatchSet *set)
+{
+BtPool *pool;
+uint subpage;
+BtPage page;
+
+ // find/create maping in pool table
+ // and pin our pool slot
+
+ if( pool = bt_pinpage(bt, page_no) )
+ subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
+ else
+ return NULL;
+
+ if( set )
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ else if( !(set = bt_bindlatch (bt, page_no, 1)) )
+ return NULL;
+
+ page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
+
+#ifdef unix
+ {
+ uint idx = subpage / 8;
+ uint bit = subpage % 8;
+
+ if( mode == BtLockRead || mode == BtLockWrite )
+ if( ~((bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] >> bit) & 1 ) {
+ madvise (page, bt->mgr->page_size, MADV_WILLNEED);
+ (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] |= 1 << bit;
+ }
+ }
+#endif
+
+ switch( mode ) {
+ case BtLockRead:
+ bt_readlock (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_writelock (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_readlock (set->access);
+ break;
+ case BtLockDelete:
+ bt_writelock (set->access);
+ break;
+ case BtLockParent:
+ bt_writelock (set->parent);
+ break;
+ case BtLockPin:
+ break;
+ default:
+ return bt->err = BTERR_lock, NULL;
+ }
+
+ if( pageptr )
+ *pageptr = page;
+
+ return set;
+}
+
+// remove write, read, or parent lock on requested page_no.
+
+BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode, BtLatchSet *set)
+{
+BtPool *pool;
+uint idx;
+
+ // since page is pinned
+ // it should still be in the buffer pool
+ // and is in no danger of being a victim for reuse
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_spinreadlock (&bt->mgr->latch[idx]);
+
+ if( !(pool = bt_findpool(bt, page_no, idx)) )
+ return bt->err = BTERR_hash;
+
+ bt_spinreleaseread (&bt->mgr->latch[idx]);
+
+ switch( mode ) {
+ case BtLockRead:
+ bt_releaseread (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_releasewrite (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_releaseread (set->access);
+ break;
+ case BtLockDelete:
+ bt_releasewrite (set->access);
+ break;
+ case BtLockParent:
+ bt_releasewrite (set->parent);
+ break;
+ case BtLockPin:
+ break;
+ default:
+ return bt->err = BTERR_lock;
+ }
+
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, -1);
+ __sync_fetch_and_add (&set->pin, -1);
+#else
+ _InterlockedDecrement16 (&pool->pin);
+ _InterlockedDecrement16 (&set->pin);
+#endif
+ return bt->err = 0;
+}
+
+// deallocate a deleted page
+// place on free chain out of allocator page
+// fence key must already be removed from parent
+
+BTERR bt_freepage(BtDb *bt, uid page_no, BtLatchSet *set)
+{
+ // obtain delete lock on deleted page
+
+ if( !bt_lockpage(bt, page_no, BtLockDelete, NULL, set) )
+ return bt->err;
+
+ // obtain write lock on deleted page
+
+ if( !bt_lockpage(bt, page_no, BtLockWrite, &bt->temp, set) )
+ return bt->err;
+
+ // lock allocation page
+
+ bt_spinwritelock(bt->mgr->latchmgr->lock);
+
+ // store free chain in allocation page second right
+ bt_putid(bt->temp->right, bt_getid(bt->mgr->latchmgr->alloc[1].right));
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, page_no);
+
+ // unlock page zero
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
+ // remove write lock on deleted node
+
+ if( bt_unlockpage(bt, page_no, BtLockWrite, set) )
+ return bt->err;
+
+ // remove delete lock on deleted node
+
+ if( bt_unlockpage(bt, page_no, BtLockDelete, set) )
+ return bt->err;
+
+ return 0;
+}
+
+// allocate a new page and write page into it
+
+uid bt_newpage(BtDb *bt, BtPage page)
+{
+BtLatchSet *set;
+uid new_page;
+BtPage pmap;
+int reuse;
+
+ // lock allocation page
+
+ bt_spinwritelock(bt->mgr->latchmgr->lock);
+
+ // use empty chain first
+ // else allocate empty page
+
+ if( new_page = bt_getid(bt->mgr->latchmgr->alloc[1].right) ) {
+ if( !(set = bt_lockpage (bt, new_page, BtLockWrite, &bt->temp, NULL)) )
+ return 0;
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, bt_getid(bt->temp->right));
+ if( bt_unlockpage (bt, new_page, BtLockWrite, set) )
+ return 0;
+ reuse = 1;
+ } else {
+ new_page = bt_getid(bt->mgr->latchmgr->alloc->right);
+ bt_putid(bt->mgr->latchmgr->alloc->right, new_page+1);
+ reuse = 0;
+ }
+#ifdef unix
+ if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+
+ // if writing first page of pool block, zero last page in the block
+
+ if ( !reuse && bt->mgr->poolmask > 0 && (new_page & bt->mgr->poolmask) == 0 )
+ {
+ // use zero buffer to write zeros
+ memset(bt->zero, 0, bt->mgr->page_size);
+ if ( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->poolmask) << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+ }
+#else
+ // bring new page into pool and copy page.
+ // this will extend the file into the new pages.
+
+ if( !(set = bt_lockpage(bt, new_page, BtLockWrite, &pmap, NULL)) )
+ return 0;
+
+ memcpy(pmap, page, bt->mgr->page_size);
+
+ if( bt_unlockpage (bt, new_page, BtLockWrite, set) )
+ return 0;
+#endif
+ // unlock allocation latch and return new page no
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+ return new_page;
+}
+
+// find slot in page for given key at a given level
+
+int bt_findslot (BtDb *bt, unsigned char *key, uint len)
+{
+uint diff, higher = bt->page->cnt, low = 1, slot;
+
+ // low is the lowest candidate, higher is already
+ // tested as .ge. the given key, loop ends when they meet
+
+ while( diff = higher - low ) {
+ slot = low + ( diff >> 1 );
+ if( keycmp (keyptr(bt->page, slot), key, len) < 0 )
+ low = slot + 1;
+ else
+ higher = slot;
+ }
+
+ return higher;
+}
+
+// find and load page at given level for given key
+// leave page rd or wr locked as requested
+
+int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, BtLock lock)
+{
+uid page_no = ROOT_page, prevpage = 0;
+BtLatchSet *set, *prevset;
+uint drill = 0xff, slot;
+uint mode, prevmode;
+
+ bt->set = NULL;
+
+ // start at root of btree and drill down
+
+ do {
+ // determine lock mode of drill level
+ mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead;
+
+ bt->page_no = page_no;
+
+ // obtain access lock using lock chaining with Access mode
+
+ if( page_no > ROOT_page )
+ if( !(bt->set = bt_lockpage(bt, page_no, BtLockAccess, NULL, NULL)) )
+ return 0;
+
+ // now unlock our (possibly foster) parent
+
+ if( prevpage )
+ if( bt_unlockpage(bt, prevpage, prevmode, prevset) )
+ return 0;
+ else
+ prevpage = 0;
+
+ // obtain read lock using lock chaining
+ // and pin page contents
+
+ if( !(bt->set = bt_lockpage(bt, page_no, mode, &bt->page, bt->set)) )
+ return 0;
+
+ if( page_no > ROOT_page )
+ if( bt_unlockpage(bt, page_no, BtLockAccess, bt->set) )
+ return 0;
+
+ // re-read and re-lock root after determining actual level of root
+
+ if( bt->page_no == ROOT_page )
+ if( bt->page->lvl != drill) {
+ drill = bt->page->lvl;
+
+ if( lock == BtLockWrite && drill == lvl )
+ if( bt_unlockpage(bt, page_no, mode, bt->set) )
+ return 0;
+ else
+ continue;
+ }
+
+ prevpage = bt->page_no;
+ prevset = bt->set;
+ prevmode = mode;
+
+ // if page is being deleted,
+ // move back to preceeding page
+
+ if( bt->page->kill ) {
+ page_no = bt_getid (bt->page->right);
+ continue;
+ }
+
+ // find key on page at this level
+ // and descend to requested level
+
+ slot = bt_findslot (bt, key, len);
+
+ // is this slot a foster child?
+
+ if( slot <= bt->page->cnt - bt->page->foster )
+ if( drill == lvl )
+ return slot;
+
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ goto slideright;
+
+ if( slot <= bt->page->cnt - bt->page->foster )
+ drill--;
+
+ // continue down / right using overlapping locks
+ // to protect pages being killed or split.
+
+ page_no = bt_getid(slotptr(bt->page, slot)->id);
+ continue;
+
+slideright:
+ page_no = bt_getid(bt->page->right);
+
+ } while( page_no );
+
+ // return error on end of chain
+
+ bt->err = BTERR_struct;
+ return 0; // return error
+}
+
+// find and delete key on page by marking delete flag bit
+// when page becomes empty, delete it from the btree
+
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl)
+{
+unsigned char leftkey[256], rightkey[256];
+BtLatchSet *rset, *set;
+uid page_no, right;
+uint slot, tod;
+BtKey ptr;
+
+ if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // if key is found delete it, otherwise ignore request
+
+ if( !keycmp (ptr, key, len) )
+ if( slotptr(bt->page, slot)->dead == 0 ) {
+ slotptr(bt->page,slot)->dead = 1;
+ if( slot < bt->page->cnt )
+ bt->page->dirty = 1;
+ bt->page->act--;
+ }
+
+ // return if page is not empty, or it has no right sibling
+
+ right = bt_getid(bt->page->right);
+ page_no = bt->page_no;
+ set = bt->set;
+
+ if( !right || bt->page->act )
+ return bt_unlockpage(bt, page_no, BtLockWrite, set);
+
+ // obtain Parent lock over write lock
+
+ if( !bt_lockpage(bt, page_no, BtLockParent, NULL, set) )
+ return bt->err;
+
+ // cache copy of key to delete
+
+ ptr = keyptr(bt->page, bt->page->cnt);
+ memcpy(leftkey, ptr, ptr->len + 1);
+
+ // lock and map right page
+
+ if( !(rset = bt_lockpage(bt, right, BtLockWrite, &bt->temp, NULL)) )
+ return bt->err;
+
+ // pull contents of next page into current empty page
+ memcpy (bt->page, bt->temp, bt->mgr->page_size);
+
+ // cache copy of key to update
+ ptr = keyptr(bt->temp, bt->temp->cnt);
+ memcpy(rightkey, ptr, ptr->len + 1);
+
+ // Mark right page as deleted and point it to left page
+ // until we can post updates at higher level.
+
+ bt_putid(bt->temp->right, page_no);
+ bt->temp->kill = 1;
+ bt->temp->cnt = 0;
+
+ if( bt_unlockpage(bt, right, BtLockWrite, rset) )
+ return bt->err;
+ if( bt_unlockpage(bt, page_no, BtLockWrite, set) )
+ return bt->err;
+
+ // delete old lower key to consolidated node
+
+ if( bt_deletekey (bt, leftkey + 1, *leftkey, lvl + 1) )
+ return bt->err;
+
+ // redirect higher key directly to consolidated node
+
+ if( slot = bt_loadpage (bt, rightkey+1, *rightkey, lvl+1, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // since key already exists, update id
+
+ if( keycmp (ptr, rightkey+1, *rightkey) )
+ return bt->err = BTERR_struct;
+
+ slotptr(bt->page, slot)->dead = 0;
+ bt_putid(slotptr(bt->page,slot)->id, page_no);
+
+ if( bt_unlockpage(bt, bt->page_no, BtLockWrite, bt->set) )
+ return bt->err;
+
+ // obtain write lock and
+ // add right block to free chain
+
+ if( bt_freepage (bt, right, rset) )
+ return bt->err;
+
+ // remove ParentModify lock
+
+ if( bt_unlockpage(bt, page_no, BtLockParent, set) )
+ return bt->err;
+
+ return 0;
+}
+
+// find key in leaf level and return row-id
+
+uid bt_findkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+BtKey ptr;
+uid id;
+
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return 0;
+
+ // if key exists, return row-id
+ // otherwise return 0
+
+ if( ptr->len == len && !memcmp (ptr->key, key, len) )
+ id = bt_getid(slotptr(bt->page,slot)->id);
+ else
+ id = 0;
+
+ if( bt_unlockpage (bt, bt->page_no, BtLockRead, bt->set) )
+ return 0;
+
+ return id;
+}
+
+// check page for space available,
+// clean if necessary and return
+// 0 - page needs splitting
+// 1 - go ahead
+
+uint bt_cleanpage(BtDb *bt, uint amt)
+{
+uint nxt = bt->mgr->page_size;
+BtPage page = bt->page;
+uint cnt = 0, idx = 0;
+uint max = page->cnt;
+BtKey key;
+
+ if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return 1;
+
+ // skip cleanup if nothing to reclaim
+
+ if( !page->dirty )
+ return 0;
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+
+ // skip page info and set rest of page to zero
+
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ page->dirty = 0;
+ page->act = 0;
+
+ // try cleaning up page first
+
+ while( cnt++ < max ) {
+ // always leave fence key and foster children in list
+ if( cnt < max - page->foster && slotptr(bt->frame,cnt)->dead )
+ continue;
+
+ // copy key
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+
+ // copy slot
+ memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId);
+ if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
+ page->act++;
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ // see if page has enough space now, or does it need splitting?
+
+ if( page->min >= (idx+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return 1;
+
+ return 0;
+}
+
+// add key to current page
+// page must already be writelocked
+
+void bt_addkeytopage (BtDb *bt, uint slot, unsigned char *key, uint len, uid id, uint tod)
+{
+BtPage page = bt->page;
+uint idx;
+
+ // calculate next available slot and copy key into page
+
+ page->min -= len + 1;
+ ((unsigned char *)page)[page->min] = len;
+ memcpy ((unsigned char *)page + page->min +1, key, len );
+
+ for( idx = slot; idx < page->cnt; idx++ )
+ if( slotptr(page, idx)->dead )
+ break;
+
+ // now insert key into array before slot
+ // preserving the fence slot
+
+ if( idx == page->cnt )
+ idx++, page->cnt++;
+
+ page->act++;
+
+ while( idx > slot )
+ *slotptr(page, idx) = *slotptr(page, idx -1), idx--;
+
+ bt_putid(slotptr(page,slot)->id, id);
+ slotptr(page, slot)->off = page->min;
+ slotptr(page, slot)->tod = tod;
+ slotptr(page, slot)->dead = 0;
+}
+
+// split the root and raise the height of the btree
+// call with current page locked and page no of foster child
+// return with current page (root) unlocked
+
+BTERR bt_splitroot(BtDb *bt, uid right)
+{
+uint nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+BtPage root = bt->page;
+uid new_page;
+BtKey key;
+
+ // Obtain an empty page to use, and copy the left page
+ // contents into it from the root. Strip foster child key.
+ // (it's the stopper key)
+
+ root->act--;
+ root->cnt--;
+ root->foster--;
+
+ // Save left fence key.
+
+ key = keyptr(root, root->cnt);
+ memcpy (fencekey, key, key->len + 1);
+
+ // copy the lower keys into a new left page
+
+ if( !(new_page = bt_newpage(bt, root)) )
+ return bt->err;
+
+ // preserve the page info at the bottom
+ // and set rest of the root to zero
+
+ memset (root+1, 0, bt->mgr->page_size - sizeof(*root));
+
+ // insert left fence key on empty newroot page
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 1)->id, new_page);
+ slotptr(root, 1)->off = nxt;
+
+ // insert stopper key on newroot page
+ // and increase the root height
+
+ nxt -= 3;
+ fencekey[0] = 2;
+ fencekey[1] = 0xff;
+ fencekey[2] = 0xff;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 2)->id, right);
+ slotptr(root, 2)->off = nxt;
+
+ bt_putid(root->right, 0);
+ root->min = nxt; // reset lowest used offset and key count
+ root->cnt = 2;
+ root->act = 2;
+ root->lvl++;
+
+ // release root (bt->page)
+
+ return bt_unlockpage(bt, ROOT_page, BtLockWrite, bt->set);
+}
+
+// split already locked full node
+// in current page variables
+// return unlocked.
+
+BTERR bt_splitpage (BtDb *bt)
+{
+uint slot, cnt, idx, max, nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+uid page_no = bt->page_no;
+BtLatchSet *set = bt->set;
+BtPage page = bt->page;
+uint tod = time(NULL);
+uint lvl = page->lvl;
+uid new_page, right;
+BtKey key;
+
+ // initialize frame buffer
+
+ memset (bt->frame, 0, bt->mgr->page_size);
+ max = page->cnt - page->foster;
+ tod = (uint)time(NULL);
+ cnt = max / 2;
+ idx = 0;
+
+ // split higher half of keys to bt->frame
+ // leaving foster children in the left node.
+
+ while( cnt++ < max ) {
+ key = keyptr(page, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1);
+ memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId);
+ slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod;
+ slotptr(bt->frame, idx)->off = nxt;
+ bt->frame->act++;
+ }
+
+ // transfer right link node
+
+ if( page_no > ROOT_page ) {
+ right = bt_getid (page->right);
+ bt_putid(bt->frame->right, right);
+ }
+
+ bt->frame->bits = bt->mgr->page_bits;
+ bt->frame->min = nxt;
+ bt->frame->cnt = idx;
+ bt->frame->lvl = lvl;
+
+ // get new free page and write frame to it.
+
+ if( !(new_page = bt_newpage(bt, bt->frame)) )
+ return bt->err;
+
+ // remember fence key for new page to add
+ // as foster child
+
+ key = keyptr(bt->frame, idx);
+ memcpy (fencekey, key, key->len + 1);
+
+ // update lower keys and foster children to continue in old page
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ nxt = bt->mgr->page_size;
+ page->act = 0;
+ cnt = 0;
+ idx = 0;
+
+ // assemble page of smaller keys
+ // to remain in the old page
+
+ while( cnt++ < max / 2 ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ page->act++;
+ }
+
+ // insert new foster child at beginning of the current foster children
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)page + nxt, fencekey, *fencekey + 1);
+ bt_putid (slotptr(page,++idx)->id, new_page);
+ slotptr(page, idx)->tod = tod;
+ slotptr(page, idx)->off = nxt;
+ page->foster++;
+ page->act++;
+
+ // continue with old foster child keys if any
+
+ cnt = bt->frame->cnt - bt->frame->foster;
+
+ while( cnt++ < bt->frame->cnt ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ page->act++;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ // link new right page
+
+ bt_putid (page->right, new_page);
+
+ // if current page is the root page, split it
+
+ if( page_no == ROOT_page )
+ return bt_splitroot (bt, new_page);
+
+ // keep our latch set
+ // release wr lock on our page
+
+ if( !bt_lockpage (bt, page_no, BtLockPin, NULL, set) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockWrite, set) )
+ return bt->err;
+
+ // obtain ParentModification lock for current page
+ // to fix fence key and highest foster child on page
+
+ if( !bt_lockpage (bt, page_no, BtLockParent, NULL, set) )
+ return bt->err;
+
+ // get our highest foster child key to find in parent node
+
+ if( !bt_lockpage (bt, page_no, BtLockRead, &page, set) )
+ return bt->err;
+
+ key = keyptr(page, page->cnt);
+ memcpy (fencekey, key, key->len+1);
+
+ if( bt_unlockpage (bt, page_no, BtLockRead, set) )
+ return bt->err;
+
+ // update our parent
+try_again:
+
+ do {
+ slot = bt_loadpage (bt, fencekey + 1, *fencekey, lvl + 1, BtLockWrite);
+
+ if( !slot )
+ return bt->err;
+
+ // check if parent page has enough space for any possible key
+
+ if( bt_cleanpage (bt, 256) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ } while( 1 );
+
+ // see if we are still a foster child from another node
+
+ if( bt_getid (slotptr(bt->page, slot)->id) != page_no ) {
+ if( bt_unlockpage (bt, bt->page_no, BtLockWrite, bt->set) )
+ return bt->err;
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ goto try_again;
+ }
+
+ // wait until readers from parent get their locks
+ // on our page
+
+ if( !bt_lockpage (bt, page_no, BtLockDelete, NULL, set) )
+ return bt->err;
+
+ // lock our page for writing
+
+ if( !bt_lockpage (bt, page_no, BtLockWrite, &page, set) )
+ return bt->err;
+
+ // switch parent fence key to foster child
+
+ if( slotptr(page, page->cnt)->dead )
+ slotptr(bt->page, slot)->dead = 1;
+ else
+ bt_putid (slotptr(bt->page, slot)->id, bt_getid(slotptr(page, page->cnt)->id));
+
+ // remove highest foster child from our page
+
+ page->cnt--;
+ page->act--;
+ page->foster--;
+ page->dirty = 1;
+ key = keyptr(page, page->cnt);
+
+ // add our new fence key for foster child to our parent
+
+ bt_addkeytopage (bt, slot, key->key, key->len, page_no, tod);
+
+ if( bt_unlockpage (bt, bt->page_no, BtLockWrite, bt->set) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockDelete, set) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockWrite, set) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockParent, set) )
+ return bt->err;
+
+ // release extra latch pin
+
+ return bt_unlockpage (bt, page_no, BtLockPin, set);
+}
+
+// Insert new key into the btree at leaf level.
+
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod)
+{
+uint slot, idx;
+BtPage page;
+BtKey ptr;
+
+ while( 1 ) {
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ {
+ if ( !bt->err )
+ bt->err = BTERR_ovflw;
+ return bt->err;
+ }
+
+ // if key already exists, update id and return
+
+ page = bt->page;
+
+ if( !keycmp (ptr, key, len) ) {
+ slotptr(page, slot)->dead = 0;
+ slotptr(page, slot)->tod = tod;
+ bt_putid(slotptr(page,slot)->id, id);
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite, bt->set);
+ }
+
+ // check if page has enough space
+
+ if( bt_cleanpage (bt, len) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ }
+
+ bt_addkeytopage (bt, slot, key, len, id, tod);
+
+ return bt_unlockpage (bt, bt->page_no, BtLockWrite, bt->set);
+}
+
+// cache page of keys into cursor and return starting slot for given key
+
+uint bt_startkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+
+ // cache page for retrieval
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ memcpy (bt->cursor, bt->page, bt->mgr->page_size);
+ bt->cursor_page = bt->page_no;
+ if ( bt_unlockpage(bt, bt->page_no, BtLockRead, bt->set) )
+ return 0;
+
+ return slot;
+}
+
+// return next slot for cursor page
+// or slide cursor right into next page
+
+uint bt_nextkey (BtDb *bt, uint slot)
+{
+BtLatchSet *rset;
+BtPage page;
+uid right;
+
+ do {
+ right = bt_getid(bt->cursor->right);
+ while( slot++ < bt->cursor->cnt - bt->cursor->foster )
+ if( slotptr(bt->cursor,slot)->dead )
+ continue;
+ else if( right || (slot < bt->cursor->cnt - bt->cursor->foster) )
+ return slot;
+ else
+ break;
+
+ if( !right )
+ break;
+
+ bt->cursor_page = right;
+
+ if( !(bt->set = bt_lockpage(bt, right, BtLockRead, &page, NULL)) )
+ return 0;
+
+ memcpy (bt->cursor, page, bt->mgr->page_size);
+
+ if ( bt_unlockpage(bt, right, BtLockRead, bt->set) )
+ return 0;
+
+ slot = 0;
+ } while( 1 );
+
+ return bt->err = 0;
+}
+
+BtKey bt_key(BtDb *bt, uint slot)
+{
+ return keyptr(bt->cursor, slot);
+}
+
+uid bt_uid(BtDb *bt, uint slot)
+{
+ return bt_getid(slotptr(bt->cursor,slot)->id);
+}
+
+uint bt_tod(BtDb *bt, uint slot)
+{
+ return slotptr(bt->cursor,slot)->tod;
+}
+
+
+#ifdef STANDALONE
+
+typedef struct {
+ char type, idx;
+ char *infile;
+ BtMgr *mgr;
+ int num;
+} ThreadArg;
+
+// standalone program to index file of keys
+// then list them onto std-out
+
+#ifdef unix
+void *index_file (void *arg)
+#else
+uint __stdcall index_file (void *arg)
+#endif
+{
+int line = 0, found = 0, cnt = 0;
+uid next, page_no = LEAF_page; // start on first page of leaves
+unsigned char key[256];
+ThreadArg *args = arg;
+int ch, len = 0, slot;
+time_t tod[1];
+BtPage page;
+BtKey ptr;
+BtDb *bt;
+FILE *in;
+
+ bt = bt_open (args->mgr);
+ time (tod);
+
+ switch(args->type | 0x20)
+ {
+ case 'w':
+ fprintf(stderr, "started indexing for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_insertkey (bt, key, len, line, *tod) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys\n", args->infile, line);
+ break;
+
+ case 'd':
+ fprintf(stderr, "started deleting keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_deletekey (bt, key, len, 0) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for keys, %d \n", args->infile, line);
+ break;
+
+ case 'f':
+ fprintf(stderr, "started finding keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_findkey (bt, key, len) )
+ found++;
+ else if( bt->err )
+ fprintf(stderr, "Error %d Syserr %d Line: %d\n", bt->err, errno, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys, found %d\n", args->infile, line, found);
+ break;
+
+ case 's':
+ len = key[0] = 0;
+
+ fprintf(stderr, "started reading\n");
+
+ if( slot = bt_startkey (bt, key, len) )
+ slot--;
+ else
+ fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0);
+
+ while( slot = bt_nextkey (bt, slot) ) {
+ ptr = bt_key(bt, slot);
+ fwrite (ptr->key, ptr->len, 1, stdout);
+ fputc ('\n', stdout);
+ }
+
+ break;
+
+ case 'c':
+ fprintf(stderr, "started reading\n");
+
+ do {
+ bt->set = bt_lockpage (bt, page_no, BtLockRead, &page, NULL);
+ cnt += page->act;
+ next = bt_getid (page->right);
+ bt_unlockpage (bt, page_no, BtLockRead, bt->set);
+ } while( page_no = next );
+
+ cnt--; // remove stopper key
+ fprintf(stderr, " Total keys read %d\n", cnt);
+ break;
+ }
+
+ bt_close (bt);
+#ifdef unix
+ return NULL;
+#else
+ return 0;
+#endif
+}
+
+typedef struct timeval timer;
+
+int main (int argc, char **argv)
+{
+int idx, cnt, len, slot, err;
+int segsize, bits = 16;
+#ifdef unix
+pthread_t *threads;
+timer start, stop;
+#else
+time_t start[1], stop[1];
+HANDLE *threads;
+#endif
+double real_time;
+ThreadArg *args;
+uint poolsize = 0;
+int num = 0;
+char key[1];
+BtMgr *mgr;
+BtKey ptr;
+BtDb *bt;
+
+ if( argc < 3 ) {
+ fprintf (stderr, "Usage: %s idx_file Read/Write/Scan/Delete/Find [page_bits mapped_segments seg_bits line_numbers src_file1 src_file2 ... ]\n", argv[0]);
+ fprintf (stderr, " where page_bits is the page size in bits\n");
+ fprintf (stderr, " mapped_segments is the number of mmap segments in buffer pool\n");
+ fprintf (stderr, " seg_bits is the size of individual segments in buffer pool in pages in bits\n");
+ fprintf (stderr, " line_numbers = 1 to append line numbers to keys\n");
+ fprintf (stderr, " src_file1 thru src_filen are files of keys separated by newline\n");
+ exit(0);
+ }
+
+#ifdef unix
+ gettimeofday(&start, NULL);
+#else
+ time(start);
+#endif
+
+ if( argc > 3 )
+ bits = atoi(argv[3]);
+
+ if( argc > 4 )
+ poolsize = atoi(argv[4]);
+
+ if( !poolsize )
+ fprintf (stderr, "Warning: no mapped_pool\n");
+
+ if( poolsize > 65535 )
+ fprintf (stderr, "Warning: mapped_pool > 65535 segments\n");
+
+ if( argc > 5 )
+ segsize = atoi(argv[5]);
+ else
+ segsize = 4; // 16 pages per mmap segment
+
+ if( argc > 6 )
+ num = atoi(argv[6]);
+
+ cnt = argc - 7;
+#ifdef unix
+ threads = malloc (cnt * sizeof(pthread_t));
+#else
+ threads = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, cnt * sizeof(HANDLE));
+#endif
+ args = malloc (cnt * sizeof(ThreadArg));
+
+ mgr = bt_mgr ((argv[1]), BT_rw, bits, poolsize, segsize, poolsize / 8);
+
+ if( !mgr ) {
+ fprintf(stderr, "Index Open Error %s\n", argv[1]);
+ exit (1);
+ }
+
+ // fire off threads
+
+ for( idx = 0; idx < cnt; idx++ ) {
+ args[idx].infile = argv[idx + 7];
+ args[idx].type = argv[2][0];
+ args[idx].mgr = mgr;
+ args[idx].num = num;
+ args[idx].idx = idx;
+#ifdef unix
+ if( err = pthread_create (threads + idx, NULL, index_file, args + idx) )
+ fprintf(stderr, "Error creating thread %d\n", err);
+#else
+ threads[idx] = (HANDLE)_beginthreadex(NULL, 65536, index_file, args + idx, 0, NULL);
+#endif
+ }
+
+ // wait for termination
+
+#ifdef unix
+ for( idx = 0; idx < cnt; idx++ )
+ pthread_join (threads[idx], NULL);
+ gettimeofday(&stop, NULL);
+ real_time = 1000.0 * ( stop.tv_sec - start.tv_sec ) + 0.001 * (stop.tv_usec - start.tv_usec );
+#else
+ WaitForMultipleObjects (cnt, threads, TRUE, INFINITE);
+
+ for( idx = 0; idx < cnt; idx++ )
+ CloseHandle(threads[idx]);
+
+ time (stop);
+ real_time = 1000 * (*stop - *start);
+#endif
+ fprintf(stderr, " Time to complete: %.2f seconds\n", real_time/1000);
+ bt_mgrclose (mgr);
+}
+
+#endif //STANDALONE
--- /dev/null
+// foster btree version e2
+// 18 JAN 2014
+
+// author: karl malbrain, malbrain@cal.berkeley.edu
+
+/*
+This work, including the source code, documentation
+and related data, is placed into the public domain.
+
+The orginal author is Karl Malbrain.
+
+THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
+OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
+MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
+ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
+RESULTING FROM THE USE, MODIFICATION, OR
+REDISTRIBUTION OF THIS SOFTWARE.
+*/
+
+// Please see the project home page for documentation
+// code.google.com/p/high-concurrency-btree
+
+#define _FILE_OFFSET_BITS 64
+#define _LARGEFILE64_SOURCE
+
+#ifdef linux
+#define _GNU_SOURCE
+#endif
+
+#ifdef unix
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/time.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <pthread.h>
+#else
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <fcntl.h>
+#include <process.h>
+#include <intrin.h>
+#endif
+
+#include <memory.h>
+#include <string.h>
+
+typedef unsigned long long uid;
+
+#ifndef unix
+typedef unsigned long long off64_t;
+typedef unsigned short ushort;
+typedef unsigned int uint;
+#endif
+
+#define BT_ro 0x6f72 // ro
+#define BT_rw 0x7772 // rw
+
+#define BT_latchtable 128 // number of latch manager slots
+
+#define BT_maxbits 24 // maximum page size in bits
+#define BT_minbits 9 // minimum page size in bits
+#define BT_minpage (1 << BT_minbits) // minimum page size
+#define BT_maxpage (1 << BT_maxbits) // maximum page size
+
+/*
+There are five lock types for each node in three independent sets:
+1. (set 1) AccessIntent: Sharable. Going to Read the node. Incompatible with NodeDelete.
+2. (set 1) NodeDelete: Exclusive. About to release the node. Incompatible with AccessIntent.
+3. (set 2) ReadLock: Sharable. Read the node. Incompatible with WriteLock.
+4. (set 2) WriteLock: Exclusive. Modify the node. Incompatible with ReadLock and other WriteLocks.
+5. (set 3) ParentLock: Exclusive. Have parent adopt/delete maximum foster child from the node.
+*/
+
+typedef enum{
+ BtLockAccess,
+ BtLockDelete,
+ BtLockRead,
+ BtLockWrite,
+ BtLockParent
+}BtLock;
+
+// Define the length of the page and key pointers
+
+#define BtId 6
+
+// Page key slot definition.
+
+// If BT_maxbits is 15 or less, you can save 4 bytes
+// for each key stored by making the first two uints
+// into ushorts. You can also save 4 bytes by removing
+// the tod field from the key.
+
+// Keys are marked dead, but remain on the page until
+// cleanup is called. The fence key (highest key) for
+// the page is always present, even after cleanup.
+
+typedef struct {
+ uint off:BT_maxbits; // page offset for key start
+ uint dead:1; // set for deleted key
+ uint tod; // time-stamp for key
+ unsigned char id[BtId]; // id associated with key
+} BtSlot;
+
+// The key structure occupies space at the upper end of
+// each page. It's a length byte followed by the value
+// bytes.
+
+typedef struct {
+ unsigned char len;
+ unsigned char key[1];
+} *BtKey;
+
+// The first part of an index page.
+// It is immediately followed
+// by the BtSlot array of keys.
+
+typedef struct Page {
+ volatile uint cnt; // count of keys in page
+ volatile uint act; // count of active keys
+ volatile uint min; // next key offset
+ volatile uint foster; // count of foster children
+ unsigned char bits; // page size in bits
+ unsigned char lvl:7; // level of page
+ unsigned char dirty:1; // page needs to be cleaned
+ unsigned char right[BtId]; // page number to right
+} *BtPage;
+
+// mode & definition for hash latch implementation
+
+enum {
+ Mutex = 1,
+ Write = 2,
+ Pending = 4,
+ Share = 8
+} LockMode;
+
+// mutex locks the other fields
+// exclusive is set for write access
+// share is count of read accessors
+
+typedef struct {
+ volatile ushort mutex:1;
+ volatile ushort exclusive:1;
+ volatile ushort pending:1;
+ volatile ushort share:13;
+} BtSpinLatch;
+
+// hash table entries
+
+typedef struct {
+ BtSpinLatch latch[1];
+ volatile ushort slot; // Latch table entry at head of chain
+} BtHashEntry;
+
+// latch manager table structure
+
+typedef struct {
+#ifdef unix
+ pthread_rwlock_t lock[1];
+#else
+ SRWLOCK srw[1];
+#endif
+} BtLatch;
+
+typedef struct {
+ BtLatch readwr[1]; // read/write page lock
+ BtLatch access[1]; // Access Intent/Page delete
+ BtLatch parent[1]; // adoption of foster children
+ BtSpinLatch busy[1]; // slot is being moved between chains
+ volatile ushort next; // next entry in hash table chain
+ volatile ushort prev; // prev entry in hash table chain
+ volatile ushort pin; // number of outstanding locks
+ volatile ushort hash; // hash slot entry is under
+ volatile uid page_no; // latch set page number
+} BtLatchSet;
+
+// The memory mapping pool table buffer manager entry
+
+typedef struct {
+ unsigned long long int lru; // number of times accessed
+ uid basepage; // mapped base page number
+ char *map; // mapped memory pointer
+ ushort pin; // mapped page pin counter
+ ushort slot; // slot index in this array
+ void *hashprev; // previous pool entry for the same hash idx
+ void *hashnext; // next pool entry for the same hash idx
+#ifndef unix
+ HANDLE hmap; // Windows memory mapping handle
+#endif
+} BtPool;
+
+// structure for latch manager on ALLOC_page
+
+typedef struct {
+ struct Page alloc[2]; // next & free page_nos in right ptr
+ BtSpinLatch lock[1]; // allocation area lite latch
+ ushort latchdeployed; // highest number of latch entries deployed
+ ushort nlatchpage; // number of latch pages at BT_latch
+ ushort latchtotal; // number of page latch entries
+ ushort latchhash; // number of latch hash table slots
+ ushort latchvictim; // next latch entry to examine
+ BtHashEntry table[0]; // the hash table
+} BtLatchMgr;
+
+// The object structure for Btree access
+
+typedef struct {
+ uint page_size; // page size
+ uint page_bits; // page size in bits
+ uint seg_bits; // seg size in pages in bits
+ uint mode; // read-write mode
+#ifdef unix
+ int idx;
+ char *pooladvise; // bit maps for pool page advisements
+#else
+ HANDLE idx;
+#endif
+ ushort poolcnt; // highest page pool node in use
+ ushort poolmax; // highest page pool node allocated
+ ushort poolmask; // total number of pages in mmap segment - 1
+ ushort hashsize; // size of Hash Table for pool entries
+ ushort evicted; // last evicted hash table slot
+ ushort *hash; // hash table of pool entries
+ BtPool *pool; // memory pool page segments
+ BtSpinLatch *latch; // latches for pool hash slots
+ BtLatchMgr *latchmgr; // mapped latch page from allocation page
+ BtLatchSet *latchsets; // mapped latch set from latch pages
+#ifndef unix
+ HANDLE halloc; // allocation and latch table handle
+#endif
+} BtMgr;
+
+typedef struct {
+ BtMgr *mgr; // buffer manager for thread
+ BtPage cursor; // cached frame for start/next (never mapped)
+ BtPage frame; // spare frame for the page split (never mapped)
+ BtPage zero; // page frame for zeroes at end of file
+ BtPage page; // current page
+ uid page_no; // current page number
+ uid cursor_page; // current cursor page number
+ BtLatchSet *set; // current page latch set
+ BtPool *pool; // current page pool
+ unsigned char *mem; // frame, cursor, page memory buffer
+ int found; // last delete was found
+ int err; // last error
+} BtDb;
+
+typedef enum {
+ BTERR_ok = 0,
+ BTERR_struct,
+ BTERR_ovflw,
+ BTERR_lock,
+ BTERR_map,
+ BTERR_wrt,
+ BTERR_hash,
+ BTERR_latch
+} BTERR;
+
+// B-Tree functions
+extern void bt_close (BtDb *bt);
+extern BtDb *bt_open (BtMgr *mgr);
+extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod, uint lvl);
+extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len);
+extern uid bt_findkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_startkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_nextkey (BtDb *bt, uint slot);
+
+// manager functions
+extern BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolsize, uint segsize, uint hashsize);
+void bt_mgrclose (BtMgr *mgr);
+
+// Helper functions to return cursor slot values
+
+extern BtKey bt_key (BtDb *bt, uint slot);
+extern uid bt_uid (BtDb *bt, uint slot);
+extern uint bt_tod (BtDb *bt, uint slot);
+
+// BTree page number constants
+#define ALLOC_page 0 // allocation & lock manager hash table
+#define ROOT_page 1 // root of the btree
+#define LEAF_page 2 // first page of leaves
+#define LATCH_page 3 // pages for lock manager
+
+// Number of levels to create in a new BTree
+
+#define MIN_lvl 2
+
+// The page is allocated from low and hi ends.
+// The key offsets and row-id's are allocated
+// from the bottom, while the text of the key
+// is allocated from the top. When the two
+// areas meet, the page is split into two.
+
+// A key consists of a length byte, two bytes of
+// index number (0 - 65534), and up to 253 bytes
+// of key value. Duplicate keys are discarded.
+// Associated with each key is a 48 bit row-id.
+
+// The b-tree root is always located at page 1.
+// The first leaf page of level zero is always
+// located on page 2.
+
+// When to root page fills, it is split in two and
+// the tree height is raised by a new root at page
+// one with two keys.
+
+// Deleted keys are marked with a dead bit until
+// page cleanup The fence key for a node is always
+// present, even after deletion and cleanup.
+
+// Groups of pages called segments from the btree are
+// cached with memory mapping. A hash table is used to keep
+// track of the cached segments. This behaviour is controlled
+// by the cache block size parameter to bt_open.
+
+// To achieve maximum concurrency one page is locked at a time
+// as the tree is traversed to find leaf key in question.
+
+// An adoption traversal leaves the parent node locked as the
+// tree is traversed to the level in quesiton.
+
+// Page 0 is dedicated to lock for new page extensions,
+// and chains empty pages together for reuse.
+
+// Empty pages are chained together through the ALLOC page and reused.
+
+// Access macros to address slot and key values from the page
+
+#define slotptr(page, slot) (((BtSlot *)(page+1)) + (slot-1))
+#define keyptr(page, slot) ((BtKey)((unsigned char*)(page) + slotptr(page, slot)->off))
+
+void bt_putid(unsigned char *dest, uid id)
+{
+int i = BtId;
+
+ while( i-- )
+ dest[i] = (unsigned char)id, id >>= 8;
+}
+
+uid bt_getid(unsigned char *src)
+{
+uid id = 0;
+int i;
+
+ for( i = 0; i < BtId; i++ )
+ id <<= 8, id |= *src++;
+
+ return id;
+}
+
+// wait until write lock mode is clear
+// and add 1 to the share count
+
+void bt_spinreadlock(BtSpinLatch *latch)
+{
+ushort prev;
+
+ do {
+#ifdef unix
+ while( __sync_fetch_and_or((ushort *)latch, Mutex) & Mutex )
+ sched_yield();
+#else
+ while( _InterlockedOr16((ushort *)latch, Mutex) & Mutex )
+ SwitchToThread();
+#endif
+
+ // see if exclusive request is granted or pending
+
+ if( prev = !(latch->exclusive | latch->pending) )
+#ifdef unix
+ __sync_fetch_and_add((ushort *)latch, Share);
+#else
+ _InterlockedExchangeAdd16 ((ushort *)latch, Share);
+#endif
+
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Mutex);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Mutex);
+#endif
+ if( prev )
+ return;
+#ifdef unix
+ } while( sched_yield(), 1 );
+#else
+ } while( SwitchToThread(), 1 );
+#endif
+}
+
+// wait for other read and write latches to relinquish
+
+void bt_spinwritelock(BtSpinLatch *latch)
+{
+ do {
+#ifdef unix
+ while( __sync_fetch_and_or((ushort *)latch, Mutex | Pending) & Mutex )
+ sched_yield();
+#else
+ while( _InterlockedOr16((ushort *)latch, Mutex | Pending) & Mutex )
+ SwitchToThread();
+#endif
+ if( !(latch->share | latch->exclusive) ) {
+#ifdef unix
+ __sync_fetch_and_or((ushort *)latch, Write);
+ __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending));
+#else
+ _InterlockedOr16((ushort *)latch, Write);
+ _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending));
+#endif
+ return;
+ }
+
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Mutex);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Mutex);
+#endif
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ } while( 1 );
+}
+
+// try to obtain write lock
+
+// return 1 if obtained,
+// 0 otherwise
+
+int bt_spinwritetry(BtSpinLatch *latch)
+{
+ushort prev;
+
+#ifdef unix
+ if( prev = __sync_fetch_and_or((ushort *)latch, Mutex), prev & Mutex )
+ return 0;
+#else
+ if( prev = _InterlockedOr16((ushort *)latch, Mutex), prev & Mutex )
+ return 0;
+#endif
+ // take write access if all bits are clear
+
+ if( !prev )
+#ifdef unix
+ __sync_fetch_and_or ((ushort *)latch, Write);
+#else
+ _InterlockedOr16((ushort *)latch, Write);
+#endif
+
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Mutex);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Mutex);
+#endif
+ return !prev;
+}
+
+// clear write mode
+
+void bt_spinreleasewrite(BtSpinLatch *latch)
+{
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Write);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Write);
+#endif
+}
+
+// decrement reader count
+
+void bt_spinreleaseread(BtSpinLatch *latch)
+{
+#ifdef unix
+ __sync_fetch_and_add((ushort *)latch, -Share);
+#else
+ _InterlockedExchangeAdd16 ((ushort *)latch, -Share);
+#endif
+}
+
+void bt_initlockset (BtLatchSet *set, int reuse)
+{
+#ifdef unix
+pthread_rwlockattr_t rwattr[1];
+
+ if( reuse ) {
+ pthread_rwlock_destroy (set->readwr->lock);
+ pthread_rwlock_destroy (set->access->lock);
+ pthread_rwlock_destroy (set->parent->lock);
+ }
+
+ pthread_rwlockattr_init (rwattr);
+ pthread_rwlockattr_setkind_np (rwattr, PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
+ pthread_rwlockattr_setpshared (rwattr, PTHREAD_PROCESS_SHARED);
+
+ pthread_rwlock_init (set->readwr->lock, rwattr);
+ pthread_rwlock_init (set->access->lock, rwattr);
+ pthread_rwlock_init (set->parent->lock, rwattr);
+ pthread_rwlockattr_destroy (rwattr);
+#else
+ InitializeSRWLock (set->readwr->srw);
+ InitializeSRWLock (set->access->srw);
+ InitializeSRWLock (set->parent->srw);
+#endif
+}
+
+// link latch table entry into latch hash table
+
+void bt_latchlink (BtDb *bt, ushort hashidx, ushort victim, uid page_no)
+{
+BtLatchSet *set = bt->mgr->latchsets + victim;
+
+ if( set->next = bt->mgr->latchmgr->table[hashidx].slot )
+ bt->mgr->latchsets[set->next].prev = victim;
+
+ bt->mgr->latchmgr->table[hashidx].slot = victim;
+ set->page_no = page_no;
+ set->hash = hashidx;
+ set->prev = 0;
+}
+
+void bt_unpinlatch (BtLatchSet *set)
+{
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, -1);
+#else
+ _InterlockedDecrement16 (&set->pin);
+#endif
+}
+
+// find existing latchset or inspire new one
+// return with latchset pinned
+
+BtLatchSet *bt_pinlatch (BtDb *bt, uid page_no)
+{
+ushort hashidx = page_no % bt->mgr->latchmgr->latchhash;
+ushort slot, avail = 0, victim, idx;
+BtLatchSet *set;
+
+ // obtain read lock on hash table entry
+
+ bt_spinreadlock(bt->mgr->latchmgr->table[hashidx].latch);
+
+ if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
+ {
+ set = bt->mgr->latchsets + slot;
+ if( page_no == set->page_no )
+ break;
+ } while( slot = set->next );
+
+ if( slot ) {
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ }
+
+ bt_spinreleaseread (bt->mgr->latchmgr->table[hashidx].latch);
+
+ if( slot )
+ return set;
+
+ // try again, this time with write lock
+
+ bt_spinwritelock(bt->mgr->latchmgr->table[hashidx].latch);
+
+ if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
+ {
+ set = bt->mgr->latchsets + slot;
+ if( page_no == set->page_no )
+ break;
+ if( !set->pin && !avail )
+ avail = slot;
+ } while( slot = set->next );
+
+ // found our entry, or take over an unpinned one
+
+ if( slot || (slot = avail) ) {
+ set = bt->mgr->latchsets + slot;
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ set->page_no = page_no;
+ bt_spinreleasewrite(bt->mgr->latchmgr->table[hashidx].latch);
+ return set;
+ }
+
+ // see if there are any unused entries
+#ifdef unix
+ victim = __sync_fetch_and_add (&bt->mgr->latchmgr->latchdeployed, 1) + 1;
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->latchmgr->latchdeployed);
+#endif
+
+ if( victim < bt->mgr->latchmgr->latchtotal ) {
+ set = bt->mgr->latchsets + victim;
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ bt_initlockset (set, 0);
+ bt_latchlink (bt, hashidx, victim, page_no);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch);
+ return set;
+ }
+
+#ifdef unix
+ victim = __sync_fetch_and_add (&bt->mgr->latchmgr->latchdeployed, -1);
+#else
+ victim = _InterlockedDecrement16 (&bt->mgr->latchmgr->latchdeployed);
+#endif
+ // find and reuse previous lock entry
+
+ while( 1 ) {
+#ifdef unix
+ victim = __sync_fetch_and_add(&bt->mgr->latchmgr->latchvictim, 1);
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->latchmgr->latchvictim) - 1;
+#endif
+ // we don't use slot zero
+
+ if( victim %= bt->mgr->latchmgr->latchtotal )
+ set = bt->mgr->latchsets + victim;
+ else
+ continue;
+
+ // take control of our slot
+ // from other threads
+
+ if( set->pin || !bt_spinwritetry (set->busy) )
+ continue;
+
+ idx = set->hash;
+
+ // try to get write lock on hash chain
+ // skip entry if not obtained
+ // or has outstanding locks
+
+ if( !bt_spinwritetry (bt->mgr->latchmgr->table[idx].latch) ) {
+ bt_spinreleasewrite (set->busy);
+ continue;
+ }
+
+ if( set->pin ) {
+ bt_spinreleasewrite (set->busy);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[idx].latch);
+ continue;
+ }
+
+ // unlink our available victim from its hash chain
+
+ if( set->prev )
+ bt->mgr->latchsets[set->prev].next = set->next;
+ else
+ bt->mgr->latchmgr->table[idx].slot = set->next;
+
+ if( set->next )
+ bt->mgr->latchsets[set->next].prev = set->prev;
+
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[idx].latch);
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ bt_initlockset (set, 1);
+ bt_latchlink (bt, hashidx, victim, page_no);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch);
+ bt_spinreleasewrite (set->busy);
+ return set;
+ }
+}
+
+void bt_mgrclose (BtMgr *mgr)
+{
+BtPool *pool;
+uint slot;
+
+ // release mapped pages
+ // note that slot zero is never used
+
+ for( slot = 1; slot < mgr->poolmax; slot++ ) {
+ pool = mgr->pool + slot;
+ if( pool->slot )
+#ifdef unix
+ munmap (pool->map, (mgr->poolmask+1) << mgr->page_bits);
+#else
+ {
+ FlushViewOfFile(pool->map, 0);
+ UnmapViewOfFile(pool->map);
+ CloseHandle(pool->hmap);
+ }
+#endif
+ }
+
+#ifdef unix
+ munmap (mgr->latchsets, mgr->latchmgr->nlatchpage * mgr->page_size);
+ munmap (mgr->latchmgr, mgr->page_size);
+#else
+ FlushViewOfFile(mgr->latchmgr, 0);
+ UnmapViewOfFile(mgr->latchmgr);
+ CloseHandle(mgr->halloc);
+#endif
+#ifdef unix
+ close (mgr->idx);
+ free (mgr->pool);
+ free (mgr->hash);
+ free (mgr->latch);
+ free (mgr->pooladvise);
+ free (mgr);
+#else
+ FlushFileBuffers(mgr->idx);
+ CloseHandle(mgr->idx);
+ GlobalFree (mgr->pool);
+ GlobalFree (mgr->hash);
+ GlobalFree (mgr->latch);
+ GlobalFree (mgr);
+#endif
+}
+
+// close and release memory
+
+void bt_close (BtDb *bt)
+{
+#ifdef unix
+ if ( bt->mem )
+ free (bt->mem);
+#else
+ if ( bt->mem)
+ VirtualFree (bt->mem, 0, MEM_RELEASE);
+#endif
+ free (bt);
+}
+
+// open/create new btree buffer manager
+
+// call with file_name, BT_openmode, bits in page size (e.g. 16),
+// size of mapped page pool (e.g. 8192)
+
+BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolmax, uint segsize, uint hashsize)
+{
+uint lvl, attr, cacheblk, last, slot, idx;
+uint nlatchpage, latchhash;
+BtLatchMgr *latchmgr;
+off64_t size;
+uint amt[1];
+BtMgr* mgr;
+BtKey key;
+int flag;
+
+#ifndef unix
+SYSTEM_INFO sysinfo[1];
+#endif
+
+ // determine sanity of page size and buffer pool
+
+ if( bits > BT_maxbits )
+ bits = BT_maxbits;
+ else if( bits < BT_minbits )
+ bits = BT_minbits;
+
+ if( !poolmax )
+ return NULL; // must have buffer pool
+
+#ifdef unix
+ mgr = calloc (1, sizeof(BtMgr));
+
+ mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
+
+ if( mgr->idx == -1 )
+ return free(mgr), NULL;
+
+ cacheblk = 4096; // minimum mmap segment size for unix
+
+#else
+ mgr = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtMgr));
+ attr = FILE_ATTRIBUTE_NORMAL;
+ mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
+
+ if( mgr->idx == INVALID_HANDLE_VALUE )
+ return GlobalFree(mgr), NULL;
+
+ // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity
+ GetSystemInfo(sysinfo);
+ cacheblk = sysinfo->dwAllocationGranularity;
+#endif
+
+#ifdef unix
+ latchmgr = malloc (BT_maxpage);
+ *amt = 0;
+
+ // read minimum page size to get root info
+
+ if( size = lseek (mgr->idx, 0L, 2) ) {
+ if( pread(mgr->idx, latchmgr, BT_minpage, 0) == BT_minpage )
+ bits = latchmgr->alloc->bits;
+ else
+ return free(mgr), free(latchmgr), NULL;
+ } else if( mode == BT_ro )
+ return free(latchmgr), free (mgr), NULL;
+#else
+ latchmgr = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE);
+ size = GetFileSize(mgr->idx, amt);
+
+ if( size || *amt ) {
+ if( !ReadFile(mgr->idx, (char *)latchmgr, BT_minpage, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ bits = latchmgr->alloc->bits;
+ } else if( mode == BT_ro )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ mgr->page_size = 1 << bits;
+ mgr->page_bits = bits;
+
+ mgr->poolmax = poolmax;
+ mgr->mode = mode;
+
+ if( cacheblk < mgr->page_size )
+ cacheblk = mgr->page_size;
+
+ // mask for partial memmaps
+
+ mgr->poolmask = (cacheblk >> bits) - 1;
+
+ // see if requested size of pages per memmap is greater
+
+ if( (1 << segsize) > mgr->poolmask )
+ mgr->poolmask = (1 << segsize) - 1;
+
+ mgr->seg_bits = 0;
+
+ while( (1 << mgr->seg_bits) <= mgr->poolmask )
+ mgr->seg_bits++;
+
+ mgr->hashsize = hashsize;
+
+#ifdef unix
+ mgr->pool = calloc (poolmax, sizeof(BtPool));
+ mgr->hash = calloc (hashsize, sizeof(ushort));
+ mgr->latch = calloc (hashsize, sizeof(BtSpinLatch));
+ mgr->pooladvise = calloc (poolmax, (mgr->poolmask + 8) / 8);
+#else
+ mgr->pool = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, poolmax * sizeof(BtPool));
+ mgr->hash = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(ushort));
+ mgr->latch = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(BtSpinLatch));
+#endif
+
+ if( size || *amt )
+ goto mgrlatch;
+
+ // initialize an empty b-tree with latch page, root page, page of leaves
+ // and page(s) of latches
+
+ memset (latchmgr, 0, 1 << bits);
+ nlatchpage = BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1;
+ bt_putid(latchmgr->alloc->right, MIN_lvl+1+nlatchpage);
+ latchmgr->alloc->bits = mgr->page_bits;
+
+ latchmgr->nlatchpage = nlatchpage;
+ latchmgr->latchtotal = nlatchpage * (mgr->page_size / sizeof(BtLatchSet));
+
+ // initialize latch manager
+
+ latchhash = (mgr->page_size - sizeof(BtLatchMgr)) / sizeof(BtHashEntry);
+
+ // size of hash table = total number of latchsets
+
+ if( latchhash > latchmgr->latchtotal )
+ latchhash = latchmgr->latchtotal;
+
+ latchmgr->latchhash = latchhash;
+
+#ifdef unix
+ if( write (mgr->idx, latchmgr, mgr->page_size) < mgr->page_size )
+ return free(latchmgr), bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ memset (latchmgr, 0, 1 << bits);
+ latchmgr->alloc->bits = mgr->page_bits;
+
+ for( lvl=MIN_lvl; lvl--; ) {
+ slotptr(latchmgr->alloc, 1)->off = mgr->page_size - 3;
+ bt_putid(slotptr(latchmgr->alloc, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number
+ key = keyptr(latchmgr->alloc, 1);
+ key->len = 2; // create stopper key
+ key->key[0] = 0xff;
+ key->key[1] = 0xff;
+ latchmgr->alloc->min = mgr->page_size - 3;
+ latchmgr->alloc->lvl = lvl;
+ latchmgr->alloc->cnt = 1;
+ latchmgr->alloc->act = 1;
+#ifdef unix
+ if( write (mgr->idx, latchmgr, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ }
+
+ // clear out latch manager locks
+ // and rest of pages to round out segment
+
+ memset(latchmgr, 0, mgr->page_size);
+ last = MIN_lvl + 1;
+
+ while( last <= ((MIN_lvl + 1 + nlatchpage) | mgr->poolmask) ) {
+#ifdef unix
+ pwrite(mgr->idx, latchmgr, mgr->page_size, last << mgr->page_bits);
+#else
+ SetFilePointer (mgr->idx, last << mgr->page_bits, NULL, FILE_BEGIN);
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ last++;
+ }
+
+mgrlatch:
+#ifdef unix
+ flag = PROT_READ | PROT_WRITE;
+ mgr->latchmgr = mmap (0, mgr->page_size, flag, MAP_SHARED, mgr->idx, ALLOC_page * mgr->page_size);
+ if( mgr->latchmgr == MAP_FAILED )
+ return bt_mgrclose (mgr), NULL;
+ mgr->latchsets = (BtLatchSet *)mmap (0, mgr->latchmgr->nlatchpage * mgr->page_size, flag, MAP_SHARED, mgr->idx, LATCH_page * mgr->page_size);
+ if( mgr->latchsets == MAP_FAILED )
+ return bt_mgrclose (mgr), NULL;
+#else
+ flag = PAGE_READWRITE;
+ mgr->halloc = CreateFileMapping(mgr->idx, NULL, flag, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size, NULL);
+ if( !mgr->halloc )
+ return bt_mgrclose (mgr), NULL;
+
+ flag = FILE_MAP_WRITE;
+ mgr->latchmgr = MapViewOfFile(mgr->halloc, flag, 0, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size);
+ if( !mgr->latchmgr )
+ return GetLastError(), bt_mgrclose (mgr), NULL;
+
+ mgr->latchsets = (void *)((char *)mgr->latchmgr + LATCH_page * mgr->page_size);
+#endif
+
+#ifdef unix
+ free (latchmgr);
+#else
+ VirtualFree (latchmgr, 0, MEM_RELEASE);
+#endif
+ return mgr;
+}
+
+// open BTree access method
+// based on buffer manager
+
+BtDb *bt_open (BtMgr *mgr)
+{
+BtDb *bt = malloc (sizeof(*bt));
+
+ memset (bt, 0, sizeof(*bt));
+ bt->mgr = mgr;
+#ifdef unix
+ bt->mem = malloc (3 *mgr->page_size);
+#else
+ bt->mem = VirtualAlloc(NULL, 3 * mgr->page_size, MEM_COMMIT, PAGE_READWRITE);
+#endif
+ bt->frame = (BtPage)bt->mem;
+ bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size);
+ bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size);
+
+ memset(bt->zero, 0, mgr->page_size);
+ return bt;
+}
+
+// compare two keys, returning > 0, = 0, or < 0
+// as the comparison value
+
+int keycmp (BtKey key1, unsigned char *key2, uint len2)
+{
+uint len1 = key1->len;
+int ans;
+
+ if( ans = memcmp (key1->key, key2, len1 > len2 ? len2 : len1) )
+ return ans;
+
+ if( len1 > len2 )
+ return 1;
+ if( len1 < len2 )
+ return -1;
+
+ return 0;
+}
+
+// Latch Manager
+
+void bt_readlock(BtLatch *latch)
+{
+#ifdef unix
+ pthread_rwlock_rdlock (latch->lock);
+#else
+ AcquireSRWLockShared (latch->srw);
+#endif
+}
+
+// wait for other read and write latches to relinquish
+
+void bt_writelock(BtLatch *latch)
+{
+#ifdef unix
+ pthread_rwlock_wrlock (latch->lock);
+#else
+ AcquireSRWLockExclusive (latch->srw);
+#endif
+}
+
+// try to obtain write lock
+
+// return 1 if obtained,
+// 0 if already write or read locked
+
+int bt_writetry(BtLatch *latch)
+{
+int result = 0;
+
+#ifdef unix
+ result = !pthread_rwlock_trywrlock (latch->lock);
+#else
+ result = TryAcquireSRWLockExclusive (latch->srw);
+#endif
+ return result;
+}
+
+// clear write mode
+
+void bt_releasewrite(BtLatch *latch)
+{
+#ifdef unix
+ pthread_rwlock_unlock (latch->lock);
+#else
+ ReleaseSRWLockExclusive (latch->srw);
+#endif
+}
+
+// decrement reader count
+
+void bt_releaseread(BtLatch *latch)
+{
+#ifdef unix
+ pthread_rwlock_unlock (latch->lock);
+#else
+ ReleaseSRWLockShared (latch->srw);
+#endif
+}
+
+// Buffer Pool mgr
+
+// find segment in pool
+// must be called with hashslot idx locked
+// return NULL if not there
+// otherwise return node
+
+BtPool *bt_findpool(BtDb *bt, uid page_no, uint idx)
+{
+BtPool *pool;
+uint slot;
+
+ // compute start of hash chain in pool
+
+ if( slot = bt->mgr->hash[idx] )
+ pool = bt->mgr->pool + slot;
+ else
+ return NULL;
+
+ page_no &= ~bt->mgr->poolmask;
+
+ while( pool->basepage != page_no )
+ if( pool = pool->hashnext )
+ continue;
+ else
+ return NULL;
+
+ return pool;
+}
+
+// add segment to hash table
+
+void bt_linkhash(BtDb *bt, BtPool *pool, uid page_no, int idx)
+{
+BtPool *node;
+uint slot;
+
+ pool->hashprev = pool->hashnext = NULL;
+ pool->basepage = page_no & ~bt->mgr->poolmask;
+ pool->lru = 1;
+
+ if( slot = bt->mgr->hash[idx] ) {
+ node = bt->mgr->pool + slot;
+ pool->hashnext = node;
+ node->hashprev = pool;
+ }
+
+ bt->mgr->hash[idx] = pool->slot;
+}
+
+// find best segment to evict from buffer pool
+
+BtPool *bt_findlru (BtDb *bt, uint hashslot)
+{
+unsigned long long int target = ~0LL;
+BtPool *pool = NULL, *node;
+
+ if( !hashslot )
+ return NULL;
+
+ node = bt->mgr->pool + hashslot;
+
+ // scan pool entries under hash table slot
+
+ do {
+ if( node->pin )
+ continue;
+ if( node->lru > target )
+ continue;
+ target = node->lru;
+ pool = node;
+ } while( node = node->hashnext );
+
+ return pool;
+}
+
+// map new buffer pool segment to virtual memory
+
+BTERR bt_mapsegment(BtDb *bt, BtPool *pool, uid page_no)
+{
+off64_t off = (page_no & ~bt->mgr->poolmask) << bt->mgr->page_bits;
+off64_t limit = off + ((bt->mgr->poolmask+1) << bt->mgr->page_bits);
+int flag;
+
+#ifdef unix
+ flag = PROT_READ | ( bt->mgr->mode == BT_ro ? 0 : PROT_WRITE );
+ pool->map = mmap (0, (bt->mgr->poolmask+1) << bt->mgr->page_bits, flag, MAP_SHARED, bt->mgr->idx, off);
+ if( pool->map == MAP_FAILED )
+ return bt->err = BTERR_map;
+ // clear out madvise issued bits
+ memset (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8) / 8), 0, (bt->mgr->poolmask + 8)/8);
+#else
+ flag = ( bt->mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE );
+ pool->hmap = CreateFileMapping(bt->mgr->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL);
+ if( !pool->hmap )
+ return bt->err = BTERR_map;
+
+ flag = ( bt->mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE );
+ pool->map = MapViewOfFile(pool->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->mgr->poolmask+1) << bt->mgr->page_bits);
+ if( !pool->map )
+ return bt->err = BTERR_map;
+#endif
+ return bt->err = 0;
+}
+
+// calculate page within pool
+
+BtPage bt_page (BtDb *bt, BtPool *pool, uid page_no)
+{
+uint subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
+BtPage page;
+
+ page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
+#ifdef unix
+ {
+ uint idx = subpage / 8;
+ uint bit = subpage % 8;
+
+ if( ~((bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] >> bit) & 1 ) {
+ madvise (page, bt->mgr->page_size, MADV_WILLNEED);
+ (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] |= 1 << bit;
+ }
+ }
+#endif
+ return page;
+}
+
+// release pool pin
+
+void bt_unpinpool (BtPool *pool)
+{
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, -1);
+#else
+ _InterlockedDecrement16 (&pool->pin);
+#endif
+}
+
+// find or place requested page in segment-pool
+// return pool table entry, incrementing pin
+
+BtPool *bt_pinpool(BtDb *bt, uid page_no)
+{
+BtPool *pool, *node, *next;
+uint slot, idx, victim;
+BtLatchSet *set;
+
+ // lock hash table chain
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_spinreadlock (&bt->mgr->latch[idx]);
+
+ // look up in hash table
+
+ if( pool = bt_findpool(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleaseread (&bt->mgr->latch[idx]);
+ pool->lru++;
+ return pool;
+ }
+
+ // upgrade to write lock
+
+ bt_spinreleaseread (&bt->mgr->latch[idx]);
+ bt_spinwritelock (&bt->mgr->latch[idx]);
+
+ // try to find page in pool with write lock
+
+ if( pool = bt_findpool(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ pool->lru++;
+ return pool;
+ }
+
+ // allocate a new pool node
+ // and add to hash table
+
+#ifdef unix
+ slot = __sync_fetch_and_add(&bt->mgr->poolcnt, 1);
+#else
+ slot = _InterlockedIncrement16 (&bt->mgr->poolcnt) - 1;
+#endif
+
+ if( ++slot < bt->mgr->poolmax ) {
+ pool = bt->mgr->pool + slot;
+ pool->slot = slot;
+
+ if( bt_mapsegment(bt, pool, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, pool, page_no, idx);
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ return pool;
+ }
+
+ // pool table is full
+ // find best pool entry to evict
+
+#ifdef unix
+ __sync_fetch_and_add(&bt->mgr->poolcnt, -1);
+#else
+ _InterlockedDecrement16 (&bt->mgr->poolcnt);
+#endif
+
+ while( 1 ) {
+#ifdef unix
+ victim = __sync_fetch_and_add(&bt->mgr->evicted, 1);
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->evicted) - 1;
+#endif
+ victim %= bt->mgr->hashsize;
+
+ // try to get write lock
+ // skip entry if not obtained
+
+ if( !bt_spinwritetry (&bt->mgr->latch[victim]) )
+ continue;
+
+ // if cache entry is empty
+ // or no slots are unpinned
+ // skip this entry
+
+ if( !(pool = bt_findlru(bt, bt->mgr->hash[victim])) ) {
+ bt_spinreleasewrite (&bt->mgr->latch[victim]);
+ continue;
+ }
+
+ // unlink victim pool node from hash table
+
+ if( node = pool->hashprev )
+ node->hashnext = pool->hashnext;
+ else if( node = pool->hashnext )
+ bt->mgr->hash[victim] = node->slot;
+ else
+ bt->mgr->hash[victim] = 0;
+
+ if( node = pool->hashnext )
+ node->hashprev = pool->hashprev;
+
+ bt_spinreleasewrite (&bt->mgr->latch[victim]);
+
+ // remove old file mapping
+#ifdef unix
+ munmap (pool->map, (bt->mgr->poolmask+1) << bt->mgr->page_bits);
+#else
+ FlushViewOfFile(pool->map, 0);
+ UnmapViewOfFile(pool->map);
+ CloseHandle(pool->hmap);
+#endif
+ pool->map = NULL;
+
+ // create new pool mapping
+ // and link into hash table
+
+ if( bt_mapsegment(bt, pool, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, pool, page_no, idx);
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ return pool;
+ }
+}
+
+// place write, read, or parent lock on requested page_no.
+// pin to buffer pool and return latchset pointer
+
+void bt_lockpage(BtLock mode, BtLatchSet *set)
+{
+ switch( mode ) {
+ case BtLockRead:
+ bt_readlock (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_writelock (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_readlock (set->access);
+ break;
+ case BtLockDelete:
+ bt_writelock (set->access);
+ break;
+ case BtLockParent:
+ bt_writelock (set->parent);
+ break;
+ }
+}
+
+// remove write, read, or parent lock on requested page_no.
+
+void bt_unlockpage(BtLock mode, BtLatchSet *set)
+{
+ switch( mode ) {
+ case BtLockRead:
+ bt_releaseread (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_releasewrite (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_releaseread (set->access);
+ break;
+ case BtLockDelete:
+ bt_releasewrite (set->access);
+ break;
+ case BtLockParent:
+ bt_releasewrite (set->parent);
+ break;
+ }
+}
+
+// allocate a new page and write page into it
+
+uid bt_newpage(BtDb *bt, BtPage page)
+{
+BtLatchSet *set;
+BtPool *pool;
+uid new_page;
+BtPage pmap;
+int reuse;
+
+ // lock allocation page
+
+ bt_spinwritelock(bt->mgr->latchmgr->lock);
+
+ // use empty chain first
+ // else allocate empty page
+
+ if( new_page = bt_getid(bt->mgr->latchmgr->alloc[1].right) ) {
+ if( pool = bt_pinpool (bt, new_page) )
+ pmap = bt_page (bt, pool, new_page);
+ else
+ return 0;
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, bt_getid(pmap->right));
+ bt_unpinpool (pool);
+ reuse = 1;
+ } else {
+ new_page = bt_getid(bt->mgr->latchmgr->alloc->right);
+ bt_putid(bt->mgr->latchmgr->alloc->right, new_page+1);
+ reuse = 0;
+ }
+#ifdef unix
+ // if writing first page of pool block, zero last page in the block
+
+ if ( !reuse && bt->mgr->poolmask > 0 && (new_page & bt->mgr->poolmask) == 0 )
+ {
+ // use zero buffer to write zeros
+ if ( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->poolmask) << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+ }
+
+ // unlock allocation latch
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
+ if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+
+#else
+ // unlock allocation latch
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
+ // bring new page into pool and copy page.
+ // this will extend the file into the new pages.
+ // NB -- no latch required
+
+ if( pool = bt_pinpool (bt, new_page) )
+ pmap = bt_page (bt, pool, new_page);
+ else
+ return 0;
+
+ memcpy(pmap, page, bt->mgr->page_size);
+ bt_unpinpool (pool);
+#endif
+ return new_page;
+}
+
+// find slot in page for given key at a given level
+
+int bt_findslot (BtDb *bt, unsigned char *key, uint len)
+{
+uint diff, higher = bt->page->cnt, low = 1, slot;
+
+ // low is the lowest candidate, higher is already
+ // tested as .ge. the given key, loop ends when they meet
+
+ while( diff = higher - low ) {
+ slot = low + ( diff >> 1 );
+ if( keycmp (keyptr(bt->page, slot), key, len) < 0 )
+ low = slot + 1;
+ else
+ higher = slot;
+ }
+
+ return higher;
+}
+
+// find and load page at given level for given key
+// leave page rd or wr locked as requested
+
+int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, BtLock lock)
+{
+uid page_no = ROOT_page, prevpage = 0;
+BtLatchSet *set, *prevset;
+uint drill = 0xff, slot;
+uint mode, prevmode;
+BtPool *prevpool;
+
+ // start at root of btree and drill down
+
+ do {
+ // determine lock mode of drill level
+ mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead;
+
+ // obtain latch set for this page
+
+ bt->set = bt_pinlatch (bt, page_no);
+ bt->page_no = page_no;
+
+ // pin page contents
+
+ if( bt->pool = bt_pinpool (bt, page_no) )
+ bt->page = bt_page (bt, bt->pool, page_no);
+ else
+ return 0;
+
+ // obtain access lock using lock chaining with Access mode
+
+ if( page_no > ROOT_page )
+ bt_lockpage(BtLockAccess, bt->set);
+
+ // now unlock and unpin our (possibly foster) parent
+
+ if( prevpage ) {
+ bt_unlockpage(prevmode, prevset);
+ bt_unpinlatch (prevset);
+ bt_unpinpool (prevpool);
+ prevpage = 0;
+ }
+
+ // obtain read lock using lock chaining
+
+ bt_lockpage(mode, bt->set);
+
+ if( page_no > ROOT_page )
+ bt_unlockpage(BtLockAccess, bt->set);
+
+ // re-read and re-lock root after determining actual level of root
+
+ if( page_no == ROOT_page )
+ if( bt->page->lvl != drill) {
+ drill = bt->page->lvl;
+
+ if( lock == BtLockWrite && drill == lvl ) {
+ bt_unlockpage(mode, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ continue;
+ }
+ }
+
+ prevpage = bt->page_no;
+ prevpool = bt->pool;
+ prevset = bt->set;
+ prevmode = mode;
+
+ // find key on page at this level
+ // and either descend to requested level
+ // or return key slot
+
+ slot = bt_findslot (bt, key, len);
+
+ // is this slot < foster child area
+ // on the requested level?
+
+ // if so, return actual slot even if dead
+
+ if( slot <= bt->page->cnt - bt->page->foster )
+ if( drill == lvl )
+ return slot;
+
+ // find next active slot
+
+ // note: foster children are never dead
+ // nor fence keys for interiour nodes
+
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ return bt->err = BTERR_struct, 0; // last key shouldn't be deleted
+
+ // is this slot < foster child area
+ // if so, drill to next level
+
+ if( slot <= bt->page->cnt - bt->page->foster )
+ drill--;
+
+ // continue right onto foster child
+ // or down to next level.
+
+ page_no = bt_getid(slotptr(bt->page, slot)->id);
+
+ } while( page_no );
+
+ // return error on end of chain
+
+ bt->err = BTERR_struct;
+ return 0; // return error
+}
+
+// find and delete key on page by marking delete flag bit
+// when leaf page becomes empty, delete it from the btree
+
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len)
+{
+unsigned char leftkey[256];
+BtLatchSet *rset, *set;
+BtPool *pool, *rpool;
+BtPage rpage, page;
+uid page_no, right;
+uint slot, tod;
+BtKey ptr;
+
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // if key is found delete it, otherwise ignore request
+ // note that fence keys of interiour nodes are not deleted.
+
+ if( bt->found = !keycmp (ptr, key, len) )
+ if( bt->found = slotptr(bt->page, slot)->dead == 0 ) {
+ slotptr(bt->page,slot)->dead = 1;
+ if( slot < bt->page->cnt )
+ bt->page->dirty = 1;
+ bt->page->act--;
+ }
+
+ page_no = bt->page_no;
+ pool = bt->pool;
+ page = bt->page;
+ set = bt->set;
+
+ // return if page is not empty or not found
+
+ if( page->act || !bt->found ) {
+ bt_unlockpage(BtLockWrite, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ return bt->err;
+ }
+
+ // cache copy of fence key of empty node
+
+ ptr = keyptr(page, page->cnt);
+ memcpy(leftkey, ptr, ptr->len + 1);
+
+ // release write lock on empty node
+ // obtain Parent lock
+
+ bt_unlockpage(BtLockWrite, set);
+ bt_lockpage(BtLockParent, set);
+
+ // load and lock parent to see
+ // if delete of empty node is OK
+ // ie, not a fence key of parent
+
+ while( 1 ) {
+ if( slot = bt_loadpage (bt, leftkey+1, *leftkey, 1, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // does parent level contain our fence key yet?
+ // and is it free of foster children?
+
+ if( !bt->page->foster )
+ if( !keycmp (ptr, leftkey+1, *leftkey) )
+ break;
+
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ }
+
+ // find our left fence key
+
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ return bt->err = BTERR_struct; // last key shouldn't be deleted
+
+ // now we have both parent and child
+
+ bt_lockpage(BtLockDelete, set);
+ bt_lockpage(BtLockWrite, set);
+
+ // return if page has no right sibling within parent
+ // or if empty node is no longer empty
+
+ if( page->act || slot == bt->page->cnt ) {
+ // unpin parent
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ // unpin empty node
+ bt_unlockpage(BtLockParent, set);
+ bt_unlockpage(BtLockDelete, set);
+ bt_unlockpage(BtLockWrite, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ return bt->err;
+ }
+
+ // lock and map our right page
+ // note that it cannot be our foster child
+ // since the our node is empty
+
+ right = bt_getid(page->right);
+
+ if( rpool = bt_pinpool (bt, right) )
+ rpage = bt_page (bt, rpool, right);
+ else
+ return bt->err;
+
+ rset = bt_pinlatch (bt, right);
+ bt_lockpage(BtLockWrite, rset);
+ bt_lockpage(BtLockDelete, rset);
+
+ // pull contents of right page into empty page
+
+ memcpy (page, rpage, bt->mgr->page_size);
+
+ // delete left parent slot for old empty page
+ // and redirect right parent slot to it
+
+ bt->page->act--;
+ bt->page->dirty = 1;
+ slotptr(bt->page, slot)->dead = 1;
+
+ while( slot++ < bt->page->cnt )
+ if( !slotptr(bt->page, slot)->dead )
+ break;
+
+ bt_putid(slotptr(bt->page,slot)->id, page_no);
+
+ // release parent level lock
+ // and our empty node lock
+
+ bt_unlockpage(BtLockWrite, set);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+
+ // add killed right block to free chain
+ // lock latch mgr
+
+ bt_spinwritelock(bt->mgr->latchmgr->lock);
+
+ // store free chain in allocation page second right
+ bt_putid(rpage->right, bt_getid(bt->mgr->latchmgr->alloc[1].right));
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, right);
+
+ // unlock latch mgr and right page
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
+ bt_unlockpage(BtLockWrite, rset);
+ bt_unlockpage(BtLockDelete, rset);
+ bt_unpinlatch (rset);
+ bt_unpinpool (rpool);
+
+ // remove ParentModify lock
+
+ bt_unlockpage(BtLockParent, set);
+ bt_unlockpage(BtLockDelete, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ return 0;
+}
+
+// find key in leaf level and return row-id
+
+uid bt_findkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+BtKey ptr;
+uid id;
+
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return 0;
+
+ // if key exists, return row-id
+ // otherwise return 0
+
+ if( slot <= bt->page->cnt && !keycmp (ptr, key, len) )
+ id = bt_getid(slotptr(bt->page,slot)->id);
+ else
+ id = 0;
+
+ bt_unlockpage (BtLockRead, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return id;
+}
+
+// check page for space available,
+// clean if necessary and return
+// 0 - page needs splitting
+// >0 new slot value
+
+uint bt_cleanpage(BtDb *bt, uint amt, uint slot)
+{
+uint nxt = bt->mgr->page_size;
+BtPage page = bt->page;
+uint cnt = 0, idx = 0;
+uint max = page->cnt;
+uint newslot;
+BtKey key;
+
+ if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return slot;
+
+ // skip cleanup if nothing to reclaim
+
+ if( !page->dirty )
+ return 0;
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+
+ // skip page info and set rest of page to zero
+
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ page->dirty = 0;
+ page->act = 0;
+
+ // try cleaning up page first
+
+ // always leave fence key in the array
+ // otherwise, remove deleted key
+
+ // note: foster children are never dead
+ // nor are fence keys for interiour nodes
+
+ while( cnt++ < max ) {
+ if( cnt == slot )
+ newslot = idx + 1;
+ else if( cnt < max && slotptr(bt->frame,cnt)->dead )
+ continue;
+
+ // copy key
+
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+
+ // copy slot
+ memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId);
+ if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
+ page->act++;
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ // see if page has enough space now, or does it need splitting?
+
+ if( page->min >= (idx+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return newslot;
+
+ return 0;
+}
+
+// add key to current page
+// page must already be writelocked
+
+void bt_addkeytopage (BtDb *bt, uint slot, unsigned char *key, uint len, uid id, uint tod)
+{
+BtPage page = bt->page;
+uint idx;
+
+ // find next available dead slot and copy key onto page
+ // note that foster children on the page are never dead
+
+ // look for next hole, but stay back from the fence key
+
+ for( idx = slot; idx < page->cnt; idx++ )
+ if( slotptr(page, idx)->dead )
+ break;
+
+ if( idx == page->cnt )
+ idx++, page->cnt++;
+
+ page->act++;
+
+ // now insert key into array before slot
+
+ while( idx > slot )
+ *slotptr(page, idx) = *slotptr(page, idx -1), idx--;
+
+ page->min -= len + 1;
+ ((unsigned char *)page)[page->min] = len;
+ memcpy ((unsigned char *)page + page->min +1, key, len );
+
+ bt_putid(slotptr(page,slot)->id, id);
+ slotptr(page, slot)->off = page->min;
+ slotptr(page, slot)->tod = tod;
+ slotptr(page, slot)->dead = 0;
+}
+
+// split the root and raise the height of the btree
+// call with current page locked and page no of foster child
+// return with current page (root) unlocked
+
+BTERR bt_splitroot(BtDb *bt, uid right)
+{
+uint nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+BtPage root = bt->page;
+uid new_page;
+BtKey key;
+
+ // Obtain an empty page to use, and copy the left page
+ // contents into it from the root. Strip foster child key.
+ // (it's the stopper key)
+
+ memset (slotptr(root, root->cnt), 0, sizeof(BtSlot));
+ root->dirty = 1;
+ root->foster--;
+ root->act--;
+ root->cnt--;
+
+ // Save left fence key.
+
+ key = keyptr(root, root->cnt);
+ memcpy (fencekey, key, key->len + 1);
+
+ // copy the lower keys into a new left page
+
+ if( !(new_page = bt_newpage(bt, root)) )
+ return bt->err;
+
+ // preserve the page info at the bottom
+ // and set rest of the root to zero
+
+ memset (root+1, 0, bt->mgr->page_size - sizeof(*root));
+
+ // insert left fence key on empty newroot page
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 1)->id, new_page);
+ slotptr(root, 1)->off = nxt;
+
+ // insert stopper key on newroot page
+ // and increase the root height
+
+ nxt -= 3;
+ fencekey[0] = 2;
+ fencekey[1] = 0xff;
+ fencekey[2] = 0xff;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 2)->id, right);
+ slotptr(root, 2)->off = nxt;
+
+ bt_putid(root->right, 0);
+ root->min = nxt; // reset lowest used offset and key count
+ root->cnt = 2;
+ root->act = 2;
+ root->lvl++;
+
+ // release and unpin root (bt->page)
+
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return 0;
+}
+
+// split already locked full node
+// in current page variables
+// return unlocked and unpinned.
+
+BTERR bt_splitpage (BtDb *bt)
+{
+uint slot, cnt, idx, max, nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+uid page_no = bt->page_no;
+BtLatchSet *set = bt->set;
+BtPool *pool = bt->pool;
+BtPage page = bt->page;
+uint tod = time(NULL);
+uint lvl = page->lvl;
+uid new_page, right;
+BtKey key;
+
+ // initialize frame buffer for right node
+
+ memset (bt->frame, 0, bt->mgr->page_size);
+ max = page->cnt - page->foster;
+ tod = (uint)time(NULL);
+ cnt = max / 2;
+ idx = 0;
+
+ // split higher half of keys to bt->frame
+ // leaving old foster children in the left node,
+ // and adding a new foster child there.
+
+ while( cnt++ < max ) {
+ key = keyptr(page, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1);
+ memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId);
+ if( !(slotptr(bt->frame, idx)->dead = slotptr(page, cnt)->dead) )
+ bt->frame->act++;
+ slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod;
+ slotptr(bt->frame, idx)->off = nxt;
+ }
+
+ // transfer right link node to new right node
+
+ if( page_no > ROOT_page ) {
+ right = bt_getid (page->right);
+ bt_putid(bt->frame->right, right);
+ }
+
+ bt->frame->bits = bt->mgr->page_bits;
+ bt->frame->min = nxt;
+ bt->frame->cnt = idx;
+ bt->frame->lvl = lvl;
+
+ // get new free page and write right frame to it.
+
+ if( !(new_page = bt_newpage(bt, bt->frame)) )
+ return bt->err;
+
+ // remember fence key for new right page to add
+ // as foster child to the left node
+
+ key = keyptr(bt->frame, idx);
+ memcpy (fencekey, key, key->len + 1);
+
+ // update lower keys and foster children to continue in old page
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ nxt = bt->mgr->page_size;
+ page->dirty = 0;
+ page->act = 0;
+ cnt = 0;
+ idx = 0;
+
+ // assemble page of smaller keys
+ // to remain in the old page
+
+ while( cnt++ < max / 2 ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
+ page->act++;
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ }
+
+ // insert new foster child for right page in queue
+ // before any of the current foster children
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)page + nxt, fencekey, *fencekey + 1);
+
+ bt_putid (slotptr(page,++idx)->id, new_page);
+ slotptr(page, idx)->tod = tod;
+ slotptr(page, idx)->off = nxt;
+ page->foster++;
+ page->act++;
+
+ // continue with old foster child keys
+ // note that none will be dead
+
+ cnt = bt->frame->cnt - bt->frame->foster;
+
+ while( cnt++ < bt->frame->cnt ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ page->act++;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ // link new right page
+
+ bt_putid (page->right, new_page);
+
+ // if current page is the root page, split it
+
+ if( page_no == ROOT_page )
+ return bt_splitroot (bt, new_page);
+
+ // release wr lock on our page
+
+ bt_unlockpage (BtLockWrite, set);
+
+ // obtain ParentModification lock for current page
+ // to fix new fence key and oldest foster child on page
+
+ bt_lockpage (BtLockParent, set);
+
+ // get our new fence key to insert in parent node
+
+ bt_lockpage (BtLockRead, set);
+
+ key = keyptr(page, page->cnt-1);
+ memcpy (fencekey, key, key->len+1);
+
+ bt_unlockpage (BtLockRead, set);
+
+ if( bt_insertkey (bt, fencekey + 1, *fencekey, page_no, tod, lvl + 1) )
+ return bt->err;
+
+ // lock our page for writing
+
+ bt_lockpage (BtLockRead, set);
+
+ // switch old parent key from us to our oldest foster child
+
+ key = keyptr(page, page->cnt);
+ memcpy (fencekey, key, key->len+1);
+
+ new_page = bt_getid (slotptr(page, page->cnt)->id);
+ bt_unlockpage (BtLockRead, set);
+
+ if( bt_insertkey (bt, fencekey + 1, *fencekey, new_page, tod, lvl + 1) )
+ return bt->err;
+
+ // now that it has its own parent pointer,
+ // remove oldest foster child from our page
+
+ bt_lockpage (BtLockWrite, set);
+ memset (slotptr(page, page->cnt), 0, sizeof(BtSlot));
+ page->dirty = 1;
+ page->foster--;
+ page->cnt--;
+ page->act--;
+
+ // unlock and unpin
+
+ bt_unlockpage (BtLockWrite, set);
+ bt_unlockpage (BtLockParent, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ return 0;
+}
+
+// Insert new key into the btree at leaf level.
+
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod, uint lvl)
+{
+uint slot, idx;
+BtPage page;
+BtKey ptr;
+
+ while( 1 ) {
+ if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ {
+ if ( !bt->err )
+ bt->err = BTERR_ovflw;
+ return bt->err;
+ }
+
+ // if key already exists, update id and return
+
+ page = bt->page;
+
+ if( !keycmp (ptr, key, len) ) {
+ if( slotptr(page, slot)->dead )
+ page->act++;
+ slotptr(page, slot)->dead = 0;
+ slotptr(page, slot)->tod = tod;
+ bt_putid(slotptr(page,slot)->id, id);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return bt->err;
+ }
+
+ // check if page has enough space
+
+ if( slot = bt_cleanpage (bt, len, slot) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ }
+
+ bt_addkeytopage (bt, slot, key, len, id, tod);
+
+ bt_unlockpage (BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return 0;
+}
+
+// cache page of keys into cursor and return starting slot for given key
+
+uint bt_startkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+
+ // cache page for retrieval
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ memcpy (bt->cursor, bt->page, bt->mgr->page_size);
+
+ bt->cursor_page = bt->page_no;
+
+ bt_unlockpage(BtLockRead, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return slot;
+}
+
+// return next slot for cursor page
+// or slide cursor right into next page
+
+uint bt_nextkey (BtDb *bt, uint slot)
+{
+BtLatchSet *set;
+BtPool *pool;
+BtPage page;
+uid right;
+
+ do {
+ right = bt_getid(bt->cursor->right);
+ while( slot++ < bt->cursor->cnt - bt->cursor->foster )
+ if( slotptr(bt->cursor,slot)->dead )
+ continue;
+ else if( right || (slot < bt->cursor->cnt - bt->cursor->foster) )
+ return slot;
+ else
+ break;
+
+ if( !right )
+ break;
+
+ bt->cursor_page = right;
+ if( pool = bt_pinpool (bt, right) )
+ page = bt_page (bt, pool, right);
+ else
+ return 0;
+
+ set = bt_pinlatch (bt, right);
+ bt_lockpage(BtLockRead, set);
+
+ memcpy (bt->cursor, page, bt->mgr->page_size);
+
+ bt_unlockpage(BtLockRead, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ slot = 0;
+ } while( 1 );
+
+ return bt->err = 0;
+}
+
+BtKey bt_key(BtDb *bt, uint slot)
+{
+ return keyptr(bt->cursor, slot);
+}
+
+uid bt_uid(BtDb *bt, uint slot)
+{
+ return bt_getid(slotptr(bt->cursor,slot)->id);
+}
+
+uint bt_tod(BtDb *bt, uint slot)
+{
+ return slotptr(bt->cursor,slot)->tod;
+}
+
+
+#ifdef STANDALONE
+
+typedef struct {
+ char type, idx;
+ char *infile;
+ BtMgr *mgr;
+ int num;
+} ThreadArg;
+
+// standalone program to index file of keys
+// then list them onto std-out
+
+#ifdef unix
+void *index_file (void *arg)
+#else
+uint __stdcall index_file (void *arg)
+#endif
+{
+int line = 0, found = 0, cnt = 0;
+uid next, page_no = LEAF_page; // start on first page of leaves
+unsigned char key[256];
+ThreadArg *args = arg;
+int ch, len = 0, slot;
+BtLatchSet *set;
+time_t tod[1];
+BtPool *pool;
+BtPage page;
+BtKey ptr;
+BtDb *bt;
+FILE *in;
+
+ bt = bt_open (args->mgr);
+ time (tod);
+
+ switch(args->type | 0x20)
+ {
+ case 'w':
+ fprintf(stderr, "started indexing for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_insertkey (bt, key, len, line, *tod, 0) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys\n", args->infile, line);
+ break;
+
+ case 'd':
+ fprintf(stderr, "started deleting keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_deletekey (bt, key, len) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for keys, %d \n", args->infile, line);
+ break;
+
+ case 'f':
+ fprintf(stderr, "started finding keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_findkey (bt, key, len) )
+ found++;
+ else if( bt->err )
+ fprintf(stderr, "Error %d Syserr %d Line: %d\n", bt->err, errno, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys, found %d\n", args->infile, line, found);
+ break;
+
+ case 's':
+ len = key[0] = 0;
+
+ fprintf(stderr, "started reading\n");
+
+ if( slot = bt_startkey (bt, key, len) )
+ slot--;
+ else
+ fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0);
+
+ while( slot = bt_nextkey (bt, slot) ) {
+ ptr = bt_key(bt, slot);
+ fwrite (ptr->key, ptr->len, 1, stdout);
+ fputc ('\n', stdout);
+ }
+
+ break;
+
+ case 'c':
+ fprintf(stderr, "started reading\n");
+
+ do {
+ if( pool = bt_pinpool (bt, page_no) )
+ page = bt_page (bt, pool, page_no);
+ else
+ break;
+ set = bt_pinlatch (bt, page_no);
+ bt_lockpage (BtLockRead, set);
+ cnt += page->act;
+ next = bt_getid (page->right);
+ bt_unlockpage (BtLockRead, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ } while( page_no = next );
+
+ cnt--; // remove stopper key
+ fprintf(stderr, " Total keys read %d\n", cnt);
+ break;
+ }
+
+ bt_close (bt);
+#ifdef unix
+ return NULL;
+#else
+ return 0;
+#endif
+}
+
+typedef struct timeval timer;
+
+int main (int argc, char **argv)
+{
+int idx, cnt, len, slot, err;
+int segsize, bits = 16;
+#ifdef unix
+pthread_t *threads;
+timer start, stop;
+#else
+time_t start[1], stop[1];
+HANDLE *threads;
+#endif
+double real_time;
+ThreadArg *args;
+uint poolsize = 0;
+int num = 0;
+char key[1];
+BtMgr *mgr;
+BtKey ptr;
+BtDb *bt;
+
+ if( argc < 3 ) {
+ fprintf (stderr, "Usage: %s idx_file Read/Write/Scan/Delete/Find [page_bits mapped_segments seg_bits line_numbers src_file1 src_file2 ... ]\n", argv[0]);
+ fprintf (stderr, " where page_bits is the page size in bits\n");
+ fprintf (stderr, " mapped_segments is the number of mmap segments in buffer pool\n");
+ fprintf (stderr, " seg_bits is the size of individual segments in buffer pool in pages in bits\n");
+ fprintf (stderr, " line_numbers = 1 to append line numbers to keys\n");
+ fprintf (stderr, " src_file1 thru src_filen are files of keys separated by newline\n");
+ exit(0);
+ }
+
+#ifdef unix
+ gettimeofday(&start, NULL);
+#else
+ time(start);
+#endif
+
+ if( argc > 3 )
+ bits = atoi(argv[3]);
+
+ if( argc > 4 )
+ poolsize = atoi(argv[4]);
+
+ if( !poolsize )
+ fprintf (stderr, "Warning: no mapped_pool\n");
+
+ if( poolsize > 65535 )
+ fprintf (stderr, "Warning: mapped_pool > 65535 segments\n");
+
+ if( argc > 5 )
+ segsize = atoi(argv[5]);
+ else
+ segsize = 4; // 16 pages per mmap segment
+
+ if( argc > 6 )
+ num = atoi(argv[6]);
+
+ cnt = argc - 7;
+#ifdef unix
+ threads = malloc (cnt * sizeof(pthread_t));
+#else
+ threads = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, cnt * sizeof(HANDLE));
+#endif
+ args = malloc (cnt * sizeof(ThreadArg));
+
+ mgr = bt_mgr ((argv[1]), BT_rw, bits, poolsize, segsize, poolsize / 8);
+
+ if( !mgr ) {
+ fprintf(stderr, "Index Open Error %s\n", argv[1]);
+ exit (1);
+ }
+
+ // fire off threads
+
+ for( idx = 0; idx < cnt; idx++ ) {
+ args[idx].infile = argv[idx + 7];
+ args[idx].type = argv[2][0];
+ args[idx].mgr = mgr;
+ args[idx].num = num;
+ args[idx].idx = idx;
+#ifdef unix
+ if( err = pthread_create (threads + idx, NULL, index_file, args + idx) )
+ fprintf(stderr, "Error creating thread %d\n", err);
+#else
+ threads[idx] = (HANDLE)_beginthreadex(NULL, 65536, index_file, args + idx, 0, NULL);
+#endif
+ }
+
+ // wait for termination
+
+#ifdef unix
+ for( idx = 0; idx < cnt; idx++ )
+ pthread_join (threads[idx], NULL);
+ gettimeofday(&stop, NULL);
+ real_time = 1000.0 * ( stop.tv_sec - start.tv_sec ) + 0.001 * (stop.tv_usec - start.tv_usec );
+#else
+ WaitForMultipleObjects (cnt, threads, TRUE, INFINITE);
+
+ for( idx = 0; idx < cnt; idx++ )
+ CloseHandle(threads[idx]);
+
+ time (stop);
+ real_time = 1000 * (*stop - *start);
+#endif
+ fprintf(stderr, " Time to complete: %.2f seconds\n", real_time/1000);
+ bt_mgrclose (mgr);
+}
+
+#endif //STANDALONE
-// foster btree version f
-// 30 DEC 2013
+// foster btree version f2
+// 18 JAN 2014
// author: karl malbrain, malbrain@cal.berkeley.edu
// by the BtSlot array of keys.
typedef struct Page {
- uint cnt; // count of keys in page
- uint act; // count of active keys
- uint min; // next key offset
- uint foster; // count of foster children
+ volatile uint cnt; // count of keys in page
+ volatile uint act; // count of active keys
+ volatile uint min; // next key offset
+ volatile uint foster; // count of foster children
unsigned char bits; // page size in bits
- unsigned char lvl:6; // level of page
- unsigned char kill:1; // page is being deleted
+ unsigned char lvl:7; // level of page
unsigned char dirty:1; // page needs to be cleaned
unsigned char right[BtId]; // page number to right
} *BtPage;
-// mode & definition for spin latch implementation
+// mode & definition for hash latch implementation
enum {
Mutex = 1,
volatile ushort slot; // Latch table entry at head of chain
} BtHashEntry;
+// latch manager table structure
+
typedef struct {
- BtSpinLatch readwr[1]; // read/write page lock
- BtSpinLatch access[1]; // Access Intent/Page delete
- BtSpinLatch parent[1]; // adoption of foster children
+ BtSpinLatch readwr[1]; // read/write page lock
+ BtSpinLatch access[1]; // Access Intent/Page delete
+ BtSpinLatch parent[1]; // adoption of foster children
BtSpinLatch busy[1]; // slot is being moved between chains
volatile ushort next; // next entry in hash table chain
volatile ushort prev; // prev entry in hash table chain
#endif
ushort poolcnt; // highest page pool node in use
ushort poolmax; // highest page pool node allocated
- ushort poolmask; // total size of pages in mmap segment - 1
+ ushort poolmask; // total number of pages in mmap segment - 1
ushort hashsize; // size of Hash Table for pool entries
ushort evicted; // last evicted hash table slot
ushort *hash; // hash table of pool entries
BtPool *pool; // memory pool page segments
BtSpinLatch *latch; // latches for pool hash slots
BtLatchMgr *latchmgr; // mapped latch page from allocation page
- BtLatchSet *latchset; // first mapped latch set from latch pages
+ BtLatchSet *latchsets; // mapped latch set from latch pages
#ifndef unix
- HANDLE halloc; // allocation and latch table
+ HANDLE halloc; // allocation and latch table handle
#endif
} BtMgr;
typedef struct {
BtMgr *mgr; // buffer manager for thread
- BtPage temp; // temporary frame buffer (memory mapped/file IO)
BtPage cursor; // cached frame for start/next (never mapped)
BtPage frame; // spare frame for the page split (never mapped)
BtPage zero; // page frame for zeroes at end of file
BtPage page; // current page
uid page_no; // current page number
uid cursor_page; // current cursor page number
+ BtLatchSet *set; // current page latch set
+ BtPool *pool; // current page pool
unsigned char *mem; // frame, cursor, page memory buffer
+ int found; // last delete was found
int err; // last error
} BtDb;
// B-Tree functions
extern void bt_close (BtDb *bt);
extern BtDb *bt_open (BtMgr *mgr);
-extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod);
-extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl);
+extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod, uint lvl);
+extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len);
extern uid bt_findkey (BtDb *bt, unsigned char *key, uint len);
extern uint bt_startkey (BtDb *bt, unsigned char *key, uint len);
extern uint bt_nextkey (BtDb *bt, uint slot);
#else
_InterlockedAnd16((ushort *)latch, ~Mutex);
#endif
-
if( prev )
return;
#ifdef unix
void bt_spinwritelock(BtSpinLatch *latch)
{
-ushort prev;
-
do {
#ifdef unix
while( __sync_fetch_and_or((ushort *)latch, Mutex | Pending) & Mutex )
while( _InterlockedOr16((ushort *)latch, Mutex | Pending) & Mutex )
SwitchToThread();
#endif
- if( prev = !(latch->share | latch->exclusive) )
+ if( !(latch->share | latch->exclusive) ) {
#ifdef unix
__sync_fetch_and_or((ushort *)latch, Write);
+ __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending));
#else
_InterlockedOr16((ushort *)latch, Write);
+ _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending));
#endif
+ return;
+ }
#ifdef unix
- __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending));
-#else
- _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending));
-#endif
- if( prev )
- return;
-#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Mutex);
sched_yield();
#else
+ _InterlockedAnd16((ushort *)latch, ~Mutex);
SwitchToThread();
#endif
} while( 1 );
void bt_latchlink (BtDb *bt, ushort hashidx, ushort victim, uid page_no)
{
-BtLatchSet *set = bt->mgr->latchset + victim;
+BtLatchSet *set = bt->mgr->latchsets + victim;
if( set->next = bt->mgr->latchmgr->table[hashidx].slot )
- bt->mgr->latchset[set->next].prev = victim;
+ bt->mgr->latchsets[set->next].prev = victim;
bt->mgr->latchmgr->table[hashidx].slot = victim;
set->page_no = page_no;
set->prev = 0;
}
+// release latch pin
+
+void bt_unpinlatch (BtLatchSet *set)
+{
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, -1);
+#else
+ _InterlockedDecrement16 (&set->pin);
+#endif
+}
+
// find existing latchset or inspire new one
// return with latchset pinned
-BtLatchSet *bt_bindlatch (BtDb *bt, uid page_no, int incr)
+BtLatchSet *bt_pinlatch (BtDb *bt, uid page_no)
{
ushort hashidx = page_no % bt->mgr->latchmgr->latchhash;
ushort slot, avail = 0, victim, idx;
if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
{
- set = bt->mgr->latchset + slot;
+ set = bt->mgr->latchsets + slot;
if( page_no == set->page_no )
break;
} while( slot = set->next );
- if( slot && incr ) {
+ if( slot ) {
#ifdef unix
__sync_fetch_and_add(&set->pin, 1);
#else
if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
{
- set = bt->mgr->latchset + slot;
+ set = bt->mgr->latchsets + slot;
if( page_no == set->page_no )
break;
if( !set->pin && !avail )
// found our entry, or take over an unpinned one
if( slot || (slot = avail) ) {
- set = bt->mgr->latchset + slot;
- if( incr ) {
+ set = bt->mgr->latchsets + slot;
#ifdef unix
- __sync_fetch_and_add(&set->pin, 1);
+ __sync_fetch_and_add(&set->pin, 1);
#else
- _InterlockedIncrement16 (&set->pin);
+ _InterlockedIncrement16 (&set->pin);
#endif
- }
set->page_no = page_no;
bt_spinreleasewrite(bt->mgr->latchmgr->table[hashidx].latch);
return set;
#endif
if( victim < bt->mgr->latchmgr->latchtotal ) {
- set = bt->mgr->latchset + victim;
+ set = bt->mgr->latchsets + victim;
#ifdef unix
__sync_fetch_and_add(&set->pin, 1);
#else
// we don't use slot zero
if( victim %= bt->mgr->latchmgr->latchtotal )
- set = bt->mgr->latchset + victim;
+ set = bt->mgr->latchsets + victim;
else
continue;
// unlink our available victim from its hash chain
if( set->prev )
- bt->mgr->latchset[set->prev].next = set->next;
+ bt->mgr->latchsets[set->prev].next = set->next;
else
bt->mgr->latchmgr->table[idx].slot = set->next;
if( set->next )
- bt->mgr->latchset[set->next].prev = set->prev;
+ bt->mgr->latchsets[set->next].prev = set->prev;
bt_spinreleasewrite (bt->mgr->latchmgr->table[idx].latch);
-
- if( incr )
- set->pin++;
-
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
bt_latchlink (bt, hashidx, victim, page_no);
bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch);
bt_spinreleasewrite (set->busy);
#endif
}
+#ifdef unix
+ munmap (mgr->latchsets, mgr->latchmgr->nlatchpage * mgr->page_size);
+ munmap (mgr->latchmgr, mgr->page_size);
+#else
+ FlushViewOfFile(mgr->latchmgr, 0);
+ UnmapViewOfFile(mgr->latchmgr);
+ CloseHandle(mgr->halloc);
+#endif
#ifdef unix
close (mgr->idx);
free (mgr->pool);
uint lvl, attr, cacheblk, last, slot, idx;
uint nlatchpage, latchhash;
BtLatchMgr *latchmgr;
-int lockmode;
off64_t size;
uint amt[1];
BtMgr* mgr;
#ifdef unix
mgr = calloc (1, sizeof(BtMgr));
- switch (mode & 0x7fff)
- {
- case BT_rw:
- mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
- lockmode = 1;
- break;
+ mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
- case BT_ro:
- default:
- mgr->idx = open ((char*)name, O_RDONLY);
- lockmode = 0;
- break;
- }
if( mgr->idx == -1 )
return free(mgr), NULL;
#else
mgr = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtMgr));
attr = FILE_ATTRIBUTE_NORMAL;
- switch (mode & 0x7fff)
- {
- case BT_rw:
- mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
- lockmode = 1;
- break;
+ mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
- case BT_ro:
- default:
- mgr->idx = CreateFile(name, GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, attr, NULL);
- lockmode = 0;
- break;
- }
if( mgr->idx == INVALID_HANDLE_VALUE )
return GlobalFree(mgr), NULL;
else
return free(mgr), free(latchmgr), NULL;
} else if( mode == BT_ro )
- return bt_mgrclose (mgr), NULL;
+ return free(latchmgr), bt_mgrclose (mgr), NULL;
#else
latchmgr = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE);
size = GetFileSize(mgr->idx, amt);
mgrlatch:
#ifdef unix
- flag = PROT_READ | ( mgr->mode == BT_ro ? 0 : PROT_WRITE );
+ flag = PROT_READ | PROT_WRITE;
mgr->latchmgr = mmap (0, mgr->page_size, flag, MAP_SHARED, mgr->idx, ALLOC_page * mgr->page_size);
if( mgr->latchmgr == MAP_FAILED )
return bt_mgrclose (mgr), NULL;
- mgr->latchset = (BtLatchSet *)mmap (0, mgr->latchmgr->nlatchpage * mgr->page_size, flag, MAP_SHARED, mgr->idx, LATCH_page * mgr->page_size);
- if( mgr->latchset == MAP_FAILED )
+ mgr->latchsets = (BtLatchSet *)mmap (0, mgr->latchmgr->nlatchpage * mgr->page_size, flag, MAP_SHARED, mgr->idx, LATCH_page * mgr->page_size);
+ if( mgr->latchsets == MAP_FAILED )
return bt_mgrclose (mgr), NULL;
#else
- flag = ( mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE );
+ flag = PAGE_READWRITE;
mgr->halloc = CreateFileMapping(mgr->idx, NULL, flag, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size, NULL);
if( !mgr->halloc )
return bt_mgrclose (mgr), NULL;
- flag = ( mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE );
+ flag = FILE_MAP_WRITE;
mgr->latchmgr = MapViewOfFile(mgr->halloc, flag, 0, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size);
if( !mgr->latchmgr )
return GetLastError(), bt_mgrclose (mgr), NULL;
- mgr->latchset = (void *)((char *)mgr->latchmgr + LATCH_page * mgr->page_size);
+ mgr->latchsets = (void *)((char *)mgr->latchmgr + LATCH_page * mgr->page_size);
#endif
#ifdef unix
bt->frame = (BtPage)bt->mem;
bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size);
bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size);
+
+ memset(bt->zero, 0, mgr->page_size);
return bt;
}
return bt->err = 0;
}
+// calculate page within pool
+
+BtPage bt_page (BtDb *bt, BtPool *pool, uid page_no)
+{
+uint subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
+BtPage page;
+
+ page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
+#ifdef unix
+ {
+ uint idx = subpage / 8;
+ uint bit = subpage % 8;
+
+ if( ~((bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] >> bit) & 1 ) {
+ madvise (page, bt->mgr->page_size, MADV_WILLNEED);
+ (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] |= 1 << bit;
+ }
+ }
+#endif
+ return page;
+}
+
+// release pool pin
+
+void bt_unpinpool (BtPool *pool)
+{
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, -1);
+#else
+ _InterlockedDecrement16 (&pool->pin);
+#endif
+}
+
// find or place requested page in segment-pool
// return pool table entry, incrementing pin
-BtPool *bt_pinpage(BtDb *bt, uid page_no)
+BtPool *bt_pinpool(BtDb *bt, uid page_no)
{
BtPool *pool, *node, *next;
uint slot, idx, victim;
}
// place write, read, or parent lock on requested page_no.
-// pin to buffer pool and return page pointer
+// pin to buffer pool and return latchset pointer
-BTERR bt_lockpage(BtDb *bt, uid page_no, BtLock mode, BtPage *pageptr)
+void bt_lockpage(BtLock mode, BtLatchSet *set)
{
-BtLatchSet *set;
-BtPool *pool;
-uint subpage;
-BtPage page;
-
- // find/create maping in pool table
- // and pin our pool slot
-
- if( pool = bt_pinpage(bt, page_no) )
- subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
- else
- return bt->err;
-
- if( !(set = bt_bindlatch (bt, page_no, 1)) )
- return bt->err;
-
- page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
-
-#ifdef unix
- {
- uint idx = subpage / 8;
- uint bit = subpage % 8;
-
- if( mode == BtLockRead || mode == BtLockWrite )
- if( ~((bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] >> bit) & 1 ) {
- madvise (page, bt->mgr->page_size, MADV_WILLNEED);
- (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] |= 1 << bit;
- }
- }
-#endif
-
switch( mode ) {
case BtLockRead:
bt_spinreadlock (set->readwr);
case BtLockParent:
bt_spinwritelock (set->parent);
break;
- default:
- return bt->err = BTERR_lock;
}
-
- if( pageptr )
- *pageptr = page;
-
- return bt->err = 0;
}
// remove write, read, or parent lock on requested page_no.
-BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode)
+void bt_unlockpage(BtLock mode, BtLatchSet *set)
{
-BtLatchSet *set;
-BtPool *pool;
-uint idx;
-
- // since page is pinned
- // it should still be in the buffer pool
- // and is in no danger of being a victim for reuse
-
- if( !(set = bt_bindlatch (bt, page_no, 0)) )
- return bt->err = BTERR_latch;
-
- idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
- bt_spinreadlock (&bt->mgr->latch[idx]);
-
- if( !(pool = bt_findpool(bt, page_no, idx)) )
- return bt->err = BTERR_hash;
-
- bt_spinreleaseread (&bt->mgr->latch[idx]);
-
switch( mode ) {
case BtLockRead:
bt_spinreleaseread (set->readwr);
case BtLockParent:
bt_spinreleasewrite (set->parent);
break;
- default:
- return bt->err = BTERR_lock;
}
-
-#ifdef unix
- __sync_fetch_and_add(&pool->pin, -1);
- __sync_fetch_and_add (&set->pin, -1);
-#else
- _InterlockedDecrement16 (&pool->pin);
- _InterlockedDecrement16 (&set->pin);
-#endif
- return bt->err = 0;
-}
-
-// deallocate a deleted page
-// place on free chain out of allocator page
-// fence key must already be removed from parent
-
-BTERR bt_freepage(BtDb *bt, uid page_no)
-{
- // obtain delete lock on deleted page
-
- if( bt_lockpage(bt, page_no, BtLockDelete, NULL) )
- return bt->err;
-
- // obtain write lock on deleted page
-
- if( bt_lockpage(bt, page_no, BtLockWrite, &bt->temp) )
- return bt->err;
-
- // lock allocation page
-
- bt_spinwritelock(bt->mgr->latchmgr->lock);
-
- // store free chain in allocation page second right
- bt_putid(bt->temp->right, bt_getid(bt->mgr->latchmgr->alloc[1].right));
- bt_putid(bt->mgr->latchmgr->alloc[1].right, page_no);
-
- // unlock page zero
-
- bt_spinreleasewrite(bt->mgr->latchmgr->lock);
-
- // remove write lock on deleted node
-
- if( bt_unlockpage(bt, page_no, BtLockWrite) )
- return bt->err;
-
- // remove delete lock on deleted node
-
- if( bt_unlockpage(bt, page_no, BtLockDelete) )
- return bt->err;
-
- return 0;
}
// allocate a new page and write page into it
uid bt_newpage(BtDb *bt, BtPage page)
{
+BtLatchSet *set;
+BtPool *pool;
uid new_page;
BtPage pmap;
int reuse;
// else allocate empty page
if( new_page = bt_getid(bt->mgr->latchmgr->alloc[1].right) ) {
- if( bt_lockpage (bt, new_page, BtLockWrite, &bt->temp) )
- return 0;
- bt_putid(bt->mgr->latchmgr->alloc[1].right, bt_getid(bt->temp->right));
- if( bt_unlockpage (bt, new_page, BtLockWrite) )
+ if( pool = bt_pinpool (bt, new_page) )
+ pmap = bt_page (bt, pool, new_page);
+ else
return 0;
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, bt_getid(pmap->right));
+ bt_unpinpool (pool);
reuse = 1;
} else {
new_page = bt_getid(bt->mgr->latchmgr->alloc->right);
reuse = 0;
}
#ifdef unix
- if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
- return bt->err = BTERR_wrt, 0;
-
// if writing first page of pool block, zero last page in the block
if ( !reuse && bt->mgr->poolmask > 0 && (new_page & bt->mgr->poolmask) == 0 )
{
// use zero buffer to write zeros
- memset(bt->zero, 0, bt->mgr->page_size);
if ( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->poolmask) << bt->mgr->page_bits) < bt->mgr->page_size )
return bt->err = BTERR_wrt, 0;
}
+
+ // unlock allocation latch
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
+ if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+
#else
+ // unlock allocation latch
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
// bring new page into pool and copy page.
// this will extend the file into the new pages.
+ // NB -- no latch required
- if( bt_lockpage(bt, new_page, BtLockWrite, &pmap) )
+ if( pool = bt_pinpool (bt, new_page) )
+ pmap = bt_page (bt, pool, new_page);
+ else
return 0;
memcpy(pmap, page, bt->mgr->page_size);
-
- if( bt_unlockpage (bt, new_page, BtLockWrite) )
- return 0;
+ bt_unpinpool (pool);
#endif
- // unlock allocation latch and return new page no
-
- bt_spinreleasewrite(bt->mgr->latchmgr->lock);
return new_page;
}
// find and load page at given level for given key
// leave page rd or wr locked as requested
-int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, uint lock)
+int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, BtLock lock)
{
uid page_no = ROOT_page, prevpage = 0;
+BtLatchSet *set, *prevset;
uint drill = 0xff, slot;
uint mode, prevmode;
+BtPool *prevpool;
// start at root of btree and drill down
// determine lock mode of drill level
mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead;
+ // obtain latch set for this page
+
+ bt->set = bt_pinlatch (bt, page_no);
bt->page_no = page_no;
+ // pin page contents
+
+ if( bt->pool = bt_pinpool (bt, page_no) )
+ bt->page = bt_page (bt, bt->pool, page_no);
+ else
+ return 0;
+
// obtain access lock using lock chaining with Access mode
if( page_no > ROOT_page )
- if( bt_lockpage(bt, page_no, BtLockAccess, NULL) )
- return 0;
+ bt_lockpage(BtLockAccess, bt->set);
- // now unlock our (possibly foster) parent
+ // now unlock and unpin our (possibly foster) parent
- if( prevpage )
- if( bt_unlockpage(bt, prevpage, prevmode) )
- return 0;
- else
- prevpage = 0;
+ if( prevpage ) {
+ bt_unlockpage(prevmode, prevset);
+ bt_unpinlatch (prevset);
+ bt_unpinpool (prevpool);
+ prevpage = 0;
+ }
// obtain read lock using lock chaining
- // and pin page contents
- if( bt_lockpage(bt, page_no, mode, &bt->page) )
- return 0;
+ bt_lockpage(mode, bt->set);
if( page_no > ROOT_page )
- if( bt_unlockpage(bt, page_no, BtLockAccess) )
- return 0;
+ bt_unlockpage(BtLockAccess, bt->set);
// re-read and re-lock root after determining actual level of root
- if( bt->page_no == ROOT_page )
+ if( page_no == ROOT_page )
if( bt->page->lvl != drill) {
drill = bt->page->lvl;
- if( lock == BtLockWrite && drill == lvl )
- if( bt_unlockpage(bt, page_no, mode) )
- return 0;
- else
- continue;
+ if( lock == BtLockWrite && drill == lvl ) {
+ bt_unlockpage(mode, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ continue;
+ }
}
prevpage = bt->page_no;
+ prevpool = bt->pool;
+ prevset = bt->set;
prevmode = mode;
- // if page is being deleted,
- // move back to preceeding page
-
- if( bt->page->kill ) {
- page_no = bt_getid (bt->page->right);
- continue;
- }
-
// find key on page at this level
- // and descend to requested level
+ // and either descend to requested level
+ // or return key slot
slot = bt_findslot (bt, key, len);
- // is this slot a foster child?
+ // is this slot < foster child area
+ // on the requested level?
+
+ // if so, return actual slot even if dead
if( slot <= bt->page->cnt - bt->page->foster )
if( drill == lvl )
return slot;
+ // find next active slot
+
+ // note: foster children are never dead
+ // nor fence keys for interiour nodes
+
while( slotptr(bt->page, slot)->dead )
if( slot++ < bt->page->cnt )
continue;
else
- goto slideright;
+ return bt->err = BTERR_struct, 0; // last key shouldn't be deleted
+
+ // is this slot < foster child area
+ // if so, drill to next level
if( slot <= bt->page->cnt - bt->page->foster )
drill--;
- // continue down / right using overlapping locks
- // to protect pages being killed or split.
+ // continue right onto foster child
+ // or down to next level.
page_no = bt_getid(slotptr(bt->page, slot)->id);
- continue;
-
-slideright:
- page_no = bt_getid(bt->page->right);
} while( page_no );
}
// find and delete key on page by marking delete flag bit
-// when page becomes empty, delete it from the btree
+// when leaf page becomes empty, delete it from the btree
-BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl)
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len)
{
-unsigned char leftkey[256], rightkey[256];
+unsigned char leftkey[256];
+BtLatchSet *rset, *set;
+BtPool *pool, *rpool;
+BtPage rpage, page;
uid page_no, right;
uint slot, tod;
BtKey ptr;
- if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
ptr = keyptr(bt->page, slot);
else
return bt->err;
// if key is found delete it, otherwise ignore request
+ // note that fence keys of interiour nodes are not deleted.
- if( !keycmp (ptr, key, len) )
- if( slotptr(bt->page, slot)->dead == 0 ) {
+ if( bt->found = !keycmp (ptr, key, len) )
+ if( bt->found = slotptr(bt->page, slot)->dead == 0 ) {
slotptr(bt->page,slot)->dead = 1;
if( slot < bt->page->cnt )
bt->page->dirty = 1;
bt->page->act--;
}
- // return if page is not empty, or it has no right sibling
-
- right = bt_getid(bt->page->right);
page_no = bt->page_no;
+ pool = bt->pool;
+ page = bt->page;
+ set = bt->set;
- if( !right || bt->page->act )
- return bt_unlockpage(bt, page_no, BtLockWrite);
+ // return if page is not empty or not found
- // obtain Parent lock over write lock
-
- if( bt_lockpage(bt, page_no, BtLockParent, NULL) )
+ if( page->act || !bt->found ) {
+ bt_unlockpage(BtLockWrite, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
return bt->err;
+ }
- // cache copy of key to delete
+ // cache copy of fence key of empty node
- ptr = keyptr(bt->page, bt->page->cnt);
+ ptr = keyptr(page, page->cnt);
memcpy(leftkey, ptr, ptr->len + 1);
- // lock and map right page
+ // release write lock on empty node
+ // obtain Parent lock
- if( bt_lockpage(bt, right, BtLockWrite, &bt->temp) )
- return bt->err;
+ bt_unlockpage(BtLockWrite, set);
+ bt_lockpage(BtLockParent, set);
- // pull contents of next page into current empty page
- memcpy (bt->page, bt->temp, bt->mgr->page_size);
+ // load and lock parent to see
+ // if delete of empty node is OK
+ // ie, not a fence key of parent
- // cache copy of key to update
- ptr = keyptr(bt->temp, bt->temp->cnt);
- memcpy(rightkey, ptr, ptr->len + 1);
+ while( 1 ) {
+ if( slot = bt_loadpage (bt, leftkey+1, *leftkey, 1, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
- // Mark right page as deleted and point it to left page
- // until we can post updates at higher level.
+ // does parent level contain our fence key yet?
+ // and is it free of foster children?
- bt_putid(bt->temp->right, page_no);
- bt->temp->kill = 1;
- bt->temp->cnt = 0;
+ if( !bt->page->foster )
+ if( !keycmp (ptr, leftkey+1, *leftkey) )
+ break;
- if( bt_unlockpage(bt, right, BtLockWrite) )
- return bt->err;
- if( bt_unlockpage(bt, page_no, BtLockWrite) )
- return bt->err;
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ }
- // delete old lower key to consolidated node
+ // find our left fence key
- if( bt_deletekey (bt, leftkey + 1, *leftkey, lvl + 1) )
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ return bt->err = BTERR_struct; // last key shouldn't be deleted
+
+ // now we have both parent and child
+
+ bt_lockpage(BtLockDelete, set);
+ bt_lockpage(BtLockWrite, set);
+
+ // return if page has no right sibling within parent
+ // or if empty node is no longer empty
+
+ if( page->act || slot == bt->page->cnt ) {
+ // unpin parent
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ // unpin empty node
+ bt_unlockpage(BtLockParent, set);
+ bt_unlockpage(BtLockDelete, set);
+ bt_unlockpage(BtLockWrite, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
return bt->err;
+ }
- // redirect higher key directly to consolidated node
+ // lock and map our right page
+ // note that it cannot be our foster child
+ // since the our node is empty
- if( slot = bt_loadpage (bt, rightkey+1, *rightkey, lvl+1, BtLockWrite) )
- ptr = keyptr(bt->page, slot);
+ right = bt_getid(page->right);
+
+ if( rpool = bt_pinpool (bt, right) )
+ rpage = bt_page (bt, rpool, right);
else
return bt->err;
- // since key already exists, update id
+ rset = bt_pinlatch (bt, right);
+ bt_lockpage(BtLockWrite, rset);
+ bt_lockpage(BtLockDelete, rset);
+
+ // pull contents of right page into empty page
- if( keycmp (ptr, rightkey+1, *rightkey) )
- return bt->err = BTERR_struct;
+ memcpy (page, rpage, bt->mgr->page_size);
+
+ // delete left parent slot for old empty page
+ // and redirect right parent slot to it
+
+ bt->page->act--;
+ bt->page->dirty = 1;
+ slotptr(bt->page, slot)->dead = 1;
+
+ while( slot++ < bt->page->cnt )
+ if( !slotptr(bt->page, slot)->dead )
+ break;
- slotptr(bt->page, slot)->dead = 0;
bt_putid(slotptr(bt->page,slot)->id, page_no);
- if( bt_unlockpage(bt, bt->page_no, BtLockWrite) )
- return bt->err;
+ // release parent level lock
+ // and our empty node lock
- // obtain write lock and
- // add right block to free chain
+ bt_unlockpage(BtLockWrite, set);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
- if( bt_freepage (bt, right) )
- return bt->err;
+ // add killed right block to free chain
+ // lock latch mgr
+
+ bt_spinwritelock(bt->mgr->latchmgr->lock);
+
+ // store free chain in allocation page second right
+ bt_putid(rpage->right, bt_getid(bt->mgr->latchmgr->alloc[1].right));
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, right);
+
+ // unlock latch mgr and right page
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
+ bt_unlockpage(BtLockWrite, rset);
+ bt_unlockpage(BtLockDelete, rset);
+ bt_unpinlatch (rset);
+ bt_unpinpool (rpool);
// remove ParentModify lock
- if( bt_unlockpage(bt, page_no, BtLockParent) )
- return bt->err;
-
+ bt_unlockpage(BtLockParent, set);
+ bt_unlockpage(BtLockDelete, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
return 0;
-}
+}
// find key in leaf level and return row-id
// if key exists, return row-id
// otherwise return 0
- if( ptr->len == len && !memcmp (ptr->key, key, len) )
+ if( slot <= bt->page->cnt && !keycmp (ptr, key, len) )
id = bt_getid(slotptr(bt->page,slot)->id);
else
id = 0;
- if( bt_unlockpage (bt, bt->page_no, BtLockRead) )
- return 0;
-
+ bt_unlockpage (BtLockRead, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
return id;
}
// check page for space available,
// clean if necessary and return
// 0 - page needs splitting
-// 1 - go ahead
+// >0 new slot value
-uint bt_cleanpage(BtDb *bt, uint amt)
+uint bt_cleanpage(BtDb *bt, uint amt, uint slot)
{
uint nxt = bt->mgr->page_size;
BtPage page = bt->page;
uint cnt = 0, idx = 0;
uint max = page->cnt;
+uint newslot;
BtKey key;
if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
- return 1;
+ return slot;
// skip cleanup if nothing to reclaim
// try cleaning up page first
+ // always leave fence key in the array
+ // otherwise, remove deleted key
+
+ // note: foster children are never dead
+ // nor are fence keys for interiour nodes
+
while( cnt++ < max ) {
- // always leave fence key and foster children in list
- if( cnt < max - page->foster && slotptr(bt->frame,cnt)->dead )
+ if( cnt == slot )
+ newslot = idx + 1;
+ else if( cnt < max && slotptr(bt->frame,cnt)->dead )
continue;
// copy key
+
key = keyptr(bt->frame, cnt);
nxt -= key->len + 1;
memcpy ((unsigned char *)page + nxt, key, key->len + 1);
// see if page has enough space now, or does it need splitting?
if( page->min >= (idx+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
- return 1;
+ return newslot;
return 0;
}
BtPage page = bt->page;
uint idx;
- // calculate next available slot and copy key into page
+ // find next available dead slot and copy key onto page
+ // note that foster children on the page are never dead
- page->min -= len + 1;
- ((unsigned char *)page)[page->min] = len;
- memcpy ((unsigned char *)page + page->min +1, key, len );
+ // look for next hole, but stay back from the fence key
for( idx = slot; idx < page->cnt; idx++ )
if( slotptr(page, idx)->dead )
break;
- // now insert key into array before slot
- // preserving the fence slot
-
if( idx == page->cnt )
idx++, page->cnt++;
page->act++;
+ // now insert key into array before slot
+
while( idx > slot )
*slotptr(page, idx) = *slotptr(page, idx -1), idx--;
+ page->min -= len + 1;
+ ((unsigned char *)page)[page->min] = len;
+ memcpy ((unsigned char *)page + page->min +1, key, len );
+
bt_putid(slotptr(page,slot)->id, id);
slotptr(page, slot)->off = page->min;
slotptr(page, slot)->tod = tod;
// contents into it from the root. Strip foster child key.
// (it's the stopper key)
+ memset (slotptr(root, root->cnt), 0, sizeof(BtSlot));
+ root->dirty = 1;
+ root->foster--;
root->act--;
root->cnt--;
- root->foster--;
// Save left fence key.
root->act = 2;
root->lvl++;
- // release root (bt->page)
+ // release and unpin root (bt->page)
- return bt_unlockpage(bt, ROOT_page, BtLockWrite);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return 0;
}
// split already locked full node
// in current page variables
-// return unlocked.
+// return unlocked and unpinned.
BTERR bt_splitpage (BtDb *bt)
{
uint slot, cnt, idx, max, nxt = bt->mgr->page_size;
unsigned char fencekey[256];
uid page_no = bt->page_no;
+BtLatchSet *set = bt->set;
+BtPool *pool = bt->pool;
BtPage page = bt->page;
uint tod = time(NULL);
uint lvl = page->lvl;
uid new_page, right;
BtKey key;
- // initialize frame buffer
+ // initialize frame buffer for right node
memset (bt->frame, 0, bt->mgr->page_size);
max = page->cnt - page->foster;
idx = 0;
// split higher half of keys to bt->frame
- // leaving foster children in the left node.
+ // leaving old foster children in the left node,
+ // and adding a new foster child there.
while( cnt++ < max ) {
key = keyptr(page, cnt);
nxt -= key->len + 1;
memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1);
memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId);
+ if( !(slotptr(bt->frame, idx)->dead = slotptr(page, cnt)->dead) )
+ bt->frame->act++;
slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod;
slotptr(bt->frame, idx)->off = nxt;
- bt->frame->act++;
}
- // transfer right link node
+ // transfer right link node to new right node
if( page_no > ROOT_page ) {
right = bt_getid (page->right);
bt->frame->cnt = idx;
bt->frame->lvl = lvl;
- // get new free page and write frame to it.
+ // get new free page and write right frame to it.
if( !(new_page = bt_newpage(bt, bt->frame)) )
return bt->err;
- // remember fence key for new page to add
- // as foster child
+ // remember fence key for new right page to add
+ // as foster child to the left node
key = keyptr(bt->frame, idx);
memcpy (fencekey, key, key->len + 1);
memcpy (bt->frame, page, bt->mgr->page_size);
memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
nxt = bt->mgr->page_size;
+ page->dirty = 0;
page->act = 0;
cnt = 0;
idx = 0;
nxt -= key->len + 1;
memcpy ((unsigned char *)page + nxt, key, key->len + 1);
memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
+ page->act++;
slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
slotptr(page, idx)->off = nxt;
- page->act++;
}
- // insert new foster child at beginning of the current foster children
+ // insert new foster child for right page in queue
+ // before any of the current foster children
nxt -= *fencekey + 1;
memcpy ((unsigned char *)page + nxt, fencekey, *fencekey + 1);
+
bt_putid (slotptr(page,++idx)->id, new_page);
slotptr(page, idx)->tod = tod;
slotptr(page, idx)->off = nxt;
page->foster++;
page->act++;
- // continue with old foster child keys if any
+ // continue with old foster child keys
+ // note that none will be dead
cnt = bt->frame->cnt - bt->frame->foster;
// release wr lock on our page
- if( bt_unlockpage (bt, page_no, BtLockWrite) )
- return bt->err;
+ bt_unlockpage (BtLockWrite, set);
// obtain ParentModification lock for current page
- // to fix fence key and highest foster child on page
+ // to fix new fence key and oldest foster child on page
- if( bt_lockpage (bt, page_no, BtLockParent, NULL) )
- return bt->err;
+ bt_lockpage (BtLockParent, set);
- // get our highest foster child key to find in parent node
+ // get our new fence key to insert in parent node
- if( bt_lockpage (bt, page_no, BtLockRead, &page) )
- return bt->err;
+ bt_lockpage (BtLockRead, set);
- key = keyptr(page, page->cnt);
+ key = keyptr(page, page->cnt-1);
memcpy (fencekey, key, key->len+1);
- if( bt_unlockpage (bt, page_no, BtLockRead) )
- return bt->err;
-
- // update our parent
-try_again:
-
- do {
- slot = bt_loadpage (bt, fencekey + 1, *fencekey, lvl + 1, BtLockWrite);
-
- if( !slot )
- return bt->err;
-
- // check if parent page has enough space for any possible key
+ bt_unlockpage (BtLockRead, set);
- if( bt_cleanpage (bt, 256) )
- break;
-
- if( bt_splitpage (bt) )
+ if( bt_insertkey (bt, fencekey + 1, *fencekey, page_no, tod, lvl + 1) )
return bt->err;
- } while( 1 );
- // see if we are still a foster child from another node
+ // lock our page for writing
- if( bt_getid (slotptr(bt->page, slot)->id) != page_no ) {
- if( bt_unlockpage (bt, bt->page_no, BtLockWrite) )
- return bt->err;
-#ifdef unix
- sched_yield();
-#else
- SwitchToThread();
-#endif
- goto try_again;
- }
+ bt_lockpage (BtLockRead, set);
- // wait until readers from parent get their locks
- // on our page
+ // switch old parent key from us to our oldest foster child
- if( bt_lockpage (bt, page_no, BtLockDelete, NULL) )
- return bt->err;
+ key = keyptr(page, page->cnt);
+ memcpy (fencekey, key, key->len+1);
- // lock our page for writing
+ new_page = bt_getid (slotptr(page, page->cnt)->id);
+ bt_unlockpage (BtLockRead, set);
- if( bt_lockpage (bt, page_no, BtLockWrite, &page) )
+ if( bt_insertkey (bt, fencekey + 1, *fencekey, new_page, tod, lvl + 1) )
return bt->err;
- // switch parent fence key to foster child
-
- if( slotptr(page, page->cnt)->dead )
- slotptr(bt->page, slot)->dead = 1;
- else
- bt_putid (slotptr(bt->page, slot)->id, bt_getid(slotptr(page, page->cnt)->id));
-
- // remove highest foster child from our page
+ // now that it has its own parent pointer,
+ // remove oldest foster child from our page
+ bt_lockpage (BtLockWrite, set);
+ memset (slotptr(page, page->cnt), 0, sizeof(BtSlot));
+ page->dirty = 1;
+ page->foster--;
page->cnt--;
page->act--;
- page->foster--;
- page->dirty = 1;
- key = keyptr(page, page->cnt);
-
- // add our new fence key for foster child to our parent
-
- bt_addkeytopage (bt, slot, key->key, key->len, page_no, tod);
-
- if( bt_unlockpage (bt, bt->page_no, BtLockWrite) )
- return bt->err;
- if( bt_unlockpage (bt, page_no, BtLockDelete) )
- return bt->err;
+ // unlock and unpin
- if( bt_unlockpage (bt, page_no, BtLockWrite) )
- return bt->err;
-
- return bt_unlockpage (bt, page_no, BtLockParent);
+ bt_unlockpage (BtLockWrite, set);
+ bt_unlockpage (BtLockParent, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ return 0;
}
// Insert new key into the btree at leaf level.
-BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod)
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod, uint lvl)
{
uint slot, idx;
BtPage page;
BtKey ptr;
while( 1 ) {
- if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
+ if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
ptr = keyptr(bt->page, slot);
else
{
page = bt->page;
if( !keycmp (ptr, key, len) ) {
+ if( slotptr(page, slot)->dead )
+ page->act++;
slotptr(page, slot)->dead = 0;
slotptr(page, slot)->tod = tod;
bt_putid(slotptr(page,slot)->id, id);
- return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return bt->err;
}
// check if page has enough space
- if( bt_cleanpage (bt, len) )
+ if( slot = bt_cleanpage (bt, len, slot) )
break;
if( bt_splitpage (bt) )
bt_addkeytopage (bt, slot, key, len, id, tod);
- return bt_unlockpage (bt, bt->page_no, BtLockWrite);
+ bt_unlockpage (BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return 0;
}
// cache page of keys into cursor and return starting slot for given key
// cache page for retrieval
if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
memcpy (bt->cursor, bt->page, bt->mgr->page_size);
+
bt->cursor_page = bt->page_no;
- if ( bt_unlockpage(bt, bt->page_no, BtLockRead) )
- return 0;
+ bt_unlockpage(BtLockRead, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
return slot;
}
uint bt_nextkey (BtDb *bt, uint slot)
{
+BtLatchSet *set;
+BtPool *pool;
BtPage page;
uid right;
break;
bt->cursor_page = right;
-
- if( bt_lockpage(bt, right, BtLockRead, &page) )
+ if( pool = bt_pinpool (bt, right) )
+ page = bt_page (bt, pool, right);
+ else
return 0;
- memcpy (bt->cursor, page, bt->mgr->page_size);
+ set = bt_pinlatch (bt, right);
+ bt_lockpage(BtLockRead, set);
- if ( bt_unlockpage(bt, right, BtLockRead) )
- return 0;
+ memcpy (bt->cursor, page, bt->mgr->page_size);
+ bt_unlockpage(BtLockRead, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
slot = 0;
} while( 1 );
#ifdef STANDALONE
+void bt_latchaudit (BtDb *bt)
+{
+ushort idx, hashidx;
+BtLatchSet *set;
+BtPool *pool;
+BtPage page;
+uid page_no;
+
+#ifdef unix
+ for( idx = 1; idx < bt->mgr->latchmgr->latchdeployed; idx++ ) {
+ set = bt->mgr->latchsets + idx;
+ if( *(ushort *)set->readwr || *(ushort *)set->access || *(ushort *)set->parent ) {
+ fprintf(stderr, "latchset %d locked for page %6x\n", idx, set->page_no);
+ *(ushort *)set->readwr = 0;
+ *(ushort *)set->access = 0;
+ *(ushort *)set->parent = 0;
+ }
+ if( set->pin ) {
+ fprintf(stderr, "latchset %d pinned\n", idx);
+ set->pin = 0;
+ }
+ }
+
+ for( hashidx = 0; hashidx < bt->mgr->latchmgr->latchhash; hashidx++ ) {
+ if( *(ushort *)bt->mgr->latchmgr->table[hashidx].latch )
+ fprintf(stderr, "latchmgr locked\n");
+ if( idx = bt->mgr->latchmgr->table[hashidx].slot ) do {
+ set = bt->mgr->latchsets + idx;
+ if( *(ushort *)set->readwr || *(ushort *)set->access || *(ushort *)set->parent )
+ fprintf(stderr, "latchset %d locked\n", idx);
+ if( set->hash != hashidx )
+ fprintf(stderr, "latchset %d wrong hashidx\n", idx);
+ if( set->pin )
+ fprintf(stderr, "latchset %d pinned\n", idx);
+ } while( idx = set->next );
+ }
+ page_no = bt_getid(bt->mgr->latchmgr->alloc[1].right);
+
+ while( page_no ) {
+ fprintf(stderr, "free: %.6x\n", (uint)page_no);
+ pool = bt_pinpool (bt, page_no);
+ page = bt_page (bt, pool, page_no);
+ page_no = bt_getid(page->right);
+ bt_unpinpool (pool);
+ }
+#endif
+}
+
typedef struct {
char type, idx;
char *infile;
unsigned char key[256];
ThreadArg *args = arg;
int ch, len = 0, slot;
+BtLatchSet *set;
time_t tod[1];
+BtPool *pool;
BtPage page;
BtKey ptr;
BtDb *bt;
switch(args->type | 0x20)
{
+ case 'a':
+ fprintf(stderr, "started latch mgr audit\n");
+ bt_latchaudit (bt);
+ fprintf(stderr, "finished latch mgr audit\n");
+ break;
case 'w':
fprintf(stderr, "started indexing for %s\n", args->infile);
if( in = fopen (args->infile, "rb") )
else if( args->num )
sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
- if( bt_insertkey (bt, key, len, line, *tod) )
+ if( bt_insertkey (bt, key, len, line, *tod, 0) )
fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
len = 0;
}
else if( args->num )
sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
- if( bt_deletekey (bt, key, len, 0) )
+ if( bt_deletekey (bt, key, len) )
fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
len = 0;
}
fprintf(stderr, "started reading\n");
do {
- bt_lockpage (bt, page_no, BtLockRead, &page);
+ if( pool = bt_pinpool (bt, page_no) )
+ page = bt_page (bt, pool, page_no);
+ else
+ break;
+ set = bt_pinlatch (bt, page_no);
+ bt_lockpage (BtLockRead, set);
cnt += page->act;
next = bt_getid (page->right);
- bt_unlockpage (bt, page_no, BtLockRead);
+ bt_unlockpage (BtLockRead, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
} while( page_no = next );
cnt--; // remove stopper key
--- /dev/null
+// foster btree version f
+// 17 JAN 2014
+
+// author: karl malbrain, malbrain@cal.berkeley.edu
+
+/*
+This work, including the source code, documentation
+and related data, is placed into the public domain.
+
+The orginal author is Karl Malbrain.
+
+THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
+OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
+MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
+ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
+RESULTING FROM THE USE, MODIFICATION, OR
+REDISTRIBUTION OF THIS SOFTWARE.
+*/
+
+// Please see the project home page for documentation
+// code.google.com/p/high-concurrency-btree
+
+#define _FILE_OFFSET_BITS 64
+#define _LARGEFILE64_SOURCE
+
+#ifdef linux
+#define _GNU_SOURCE
+#endif
+
+#ifdef unix
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/time.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <pthread.h>
+#else
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <fcntl.h>
+#include <process.h>
+#include <intrin.h>
+#endif
+
+#include <memory.h>
+#include <string.h>
+
+typedef unsigned long long uid;
+
+#ifndef unix
+typedef unsigned long long off64_t;
+typedef unsigned short ushort;
+typedef unsigned int uint;
+#endif
+
+#define BT_ro 0x6f72 // ro
+#define BT_rw 0x7772 // rw
+
+#define BT_latchtable 128 // number of latch manager slots
+
+#define BT_maxbits 24 // maximum page size in bits
+#define BT_minbits 9 // minimum page size in bits
+#define BT_minpage (1 << BT_minbits) // minimum page size
+#define BT_maxpage (1 << BT_maxbits) // maximum page size
+
+/*
+There are five lock types for each node in three independent sets:
+1. (set 1) AccessIntent: Sharable. Going to Read the node. Incompatible with NodeDelete.
+2. (set 1) NodeDelete: Exclusive. About to release the node. Incompatible with AccessIntent.
+3. (set 2) ReadLock: Sharable. Read the node. Incompatible with WriteLock.
+4. (set 2) WriteLock: Exclusive. Modify the node. Incompatible with ReadLock and other WriteLocks.
+5. (set 3) ParentLock: Exclusive. Have parent adopt/delete maximum foster child from the node.
+*/
+
+typedef enum{
+ BtLockAccess,
+ BtLockDelete,
+ BtLockRead,
+ BtLockWrite,
+ BtLockParent,
+ BtLockPin
+}BtLock;
+
+// Define the length of the page and key pointers
+
+#define BtId 6
+
+// Page key slot definition.
+
+// If BT_maxbits is 15 or less, you can save 4 bytes
+// for each key stored by making the first two uints
+// into ushorts. You can also save 4 bytes by removing
+// the tod field from the key.
+
+// Keys are marked dead, but remain on the page until
+// it cleanup is called. The fence key (highest key) for
+// the page is always present, even after cleanup.
+
+typedef struct {
+ uint off:BT_maxbits; // page offset for key start
+ uint dead:1; // set for deleted key
+ uint tod; // time-stamp for key
+ unsigned char id[BtId]; // id associated with key
+} BtSlot;
+
+// The key structure occupies space at the upper end of
+// each page. It's a length byte followed by the value
+// bytes.
+
+typedef struct {
+ unsigned char len;
+ unsigned char key[1];
+} *BtKey;
+
+// The first part of an index page.
+// It is immediately followed
+// by the BtSlot array of keys.
+
+typedef struct Page {
+ uint cnt; // count of keys in page
+ uint act; // count of active keys
+ uint min; // next key offset
+ uint foster; // count of foster children
+ unsigned char bits; // page size in bits
+ unsigned char lvl:6; // level of page
+ unsigned char kill:1; // page is being deleted
+ unsigned char dirty:1; // page needs to be cleaned
+ unsigned char right[BtId]; // page number to right
+} *BtPage;
+
+// mode & definition for hash latch implementation
+
+enum {
+ Mutex = 1,
+ Write = 2,
+ Pending = 4,
+ Share = 8
+} LockMode;
+
+// mutex locks the other fields
+// exclusive is set for write access
+// share is count of read accessors
+
+typedef struct {
+ volatile ushort mutex:1;
+ volatile ushort exclusive:1;
+ volatile ushort pending:1;
+ volatile ushort share:13;
+} BtSpinLatch;
+
+// hash table entries
+
+typedef struct {
+ BtSpinLatch latch[1];
+ volatile ushort slot; // Latch table entry at head of chain
+} BtHashEntry;
+
+// latch table lock structure
+// implements a fair read-write lock
+
+typedef struct {
+#ifdef unix
+ pthread_rwlock_t lock[1];
+#else
+ SRWLOCK srw[1];
+#endif
+} BtLatch;
+
+typedef struct {
+ BtSpinLatch readwr[1]; // read/write page lock
+ BtSpinLatch access[1]; // Access Intent/Page delete
+ BtSpinLatch parent[1]; // adoption of foster children
+ BtSpinLatch busy[1]; // slot is being moved between chains
+ volatile ushort next; // next entry in hash table chain
+ volatile ushort prev; // prev entry in hash table chain
+ volatile ushort pin; // number of outstanding locks
+ volatile ushort hash; // hash slot entry is under
+ volatile uid page_no; // latch set page number
+} BtLatchSet;
+
+// The memory mapping pool table buffer manager entry
+
+typedef struct {
+ unsigned long long int lru; // number of times accessed
+ uid basepage; // mapped base page number
+ char *map; // mapped memory pointer
+ ushort pin; // mapped page pin counter
+ ushort slot; // slot index in this array
+ void *hashprev; // previous pool entry for the same hash idx
+ void *hashnext; // next pool entry for the same hash idx
+#ifndef unix
+ HANDLE hmap; // Windows memory mapping handle
+#endif
+} BtPool;
+
+// structure for latch manager on ALLOC_page
+
+typedef struct {
+ struct Page alloc[2]; // next & free page_nos in right ptr
+ BtSpinLatch lock[1]; // allocation area lite latch
+ ushort latchdeployed; // highest number of latch entries deployed
+ ushort nlatchpage; // number of latch pages at BT_latch
+ ushort latchtotal; // number of page latch entries
+ ushort latchhash; // number of latch hash table slots
+ ushort latchvictim; // next latch entry to examine
+ BtHashEntry table[0]; // the hash table
+} BtLatchMgr;
+
+// The object structure for Btree access
+
+typedef struct {
+ uint page_size; // page size
+ uint page_bits; // page size in bits
+ uint seg_bits; // seg size in pages in bits
+ uint mode; // read-write mode
+#ifdef unix
+ int idx;
+ char *pooladvise; // bit maps for pool page advisements
+#else
+ HANDLE idx;
+#endif
+ ushort poolcnt; // highest page pool node in use
+ ushort poolmax; // highest page pool node allocated
+ ushort poolmask; // total size of pages in mmap segment - 1
+ ushort hashsize; // size of Hash Table for pool entries
+ ushort evicted; // last evicted hash table slot
+ ushort *hash; // hash table of pool entries
+ BtPool *pool; // memory pool page segments
+ BtSpinLatch *latch; // latches for pool hash slots
+ BtLatchMgr *latchmgr; // mapped latch page from allocation page
+ BtLatchSet *latchsets; // mapped latch set from latch pages
+#ifndef unix
+ HANDLE halloc; // allocation and latch table handle
+#endif
+} BtMgr;
+
+typedef struct {
+ BtMgr *mgr; // buffer manager for thread
+ BtPage temp; // temporary frame buffer (memory mapped/file IO)
+ BtPage cursor; // cached frame for start/next (never mapped)
+ BtPage frame; // spare frame for the page split (never mapped)
+ BtPage zero; // page frame for zeroes at end of file
+ BtPage page; // current page
+ uid page_no; // current page number
+ uid cursor_page; // current cursor page number
+ BtLatchSet *set; // current page latch set
+ unsigned char *mem; // frame, cursor, page memory buffer
+ int err; // last error
+} BtDb;
+
+typedef enum {
+ BTERR_ok = 0,
+ BTERR_struct,
+ BTERR_ovflw,
+ BTERR_lock,
+ BTERR_map,
+ BTERR_wrt,
+ BTERR_hash,
+ BTERR_latch
+} BTERR;
+
+// B-Tree functions
+extern void bt_close (BtDb *bt);
+extern BtDb *bt_open (BtMgr *mgr);
+extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod);
+extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl);
+extern uid bt_findkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_startkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_nextkey (BtDb *bt, uint slot);
+
+// manager functions
+extern BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolsize, uint segsize, uint hashsize);
+void bt_mgrclose (BtMgr *mgr);
+
+// Helper functions to return cursor slot values
+
+extern BtKey bt_key (BtDb *bt, uint slot);
+extern uid bt_uid (BtDb *bt, uint slot);
+extern uint bt_tod (BtDb *bt, uint slot);
+
+// BTree page number constants
+#define ALLOC_page 0 // allocation & lock manager hash table
+#define ROOT_page 1 // root of the btree
+#define LEAF_page 2 // first page of leaves
+#define LATCH_page 3 // pages for lock manager
+
+// Number of levels to create in a new BTree
+
+#define MIN_lvl 2
+
+// The page is allocated from low and hi ends.
+// The key offsets and row-id's are allocated
+// from the bottom, while the text of the key
+// is allocated from the top. When the two
+// areas meet, the page is split into two.
+
+// A key consists of a length byte, two bytes of
+// index number (0 - 65534), and up to 253 bytes
+// of key value. Duplicate keys are discarded.
+// Associated with each key is a 48 bit row-id.
+
+// The b-tree root is always located at page 1.
+// The first leaf page of level zero is always
+// located on page 2.
+
+// When to root page fills, it is split in two and
+// the tree height is raised by a new root at page
+// one with two keys.
+
+// Deleted keys are marked with a dead bit until
+// page cleanup The fence key for a node is always
+// present, even after deletion and cleanup.
+
+// Groups of pages called segments from the btree are
+// cached with memory mapping. A hash table is used to keep
+// track of the cached segments. This behaviour is controlled
+// by the cache block size parameter to bt_open.
+
+// To achieve maximum concurrency one page is locked at a time
+// as the tree is traversed to find leaf key in question.
+
+// An adoption traversal leaves the parent node locked as the
+// tree is traversed to the level in quesiton.
+
+// Page 0 is dedicated to lock for new page extensions,
+// and chains empty pages together for reuse.
+
+// Empty pages are chained together through the ALLOC page and reused.
+
+// Access macros to address slot and key values from the page
+
+#define slotptr(page, slot) (((BtSlot *)(page+1)) + (slot-1))
+#define keyptr(page, slot) ((BtKey)((unsigned char*)(page) + slotptr(page, slot)->off))
+
+void bt_putid(unsigned char *dest, uid id)
+{
+int i = BtId;
+
+ while( i-- )
+ dest[i] = (unsigned char)id, id >>= 8;
+}
+
+uid bt_getid(unsigned char *src)
+{
+uid id = 0;
+int i;
+
+ for( i = 0; i < BtId; i++ )
+ id <<= 8, id |= *src++;
+
+ return id;
+}
+
+// wait until write lock mode is clear
+// and add 1 to the share count
+
+void bt_spinreadlock(BtSpinLatch *latch)
+{
+ushort prev;
+
+ do {
+#ifdef unix
+ while( __sync_fetch_and_or((ushort *)latch, Mutex) & Mutex )
+ sched_yield();
+#else
+ while( _InterlockedOr16((ushort *)latch, Mutex) & Mutex )
+ SwitchToThread();
+#endif
+
+ // see if exclusive request is granted or pending
+
+ if( prev = !(latch->exclusive | latch->pending) )
+#ifdef unix
+ __sync_fetch_and_add((ushort *)latch, Share);
+#else
+ _InterlockedExchangeAdd16 ((ushort *)latch, Share);
+#endif
+
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Mutex);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Mutex);
+#endif
+ if( prev )
+ return;
+#ifdef unix
+ } while( sched_yield(), 1 );
+#else
+ } while( SwitchToThread(), 1 );
+#endif
+}
+
+// wait for other read and write latches to relinquish
+
+void bt_spinwritelock(BtSpinLatch *latch)
+{
+ushort prev;
+
+ do {
+#ifdef unix
+ while( __sync_fetch_and_or((ushort *)latch, Mutex | Pending) & Mutex )
+ sched_yield();
+#else
+ while( _InterlockedOr16((ushort *)latch, Mutex | Pending) & Mutex )
+ SwitchToThread();
+#endif
+ if( prev = !(latch->share | latch->exclusive) )
+#ifdef unix
+ __sync_fetch_and_or((ushort *)latch, Write);
+#else
+ _InterlockedOr16((ushort *)latch, Write);
+#endif
+
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending));
+#else
+ _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending));
+#endif
+ if( prev )
+ return;
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ } while( 1 );
+}
+
+// try to obtain write lock
+
+// return 1 if obtained,
+// 0 otherwise
+
+int bt_spinwritetry(BtSpinLatch *latch)
+{
+ushort prev;
+
+#ifdef unix
+ if( prev = __sync_fetch_and_or((ushort *)latch, Mutex), prev & Mutex )
+ return 0;
+#else
+ if( prev = _InterlockedOr16((ushort *)latch, Mutex), prev & Mutex )
+ return 0;
+#endif
+ // take write access if all bits are clear
+
+ if( !prev )
+#ifdef unix
+ __sync_fetch_and_or ((ushort *)latch, Write);
+#else
+ _InterlockedOr16((ushort *)latch, Write);
+#endif
+
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Mutex);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Mutex);
+#endif
+ return !prev;
+}
+
+// clear write mode
+
+void bt_spinreleasewrite(BtSpinLatch *latch)
+{
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Write);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Write);
+#endif
+}
+
+// decrement reader count
+
+void bt_spinreleaseread(BtSpinLatch *latch)
+{
+#ifdef unix
+ __sync_fetch_and_add((ushort *)latch, -Share);
+#else
+ _InterlockedExchangeAdd16 ((ushort *)latch, -Share);
+#endif
+}
+
+// link latch table entry into latch hash table
+
+void bt_latchlink (BtDb *bt, ushort hashidx, ushort victim, uid page_no)
+{
+BtLatchSet *set = bt->mgr->latchsets + victim;
+
+ if( set->next = bt->mgr->latchmgr->table[hashidx].slot )
+ bt->mgr->latchsets[set->next].prev = victim;
+
+ bt->mgr->latchmgr->table[hashidx].slot = victim;
+ set->page_no = page_no;
+ set->hash = hashidx;
+ set->prev = 0;
+}
+
+// find existing latchset or inspire new one
+// return with latchset pinned
+
+BtLatchSet *bt_bindlatch (BtDb *bt, uid page_no, int incr)
+{
+ushort hashidx = page_no % bt->mgr->latchmgr->latchhash;
+ushort slot, avail = 0, victim, idx;
+BtLatchSet *set;
+
+ // obtain read lock on hash table entry
+
+ bt_spinreadlock(bt->mgr->latchmgr->table[hashidx].latch);
+
+ if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
+ {
+ set = bt->mgr->latchsets + slot;
+ if( page_no == set->page_no )
+ break;
+ } while( slot = set->next );
+
+ if( slot && incr ) {
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ }
+
+ bt_spinreleaseread (bt->mgr->latchmgr->table[hashidx].latch);
+
+ if( slot )
+ return set;
+
+ // try again, this time with write lock
+
+ bt_spinwritelock(bt->mgr->latchmgr->table[hashidx].latch);
+
+ if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
+ {
+ set = bt->mgr->latchsets + slot;
+ if( page_no == set->page_no )
+ break;
+ if( !set->pin && !avail )
+ avail = slot;
+ } while( slot = set->next );
+
+ // found our entry, or take over an unpinned one
+
+ if( slot || (slot = avail) ) {
+ set = bt->mgr->latchsets + slot;
+ if( incr )
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ set->page_no = page_no;
+ bt_spinreleasewrite(bt->mgr->latchmgr->table[hashidx].latch);
+ return set;
+ }
+
+ // see if there are any unused entries
+#ifdef unix
+ victim = __sync_fetch_and_add (&bt->mgr->latchmgr->latchdeployed, 1) + 1;
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->latchmgr->latchdeployed);
+#endif
+
+ if( victim < bt->mgr->latchmgr->latchtotal ) {
+ set = bt->mgr->latchsets + victim;
+ if( incr )
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ bt_latchlink (bt, hashidx, victim, page_no);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch);
+ return set;
+ }
+
+#ifdef unix
+ victim = __sync_fetch_and_add (&bt->mgr->latchmgr->latchdeployed, -1);
+#else
+ victim = _InterlockedDecrement16 (&bt->mgr->latchmgr->latchdeployed);
+#endif
+ // find and reuse previous lock entry
+
+ while( 1 ) {
+#ifdef unix
+ victim = __sync_fetch_and_add(&bt->mgr->latchmgr->latchvictim, 1);
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->latchmgr->latchvictim) - 1;
+#endif
+ // we don't use slot zero
+
+ if( victim %= bt->mgr->latchmgr->latchtotal )
+ set = bt->mgr->latchsets + victim;
+ else
+ continue;
+
+ // take control of our slot
+ // from other threads
+
+ if( set->pin || !bt_spinwritetry (set->busy) )
+ continue;
+
+ idx = set->hash;
+
+ // try to get write lock on hash chain
+ // skip entry if not obtained
+ // or has outstanding locks
+
+ if( !bt_spinwritetry (bt->mgr->latchmgr->table[idx].latch) ) {
+ bt_spinreleasewrite (set->busy);
+ continue;
+ }
+
+ if( set->pin ) {
+ bt_spinreleasewrite (set->busy);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[idx].latch);
+ continue;
+ }
+
+ // unlink our available victim from its hash chain
+
+ if( set->prev )
+ bt->mgr->latchsets[set->prev].next = set->next;
+ else
+ bt->mgr->latchmgr->table[idx].slot = set->next;
+
+ if( set->next )
+ bt->mgr->latchsets[set->next].prev = set->prev;
+
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[idx].latch);
+
+ if( incr )
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+
+ bt_latchlink (bt, hashidx, victim, page_no);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch);
+ bt_spinreleasewrite (set->busy);
+ return set;
+ }
+}
+
+void bt_mgrclose (BtMgr *mgr)
+{
+BtPool *pool;
+uint slot;
+
+ // release mapped pages
+ // note that slot zero is never used
+
+ for( slot = 1; slot < mgr->poolmax; slot++ ) {
+ pool = mgr->pool + slot;
+ if( pool->slot )
+#ifdef unix
+ munmap (pool->map, (mgr->poolmask+1) << mgr->page_bits);
+#else
+ {
+ FlushViewOfFile(pool->map, 0);
+ UnmapViewOfFile(pool->map);
+ CloseHandle(pool->hmap);
+ }
+#endif
+ }
+
+#ifdef unix
+ close (mgr->idx);
+ free (mgr->pool);
+ free (mgr->hash);
+ free (mgr->latch);
+ free (mgr->pooladvise);
+ free (mgr);
+#else
+ FlushFileBuffers(mgr->idx);
+ CloseHandle(mgr->idx);
+ GlobalFree (mgr->pool);
+ GlobalFree (mgr->hash);
+ GlobalFree (mgr->latch);
+ GlobalFree (mgr);
+#endif
+}
+
+// close and release memory
+
+void bt_close (BtDb *bt)
+{
+#ifdef unix
+ if ( bt->mem )
+ free (bt->mem);
+#else
+ if ( bt->mem)
+ VirtualFree (bt->mem, 0, MEM_RELEASE);
+#endif
+ free (bt);
+}
+
+// open/create new btree buffer manager
+
+// call with file_name, BT_openmode, bits in page size (e.g. 16),
+// size of mapped page pool (e.g. 8192)
+
+BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolmax, uint segsize, uint hashsize)
+{
+uint lvl, attr, cacheblk, last, slot, idx;
+uint nlatchpage, latchhash;
+BtLatchMgr *latchmgr;
+off64_t size;
+uint amt[1];
+BtMgr* mgr;
+BtKey key;
+int flag;
+
+#ifndef unix
+SYSTEM_INFO sysinfo[1];
+#endif
+
+ // determine sanity of page size and buffer pool
+
+ if( bits > BT_maxbits )
+ bits = BT_maxbits;
+ else if( bits < BT_minbits )
+ bits = BT_minbits;
+
+ if( !poolmax )
+ return NULL; // must have buffer pool
+
+#ifdef unix
+ mgr = calloc (1, sizeof(BtMgr));
+
+ mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
+
+ if( mgr->idx == -1 )
+ return free(mgr), NULL;
+
+ cacheblk = 4096; // minimum mmap segment size for unix
+
+#else
+ mgr = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtMgr));
+ attr = FILE_ATTRIBUTE_NORMAL;
+ mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
+
+ if( mgr->idx == INVALID_HANDLE_VALUE )
+ return GlobalFree(mgr), NULL;
+
+ // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity
+ GetSystemInfo(sysinfo);
+ cacheblk = sysinfo->dwAllocationGranularity;
+#endif
+
+#ifdef unix
+ latchmgr = malloc (BT_maxpage);
+ *amt = 0;
+
+ // read minimum page size to get root info
+
+ if( size = lseek (mgr->idx, 0L, 2) ) {
+ if( pread(mgr->idx, latchmgr, BT_minpage, 0) == BT_minpage )
+ bits = latchmgr->alloc->bits;
+ else
+ return free(mgr), free(latchmgr), NULL;
+ } else if( mode == BT_ro )
+ return bt_mgrclose (mgr), NULL;
+#else
+ latchmgr = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE);
+ size = GetFileSize(mgr->idx, amt);
+
+ if( size || *amt ) {
+ if( !ReadFile(mgr->idx, (char *)latchmgr, BT_minpage, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ bits = latchmgr->alloc->bits;
+ } else if( mode == BT_ro )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ mgr->page_size = 1 << bits;
+ mgr->page_bits = bits;
+
+ mgr->poolmax = poolmax;
+ mgr->mode = mode;
+
+ if( cacheblk < mgr->page_size )
+ cacheblk = mgr->page_size;
+
+ // mask for partial memmaps
+
+ mgr->poolmask = (cacheblk >> bits) - 1;
+
+ // see if requested size of pages per memmap is greater
+
+ if( (1 << segsize) > mgr->poolmask )
+ mgr->poolmask = (1 << segsize) - 1;
+
+ mgr->seg_bits = 0;
+
+ while( (1 << mgr->seg_bits) <= mgr->poolmask )
+ mgr->seg_bits++;
+
+ mgr->hashsize = hashsize;
+
+#ifdef unix
+ mgr->pool = calloc (poolmax, sizeof(BtPool));
+ mgr->hash = calloc (hashsize, sizeof(ushort));
+ mgr->latch = calloc (hashsize, sizeof(BtSpinLatch));
+ mgr->pooladvise = calloc (poolmax, (mgr->poolmask + 8) / 8);
+#else
+ mgr->pool = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, poolmax * sizeof(BtPool));
+ mgr->hash = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(ushort));
+ mgr->latch = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(BtSpinLatch));
+#endif
+
+ if( size || *amt )
+ goto mgrlatch;
+
+ // initialize an empty b-tree with latch page, root page, page of leaves
+ // and page(s) of latches
+
+ memset (latchmgr, 0, 1 << bits);
+ nlatchpage = BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1;
+ bt_putid(latchmgr->alloc->right, MIN_lvl+1+nlatchpage);
+ latchmgr->alloc->bits = mgr->page_bits;
+
+ latchmgr->nlatchpage = nlatchpage;
+ latchmgr->latchtotal = nlatchpage * (mgr->page_size / sizeof(BtLatchSet));
+
+ // initialize latch manager
+
+ latchhash = (mgr->page_size - sizeof(BtLatchMgr)) / sizeof(BtHashEntry);
+
+ // size of hash table = total number of latchsets
+
+ if( latchhash > latchmgr->latchtotal )
+ latchhash = latchmgr->latchtotal;
+
+ latchmgr->latchhash = latchhash;
+
+#ifdef unix
+ if( write (mgr->idx, latchmgr, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ memset (latchmgr, 0, 1 << bits);
+ latchmgr->alloc->bits = mgr->page_bits;
+
+ for( lvl=MIN_lvl; lvl--; ) {
+ slotptr(latchmgr->alloc, 1)->off = mgr->page_size - 3;
+ bt_putid(slotptr(latchmgr->alloc, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number
+ key = keyptr(latchmgr->alloc, 1);
+ key->len = 2; // create stopper key
+ key->key[0] = 0xff;
+ key->key[1] = 0xff;
+ latchmgr->alloc->min = mgr->page_size - 3;
+ latchmgr->alloc->lvl = lvl;
+ latchmgr->alloc->cnt = 1;
+ latchmgr->alloc->act = 1;
+#ifdef unix
+ if( write (mgr->idx, latchmgr, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ }
+
+ // clear out latch manager locks
+ // and rest of pages to round out segment
+
+ memset(latchmgr, 0, mgr->page_size);
+ last = MIN_lvl + 1;
+
+ while( last <= ((MIN_lvl + 1 + nlatchpage) | mgr->poolmask) ) {
+#ifdef unix
+ pwrite(mgr->idx, latchmgr, mgr->page_size, last << mgr->page_bits);
+#else
+ SetFilePointer (mgr->idx, last << mgr->page_bits, NULL, FILE_BEGIN);
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ last++;
+ }
+
+mgrlatch:
+#ifdef unix
+ flag = PROT_READ | PROT_WRITE;
+ mgr->latchmgr = mmap (0, mgr->page_size, flag, MAP_SHARED, mgr->idx, ALLOC_page * mgr->page_size);
+ if( mgr->latchmgr == MAP_FAILED )
+ return bt_mgrclose (mgr), NULL;
+ mgr->latchsets = (BtLatchSet *)mmap (0, mgr->latchmgr->nlatchpage * mgr->page_size, flag, MAP_SHARED, mgr->idx, LATCH_page * mgr->page_size);
+ if( mgr->latchsets == MAP_FAILED )
+ return bt_mgrclose (mgr), NULL;
+#else
+ flag = PAGE_READWRITE;
+ mgr->halloc = CreateFileMapping(mgr->idx, NULL, flag, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size, NULL);
+ if( !mgr->halloc )
+ return bt_mgrclose (mgr), NULL;
+
+ flag = FILE_MAP_WRITE;
+ mgr->latchmgr = MapViewOfFile(mgr->halloc, flag, 0, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size);
+ if( !mgr->latchmgr )
+ return GetLastError(), bt_mgrclose (mgr), NULL;
+
+ mgr->latchsets = (void *)((char *)mgr->latchmgr + LATCH_page * mgr->page_size);
+#endif
+
+#ifdef unix
+ free (latchmgr);
+#else
+ VirtualFree (latchmgr, 0, MEM_RELEASE);
+#endif
+ return mgr;
+}
+
+// open BTree access method
+// based on buffer manager
+
+BtDb *bt_open (BtMgr *mgr)
+{
+BtDb *bt = malloc (sizeof(*bt));
+
+ memset (bt, 0, sizeof(*bt));
+ bt->mgr = mgr;
+#ifdef unix
+ bt->mem = malloc (3 *mgr->page_size);
+#else
+ bt->mem = VirtualAlloc(NULL, 3 * mgr->page_size, MEM_COMMIT, PAGE_READWRITE);
+#endif
+ bt->frame = (BtPage)bt->mem;
+ bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size);
+ bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size);
+ return bt;
+}
+
+// compare two keys, returning > 0, = 0, or < 0
+// as the comparison value
+
+int keycmp (BtKey key1, unsigned char *key2, uint len2)
+{
+uint len1 = key1->len;
+int ans;
+
+ if( ans = memcmp (key1->key, key2, len1 > len2 ? len2 : len1) )
+ return ans;
+
+ if( len1 > len2 )
+ return 1;
+ if( len1 < len2 )
+ return -1;
+
+ return 0;
+}
+
+// Buffer Pool mgr
+
+// find segment in pool
+// must be called with hashslot idx locked
+// return NULL if not there
+// otherwise return node
+
+BtPool *bt_findpool(BtDb *bt, uid page_no, uint idx)
+{
+BtPool *pool;
+uint slot;
+
+ // compute start of hash chain in pool
+
+ if( slot = bt->mgr->hash[idx] )
+ pool = bt->mgr->pool + slot;
+ else
+ return NULL;
+
+ page_no &= ~bt->mgr->poolmask;
+
+ while( pool->basepage != page_no )
+ if( pool = pool->hashnext )
+ continue;
+ else
+ return NULL;
+
+ return pool;
+}
+
+// add segment to hash table
+
+void bt_linkhash(BtDb *bt, BtPool *pool, uid page_no, int idx)
+{
+BtPool *node;
+uint slot;
+
+ pool->hashprev = pool->hashnext = NULL;
+ pool->basepage = page_no & ~bt->mgr->poolmask;
+ pool->lru = 1;
+
+ if( slot = bt->mgr->hash[idx] ) {
+ node = bt->mgr->pool + slot;
+ pool->hashnext = node;
+ node->hashprev = pool;
+ }
+
+ bt->mgr->hash[idx] = pool->slot;
+}
+
+// find best segment to evict from buffer pool
+
+BtPool *bt_findlru (BtDb *bt, uint hashslot)
+{
+unsigned long long int target = ~0LL;
+BtPool *pool = NULL, *node;
+
+ if( !hashslot )
+ return NULL;
+
+ node = bt->mgr->pool + hashslot;
+
+ // scan pool entries under hash table slot
+
+ do {
+ if( node->pin )
+ continue;
+ if( node->lru > target )
+ continue;
+ target = node->lru;
+ pool = node;
+ } while( node = node->hashnext );
+
+ return pool;
+}
+
+// map new buffer pool segment to virtual memory
+
+BTERR bt_mapsegment(BtDb *bt, BtPool *pool, uid page_no)
+{
+off64_t off = (page_no & ~bt->mgr->poolmask) << bt->mgr->page_bits;
+off64_t limit = off + ((bt->mgr->poolmask+1) << bt->mgr->page_bits);
+int flag;
+
+#ifdef unix
+ flag = PROT_READ | ( bt->mgr->mode == BT_ro ? 0 : PROT_WRITE );
+ pool->map = mmap (0, (bt->mgr->poolmask+1) << bt->mgr->page_bits, flag, MAP_SHARED, bt->mgr->idx, off);
+ if( pool->map == MAP_FAILED )
+ return bt->err = BTERR_map;
+ // clear out madvise issued bits
+ memset (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8) / 8), 0, (bt->mgr->poolmask + 8)/8);
+#else
+ flag = ( bt->mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE );
+ pool->hmap = CreateFileMapping(bt->mgr->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL);
+ if( !pool->hmap )
+ return bt->err = BTERR_map;
+
+ flag = ( bt->mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE );
+ pool->map = MapViewOfFile(pool->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->mgr->poolmask+1) << bt->mgr->page_bits);
+ if( !pool->map )
+ return bt->err = BTERR_map;
+#endif
+ return bt->err = 0;
+}
+
+// find or place requested page in segment-pool
+// return pool table entry, incrementing pin
+
+BtPool *bt_pinpage(BtDb *bt, uid page_no)
+{
+BtPool *pool, *node, *next;
+uint slot, idx, victim;
+BtLatchSet *set;
+
+ // lock hash table chain
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_spinreadlock (&bt->mgr->latch[idx]);
+
+ // look up in hash table
+
+ if( pool = bt_findpool(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleaseread (&bt->mgr->latch[idx]);
+ pool->lru++;
+ return pool;
+ }
+
+ // upgrade to write lock
+
+ bt_spinreleaseread (&bt->mgr->latch[idx]);
+ bt_spinwritelock (&bt->mgr->latch[idx]);
+
+ // try to find page in pool with write lock
+
+ if( pool = bt_findpool(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ pool->lru++;
+ return pool;
+ }
+
+ // allocate a new pool node
+ // and add to hash table
+
+#ifdef unix
+ slot = __sync_fetch_and_add(&bt->mgr->poolcnt, 1);
+#else
+ slot = _InterlockedIncrement16 (&bt->mgr->poolcnt) - 1;
+#endif
+
+ if( ++slot < bt->mgr->poolmax ) {
+ pool = bt->mgr->pool + slot;
+ pool->slot = slot;
+
+ if( bt_mapsegment(bt, pool, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, pool, page_no, idx);
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ return pool;
+ }
+
+ // pool table is full
+ // find best pool entry to evict
+
+#ifdef unix
+ __sync_fetch_and_add(&bt->mgr->poolcnt, -1);
+#else
+ _InterlockedDecrement16 (&bt->mgr->poolcnt);
+#endif
+
+ while( 1 ) {
+#ifdef unix
+ victim = __sync_fetch_and_add(&bt->mgr->evicted, 1);
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->evicted) - 1;
+#endif
+ victim %= bt->mgr->hashsize;
+
+ // try to get write lock
+ // skip entry if not obtained
+
+ if( !bt_spinwritetry (&bt->mgr->latch[victim]) )
+ continue;
+
+ // if cache entry is empty
+ // or no slots are unpinned
+ // skip this entry
+
+ if( !(pool = bt_findlru(bt, bt->mgr->hash[victim])) ) {
+ bt_spinreleasewrite (&bt->mgr->latch[victim]);
+ continue;
+ }
+
+ // unlink victim pool node from hash table
+
+ if( node = pool->hashprev )
+ node->hashnext = pool->hashnext;
+ else if( node = pool->hashnext )
+ bt->mgr->hash[victim] = node->slot;
+ else
+ bt->mgr->hash[victim] = 0;
+
+ if( node = pool->hashnext )
+ node->hashprev = pool->hashprev;
+
+ bt_spinreleasewrite (&bt->mgr->latch[victim]);
+
+ // remove old file mapping
+#ifdef unix
+ munmap (pool->map, (bt->mgr->poolmask+1) << bt->mgr->page_bits);
+#else
+ FlushViewOfFile(pool->map, 0);
+ UnmapViewOfFile(pool->map);
+ CloseHandle(pool->hmap);
+#endif
+ pool->map = NULL;
+
+ // create new pool mapping
+ // and link into hash table
+
+ if( bt_mapsegment(bt, pool, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, pool, page_no, idx);
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ return pool;
+ }
+}
+
+// place write, read, or parent lock on requested page_no.
+// pin to buffer pool and return latchset pointer
+
+BtLatchSet *bt_lockpage(BtDb *bt, uid page_no, BtLock mode, BtPage *pageptr, BtLatchSet *set)
+{
+BtPool *pool;
+uint subpage;
+BtPage page;
+
+ // find/create maping in pool table
+ // and pin our pool slot
+
+ if( pool = bt_pinpage(bt, page_no) )
+ subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
+ else
+ return NULL;
+
+ if( set )
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ else if( !(set = bt_bindlatch (bt, page_no, 1)) )
+ return NULL;
+
+ page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
+
+#ifdef unix
+ {
+ uint idx = subpage / 8;
+ uint bit = subpage % 8;
+
+ if( mode == BtLockRead || mode == BtLockWrite )
+ if( ~((bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] >> bit) & 1 ) {
+ madvise (page, bt->mgr->page_size, MADV_WILLNEED);
+ (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] |= 1 << bit;
+ }
+ }
+#endif
+
+ switch( mode ) {
+ case BtLockRead:
+ bt_spinreadlock (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_spinwritelock (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_spinreadlock (set->access);
+ break;
+ case BtLockDelete:
+ bt_spinwritelock (set->access);
+ break;
+ case BtLockParent:
+ bt_spinwritelock (set->parent);
+ break;
+ case BtLockPin:
+ break;
+ default:
+ return bt->err = BTERR_lock, NULL;
+ }
+
+ if( pageptr )
+ *pageptr = page;
+
+ return set;
+}
+
+// remove write, read, or parent lock on requested page_no.
+
+BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode, BtLatchSet *set)
+{
+BtPool *pool;
+uint idx;
+
+ // since page is pinned
+ // it should still be in the buffer pool
+ // and is in no danger of being a victim for reuse
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_spinreadlock (&bt->mgr->latch[idx]);
+
+ if( !(pool = bt_findpool(bt, page_no, idx)) )
+ return bt->err = BTERR_hash;
+
+ bt_spinreleaseread (&bt->mgr->latch[idx]);
+
+ switch( mode ) {
+ case BtLockRead:
+ bt_spinreleaseread (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_spinreleasewrite (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_spinreleaseread (set->access);
+ break;
+ case BtLockDelete:
+ bt_spinreleasewrite (set->access);
+ break;
+ case BtLockParent:
+ bt_spinreleasewrite (set->parent);
+ break;
+ case BtLockPin:
+ break;
+ default:
+ return bt->err = BTERR_lock;
+ }
+
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, -1);
+ __sync_fetch_and_add (&set->pin, -1);
+#else
+ _InterlockedDecrement16 (&pool->pin);
+ _InterlockedDecrement16 (&set->pin);
+#endif
+ return bt->err = 0;
+}
+
+// deallocate a deleted page
+// place on free chain out of allocator page
+// fence key must already be removed from parent
+
+BTERR bt_freepage(BtDb *bt, uid page_no, BtLatchSet *set)
+{
+ // obtain delete lock on deleted page
+
+ if( !bt_lockpage(bt, page_no, BtLockDelete, NULL, set) )
+ return bt->err;
+
+ // obtain write lock on deleted page
+
+ if( !bt_lockpage(bt, page_no, BtLockWrite, &bt->temp, set) )
+ return bt->err;
+
+ // lock allocation page
+
+ bt_spinwritelock(bt->mgr->latchmgr->lock);
+
+ // store free chain in allocation page second right
+ bt_putid(bt->temp->right, bt_getid(bt->mgr->latchmgr->alloc[1].right));
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, page_no);
+
+ // unlock page zero
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
+ // remove write lock on deleted node
+
+ if( bt_unlockpage(bt, page_no, BtLockWrite, set) )
+ return bt->err;
+
+ // remove delete lock on deleted node
+
+ if( bt_unlockpage(bt, page_no, BtLockDelete, set) )
+ return bt->err;
+
+ return 0;
+}
+
+// allocate a new page and write page into it
+
+uid bt_newpage(BtDb *bt, BtPage page)
+{
+BtLatchSet *set;
+uid new_page;
+BtPage pmap;
+int reuse;
+
+ // lock allocation page
+
+ bt_spinwritelock(bt->mgr->latchmgr->lock);
+
+ // use empty chain first
+ // else allocate empty page
+
+ if( new_page = bt_getid(bt->mgr->latchmgr->alloc[1].right) ) {
+ if( !(set = bt_lockpage (bt, new_page, BtLockWrite, &bt->temp, NULL)) )
+ return 0;
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, bt_getid(bt->temp->right));
+ if( bt_unlockpage (bt, new_page, BtLockWrite, set) )
+ return 0;
+ reuse = 1;
+ } else {
+ new_page = bt_getid(bt->mgr->latchmgr->alloc->right);
+ bt_putid(bt->mgr->latchmgr->alloc->right, new_page+1);
+ reuse = 0;
+ }
+#ifdef unix
+ if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+
+ // if writing first page of pool block, zero last page in the block
+
+ if ( !reuse && bt->mgr->poolmask > 0 && (new_page & bt->mgr->poolmask) == 0 )
+ {
+ // use zero buffer to write zeros
+ memset(bt->zero, 0, bt->mgr->page_size);
+ if ( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->poolmask) << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+ }
+#else
+ // bring new page into pool and copy page.
+ // this will extend the file into the new pages.
+
+ if( !(set = bt_lockpage(bt, new_page, BtLockWrite, &pmap, NULL)) )
+ return 0;
+
+ memcpy(pmap, page, bt->mgr->page_size);
+
+ if( bt_unlockpage (bt, new_page, BtLockWrite, set) )
+ return 0;
+#endif
+ // unlock allocation latch and return new page no
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+ return new_page;
+}
+
+// find slot in page for given key at a given level
+
+int bt_findslot (BtDb *bt, unsigned char *key, uint len)
+{
+uint diff, higher = bt->page->cnt, low = 1, slot;
+
+ // low is the lowest candidate, higher is already
+ // tested as .ge. the given key, loop ends when they meet
+
+ while( diff = higher - low ) {
+ slot = low + ( diff >> 1 );
+ if( keycmp (keyptr(bt->page, slot), key, len) < 0 )
+ low = slot + 1;
+ else
+ higher = slot;
+ }
+
+ return higher;
+}
+
+// find and load page at given level for given key
+// leave page rd or wr locked as requested
+
+int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, BtLock lock)
+{
+uid page_no = ROOT_page, prevpage = 0;
+BtLatchSet *set, *prevset;
+uint drill = 0xff, slot;
+uint mode, prevmode;
+
+ bt->set = NULL;
+
+ // start at root of btree and drill down
+
+ do {
+ // determine lock mode of drill level
+ mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead;
+
+ bt->page_no = page_no;
+
+ // obtain access lock using lock chaining with Access mode
+
+ if( page_no > ROOT_page )
+ if( !(bt->set = bt_lockpage(bt, page_no, BtLockAccess, NULL, NULL)) )
+ return 0;
+
+ // now unlock our (possibly foster) parent
+
+ if( prevpage )
+ if( bt_unlockpage(bt, prevpage, prevmode, prevset) )
+ return 0;
+ else
+ prevpage = 0;
+
+ // obtain read lock using lock chaining
+ // and pin page contents
+
+ if( !(bt->set = bt_lockpage(bt, page_no, mode, &bt->page, bt->set)) )
+ return 0;
+
+ if( page_no > ROOT_page )
+ if( bt_unlockpage(bt, page_no, BtLockAccess, bt->set) )
+ return 0;
+
+ // re-read and re-lock root after determining actual level of root
+
+ if( bt->page_no == ROOT_page )
+ if( bt->page->lvl != drill) {
+ drill = bt->page->lvl;
+
+ if( lock == BtLockWrite && drill == lvl )
+ if( bt_unlockpage(bt, page_no, mode, bt->set) )
+ return 0;
+ else
+ continue;
+ }
+
+ prevpage = bt->page_no;
+ prevset = bt->set;
+ prevmode = mode;
+
+ // if page is being deleted,
+ // move back to preceeding page
+
+ if( bt->page->kill ) {
+ page_no = bt_getid (bt->page->right);
+ continue;
+ }
+
+ // find key on page at this level
+ // and descend to requested level
+
+ slot = bt_findslot (bt, key, len);
+
+ // is this slot a foster child?
+
+ if( slot <= bt->page->cnt - bt->page->foster )
+ if( drill == lvl )
+ return slot;
+
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ goto slideright;
+
+ if( slot <= bt->page->cnt - bt->page->foster )
+ drill--;
+
+ // continue down / right using overlapping locks
+ // to protect pages being killed or split.
+
+ page_no = bt_getid(slotptr(bt->page, slot)->id);
+ continue;
+
+slideright:
+ page_no = bt_getid(bt->page->right);
+
+ } while( page_no );
+
+ // return error on end of chain
+
+ bt->err = BTERR_struct;
+ return 0; // return error
+}
+
+// find and delete key on page by marking delete flag bit
+// when page becomes empty, delete it from the btree
+
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl)
+{
+unsigned char leftkey[256], rightkey[256];
+BtLatchSet *rset, *set;
+uid page_no, right;
+uint slot, tod;
+BtKey ptr;
+
+ if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // if key is found delete it, otherwise ignore request
+
+ if( !keycmp (ptr, key, len) )
+ if( slotptr(bt->page, slot)->dead == 0 ) {
+ slotptr(bt->page,slot)->dead = 1;
+ if( slot < bt->page->cnt )
+ bt->page->dirty = 1;
+ bt->page->act--;
+ }
+
+ // return if page is not empty, or it has no right sibling
+
+ right = bt_getid(bt->page->right);
+ page_no = bt->page_no;
+ set = bt->set;
+
+ if( !right || bt->page->act )
+ return bt_unlockpage(bt, page_no, BtLockWrite, set);
+
+ // obtain Parent lock over write lock
+
+ if( !bt_lockpage(bt, page_no, BtLockParent, NULL, set) )
+ return bt->err;
+
+ // cache copy of key to delete
+
+ ptr = keyptr(bt->page, bt->page->cnt);
+ memcpy(leftkey, ptr, ptr->len + 1);
+
+ // lock and map right page
+
+ if( !(rset = bt_lockpage(bt, right, BtLockWrite, &bt->temp, NULL)) )
+ return bt->err;
+
+ // pull contents of next page into current empty page
+ memcpy (bt->page, bt->temp, bt->mgr->page_size);
+
+ // cache copy of key to update
+ ptr = keyptr(bt->temp, bt->temp->cnt);
+ memcpy(rightkey, ptr, ptr->len + 1);
+
+ // Mark right page as deleted and point it to left page
+ // until we can post updates at higher level.
+
+ bt_putid(bt->temp->right, page_no);
+ bt->temp->kill = 1;
+ bt->temp->cnt = 0;
+
+ if( bt_unlockpage(bt, right, BtLockWrite, rset) )
+ return bt->err;
+ if( bt_unlockpage(bt, page_no, BtLockWrite, set) )
+ return bt->err;
+
+ // delete old lower key to consolidated node
+
+ if( bt_deletekey (bt, leftkey + 1, *leftkey, lvl + 1) )
+ return bt->err;
+
+ // redirect higher key directly to consolidated node
+
+ if( slot = bt_loadpage (bt, rightkey+1, *rightkey, lvl+1, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // since key already exists, update id
+
+ if( keycmp (ptr, rightkey+1, *rightkey) )
+ return bt->err = BTERR_struct;
+
+ slotptr(bt->page, slot)->dead = 0;
+ bt_putid(slotptr(bt->page,slot)->id, page_no);
+
+ if( bt_unlockpage(bt, bt->page_no, BtLockWrite, bt->set) )
+ return bt->err;
+
+ // obtain write lock and
+ // add right block to free chain
+
+ if( bt_freepage (bt, right, rset) )
+ return bt->err;
+
+ // remove ParentModify lock
+
+ if( bt_unlockpage(bt, page_no, BtLockParent, set) )
+ return bt->err;
+
+ return 0;
+}
+
+// find key in leaf level and return row-id
+
+uid bt_findkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+BtKey ptr;
+uid id;
+
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return 0;
+
+ // if key exists, return row-id
+ // otherwise return 0
+
+ if( ptr->len == len && !memcmp (ptr->key, key, len) )
+ id = bt_getid(slotptr(bt->page,slot)->id);
+ else
+ id = 0;
+
+ if( bt_unlockpage (bt, bt->page_no, BtLockRead, bt->set) )
+ return 0;
+
+ return id;
+}
+
+// check page for space available,
+// clean if necessary and return
+// 0 - page needs splitting
+// 1 - go ahead
+
+uint bt_cleanpage(BtDb *bt, uint amt)
+{
+uint nxt = bt->mgr->page_size;
+BtPage page = bt->page;
+uint cnt = 0, idx = 0;
+uint max = page->cnt;
+BtKey key;
+
+ if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return 1;
+
+ // skip cleanup if nothing to reclaim
+
+ if( !page->dirty )
+ return 0;
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+
+ // skip page info and set rest of page to zero
+
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ page->dirty = 0;
+ page->act = 0;
+
+ // try cleaning up page first
+
+ while( cnt++ < max ) {
+ // always leave fence key and foster children in list
+ if( cnt < max - page->foster && slotptr(bt->frame,cnt)->dead )
+ continue;
+
+ // copy key
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+
+ // copy slot
+ memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId);
+ if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
+ page->act++;
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ // see if page has enough space now, or does it need splitting?
+
+ if( page->min >= (idx+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return 1;
+
+ return 0;
+}
+
+// add key to current page
+// page must already be writelocked
+
+void bt_addkeytopage (BtDb *bt, uint slot, unsigned char *key, uint len, uid id, uint tod)
+{
+BtPage page = bt->page;
+uint idx;
+
+ // calculate next available slot and copy key into page
+
+ page->min -= len + 1;
+ ((unsigned char *)page)[page->min] = len;
+ memcpy ((unsigned char *)page + page->min +1, key, len );
+
+ for( idx = slot; idx < page->cnt; idx++ )
+ if( slotptr(page, idx)->dead )
+ break;
+
+ // now insert key into array before slot
+ // preserving the fence slot
+
+ if( idx == page->cnt )
+ idx++, page->cnt++;
+
+ page->act++;
+
+ while( idx > slot )
+ *slotptr(page, idx) = *slotptr(page, idx -1), idx--;
+
+ bt_putid(slotptr(page,slot)->id, id);
+ slotptr(page, slot)->off = page->min;
+ slotptr(page, slot)->tod = tod;
+ slotptr(page, slot)->dead = 0;
+}
+
+// split the root and raise the height of the btree
+// call with current page locked and page no of foster child
+// return with current page (root) unlocked
+
+BTERR bt_splitroot(BtDb *bt, uid right)
+{
+uint nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+BtPage root = bt->page;
+uid new_page;
+BtKey key;
+
+ // Obtain an empty page to use, and copy the left page
+ // contents into it from the root. Strip foster child key.
+ // (it's the stopper key)
+
+ root->act--;
+ root->cnt--;
+ root->foster--;
+
+ // Save left fence key.
+
+ key = keyptr(root, root->cnt);
+ memcpy (fencekey, key, key->len + 1);
+
+ // copy the lower keys into a new left page
+
+ if( !(new_page = bt_newpage(bt, root)) )
+ return bt->err;
+
+ // preserve the page info at the bottom
+ // and set rest of the root to zero
+
+ memset (root+1, 0, bt->mgr->page_size - sizeof(*root));
+
+ // insert left fence key on empty newroot page
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 1)->id, new_page);
+ slotptr(root, 1)->off = nxt;
+
+ // insert stopper key on newroot page
+ // and increase the root height
+
+ nxt -= 3;
+ fencekey[0] = 2;
+ fencekey[1] = 0xff;
+ fencekey[2] = 0xff;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 2)->id, right);
+ slotptr(root, 2)->off = nxt;
+
+ bt_putid(root->right, 0);
+ root->min = nxt; // reset lowest used offset and key count
+ root->cnt = 2;
+ root->act = 2;
+ root->lvl++;
+
+ // release root (bt->page)
+
+ return bt_unlockpage(bt, ROOT_page, BtLockWrite, bt->set);
+}
+
+// split already locked full node
+// in current page variables
+// return unlocked.
+
+BTERR bt_splitpage (BtDb *bt)
+{
+uint slot, cnt, idx, max, nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+uid page_no = bt->page_no;
+BtLatchSet *set = bt->set;
+BtPage page = bt->page;
+uint tod = time(NULL);
+uint lvl = page->lvl;
+uid new_page, right;
+BtKey key;
+
+ // initialize frame buffer
+
+ memset (bt->frame, 0, bt->mgr->page_size);
+ max = page->cnt - page->foster;
+ tod = (uint)time(NULL);
+ cnt = max / 2;
+ idx = 0;
+
+ // split higher half of keys to bt->frame
+ // leaving foster children in the left node.
+
+ while( cnt++ < max ) {
+ key = keyptr(page, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1);
+ memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId);
+ slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod;
+ slotptr(bt->frame, idx)->off = nxt;
+ bt->frame->act++;
+ }
+
+ // transfer right link node
+
+ if( page_no > ROOT_page ) {
+ right = bt_getid (page->right);
+ bt_putid(bt->frame->right, right);
+ }
+
+ bt->frame->bits = bt->mgr->page_bits;
+ bt->frame->min = nxt;
+ bt->frame->cnt = idx;
+ bt->frame->lvl = lvl;
+
+ // get new free page and write frame to it.
+
+ if( !(new_page = bt_newpage(bt, bt->frame)) )
+ return bt->err;
+
+ // remember fence key for new page to add
+ // as foster child
+
+ key = keyptr(bt->frame, idx);
+ memcpy (fencekey, key, key->len + 1);
+
+ // update lower keys and foster children to continue in old page
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ nxt = bt->mgr->page_size;
+ page->act = 0;
+ cnt = 0;
+ idx = 0;
+
+ // assemble page of smaller keys
+ // to remain in the old page
+
+ while( cnt++ < max / 2 ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ page->act++;
+ }
+
+ // insert new foster child at beginning of the current foster children
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)page + nxt, fencekey, *fencekey + 1);
+ bt_putid (slotptr(page,++idx)->id, new_page);
+ slotptr(page, idx)->tod = tod;
+ slotptr(page, idx)->off = nxt;
+ page->foster++;
+ page->act++;
+
+ // continue with old foster child keys if any
+
+ cnt = bt->frame->cnt - bt->frame->foster;
+
+ while( cnt++ < bt->frame->cnt ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ page->act++;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ // link new right page
+
+ bt_putid (page->right, new_page);
+
+ // if current page is the root page, split it
+
+ if( page_no == ROOT_page )
+ return bt_splitroot (bt, new_page);
+
+ // keep our latch set
+ // release wr lock on our page
+
+ if( !bt_lockpage (bt, page_no, BtLockPin, NULL, set) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockWrite, set) )
+ return bt->err;
+
+ // obtain ParentModification lock for current page
+ // to fix fence key and highest foster child on page
+
+ if( !bt_lockpage (bt, page_no, BtLockParent, NULL, set) )
+ return bt->err;
+
+ // get our highest foster child key to find in parent node
+
+ if( !bt_lockpage (bt, page_no, BtLockRead, &page, set) )
+ return bt->err;
+
+ key = keyptr(page, page->cnt);
+ memcpy (fencekey, key, key->len+1);
+
+ if( bt_unlockpage (bt, page_no, BtLockRead, set) )
+ return bt->err;
+
+ // update our parent
+try_again:
+
+ do {
+ slot = bt_loadpage (bt, fencekey + 1, *fencekey, lvl + 1, BtLockWrite);
+
+ if( !slot )
+ return bt->err;
+
+ // check if parent page has enough space for any possible key
+
+ if( bt_cleanpage (bt, 256) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ } while( 1 );
+
+ // see if we are still a foster child from another node
+
+ if( bt_getid (slotptr(bt->page, slot)->id) != page_no ) {
+ if( bt_unlockpage (bt, bt->page_no, BtLockWrite, bt->set) )
+ return bt->err;
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ goto try_again;
+ }
+
+ // wait until readers from parent get their locks
+ // on our page
+
+ if( !bt_lockpage (bt, page_no, BtLockDelete, NULL, set) )
+ return bt->err;
+
+ // lock our page for writing
+
+ if( !bt_lockpage (bt, page_no, BtLockWrite, &page, set) )
+ return bt->err;
+
+ // switch parent fence key to foster child
+
+ if( slotptr(page, page->cnt)->dead )
+ slotptr(bt->page, slot)->dead = 1;
+ else
+ bt_putid (slotptr(bt->page, slot)->id, bt_getid(slotptr(page, page->cnt)->id));
+
+ // remove highest foster child from our page
+
+ page->cnt--;
+ page->act--;
+ page->foster--;
+ page->dirty = 1;
+ key = keyptr(page, page->cnt);
+
+ // add our new fence key for foster child to our parent
+
+ bt_addkeytopage (bt, slot, key->key, key->len, page_no, tod);
+
+ if( bt_unlockpage (bt, bt->page_no, BtLockWrite, bt->set) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockDelete, set) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockWrite, set) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockParent, set) )
+ return bt->err;
+
+ // release extra latch pin
+
+ return bt_unlockpage (bt, page_no, BtLockPin, set);
+}
+
+// Insert new key into the btree at leaf level.
+
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod)
+{
+uint slot, idx;
+BtPage page;
+BtKey ptr;
+
+ while( 1 ) {
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ {
+ if ( !bt->err )
+ bt->err = BTERR_ovflw;
+ return bt->err;
+ }
+
+ // if key already exists, update id and return
+
+ page = bt->page;
+
+ if( !keycmp (ptr, key, len) ) {
+ slotptr(page, slot)->dead = 0;
+ slotptr(page, slot)->tod = tod;
+ bt_putid(slotptr(page,slot)->id, id);
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite, bt->set);
+ }
+
+ // check if page has enough space
+
+ if( bt_cleanpage (bt, len) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ }
+
+ bt_addkeytopage (bt, slot, key, len, id, tod);
+
+ return bt_unlockpage (bt, bt->page_no, BtLockWrite, bt->set);
+}
+
+// cache page of keys into cursor and return starting slot for given key
+
+uint bt_startkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+
+ // cache page for retrieval
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ memcpy (bt->cursor, bt->page, bt->mgr->page_size);
+ bt->cursor_page = bt->page_no;
+ if ( bt_unlockpage(bt, bt->page_no, BtLockRead, bt->set) )
+ return 0;
+
+ return slot;
+}
+
+// return next slot for cursor page
+// or slide cursor right into next page
+
+uint bt_nextkey (BtDb *bt, uint slot)
+{
+BtLatchSet *rset;
+BtPage page;
+uid right;
+
+ do {
+ right = bt_getid(bt->cursor->right);
+ while( slot++ < bt->cursor->cnt - bt->cursor->foster )
+ if( slotptr(bt->cursor,slot)->dead )
+ continue;
+ else if( right || (slot < bt->cursor->cnt - bt->cursor->foster) )
+ return slot;
+ else
+ break;
+
+ if( !right )
+ break;
+
+ bt->cursor_page = right;
+
+ if( !(bt->set = bt_lockpage(bt, right, BtLockRead, &page, NULL)) )
+ return 0;
+
+ memcpy (bt->cursor, page, bt->mgr->page_size);
+
+ if ( bt_unlockpage(bt, right, BtLockRead, bt->set) )
+ return 0;
+
+ slot = 0;
+ } while( 1 );
+
+ return bt->err = 0;
+}
+
+BtKey bt_key(BtDb *bt, uint slot)
+{
+ return keyptr(bt->cursor, slot);
+}
+
+uid bt_uid(BtDb *bt, uint slot)
+{
+ return bt_getid(slotptr(bt->cursor,slot)->id);
+}
+
+uint bt_tod(BtDb *bt, uint slot)
+{
+ return slotptr(bt->cursor,slot)->tod;
+}
+
+
+#ifdef STANDALONE
+
+typedef struct {
+ char type, idx;
+ char *infile;
+ BtMgr *mgr;
+ int num;
+} ThreadArg;
+
+// standalone program to index file of keys
+// then list them onto std-out
+
+#ifdef unix
+void *index_file (void *arg)
+#else
+uint __stdcall index_file (void *arg)
+#endif
+{
+int line = 0, found = 0, cnt = 0;
+uid next, page_no = LEAF_page; // start on first page of leaves
+unsigned char key[256];
+ThreadArg *args = arg;
+int ch, len = 0, slot;
+time_t tod[1];
+BtPage page;
+BtKey ptr;
+BtDb *bt;
+FILE *in;
+
+ bt = bt_open (args->mgr);
+ time (tod);
+
+ switch(args->type | 0x20)
+ {
+ case 'w':
+ fprintf(stderr, "started indexing for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_insertkey (bt, key, len, line, *tod) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys\n", args->infile, line);
+ break;
+
+ case 'd':
+ fprintf(stderr, "started deleting keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_deletekey (bt, key, len, 0) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for keys, %d \n", args->infile, line);
+ break;
+
+ case 'f':
+ fprintf(stderr, "started finding keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_findkey (bt, key, len) )
+ found++;
+ else if( bt->err )
+ fprintf(stderr, "Error %d Syserr %d Line: %d\n", bt->err, errno, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys, found %d\n", args->infile, line, found);
+ break;
+
+ case 's':
+ len = key[0] = 0;
+
+ fprintf(stderr, "started reading\n");
+
+ if( slot = bt_startkey (bt, key, len) )
+ slot--;
+ else
+ fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0);
+
+ while( slot = bt_nextkey (bt, slot) ) {
+ ptr = bt_key(bt, slot);
+ fwrite (ptr->key, ptr->len, 1, stdout);
+ fputc ('\n', stdout);
+ }
+
+ break;
+
+ case 'c':
+ fprintf(stderr, "started reading\n");
+
+ do {
+ bt->set = bt_lockpage (bt, page_no, BtLockRead, &page, NULL);
+ cnt += page->act;
+ next = bt_getid (page->right);
+ bt_unlockpage (bt, page_no, BtLockRead, bt->set);
+ } while( page_no = next );
+
+ cnt--; // remove stopper key
+ fprintf(stderr, " Total keys read %d\n", cnt);
+ break;
+ }
+
+ bt_close (bt);
+#ifdef unix
+ return NULL;
+#else
+ return 0;
+#endif
+}
+
+typedef struct timeval timer;
+
+int main (int argc, char **argv)
+{
+int idx, cnt, len, slot, err;
+int segsize, bits = 16;
+#ifdef unix
+pthread_t *threads;
+timer start, stop;
+#else
+time_t start[1], stop[1];
+HANDLE *threads;
+#endif
+double real_time;
+ThreadArg *args;
+uint poolsize = 0;
+int num = 0;
+char key[1];
+BtMgr *mgr;
+BtKey ptr;
+BtDb *bt;
+
+ if( argc < 3 ) {
+ fprintf (stderr, "Usage: %s idx_file Read/Write/Scan/Delete/Find [page_bits mapped_segments seg_bits line_numbers src_file1 src_file2 ... ]\n", argv[0]);
+ fprintf (stderr, " where page_bits is the page size in bits\n");
+ fprintf (stderr, " mapped_segments is the number of mmap segments in buffer pool\n");
+ fprintf (stderr, " seg_bits is the size of individual segments in buffer pool in pages in bits\n");
+ fprintf (stderr, " line_numbers = 1 to append line numbers to keys\n");
+ fprintf (stderr, " src_file1 thru src_filen are files of keys separated by newline\n");
+ exit(0);
+ }
+
+#ifdef unix
+ gettimeofday(&start, NULL);
+#else
+ time(start);
+#endif
+
+ if( argc > 3 )
+ bits = atoi(argv[3]);
+
+ if( argc > 4 )
+ poolsize = atoi(argv[4]);
+
+ if( !poolsize )
+ fprintf (stderr, "Warning: no mapped_pool\n");
+
+ if( poolsize > 65535 )
+ fprintf (stderr, "Warning: mapped_pool > 65535 segments\n");
+
+ if( argc > 5 )
+ segsize = atoi(argv[5]);
+ else
+ segsize = 4; // 16 pages per mmap segment
+
+ if( argc > 6 )
+ num = atoi(argv[6]);
+
+ cnt = argc - 7;
+#ifdef unix
+ threads = malloc (cnt * sizeof(pthread_t));
+#else
+ threads = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, cnt * sizeof(HANDLE));
+#endif
+ args = malloc (cnt * sizeof(ThreadArg));
+
+ mgr = bt_mgr ((argv[1]), BT_rw, bits, poolsize, segsize, poolsize / 8);
+
+ if( !mgr ) {
+ fprintf(stderr, "Index Open Error %s\n", argv[1]);
+ exit (1);
+ }
+
+ // fire off threads
+
+ for( idx = 0; idx < cnt; idx++ ) {
+ args[idx].infile = argv[idx + 7];
+ args[idx].type = argv[2][0];
+ args[idx].mgr = mgr;
+ args[idx].num = num;
+ args[idx].idx = idx;
+#ifdef unix
+ if( err = pthread_create (threads + idx, NULL, index_file, args + idx) )
+ fprintf(stderr, "Error creating thread %d\n", err);
+#else
+ threads[idx] = (HANDLE)_beginthreadex(NULL, 65536, index_file, args + idx, 0, NULL);
+#endif
+ }
+
+ // wait for termination
+
+#ifdef unix
+ for( idx = 0; idx < cnt; idx++ )
+ pthread_join (threads[idx], NULL);
+ gettimeofday(&stop, NULL);
+ real_time = 1000.0 * ( stop.tv_sec - start.tv_sec ) + 0.001 * (stop.tv_usec - start.tv_usec );
+#else
+ WaitForMultipleObjects (cnt, threads, TRUE, INFINITE);
+
+ for( idx = 0; idx < cnt; idx++ )
+ CloseHandle(threads[idx]);
+
+ time (stop);
+ real_time = 1000 * (*stop - *start);
+#endif
+ fprintf(stderr, " Time to complete: %.2f seconds\n", real_time/1000);
+ bt_mgrclose (mgr);
+}
+
+#endif //STANDALONE
--- /dev/null
+// foster btree version f2
+// 18 JAN 2014
+
+// author: karl malbrain, malbrain@cal.berkeley.edu
+
+/*
+This work, including the source code, documentation
+and related data, is placed into the public domain.
+
+The orginal author is Karl Malbrain.
+
+THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
+OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
+MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
+ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
+RESULTING FROM THE USE, MODIFICATION, OR
+REDISTRIBUTION OF THIS SOFTWARE.
+*/
+
+// Please see the project home page for documentation
+// code.google.com/p/high-concurrency-btree
+
+#define _FILE_OFFSET_BITS 64
+#define _LARGEFILE64_SOURCE
+
+#ifdef linux
+#define _GNU_SOURCE
+#endif
+
+#ifdef unix
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/time.h>
+#include <sys/mman.h>
+#include <errno.h>
+#include <pthread.h>
+#else
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <fcntl.h>
+#include <process.h>
+#include <intrin.h>
+#endif
+
+#include <memory.h>
+#include <string.h>
+
+typedef unsigned long long uid;
+
+#ifndef unix
+typedef unsigned long long off64_t;
+typedef unsigned short ushort;
+typedef unsigned int uint;
+#endif
+
+#define BT_ro 0x6f72 // ro
+#define BT_rw 0x7772 // rw
+
+#define BT_latchtable 128 // number of latch manager slots
+
+#define BT_maxbits 24 // maximum page size in bits
+#define BT_minbits 9 // minimum page size in bits
+#define BT_minpage (1 << BT_minbits) // minimum page size
+#define BT_maxpage (1 << BT_maxbits) // maximum page size
+
+/*
+There are five lock types for each node in three independent sets:
+1. (set 1) AccessIntent: Sharable. Going to Read the node. Incompatible with NodeDelete.
+2. (set 1) NodeDelete: Exclusive. About to release the node. Incompatible with AccessIntent.
+3. (set 2) ReadLock: Sharable. Read the node. Incompatible with WriteLock.
+4. (set 2) WriteLock: Exclusive. Modify the node. Incompatible with ReadLock and other WriteLocks.
+5. (set 3) ParentLock: Exclusive. Have parent adopt/delete maximum foster child from the node.
+*/
+
+typedef enum{
+ BtLockAccess,
+ BtLockDelete,
+ BtLockRead,
+ BtLockWrite,
+ BtLockParent
+}BtLock;
+
+// Define the length of the page and key pointers
+
+#define BtId 6
+
+// Page key slot definition.
+
+// If BT_maxbits is 15 or less, you can save 4 bytes
+// for each key stored by making the first two uints
+// into ushorts. You can also save 4 bytes by removing
+// the tod field from the key.
+
+// Keys are marked dead, but remain on the page until
+// it cleanup is called. The fence key (highest key) for
+// the page is always present, even after cleanup.
+
+typedef struct {
+ uint off:BT_maxbits; // page offset for key start
+ uint dead:1; // set for deleted key
+ uint tod; // time-stamp for key
+ unsigned char id[BtId]; // id associated with key
+} BtSlot;
+
+// The key structure occupies space at the upper end of
+// each page. It's a length byte followed by the value
+// bytes.
+
+typedef struct {
+ unsigned char len;
+ unsigned char key[1];
+} *BtKey;
+
+// The first part of an index page.
+// It is immediately followed
+// by the BtSlot array of keys.
+
+typedef struct Page {
+ volatile uint cnt; // count of keys in page
+ volatile uint act; // count of active keys
+ volatile uint min; // next key offset
+ volatile uint foster; // count of foster children
+ unsigned char bits; // page size in bits
+ unsigned char lvl:7; // level of page
+ unsigned char dirty:1; // page needs to be cleaned
+ unsigned char right[BtId]; // page number to right
+} *BtPage;
+
+// mode & definition for hash latch implementation
+
+enum {
+ Mutex = 1,
+ Write = 2,
+ Pending = 4,
+ Share = 8
+} LockMode;
+
+// mutex locks the other fields
+// exclusive is set for write access
+// share is count of read accessors
+
+typedef struct {
+ volatile ushort mutex:1;
+ volatile ushort exclusive:1;
+ volatile ushort pending:1;
+ volatile ushort share:13;
+} BtSpinLatch;
+
+// hash table entries
+
+typedef struct {
+ BtSpinLatch latch[1];
+ volatile ushort slot; // Latch table entry at head of chain
+} BtHashEntry;
+
+// latch manager table structure
+
+typedef struct {
+ BtSpinLatch readwr[1]; // read/write page lock
+ BtSpinLatch access[1]; // Access Intent/Page delete
+ BtSpinLatch parent[1]; // adoption of foster children
+ BtSpinLatch busy[1]; // slot is being moved between chains
+ volatile ushort next; // next entry in hash table chain
+ volatile ushort prev; // prev entry in hash table chain
+ volatile ushort pin; // number of outstanding locks
+ volatile ushort hash; // hash slot entry is under
+ volatile uid page_no; // latch set page number
+} BtLatchSet;
+
+// The memory mapping pool table buffer manager entry
+
+typedef struct {
+ unsigned long long int lru; // number of times accessed
+ uid basepage; // mapped base page number
+ char *map; // mapped memory pointer
+ ushort pin; // mapped page pin counter
+ ushort slot; // slot index in this array
+ void *hashprev; // previous pool entry for the same hash idx
+ void *hashnext; // next pool entry for the same hash idx
+#ifndef unix
+ HANDLE hmap; // Windows memory mapping handle
+#endif
+} BtPool;
+
+// structure for latch manager on ALLOC_page
+
+typedef struct {
+ struct Page alloc[2]; // next & free page_nos in right ptr
+ BtSpinLatch lock[1]; // allocation area lite latch
+ ushort latchdeployed; // highest number of latch entries deployed
+ ushort nlatchpage; // number of latch pages at BT_latch
+ ushort latchtotal; // number of page latch entries
+ ushort latchhash; // number of latch hash table slots
+ ushort latchvictim; // next latch entry to examine
+ BtHashEntry table[0]; // the hash table
+} BtLatchMgr;
+
+// The object structure for Btree access
+
+typedef struct {
+ uint page_size; // page size
+ uint page_bits; // page size in bits
+ uint seg_bits; // seg size in pages in bits
+ uint mode; // read-write mode
+#ifdef unix
+ int idx;
+ char *pooladvise; // bit maps for pool page advisements
+#else
+ HANDLE idx;
+#endif
+ ushort poolcnt; // highest page pool node in use
+ ushort poolmax; // highest page pool node allocated
+ ushort poolmask; // total number of pages in mmap segment - 1
+ ushort hashsize; // size of Hash Table for pool entries
+ ushort evicted; // last evicted hash table slot
+ ushort *hash; // hash table of pool entries
+ BtPool *pool; // memory pool page segments
+ BtSpinLatch *latch; // latches for pool hash slots
+ BtLatchMgr *latchmgr; // mapped latch page from allocation page
+ BtLatchSet *latchsets; // mapped latch set from latch pages
+#ifndef unix
+ HANDLE halloc; // allocation and latch table handle
+#endif
+} BtMgr;
+
+typedef struct {
+ BtMgr *mgr; // buffer manager for thread
+ BtPage cursor; // cached frame for start/next (never mapped)
+ BtPage frame; // spare frame for the page split (never mapped)
+ BtPage zero; // page frame for zeroes at end of file
+ BtPage page; // current page
+ uid page_no; // current page number
+ uid cursor_page; // current cursor page number
+ BtLatchSet *set; // current page latch set
+ BtPool *pool; // current page pool
+ unsigned char *mem; // frame, cursor, page memory buffer
+ int found; // last delete was found
+ int err; // last error
+} BtDb;
+
+typedef enum {
+ BTERR_ok = 0,
+ BTERR_struct,
+ BTERR_ovflw,
+ BTERR_lock,
+ BTERR_map,
+ BTERR_wrt,
+ BTERR_hash,
+ BTERR_latch
+} BTERR;
+
+// B-Tree functions
+extern void bt_close (BtDb *bt);
+extern BtDb *bt_open (BtMgr *mgr);
+extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod, uint lvl);
+extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len);
+extern uid bt_findkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_startkey (BtDb *bt, unsigned char *key, uint len);
+extern uint bt_nextkey (BtDb *bt, uint slot);
+
+// manager functions
+extern BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolsize, uint segsize, uint hashsize);
+void bt_mgrclose (BtMgr *mgr);
+
+// Helper functions to return cursor slot values
+
+extern BtKey bt_key (BtDb *bt, uint slot);
+extern uid bt_uid (BtDb *bt, uint slot);
+extern uint bt_tod (BtDb *bt, uint slot);
+
+// BTree page number constants
+#define ALLOC_page 0 // allocation & lock manager hash table
+#define ROOT_page 1 // root of the btree
+#define LEAF_page 2 // first page of leaves
+#define LATCH_page 3 // pages for lock manager
+
+// Number of levels to create in a new BTree
+
+#define MIN_lvl 2
+
+// The page is allocated from low and hi ends.
+// The key offsets and row-id's are allocated
+// from the bottom, while the text of the key
+// is allocated from the top. When the two
+// areas meet, the page is split into two.
+
+// A key consists of a length byte, two bytes of
+// index number (0 - 65534), and up to 253 bytes
+// of key value. Duplicate keys are discarded.
+// Associated with each key is a 48 bit row-id.
+
+// The b-tree root is always located at page 1.
+// The first leaf page of level zero is always
+// located on page 2.
+
+// When to root page fills, it is split in two and
+// the tree height is raised by a new root at page
+// one with two keys.
+
+// Deleted keys are marked with a dead bit until
+// page cleanup The fence key for a node is always
+// present, even after deletion and cleanup.
+
+// Groups of pages called segments from the btree are
+// cached with memory mapping. A hash table is used to keep
+// track of the cached segments. This behaviour is controlled
+// by the cache block size parameter to bt_open.
+
+// To achieve maximum concurrency one page is locked at a time
+// as the tree is traversed to find leaf key in question.
+
+// An adoption traversal leaves the parent node locked as the
+// tree is traversed to the level in quesiton.
+
+// Page 0 is dedicated to lock for new page extensions,
+// and chains empty pages together for reuse.
+
+// Empty pages are chained together through the ALLOC page and reused.
+
+// Access macros to address slot and key values from the page
+
+#define slotptr(page, slot) (((BtSlot *)(page+1)) + (slot-1))
+#define keyptr(page, slot) ((BtKey)((unsigned char*)(page) + slotptr(page, slot)->off))
+
+void bt_putid(unsigned char *dest, uid id)
+{
+int i = BtId;
+
+ while( i-- )
+ dest[i] = (unsigned char)id, id >>= 8;
+}
+
+uid bt_getid(unsigned char *src)
+{
+uid id = 0;
+int i;
+
+ for( i = 0; i < BtId; i++ )
+ id <<= 8, id |= *src++;
+
+ return id;
+}
+
+// wait until write lock mode is clear
+// and add 1 to the share count
+
+void bt_spinreadlock(BtSpinLatch *latch)
+{
+ushort prev;
+
+ do {
+#ifdef unix
+ while( __sync_fetch_and_or((ushort *)latch, Mutex) & Mutex )
+ sched_yield();
+#else
+ while( _InterlockedOr16((ushort *)latch, Mutex) & Mutex )
+ SwitchToThread();
+#endif
+
+ // see if exclusive request is granted or pending
+
+ if( prev = !(latch->exclusive | latch->pending) )
+#ifdef unix
+ __sync_fetch_and_add((ushort *)latch, Share);
+#else
+ _InterlockedExchangeAdd16 ((ushort *)latch, Share);
+#endif
+
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Mutex);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Mutex);
+#endif
+ if( prev )
+ return;
+#ifdef unix
+ } while( sched_yield(), 1 );
+#else
+ } while( SwitchToThread(), 1 );
+#endif
+}
+
+// wait for other read and write latches to relinquish
+
+void bt_spinwritelock(BtSpinLatch *latch)
+{
+ do {
+#ifdef unix
+ while( __sync_fetch_and_or((ushort *)latch, Mutex | Pending) & Mutex )
+ sched_yield();
+#else
+ while( _InterlockedOr16((ushort *)latch, Mutex | Pending) & Mutex )
+ SwitchToThread();
+#endif
+ if( !(latch->share | latch->exclusive) ) {
+#ifdef unix
+ __sync_fetch_and_or((ushort *)latch, Write);
+ __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending));
+#else
+ _InterlockedOr16((ushort *)latch, Write);
+ _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending));
+#endif
+ return;
+ }
+
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Mutex);
+ sched_yield();
+#else
+ _InterlockedAnd16((ushort *)latch, ~Mutex);
+ SwitchToThread();
+#endif
+ } while( 1 );
+}
+
+// try to obtain write lock
+
+// return 1 if obtained,
+// 0 otherwise
+
+int bt_spinwritetry(BtSpinLatch *latch)
+{
+ushort prev;
+
+#ifdef unix
+ if( prev = __sync_fetch_and_or((ushort *)latch, Mutex), prev & Mutex )
+ return 0;
+#else
+ if( prev = _InterlockedOr16((ushort *)latch, Mutex), prev & Mutex )
+ return 0;
+#endif
+ // take write access if all bits are clear
+
+ if( !prev )
+#ifdef unix
+ __sync_fetch_and_or ((ushort *)latch, Write);
+#else
+ _InterlockedOr16((ushort *)latch, Write);
+#endif
+
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Mutex);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Mutex);
+#endif
+ return !prev;
+}
+
+// clear write mode
+
+void bt_spinreleasewrite(BtSpinLatch *latch)
+{
+#ifdef unix
+ __sync_fetch_and_and ((ushort *)latch, ~Write);
+#else
+ _InterlockedAnd16((ushort *)latch, ~Write);
+#endif
+}
+
+// decrement reader count
+
+void bt_spinreleaseread(BtSpinLatch *latch)
+{
+#ifdef unix
+ __sync_fetch_and_add((ushort *)latch, -Share);
+#else
+ _InterlockedExchangeAdd16 ((ushort *)latch, -Share);
+#endif
+}
+
+// link latch table entry into latch hash table
+
+void bt_latchlink (BtDb *bt, ushort hashidx, ushort victim, uid page_no)
+{
+BtLatchSet *set = bt->mgr->latchsets + victim;
+
+ if( set->next = bt->mgr->latchmgr->table[hashidx].slot )
+ bt->mgr->latchsets[set->next].prev = victim;
+
+ bt->mgr->latchmgr->table[hashidx].slot = victim;
+ set->page_no = page_no;
+ set->hash = hashidx;
+ set->prev = 0;
+}
+
+// release latch pin
+
+void bt_unpinlatch (BtLatchSet *set)
+{
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, -1);
+#else
+ _InterlockedDecrement16 (&set->pin);
+#endif
+}
+
+// find existing latchset or inspire new one
+// return with latchset pinned
+
+BtLatchSet *bt_pinlatch (BtDb *bt, uid page_no)
+{
+ushort hashidx = page_no % bt->mgr->latchmgr->latchhash;
+ushort slot, avail = 0, victim, idx;
+BtLatchSet *set;
+
+ // obtain read lock on hash table entry
+
+ bt_spinreadlock(bt->mgr->latchmgr->table[hashidx].latch);
+
+ if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
+ {
+ set = bt->mgr->latchsets + slot;
+ if( page_no == set->page_no )
+ break;
+ } while( slot = set->next );
+
+ if( slot ) {
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ }
+
+ bt_spinreleaseread (bt->mgr->latchmgr->table[hashidx].latch);
+
+ if( slot )
+ return set;
+
+ // try again, this time with write lock
+
+ bt_spinwritelock(bt->mgr->latchmgr->table[hashidx].latch);
+
+ if( slot = bt->mgr->latchmgr->table[hashidx].slot ) do
+ {
+ set = bt->mgr->latchsets + slot;
+ if( page_no == set->page_no )
+ break;
+ if( !set->pin && !avail )
+ avail = slot;
+ } while( slot = set->next );
+
+ // found our entry, or take over an unpinned one
+
+ if( slot || (slot = avail) ) {
+ set = bt->mgr->latchsets + slot;
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ set->page_no = page_no;
+ bt_spinreleasewrite(bt->mgr->latchmgr->table[hashidx].latch);
+ return set;
+ }
+
+ // see if there are any unused entries
+#ifdef unix
+ victim = __sync_fetch_and_add (&bt->mgr->latchmgr->latchdeployed, 1) + 1;
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->latchmgr->latchdeployed);
+#endif
+
+ if( victim < bt->mgr->latchmgr->latchtotal ) {
+ set = bt->mgr->latchsets + victim;
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ bt_latchlink (bt, hashidx, victim, page_no);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch);
+ return set;
+ }
+
+#ifdef unix
+ victim = __sync_fetch_and_add (&bt->mgr->latchmgr->latchdeployed, -1);
+#else
+ victim = _InterlockedDecrement16 (&bt->mgr->latchmgr->latchdeployed);
+#endif
+ // find and reuse previous lock entry
+
+ while( 1 ) {
+#ifdef unix
+ victim = __sync_fetch_and_add(&bt->mgr->latchmgr->latchvictim, 1);
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->latchmgr->latchvictim) - 1;
+#endif
+ // we don't use slot zero
+
+ if( victim %= bt->mgr->latchmgr->latchtotal )
+ set = bt->mgr->latchsets + victim;
+ else
+ continue;
+
+ // take control of our slot
+ // from other threads
+
+ if( set->pin || !bt_spinwritetry (set->busy) )
+ continue;
+
+ idx = set->hash;
+
+ // try to get write lock on hash chain
+ // skip entry if not obtained
+ // or has outstanding locks
+
+ if( !bt_spinwritetry (bt->mgr->latchmgr->table[idx].latch) ) {
+ bt_spinreleasewrite (set->busy);
+ continue;
+ }
+
+ if( set->pin ) {
+ bt_spinreleasewrite (set->busy);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[idx].latch);
+ continue;
+ }
+
+ // unlink our available victim from its hash chain
+
+ if( set->prev )
+ bt->mgr->latchsets[set->prev].next = set->next;
+ else
+ bt->mgr->latchmgr->table[idx].slot = set->next;
+
+ if( set->next )
+ bt->mgr->latchsets[set->next].prev = set->prev;
+
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[idx].latch);
+#ifdef unix
+ __sync_fetch_and_add(&set->pin, 1);
+#else
+ _InterlockedIncrement16 (&set->pin);
+#endif
+ bt_latchlink (bt, hashidx, victim, page_no);
+ bt_spinreleasewrite (bt->mgr->latchmgr->table[hashidx].latch);
+ bt_spinreleasewrite (set->busy);
+ return set;
+ }
+}
+
+void bt_mgrclose (BtMgr *mgr)
+{
+BtPool *pool;
+uint slot;
+
+ // release mapped pages
+ // note that slot zero is never used
+
+ for( slot = 1; slot < mgr->poolmax; slot++ ) {
+ pool = mgr->pool + slot;
+ if( pool->slot )
+#ifdef unix
+ munmap (pool->map, (mgr->poolmask+1) << mgr->page_bits);
+#else
+ {
+ FlushViewOfFile(pool->map, 0);
+ UnmapViewOfFile(pool->map);
+ CloseHandle(pool->hmap);
+ }
+#endif
+ }
+
+#ifdef unix
+ munmap (mgr->latchsets, mgr->latchmgr->nlatchpage * mgr->page_size);
+ munmap (mgr->latchmgr, mgr->page_size);
+#else
+ FlushViewOfFile(mgr->latchmgr, 0);
+ UnmapViewOfFile(mgr->latchmgr);
+ CloseHandle(mgr->halloc);
+#endif
+#ifdef unix
+ close (mgr->idx);
+ free (mgr->pool);
+ free (mgr->hash);
+ free (mgr->latch);
+ free (mgr->pooladvise);
+ free (mgr);
+#else
+ FlushFileBuffers(mgr->idx);
+ CloseHandle(mgr->idx);
+ GlobalFree (mgr->pool);
+ GlobalFree (mgr->hash);
+ GlobalFree (mgr->latch);
+ GlobalFree (mgr);
+#endif
+}
+
+// close and release memory
+
+void bt_close (BtDb *bt)
+{
+#ifdef unix
+ if ( bt->mem )
+ free (bt->mem);
+#else
+ if ( bt->mem)
+ VirtualFree (bt->mem, 0, MEM_RELEASE);
+#endif
+ free (bt);
+}
+
+// open/create new btree buffer manager
+
+// call with file_name, BT_openmode, bits in page size (e.g. 16),
+// size of mapped page pool (e.g. 8192)
+
+BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolmax, uint segsize, uint hashsize)
+{
+uint lvl, attr, cacheblk, last, slot, idx;
+uint nlatchpage, latchhash;
+BtLatchMgr *latchmgr;
+off64_t size;
+uint amt[1];
+BtMgr* mgr;
+BtKey key;
+int flag;
+
+#ifndef unix
+SYSTEM_INFO sysinfo[1];
+#endif
+
+ // determine sanity of page size and buffer pool
+
+ if( bits > BT_maxbits )
+ bits = BT_maxbits;
+ else if( bits < BT_minbits )
+ bits = BT_minbits;
+
+ if( !poolmax )
+ return NULL; // must have buffer pool
+
+#ifdef unix
+ mgr = calloc (1, sizeof(BtMgr));
+
+ mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
+
+ if( mgr->idx == -1 )
+ return free(mgr), NULL;
+
+ cacheblk = 4096; // minimum mmap segment size for unix
+
+#else
+ mgr = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtMgr));
+ attr = FILE_ATTRIBUTE_NORMAL;
+ mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
+
+ if( mgr->idx == INVALID_HANDLE_VALUE )
+ return GlobalFree(mgr), NULL;
+
+ // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity
+ GetSystemInfo(sysinfo);
+ cacheblk = sysinfo->dwAllocationGranularity;
+#endif
+
+#ifdef unix
+ latchmgr = malloc (BT_maxpage);
+ *amt = 0;
+
+ // read minimum page size to get root info
+
+ if( size = lseek (mgr->idx, 0L, 2) ) {
+ if( pread(mgr->idx, latchmgr, BT_minpage, 0) == BT_minpage )
+ bits = latchmgr->alloc->bits;
+ else
+ return free(mgr), free(latchmgr), NULL;
+ } else if( mode == BT_ro )
+ return free(latchmgr), bt_mgrclose (mgr), NULL;
+#else
+ latchmgr = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE);
+ size = GetFileSize(mgr->idx, amt);
+
+ if( size || *amt ) {
+ if( !ReadFile(mgr->idx, (char *)latchmgr, BT_minpage, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ bits = latchmgr->alloc->bits;
+ } else if( mode == BT_ro )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ mgr->page_size = 1 << bits;
+ mgr->page_bits = bits;
+
+ mgr->poolmax = poolmax;
+ mgr->mode = mode;
+
+ if( cacheblk < mgr->page_size )
+ cacheblk = mgr->page_size;
+
+ // mask for partial memmaps
+
+ mgr->poolmask = (cacheblk >> bits) - 1;
+
+ // see if requested size of pages per memmap is greater
+
+ if( (1 << segsize) > mgr->poolmask )
+ mgr->poolmask = (1 << segsize) - 1;
+
+ mgr->seg_bits = 0;
+
+ while( (1 << mgr->seg_bits) <= mgr->poolmask )
+ mgr->seg_bits++;
+
+ mgr->hashsize = hashsize;
+
+#ifdef unix
+ mgr->pool = calloc (poolmax, sizeof(BtPool));
+ mgr->hash = calloc (hashsize, sizeof(ushort));
+ mgr->latch = calloc (hashsize, sizeof(BtSpinLatch));
+ mgr->pooladvise = calloc (poolmax, (mgr->poolmask + 8) / 8);
+#else
+ mgr->pool = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, poolmax * sizeof(BtPool));
+ mgr->hash = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(ushort));
+ mgr->latch = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(BtSpinLatch));
+#endif
+
+ if( size || *amt )
+ goto mgrlatch;
+
+ // initialize an empty b-tree with latch page, root page, page of leaves
+ // and page(s) of latches
+
+ memset (latchmgr, 0, 1 << bits);
+ nlatchpage = BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1;
+ bt_putid(latchmgr->alloc->right, MIN_lvl+1+nlatchpage);
+ latchmgr->alloc->bits = mgr->page_bits;
+
+ latchmgr->nlatchpage = nlatchpage;
+ latchmgr->latchtotal = nlatchpage * (mgr->page_size / sizeof(BtLatchSet));
+
+ // initialize latch manager
+
+ latchhash = (mgr->page_size - sizeof(BtLatchMgr)) / sizeof(BtHashEntry);
+
+ // size of hash table = total number of latchsets
+
+ if( latchhash > latchmgr->latchtotal )
+ latchhash = latchmgr->latchtotal;
+
+ latchmgr->latchhash = latchhash;
+
+#ifdef unix
+ if( write (mgr->idx, latchmgr, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+
+ memset (latchmgr, 0, 1 << bits);
+ latchmgr->alloc->bits = mgr->page_bits;
+
+ for( lvl=MIN_lvl; lvl--; ) {
+ slotptr(latchmgr->alloc, 1)->off = mgr->page_size - 3;
+ bt_putid(slotptr(latchmgr->alloc, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number
+ key = keyptr(latchmgr->alloc, 1);
+ key->len = 2; // create stopper key
+ key->key[0] = 0xff;
+ key->key[1] = 0xff;
+ latchmgr->alloc->min = mgr->page_size - 3;
+ latchmgr->alloc->lvl = lvl;
+ latchmgr->alloc->cnt = 1;
+ latchmgr->alloc->act = 1;
+#ifdef unix
+ if( write (mgr->idx, latchmgr, mgr->page_size) < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#else
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ }
+
+ // clear out latch manager locks
+ // and rest of pages to round out segment
+
+ memset(latchmgr, 0, mgr->page_size);
+ last = MIN_lvl + 1;
+
+ while( last <= ((MIN_lvl + 1 + nlatchpage) | mgr->poolmask) ) {
+#ifdef unix
+ pwrite(mgr->idx, latchmgr, mgr->page_size, last << mgr->page_bits);
+#else
+ SetFilePointer (mgr->idx, last << mgr->page_bits, NULL, FILE_BEGIN);
+ if( !WriteFile (mgr->idx, (char *)latchmgr, mgr->page_size, amt, NULL) )
+ return bt_mgrclose (mgr), NULL;
+ if( *amt < mgr->page_size )
+ return bt_mgrclose (mgr), NULL;
+#endif
+ last++;
+ }
+
+mgrlatch:
+#ifdef unix
+ flag = PROT_READ | PROT_WRITE;
+ mgr->latchmgr = mmap (0, mgr->page_size, flag, MAP_SHARED, mgr->idx, ALLOC_page * mgr->page_size);
+ if( mgr->latchmgr == MAP_FAILED )
+ return bt_mgrclose (mgr), NULL;
+ mgr->latchsets = (BtLatchSet *)mmap (0, mgr->latchmgr->nlatchpage * mgr->page_size, flag, MAP_SHARED, mgr->idx, LATCH_page * mgr->page_size);
+ if( mgr->latchsets == MAP_FAILED )
+ return bt_mgrclose (mgr), NULL;
+#else
+ flag = PAGE_READWRITE;
+ mgr->halloc = CreateFileMapping(mgr->idx, NULL, flag, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size, NULL);
+ if( !mgr->halloc )
+ return bt_mgrclose (mgr), NULL;
+
+ flag = FILE_MAP_WRITE;
+ mgr->latchmgr = MapViewOfFile(mgr->halloc, flag, 0, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size);
+ if( !mgr->latchmgr )
+ return GetLastError(), bt_mgrclose (mgr), NULL;
+
+ mgr->latchsets = (void *)((char *)mgr->latchmgr + LATCH_page * mgr->page_size);
+#endif
+
+#ifdef unix
+ free (latchmgr);
+#else
+ VirtualFree (latchmgr, 0, MEM_RELEASE);
+#endif
+ return mgr;
+}
+
+// open BTree access method
+// based on buffer manager
+
+BtDb *bt_open (BtMgr *mgr)
+{
+BtDb *bt = malloc (sizeof(*bt));
+
+ memset (bt, 0, sizeof(*bt));
+ bt->mgr = mgr;
+#ifdef unix
+ bt->mem = malloc (3 *mgr->page_size);
+#else
+ bt->mem = VirtualAlloc(NULL, 3 * mgr->page_size, MEM_COMMIT, PAGE_READWRITE);
+#endif
+ bt->frame = (BtPage)bt->mem;
+ bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size);
+ bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size);
+
+ memset(bt->zero, 0, mgr->page_size);
+ return bt;
+}
+
+// compare two keys, returning > 0, = 0, or < 0
+// as the comparison value
+
+int keycmp (BtKey key1, unsigned char *key2, uint len2)
+{
+uint len1 = key1->len;
+int ans;
+
+ if( ans = memcmp (key1->key, key2, len1 > len2 ? len2 : len1) )
+ return ans;
+
+ if( len1 > len2 )
+ return 1;
+ if( len1 < len2 )
+ return -1;
+
+ return 0;
+}
+
+// Buffer Pool mgr
+
+// find segment in pool
+// must be called with hashslot idx locked
+// return NULL if not there
+// otherwise return node
+
+BtPool *bt_findpool(BtDb *bt, uid page_no, uint idx)
+{
+BtPool *pool;
+uint slot;
+
+ // compute start of hash chain in pool
+
+ if( slot = bt->mgr->hash[idx] )
+ pool = bt->mgr->pool + slot;
+ else
+ return NULL;
+
+ page_no &= ~bt->mgr->poolmask;
+
+ while( pool->basepage != page_no )
+ if( pool = pool->hashnext )
+ continue;
+ else
+ return NULL;
+
+ return pool;
+}
+
+// add segment to hash table
+
+void bt_linkhash(BtDb *bt, BtPool *pool, uid page_no, int idx)
+{
+BtPool *node;
+uint slot;
+
+ pool->hashprev = pool->hashnext = NULL;
+ pool->basepage = page_no & ~bt->mgr->poolmask;
+ pool->lru = 1;
+
+ if( slot = bt->mgr->hash[idx] ) {
+ node = bt->mgr->pool + slot;
+ pool->hashnext = node;
+ node->hashprev = pool;
+ }
+
+ bt->mgr->hash[idx] = pool->slot;
+}
+
+// find best segment to evict from buffer pool
+
+BtPool *bt_findlru (BtDb *bt, uint hashslot)
+{
+unsigned long long int target = ~0LL;
+BtPool *pool = NULL, *node;
+
+ if( !hashslot )
+ return NULL;
+
+ node = bt->mgr->pool + hashslot;
+
+ // scan pool entries under hash table slot
+
+ do {
+ if( node->pin )
+ continue;
+ if( node->lru > target )
+ continue;
+ target = node->lru;
+ pool = node;
+ } while( node = node->hashnext );
+
+ return pool;
+}
+
+// map new buffer pool segment to virtual memory
+
+BTERR bt_mapsegment(BtDb *bt, BtPool *pool, uid page_no)
+{
+off64_t off = (page_no & ~bt->mgr->poolmask) << bt->mgr->page_bits;
+off64_t limit = off + ((bt->mgr->poolmask+1) << bt->mgr->page_bits);
+int flag;
+
+#ifdef unix
+ flag = PROT_READ | ( bt->mgr->mode == BT_ro ? 0 : PROT_WRITE );
+ pool->map = mmap (0, (bt->mgr->poolmask+1) << bt->mgr->page_bits, flag, MAP_SHARED, bt->mgr->idx, off);
+ if( pool->map == MAP_FAILED )
+ return bt->err = BTERR_map;
+ // clear out madvise issued bits
+ memset (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8) / 8), 0, (bt->mgr->poolmask + 8)/8);
+#else
+ flag = ( bt->mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE );
+ pool->hmap = CreateFileMapping(bt->mgr->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL);
+ if( !pool->hmap )
+ return bt->err = BTERR_map;
+
+ flag = ( bt->mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE );
+ pool->map = MapViewOfFile(pool->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->mgr->poolmask+1) << bt->mgr->page_bits);
+ if( !pool->map )
+ return bt->err = BTERR_map;
+#endif
+ return bt->err = 0;
+}
+
+// calculate page within pool
+
+BtPage bt_page (BtDb *bt, BtPool *pool, uid page_no)
+{
+uint subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping
+BtPage page;
+
+ page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
+#ifdef unix
+ {
+ uint idx = subpage / 8;
+ uint bit = subpage % 8;
+
+ if( ~((bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] >> bit) & 1 ) {
+ madvise (page, bt->mgr->page_size, MADV_WILLNEED);
+ (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] |= 1 << bit;
+ }
+ }
+#endif
+ return page;
+}
+
+// release pool pin
+
+void bt_unpinpool (BtPool *pool)
+{
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, -1);
+#else
+ _InterlockedDecrement16 (&pool->pin);
+#endif
+}
+
+// find or place requested page in segment-pool
+// return pool table entry, incrementing pin
+
+BtPool *bt_pinpool(BtDb *bt, uid page_no)
+{
+BtPool *pool, *node, *next;
+uint slot, idx, victim;
+BtLatchSet *set;
+
+ // lock hash table chain
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_spinreadlock (&bt->mgr->latch[idx]);
+
+ // look up in hash table
+
+ if( pool = bt_findpool(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleaseread (&bt->mgr->latch[idx]);
+ pool->lru++;
+ return pool;
+ }
+
+ // upgrade to write lock
+
+ bt_spinreleaseread (&bt->mgr->latch[idx]);
+ bt_spinwritelock (&bt->mgr->latch[idx]);
+
+ // try to find page in pool with write lock
+
+ if( pool = bt_findpool(bt, page_no, idx) ) {
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ pool->lru++;
+ return pool;
+ }
+
+ // allocate a new pool node
+ // and add to hash table
+
+#ifdef unix
+ slot = __sync_fetch_and_add(&bt->mgr->poolcnt, 1);
+#else
+ slot = _InterlockedIncrement16 (&bt->mgr->poolcnt) - 1;
+#endif
+
+ if( ++slot < bt->mgr->poolmax ) {
+ pool = bt->mgr->pool + slot;
+ pool->slot = slot;
+
+ if( bt_mapsegment(bt, pool, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, pool, page_no, idx);
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ return pool;
+ }
+
+ // pool table is full
+ // find best pool entry to evict
+
+#ifdef unix
+ __sync_fetch_and_add(&bt->mgr->poolcnt, -1);
+#else
+ _InterlockedDecrement16 (&bt->mgr->poolcnt);
+#endif
+
+ while( 1 ) {
+#ifdef unix
+ victim = __sync_fetch_and_add(&bt->mgr->evicted, 1);
+#else
+ victim = _InterlockedIncrement16 (&bt->mgr->evicted) - 1;
+#endif
+ victim %= bt->mgr->hashsize;
+
+ // try to get write lock
+ // skip entry if not obtained
+
+ if( !bt_spinwritetry (&bt->mgr->latch[victim]) )
+ continue;
+
+ // if cache entry is empty
+ // or no slots are unpinned
+ // skip this entry
+
+ if( !(pool = bt_findlru(bt, bt->mgr->hash[victim])) ) {
+ bt_spinreleasewrite (&bt->mgr->latch[victim]);
+ continue;
+ }
+
+ // unlink victim pool node from hash table
+
+ if( node = pool->hashprev )
+ node->hashnext = pool->hashnext;
+ else if( node = pool->hashnext )
+ bt->mgr->hash[victim] = node->slot;
+ else
+ bt->mgr->hash[victim] = 0;
+
+ if( node = pool->hashnext )
+ node->hashprev = pool->hashprev;
+
+ bt_spinreleasewrite (&bt->mgr->latch[victim]);
+
+ // remove old file mapping
+#ifdef unix
+ munmap (pool->map, (bt->mgr->poolmask+1) << bt->mgr->page_bits);
+#else
+ FlushViewOfFile(pool->map, 0);
+ UnmapViewOfFile(pool->map);
+ CloseHandle(pool->hmap);
+#endif
+ pool->map = NULL;
+
+ // create new pool mapping
+ // and link into hash table
+
+ if( bt_mapsegment(bt, pool, page_no) )
+ return NULL;
+
+ bt_linkhash(bt, pool, page_no, idx);
+#ifdef unix
+ __sync_fetch_and_add(&pool->pin, 1);
+#else
+ _InterlockedIncrement16 (&pool->pin);
+#endif
+ bt_spinreleasewrite (&bt->mgr->latch[idx]);
+ return pool;
+ }
+}
+
+// place write, read, or parent lock on requested page_no.
+// pin to buffer pool and return latchset pointer
+
+void bt_lockpage(BtLock mode, BtLatchSet *set)
+{
+ switch( mode ) {
+ case BtLockRead:
+ bt_spinreadlock (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_spinwritelock (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_spinreadlock (set->access);
+ break;
+ case BtLockDelete:
+ bt_spinwritelock (set->access);
+ break;
+ case BtLockParent:
+ bt_spinwritelock (set->parent);
+ break;
+ }
+}
+
+// remove write, read, or parent lock on requested page_no.
+
+void bt_unlockpage(BtLock mode, BtLatchSet *set)
+{
+ switch( mode ) {
+ case BtLockRead:
+ bt_spinreleaseread (set->readwr);
+ break;
+ case BtLockWrite:
+ bt_spinreleasewrite (set->readwr);
+ break;
+ case BtLockAccess:
+ bt_spinreleaseread (set->access);
+ break;
+ case BtLockDelete:
+ bt_spinreleasewrite (set->access);
+ break;
+ case BtLockParent:
+ bt_spinreleasewrite (set->parent);
+ break;
+ }
+}
+
+// allocate a new page and write page into it
+
+uid bt_newpage(BtDb *bt, BtPage page)
+{
+BtLatchSet *set;
+BtPool *pool;
+uid new_page;
+BtPage pmap;
+int reuse;
+
+ // lock allocation page
+
+ bt_spinwritelock(bt->mgr->latchmgr->lock);
+
+ // use empty chain first
+ // else allocate empty page
+
+ if( new_page = bt_getid(bt->mgr->latchmgr->alloc[1].right) ) {
+ if( pool = bt_pinpool (bt, new_page) )
+ pmap = bt_page (bt, pool, new_page);
+ else
+ return 0;
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, bt_getid(pmap->right));
+ bt_unpinpool (pool);
+ reuse = 1;
+ } else {
+ new_page = bt_getid(bt->mgr->latchmgr->alloc->right);
+ bt_putid(bt->mgr->latchmgr->alloc->right, new_page+1);
+ reuse = 0;
+ }
+#ifdef unix
+ // if writing first page of pool block, zero last page in the block
+
+ if ( !reuse && bt->mgr->poolmask > 0 && (new_page & bt->mgr->poolmask) == 0 )
+ {
+ // use zero buffer to write zeros
+ if ( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->poolmask) << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+ }
+
+ // unlock allocation latch
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
+ if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size )
+ return bt->err = BTERR_wrt, 0;
+
+#else
+ // unlock allocation latch
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
+ // bring new page into pool and copy page.
+ // this will extend the file into the new pages.
+ // NB -- no latch required
+
+ if( pool = bt_pinpool (bt, new_page) )
+ pmap = bt_page (bt, pool, new_page);
+ else
+ return 0;
+
+ memcpy(pmap, page, bt->mgr->page_size);
+ bt_unpinpool (pool);
+#endif
+ return new_page;
+}
+
+// find slot in page for given key at a given level
+
+int bt_findslot (BtDb *bt, unsigned char *key, uint len)
+{
+uint diff, higher = bt->page->cnt, low = 1, slot;
+
+ // low is the lowest candidate, higher is already
+ // tested as .ge. the given key, loop ends when they meet
+
+ while( diff = higher - low ) {
+ slot = low + ( diff >> 1 );
+ if( keycmp (keyptr(bt->page, slot), key, len) < 0 )
+ low = slot + 1;
+ else
+ higher = slot;
+ }
+
+ return higher;
+}
+
+// find and load page at given level for given key
+// leave page rd or wr locked as requested
+
+int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, BtLock lock)
+{
+uid page_no = ROOT_page, prevpage = 0;
+BtLatchSet *set, *prevset;
+uint drill = 0xff, slot;
+uint mode, prevmode;
+BtPool *prevpool;
+
+ // start at root of btree and drill down
+
+ do {
+ // determine lock mode of drill level
+ mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead;
+
+ // obtain latch set for this page
+
+ bt->set = bt_pinlatch (bt, page_no);
+ bt->page_no = page_no;
+
+ // pin page contents
+
+ if( bt->pool = bt_pinpool (bt, page_no) )
+ bt->page = bt_page (bt, bt->pool, page_no);
+ else
+ return 0;
+
+ // obtain access lock using lock chaining with Access mode
+
+ if( page_no > ROOT_page )
+ bt_lockpage(BtLockAccess, bt->set);
+
+ // now unlock and unpin our (possibly foster) parent
+
+ if( prevpage ) {
+ bt_unlockpage(prevmode, prevset);
+ bt_unpinlatch (prevset);
+ bt_unpinpool (prevpool);
+ prevpage = 0;
+ }
+
+ // obtain read lock using lock chaining
+
+ bt_lockpage(mode, bt->set);
+
+ if( page_no > ROOT_page )
+ bt_unlockpage(BtLockAccess, bt->set);
+
+ // re-read and re-lock root after determining actual level of root
+
+ if( page_no == ROOT_page )
+ if( bt->page->lvl != drill) {
+ drill = bt->page->lvl;
+
+ if( lock == BtLockWrite && drill == lvl ) {
+ bt_unlockpage(mode, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ continue;
+ }
+ }
+
+ prevpage = bt->page_no;
+ prevpool = bt->pool;
+ prevset = bt->set;
+ prevmode = mode;
+
+ // find key on page at this level
+ // and either descend to requested level
+ // or return key slot
+
+ slot = bt_findslot (bt, key, len);
+
+ // is this slot < foster child area
+ // on the requested level?
+
+ // if so, return actual slot even if dead
+
+ if( slot <= bt->page->cnt - bt->page->foster )
+ if( drill == lvl )
+ return slot;
+
+ // find next active slot
+
+ // note: foster children are never dead
+ // nor fence keys for interiour nodes
+
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ return bt->err = BTERR_struct, 0; // last key shouldn't be deleted
+
+ // is this slot < foster child area
+ // if so, drill to next level
+
+ if( slot <= bt->page->cnt - bt->page->foster )
+ drill--;
+
+ // continue right onto foster child
+ // or down to next level.
+
+ page_no = bt_getid(slotptr(bt->page, slot)->id);
+
+ } while( page_no );
+
+ // return error on end of chain
+
+ bt->err = BTERR_struct;
+ return 0; // return error
+}
+
+// find and delete key on page by marking delete flag bit
+// when leaf page becomes empty, delete it from the btree
+
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len)
+{
+unsigned char leftkey[256];
+BtLatchSet *rset, *set;
+BtPool *pool, *rpool;
+BtPage rpage, page;
+uid page_no, right;
+uint slot, tod;
+BtKey ptr;
+
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // if key is found delete it, otherwise ignore request
+ // note that fence keys of interiour nodes are not deleted.
+
+ if( bt->found = !keycmp (ptr, key, len) )
+ if( bt->found = slotptr(bt->page, slot)->dead == 0 ) {
+ slotptr(bt->page,slot)->dead = 1;
+ if( slot < bt->page->cnt )
+ bt->page->dirty = 1;
+ bt->page->act--;
+ }
+
+ page_no = bt->page_no;
+ pool = bt->pool;
+ page = bt->page;
+ set = bt->set;
+
+ // return if page is not empty or not found
+
+ if( page->act || !bt->found ) {
+ bt_unlockpage(BtLockWrite, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ return bt->err;
+ }
+
+ // cache copy of fence key of empty node
+
+ ptr = keyptr(page, page->cnt);
+ memcpy(leftkey, ptr, ptr->len + 1);
+
+ // release write lock on empty node
+ // obtain Parent lock
+
+ bt_unlockpage(BtLockWrite, set);
+ bt_lockpage(BtLockParent, set);
+
+ // load and lock parent to see
+ // if delete of empty node is OK
+ // ie, not a fence key of parent
+
+ while( 1 ) {
+ if( slot = bt_loadpage (bt, leftkey+1, *leftkey, 1, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return bt->err;
+
+ // does parent level contain our fence key yet?
+ // and is it free of foster children?
+
+ if( !bt->page->foster )
+ if( !keycmp (ptr, leftkey+1, *leftkey) )
+ break;
+
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+#ifdef unix
+ sched_yield();
+#else
+ SwitchToThread();
+#endif
+ }
+
+ // find our left fence key
+
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ return bt->err = BTERR_struct; // last key shouldn't be deleted
+
+ // now we have both parent and child
+
+ bt_lockpage(BtLockDelete, set);
+ bt_lockpage(BtLockWrite, set);
+
+ // return if page has no right sibling within parent
+ // or if empty node is no longer empty
+
+ if( page->act || slot == bt->page->cnt ) {
+ // unpin parent
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ // unpin empty node
+ bt_unlockpage(BtLockParent, set);
+ bt_unlockpage(BtLockDelete, set);
+ bt_unlockpage(BtLockWrite, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ return bt->err;
+ }
+
+ // lock and map our right page
+ // note that it cannot be our foster child
+ // since the our node is empty
+
+ right = bt_getid(page->right);
+
+ if( rpool = bt_pinpool (bt, right) )
+ rpage = bt_page (bt, rpool, right);
+ else
+ return bt->err;
+
+ rset = bt_pinlatch (bt, right);
+ bt_lockpage(BtLockWrite, rset);
+ bt_lockpage(BtLockDelete, rset);
+
+ // pull contents of right page into empty page
+
+ memcpy (page, rpage, bt->mgr->page_size);
+
+ // delete left parent slot for old empty page
+ // and redirect right parent slot to it
+
+ bt->page->act--;
+ bt->page->dirty = 1;
+ slotptr(bt->page, slot)->dead = 1;
+
+ while( slot++ < bt->page->cnt )
+ if( !slotptr(bt->page, slot)->dead )
+ break;
+
+ bt_putid(slotptr(bt->page,slot)->id, page_no);
+
+ // release parent level lock
+ // and our empty node lock
+
+ bt_unlockpage(BtLockWrite, set);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+
+ // add killed right block to free chain
+ // lock latch mgr
+
+ bt_spinwritelock(bt->mgr->latchmgr->lock);
+
+ // store free chain in allocation page second right
+ bt_putid(rpage->right, bt_getid(bt->mgr->latchmgr->alloc[1].right));
+ bt_putid(bt->mgr->latchmgr->alloc[1].right, right);
+
+ // unlock latch mgr and right page
+
+ bt_spinreleasewrite(bt->mgr->latchmgr->lock);
+
+ bt_unlockpage(BtLockWrite, rset);
+ bt_unlockpage(BtLockDelete, rset);
+ bt_unpinlatch (rset);
+ bt_unpinpool (rpool);
+
+ // remove ParentModify lock
+
+ bt_unlockpage(BtLockParent, set);
+ bt_unlockpage(BtLockDelete, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ return 0;
+}
+
+// find key in leaf level and return row-id
+
+uid bt_findkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+BtKey ptr;
+uid id;
+
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ ptr = keyptr(bt->page, slot);
+ else
+ return 0;
+
+ // if key exists, return row-id
+ // otherwise return 0
+
+ if( slot <= bt->page->cnt && !keycmp (ptr, key, len) )
+ id = bt_getid(slotptr(bt->page,slot)->id);
+ else
+ id = 0;
+
+ bt_unlockpage (BtLockRead, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return id;
+}
+
+// check page for space available,
+// clean if necessary and return
+// 0 - page needs splitting
+// >0 new slot value
+
+uint bt_cleanpage(BtDb *bt, uint amt, uint slot)
+{
+uint nxt = bt->mgr->page_size;
+BtPage page = bt->page;
+uint cnt = 0, idx = 0;
+uint max = page->cnt;
+uint newslot;
+BtKey key;
+
+ if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return slot;
+
+ // skip cleanup if nothing to reclaim
+
+ if( !page->dirty )
+ return 0;
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+
+ // skip page info and set rest of page to zero
+
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ page->dirty = 0;
+ page->act = 0;
+
+ // try cleaning up page first
+
+ // always leave fence key in the array
+ // otherwise, remove deleted key
+
+ // note: foster children are never dead
+ // nor are fence keys for interiour nodes
+
+ while( cnt++ < max ) {
+ if( cnt == slot )
+ newslot = idx + 1;
+ else if( cnt < max && slotptr(bt->frame,cnt)->dead )
+ continue;
+
+ // copy key
+
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+
+ // copy slot
+ memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId);
+ if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
+ page->act++;
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ // see if page has enough space now, or does it need splitting?
+
+ if( page->min >= (idx+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return newslot;
+
+ return 0;
+}
+
+// add key to current page
+// page must already be writelocked
+
+void bt_addkeytopage (BtDb *bt, uint slot, unsigned char *key, uint len, uid id, uint tod)
+{
+BtPage page = bt->page;
+uint idx;
+
+ // find next available dead slot and copy key onto page
+ // note that foster children on the page are never dead
+
+ // look for next hole, but stay back from the fence key
+
+ for( idx = slot; idx < page->cnt; idx++ )
+ if( slotptr(page, idx)->dead )
+ break;
+
+ if( idx == page->cnt )
+ idx++, page->cnt++;
+
+ page->act++;
+
+ // now insert key into array before slot
+
+ while( idx > slot )
+ *slotptr(page, idx) = *slotptr(page, idx -1), idx--;
+
+ page->min -= len + 1;
+ ((unsigned char *)page)[page->min] = len;
+ memcpy ((unsigned char *)page + page->min +1, key, len );
+
+ bt_putid(slotptr(page,slot)->id, id);
+ slotptr(page, slot)->off = page->min;
+ slotptr(page, slot)->tod = tod;
+ slotptr(page, slot)->dead = 0;
+}
+
+// split the root and raise the height of the btree
+// call with current page locked and page no of foster child
+// return with current page (root) unlocked
+
+BTERR bt_splitroot(BtDb *bt, uid right)
+{
+uint nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+BtPage root = bt->page;
+uid new_page;
+BtKey key;
+
+ // Obtain an empty page to use, and copy the left page
+ // contents into it from the root. Strip foster child key.
+ // (it's the stopper key)
+
+ memset (slotptr(root, root->cnt), 0, sizeof(BtSlot));
+ root->dirty = 1;
+ root->foster--;
+ root->act--;
+ root->cnt--;
+
+ // Save left fence key.
+
+ key = keyptr(root, root->cnt);
+ memcpy (fencekey, key, key->len + 1);
+
+ // copy the lower keys into a new left page
+
+ if( !(new_page = bt_newpage(bt, root)) )
+ return bt->err;
+
+ // preserve the page info at the bottom
+ // and set rest of the root to zero
+
+ memset (root+1, 0, bt->mgr->page_size - sizeof(*root));
+
+ // insert left fence key on empty newroot page
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 1)->id, new_page);
+ slotptr(root, 1)->off = nxt;
+
+ // insert stopper key on newroot page
+ // and increase the root height
+
+ nxt -= 3;
+ fencekey[0] = 2;
+ fencekey[1] = 0xff;
+ fencekey[2] = 0xff;
+ memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1);
+ bt_putid(slotptr(root, 2)->id, right);
+ slotptr(root, 2)->off = nxt;
+
+ bt_putid(root->right, 0);
+ root->min = nxt; // reset lowest used offset and key count
+ root->cnt = 2;
+ root->act = 2;
+ root->lvl++;
+
+ // release and unpin root (bt->page)
+
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return 0;
+}
+
+// split already locked full node
+// in current page variables
+// return unlocked and unpinned.
+
+BTERR bt_splitpage (BtDb *bt)
+{
+uint slot, cnt, idx, max, nxt = bt->mgr->page_size;
+unsigned char fencekey[256];
+uid page_no = bt->page_no;
+BtLatchSet *set = bt->set;
+BtPool *pool = bt->pool;
+BtPage page = bt->page;
+uint tod = time(NULL);
+uint lvl = page->lvl;
+uid new_page, right;
+BtKey key;
+
+ // initialize frame buffer for right node
+
+ memset (bt->frame, 0, bt->mgr->page_size);
+ max = page->cnt - page->foster;
+ tod = (uint)time(NULL);
+ cnt = max / 2;
+ idx = 0;
+
+ // split higher half of keys to bt->frame
+ // leaving old foster children in the left node,
+ // and adding a new foster child there.
+
+ while( cnt++ < max ) {
+ key = keyptr(page, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1);
+ memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId);
+ if( !(slotptr(bt->frame, idx)->dead = slotptr(page, cnt)->dead) )
+ bt->frame->act++;
+ slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod;
+ slotptr(bt->frame, idx)->off = nxt;
+ }
+
+ // transfer right link node to new right node
+
+ if( page_no > ROOT_page ) {
+ right = bt_getid (page->right);
+ bt_putid(bt->frame->right, right);
+ }
+
+ bt->frame->bits = bt->mgr->page_bits;
+ bt->frame->min = nxt;
+ bt->frame->cnt = idx;
+ bt->frame->lvl = lvl;
+
+ // get new free page and write right frame to it.
+
+ if( !(new_page = bt_newpage(bt, bt->frame)) )
+ return bt->err;
+
+ // remember fence key for new right page to add
+ // as foster child to the left node
+
+ key = keyptr(bt->frame, idx);
+ memcpy (fencekey, key, key->len + 1);
+
+ // update lower keys and foster children to continue in old page
+
+ memcpy (bt->frame, page, bt->mgr->page_size);
+ memset (page+1, 0, bt->mgr->page_size - sizeof(*page));
+ nxt = bt->mgr->page_size;
+ page->dirty = 0;
+ page->act = 0;
+ cnt = 0;
+ idx = 0;
+
+ // assemble page of smaller keys
+ // to remain in the old page
+
+ while( cnt++ < max / 2 ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
+ page->act++;
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ }
+
+ // insert new foster child for right page in queue
+ // before any of the current foster children
+
+ nxt -= *fencekey + 1;
+ memcpy ((unsigned char *)page + nxt, fencekey, *fencekey + 1);
+
+ bt_putid (slotptr(page,++idx)->id, new_page);
+ slotptr(page, idx)->tod = tod;
+ slotptr(page, idx)->off = nxt;
+ page->foster++;
+ page->act++;
+
+ // continue with old foster child keys
+ // note that none will be dead
+
+ cnt = bt->frame->cnt - bt->frame->foster;
+
+ while( cnt++ < bt->frame->cnt ) {
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+ memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ page->act++;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ // link new right page
+
+ bt_putid (page->right, new_page);
+
+ // if current page is the root page, split it
+
+ if( page_no == ROOT_page )
+ return bt_splitroot (bt, new_page);
+
+ // release wr lock on our page
+
+ bt_unlockpage (BtLockWrite, set);
+
+ // obtain ParentModification lock for current page
+ // to fix new fence key and oldest foster child on page
+
+ bt_lockpage (BtLockParent, set);
+
+ // get our new fence key to insert in parent node
+
+ bt_lockpage (BtLockRead, set);
+
+ key = keyptr(page, page->cnt-1);
+ memcpy (fencekey, key, key->len+1);
+
+ bt_unlockpage (BtLockRead, set);
+
+ if( bt_insertkey (bt, fencekey + 1, *fencekey, page_no, tod, lvl + 1) )
+ return bt->err;
+
+ // lock our page for writing
+
+ bt_lockpage (BtLockRead, set);
+
+ // switch old parent key from us to our oldest foster child
+
+ key = keyptr(page, page->cnt);
+ memcpy (fencekey, key, key->len+1);
+
+ new_page = bt_getid (slotptr(page, page->cnt)->id);
+ bt_unlockpage (BtLockRead, set);
+
+ if( bt_insertkey (bt, fencekey + 1, *fencekey, new_page, tod, lvl + 1) )
+ return bt->err;
+
+ // now that it has its own parent pointer,
+ // remove oldest foster child from our page
+
+ bt_lockpage (BtLockWrite, set);
+ memset (slotptr(page, page->cnt), 0, sizeof(BtSlot));
+ page->dirty = 1;
+ page->foster--;
+ page->cnt--;
+ page->act--;
+
+ // unlock and unpin
+
+ bt_unlockpage (BtLockWrite, set);
+ bt_unlockpage (BtLockParent, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ return 0;
+}
+
+// Insert new key into the btree at leaf level.
+
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod, uint lvl)
+{
+uint slot, idx;
+BtPage page;
+BtKey ptr;
+
+ while( 1 ) {
+ if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) )
+ ptr = keyptr(bt->page, slot);
+ else
+ {
+ if ( !bt->err )
+ bt->err = BTERR_ovflw;
+ return bt->err;
+ }
+
+ // if key already exists, update id and return
+
+ page = bt->page;
+
+ if( !keycmp (ptr, key, len) ) {
+ if( slotptr(page, slot)->dead )
+ page->act++;
+ slotptr(page, slot)->dead = 0;
+ slotptr(page, slot)->tod = tod;
+ bt_putid(slotptr(page,slot)->id, id);
+ bt_unlockpage(BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return bt->err;
+ }
+
+ // check if page has enough space
+
+ if( slot = bt_cleanpage (bt, len, slot) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ }
+
+ bt_addkeytopage (bt, slot, key, len, id, tod);
+
+ bt_unlockpage (BtLockWrite, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return 0;
+}
+
+// cache page of keys into cursor and return starting slot for given key
+
+uint bt_startkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+
+ // cache page for retrieval
+ if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) )
+ memcpy (bt->cursor, bt->page, bt->mgr->page_size);
+
+ bt->cursor_page = bt->page_no;
+
+ bt_unlockpage(BtLockRead, bt->set);
+ bt_unpinlatch (bt->set);
+ bt_unpinpool (bt->pool);
+ return slot;
+}
+
+// return next slot for cursor page
+// or slide cursor right into next page
+
+uint bt_nextkey (BtDb *bt, uint slot)
+{
+BtLatchSet *set;
+BtPool *pool;
+BtPage page;
+uid right;
+
+ do {
+ right = bt_getid(bt->cursor->right);
+ while( slot++ < bt->cursor->cnt - bt->cursor->foster )
+ if( slotptr(bt->cursor,slot)->dead )
+ continue;
+ else if( right || (slot < bt->cursor->cnt - bt->cursor->foster) )
+ return slot;
+ else
+ break;
+
+ if( !right )
+ break;
+
+ bt->cursor_page = right;
+ if( pool = bt_pinpool (bt, right) )
+ page = bt_page (bt, pool, right);
+ else
+ return 0;
+
+ set = bt_pinlatch (bt, right);
+ bt_lockpage(BtLockRead, set);
+
+ memcpy (bt->cursor, page, bt->mgr->page_size);
+
+ bt_unlockpage(BtLockRead, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ slot = 0;
+ } while( 1 );
+
+ return bt->err = 0;
+}
+
+BtKey bt_key(BtDb *bt, uint slot)
+{
+ return keyptr(bt->cursor, slot);
+}
+
+uid bt_uid(BtDb *bt, uint slot)
+{
+ return bt_getid(slotptr(bt->cursor,slot)->id);
+}
+
+uint bt_tod(BtDb *bt, uint slot)
+{
+ return slotptr(bt->cursor,slot)->tod;
+}
+
+
+#ifdef STANDALONE
+
+void bt_latchaudit (BtDb *bt)
+{
+ushort idx, hashidx;
+BtLatchSet *set;
+BtPool *pool;
+BtPage page;
+uid page_no;
+
+#ifdef unix
+ for( idx = 1; idx < bt->mgr->latchmgr->latchdeployed; idx++ ) {
+ set = bt->mgr->latchsets + idx;
+ if( *(ushort *)set->readwr || *(ushort *)set->access || *(ushort *)set->parent ) {
+ fprintf(stderr, "latchset %d locked for page %6x\n", idx, set->page_no);
+ *(ushort *)set->readwr = 0;
+ *(ushort *)set->access = 0;
+ *(ushort *)set->parent = 0;
+ }
+ if( set->pin ) {
+ fprintf(stderr, "latchset %d pinned\n", idx);
+ set->pin = 0;
+ }
+ }
+
+ for( hashidx = 0; hashidx < bt->mgr->latchmgr->latchhash; hashidx++ ) {
+ if( *(ushort *)bt->mgr->latchmgr->table[hashidx].latch )
+ fprintf(stderr, "latchmgr locked\n");
+ if( idx = bt->mgr->latchmgr->table[hashidx].slot ) do {
+ set = bt->mgr->latchsets + idx;
+ if( *(ushort *)set->readwr || *(ushort *)set->access || *(ushort *)set->parent )
+ fprintf(stderr, "latchset %d locked\n", idx);
+ if( set->hash != hashidx )
+ fprintf(stderr, "latchset %d wrong hashidx\n", idx);
+ if( set->pin )
+ fprintf(stderr, "latchset %d pinned\n", idx);
+ } while( idx = set->next );
+ }
+ page_no = bt_getid(bt->mgr->latchmgr->alloc[1].right);
+
+ while( page_no ) {
+ fprintf(stderr, "free: %.6x\n", (uint)page_no);
+ pool = bt_pinpool (bt, page_no);
+ page = bt_page (bt, pool, page_no);
+ page_no = bt_getid(page->right);
+ bt_unpinpool (pool);
+ }
+#endif
+}
+
+typedef struct {
+ char type, idx;
+ char *infile;
+ BtMgr *mgr;
+ int num;
+} ThreadArg;
+
+// standalone program to index file of keys
+// then list them onto std-out
+
+#ifdef unix
+void *index_file (void *arg)
+#else
+uint __stdcall index_file (void *arg)
+#endif
+{
+int line = 0, found = 0, cnt = 0;
+uid next, page_no = LEAF_page; // start on first page of leaves
+unsigned char key[256];
+ThreadArg *args = arg;
+int ch, len = 0, slot;
+BtLatchSet *set;
+time_t tod[1];
+BtPool *pool;
+BtPage page;
+BtKey ptr;
+BtDb *bt;
+FILE *in;
+
+ bt = bt_open (args->mgr);
+ time (tod);
+
+ switch(args->type | 0x20)
+ {
+ case 'a':
+ fprintf(stderr, "started latch mgr audit\n");
+ bt_latchaudit (bt);
+ fprintf(stderr, "finished latch mgr audit\n");
+ break;
+ case 'w':
+ fprintf(stderr, "started indexing for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_insertkey (bt, key, len, line, *tod, 0) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys\n", args->infile, line);
+ break;
+
+ case 'd':
+ fprintf(stderr, "started deleting keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_deletekey (bt, key, len) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for keys, %d \n", args->infile, line);
+ break;
+
+ case 'f':
+ fprintf(stderr, "started finding keys for %s\n", args->infile);
+ if( in = fopen (args->infile, "rb") )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ line++;
+ if( args->num == 1 )
+ sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9;
+
+ else if( args->num )
+ sprintf((char *)key+len, "%.9d", line + args->idx * args->num), len += 9;
+
+ if( bt_findkey (bt, key, len) )
+ found++;
+ else if( bt->err )
+ fprintf(stderr, "Error %d Syserr %d Line: %d\n", bt->err, errno, line), exit(0);
+ len = 0;
+ }
+ else if( len < 255 )
+ key[len++] = ch;
+ fprintf(stderr, "finished %s for %d keys, found %d\n", args->infile, line, found);
+ break;
+
+ case 's':
+ len = key[0] = 0;
+
+ fprintf(stderr, "started reading\n");
+
+ if( slot = bt_startkey (bt, key, len) )
+ slot--;
+ else
+ fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0);
+
+ while( slot = bt_nextkey (bt, slot) ) {
+ ptr = bt_key(bt, slot);
+ fwrite (ptr->key, ptr->len, 1, stdout);
+ fputc ('\n', stdout);
+ }
+
+ break;
+
+ case 'c':
+ fprintf(stderr, "started reading\n");
+
+ do {
+ if( pool = bt_pinpool (bt, page_no) )
+ page = bt_page (bt, pool, page_no);
+ else
+ break;
+ set = bt_pinlatch (bt, page_no);
+ bt_lockpage (BtLockRead, set);
+ cnt += page->act;
+ next = bt_getid (page->right);
+ bt_unlockpage (BtLockRead, set);
+ bt_unpinlatch (set);
+ bt_unpinpool (pool);
+ } while( page_no = next );
+
+ cnt--; // remove stopper key
+ fprintf(stderr, " Total keys read %d\n", cnt);
+ break;
+ }
+
+ bt_close (bt);
+#ifdef unix
+ return NULL;
+#else
+ return 0;
+#endif
+}
+
+typedef struct timeval timer;
+
+int main (int argc, char **argv)
+{
+int idx, cnt, len, slot, err;
+int segsize, bits = 16;
+#ifdef unix
+pthread_t *threads;
+timer start, stop;
+#else
+time_t start[1], stop[1];
+HANDLE *threads;
+#endif
+double real_time;
+ThreadArg *args;
+uint poolsize = 0;
+int num = 0;
+char key[1];
+BtMgr *mgr;
+BtKey ptr;
+BtDb *bt;
+
+ if( argc < 3 ) {
+ fprintf (stderr, "Usage: %s idx_file Read/Write/Scan/Delete/Find [page_bits mapped_segments seg_bits line_numbers src_file1 src_file2 ... ]\n", argv[0]);
+ fprintf (stderr, " where page_bits is the page size in bits\n");
+ fprintf (stderr, " mapped_segments is the number of mmap segments in buffer pool\n");
+ fprintf (stderr, " seg_bits is the size of individual segments in buffer pool in pages in bits\n");
+ fprintf (stderr, " line_numbers = 1 to append line numbers to keys\n");
+ fprintf (stderr, " src_file1 thru src_filen are files of keys separated by newline\n");
+ exit(0);
+ }
+
+#ifdef unix
+ gettimeofday(&start, NULL);
+#else
+ time(start);
+#endif
+
+ if( argc > 3 )
+ bits = atoi(argv[3]);
+
+ if( argc > 4 )
+ poolsize = atoi(argv[4]);
+
+ if( !poolsize )
+ fprintf (stderr, "Warning: no mapped_pool\n");
+
+ if( poolsize > 65535 )
+ fprintf (stderr, "Warning: mapped_pool > 65535 segments\n");
+
+ if( argc > 5 )
+ segsize = atoi(argv[5]);
+ else
+ segsize = 4; // 16 pages per mmap segment
+
+ if( argc > 6 )
+ num = atoi(argv[6]);
+
+ cnt = argc - 7;
+#ifdef unix
+ threads = malloc (cnt * sizeof(pthread_t));
+#else
+ threads = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, cnt * sizeof(HANDLE));
+#endif
+ args = malloc (cnt * sizeof(ThreadArg));
+
+ mgr = bt_mgr ((argv[1]), BT_rw, bits, poolsize, segsize, poolsize / 8);
+
+ if( !mgr ) {
+ fprintf(stderr, "Index Open Error %s\n", argv[1]);
+ exit (1);
+ }
+
+ // fire off threads
+
+ for( idx = 0; idx < cnt; idx++ ) {
+ args[idx].infile = argv[idx + 7];
+ args[idx].type = argv[2][0];
+ args[idx].mgr = mgr;
+ args[idx].num = num;
+ args[idx].idx = idx;
+#ifdef unix
+ if( err = pthread_create (threads + idx, NULL, index_file, args + idx) )
+ fprintf(stderr, "Error creating thread %d\n", err);
+#else
+ threads[idx] = (HANDLE)_beginthreadex(NULL, 65536, index_file, args + idx, 0, NULL);
+#endif
+ }
+
+ // wait for termination
+
+#ifdef unix
+ for( idx = 0; idx < cnt; idx++ )
+ pthread_join (threads[idx], NULL);
+ gettimeofday(&stop, NULL);
+ real_time = 1000.0 * ( stop.tv_sec - start.tv_sec ) + 0.001 * (stop.tv_usec - start.tv_usec );
+#else
+ WaitForMultipleObjects (cnt, threads, TRUE, INFINITE);
+
+ for( idx = 0; idx < cnt; idx++ )
+ CloseHandle(threads[idx]);
+
+ time (stop);
+ real_time = 1000 * (*stop - *start);
+#endif
+ fprintf(stderr, " Time to complete: %.2f seconds\n", real_time/1000);
+ bt_mgrclose (mgr);
+}
+
+#endif //STANDALONE
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