--- /dev/null
+// btree version threads2i linux futex concurrency version
+// 09 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
+#include <linux/futex.h>
+#define SYS_futex 202
+#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>
+#include <limits.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) ParentModification: Exclusive. Change the node's parent keys. Incompatible with another ParentModification.
+*/
+
+typedef enum{
+ BtLockAccess,
+ BtLockDelete,
+ BtLockRead,
+ BtLockWrite,
+ BtLockParent
+} BtLock;
+
+// mode & definition for latch implementation
+
+enum {
+ Mutex = 1 << 0, // the mutex bit
+ Write = 1 << 1, // the writers bit
+ Share = 1 << 2, // reader count
+ PendRd = 1 << 12, // reader contended count
+ PendWr = 1 << 22 // writer contended count
+} LockMode;
+
+enum {
+ QueRd = 1, // reader queue
+ QueWr = 2 // writer queue
+} RWQueue;
+
+// share is count of read accessors
+// grant write lock when share == 0
+
+typedef struct {
+ volatile uint mutex:1; // 1 = busy
+ volatile uint write:1; // 1 = exclusive
+ volatile uint share:10; // count of readers holding locks
+ volatile uint readwait:10; // count of readers waiting
+ volatile uint writewait:10; // count of writers waiting
+} BtLatch;
+
+typedef struct {
+ BtLatch readwr[1]; // read/write page lock
+ BtLatch access[1]; // Access Intent/Page delete
+ BtLatch parent[1]; // Parent modification
+} BtLatchSet;
+
+// 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 {
+ BtLatchSet latch[1]; // Set of three latches
+ uint cnt; // count of keys in page
+ uint act; // count of active keys
+ uint min; // next key offset
+ 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 has deleted keys
+ unsigned char right[BtId]; // page number to right
+} *BtPage;
+
+// 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 slot; // slot index in this array
+ volatile uint pin; // mapped page pin counter
+ 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
+} 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
+ char *pooladvise; // bit maps for pool page advisements
+ int idx;
+#else
+ HANDLE idx;
+#endif
+ volatile uint poolcnt; // highest page pool node in use
+ volatile uint evicted; // last evicted hash table slot
+ 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
+ ushort *hash; // pool index for hash entries
+ BtLatch *latch; // latches for hash table slots
+ BtPool *pool; // 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 ( mapped to page 0 )
+ BtPage cursor; // cached frame for start/next (never mapped)
+ BtPage frame; // spare frame for the page split (never mapped)
+ BtPage zero; // page of zeroes to extend the file (never mapped)
+ BtPage page; // current page mapped from file
+ 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, uint lvl, 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 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.
+
+// The b-tree pages are linked with next
+// pointers to facilitate enumerators,
+// and provide for concurrency.
+
+// 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 optionally
+// cached with a memory mapped pool. 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. The right
+// page numbers are used in cases where the page is being split,
+// or consolidated.
+
+// Page 0 is dedicated to lock for new page extensions,
+// and chains empty pages together for reuse.
+
+// The ParentModification lock on a node is obtained to prevent resplitting
+// or deleting a node before its fence is posted into its upper level.
+
+// 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 = 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;
+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->pool = calloc (poolmax, sizeof(BtPool));
+ mgr->hash = calloc (hashsize, sizeof(ushort));
+ mgr->latch = calloc (hashsize, sizeof(BtLatch));
+ 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(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);
+
+ 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
+
+int sys_futex(void *addr1, int op, int val1, struct timespec *timeout, void *addr2, int val3)
+{
+ return syscall(SYS_futex, addr1, op, val1, timeout, addr2, val3);
+}
+
+// wait until write lock mode is clear
+// and add 1 to the share count
+
+void bt_readlock(BtLatch *latch, int private)
+{
+uint prev;
+
+ if( private )
+ private = FUTEX_PRIVATE_FLAG;
+
+ while( 1 ) {
+ // obtain latch mutex
+ if( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex ) {
+ sched_yield();
+ continue;
+ }
+
+ // wait for writers to clear
+ // increment read waiters and wait
+
+ if( latch->write || latch->writewait ) {
+ __sync_fetch_and_add ((uint *)latch, PendRd);
+ prev = __sync_fetch_and_and ((uint *)latch, ~Mutex) & ~Mutex;
+ sys_futex( (uint *)latch, FUTEX_WAIT_BITSET | private, prev, NULL, NULL, QueRd );
+ __sync_fetch_and_sub ((uint *)latch, PendRd);
+ continue;
+ }
+
+ // increment reader lock count
+ // and release latch mutex
+
+ __sync_fetch_and_add ((uint *)latch, Share);
+ __sync_fetch_and_and ((uint *)latch, ~Mutex);
+ return;
+ }
+}
+
+// wait for other read and write latches to relinquish
+
+void bt_writelock(BtLatch *latch, int private)
+{
+uint prev;
+
+ if( private )
+ private = FUTEX_PRIVATE_FLAG;
+
+ while( 1 ) {
+ // obtain latch mutex
+ if( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex ) {
+ sched_yield();
+ continue;
+ }
+
+ // wait for write and reader count to clear
+
+ if( latch->write || latch->share ) {
+ __sync_fetch_and_add ((uint *)latch, PendWr);
+ prev = __sync_fetch_and_and ((uint *)latch, ~Mutex) & ~Mutex;
+ sys_futex( (uint *)latch, FUTEX_WAIT_BITSET | private, prev, NULL, NULL, QueWr );
+ __sync_fetch_and_sub ((uint *)latch, PendWr);
+ continue;
+ }
+
+ // take write mutex
+ // release latch mutex
+
+ __sync_fetch_and_or ((uint *)latch, Write);
+ __sync_fetch_and_and ((uint *)latch, ~Mutex);
+ return;
+ }
+}
+
+// try to obtain write lock
+
+// return 1 if obtained,
+// 0 otherwise
+
+int bt_writetry(BtLatch *latch)
+{
+int ans;
+
+ // try for mutex,
+ // abandon request if not taken
+
+ if( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex )
+ return 0;
+
+ // see if write mode is available
+
+ if( !latch->write && !latch->share ) {
+ __sync_fetch_and_or ((uint *)latch, Write);
+ ans = 1;
+ } else
+ ans = 0;
+
+ // release latch mutex
+
+ __sync_fetch_and_and ((uint *)latch, ~Mutex);
+ return ans;
+}
+
+// clear write lock
+
+void bt_releasewrite(BtLatch *latch, int private)
+{
+ if( private )
+ private = FUTEX_PRIVATE_FLAG;
+
+ // obtain latch mutex
+
+ while( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex )
+ sched_yield();
+
+ __sync_fetch_and_and ((uint *)latch, ~Write);
+
+ // favor writers
+
+ if( latch->writewait )
+ if( sys_futex( (uint *)latch, FUTEX_WAKE_BITSET | private, 1, NULL, NULL, QueWr ) )
+ goto wakexit;
+
+ if( latch->readwait )
+ sys_futex( (uint *)latch, FUTEX_WAKE_BITSET | private, INT_MAX, NULL, NULL, QueRd );
+
+ // release latch mutex
+
+wakexit:
+ __sync_fetch_and_and ((uint *)latch, ~Mutex);
+}
+
+// decrement reader count
+
+void bt_releaseread(BtLatch *latch, int private)
+{
+ if( private )
+ private = FUTEX_PRIVATE_FLAG;
+
+ // obtain latch mutex
+
+ while( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex )
+ sched_yield();
+
+ __sync_fetch_and_sub ((uint *)latch, Share);
+
+ // wake waiting writers
+
+ if( !latch->share && latch->writewait )
+ sys_futex( (uint *)latch, FUTEX_WAKE_BITSET | private, 1, NULL, NULL, QueWr );
+
+ // release latch mutex
+
+ __sync_fetch_and_and ((uint *)latch, ~Mutex);
+}
+
+// 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;
+
+ // lock hash table chain
+
+ idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize;
+ bt_readlock (&bt->mgr->latch[idx], 1);
+
+ // 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], 1);
+ pool->lru++;
+ return pool;
+ }
+
+ // upgrade to write lock
+
+ bt_releaseread (&bt->mgr->latch[idx], 1);
+ bt_writelock (&bt->mgr->latch[idx], 1);
+
+ // 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], 1);
+ 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 = 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
+ _InterlockedIncrement (&pool->pin);
+#endif
+ bt_releasewrite (&bt->mgr->latch[idx], 1);
+ 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 pool entry is empty
+ // or any pages are pinned
+ // skip this entry
+
+ if( !(pool = bt_findlru(bt, bt->mgr->hash[victim])) ) {
+ bt_releasewrite (&bt->mgr->latch[victim], 1);
+ 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], 1);
+
+ // 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], 1);
+ 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)
+{
+uint subpage;
+BtPool *pool;
+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;
+
+ 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
+
+ switch( mode ) {
+ case BtLockRead:
+ bt_readlock (page->latch->readwr, 0);
+ break;
+ case BtLockWrite:
+ bt_writelock (page->latch->readwr, 0);
+ break;
+ case BtLockAccess:
+ bt_readlock (page->latch->access, 0);
+ break;
+ case BtLockDelete:
+ bt_writelock (page->latch->access, 0);
+ break;
+ case BtLockParent:
+ bt_writelock (page->latch->parent, 0);
+ break;
+ default:
+ return bt->err = BTERR_lock;
+ }
+
+ if( pageptr )
+ *pageptr = page;
+ return bt->err = 0;
+}
+
+// remove write, read, or parent lock on requested page
+
+BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode)
+{
+uint subpage, idx;
+BtPool *pool;
+BtPage page;
+
+ // 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], 1);
+
+ 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], 1);
+ page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits));
+
+ switch( mode ) {
+ case BtLockRead:
+ bt_releaseread (page->latch->readwr, 0);
+ break;
+ case BtLockWrite:
+ bt_releasewrite (page->latch->readwr, 0);
+ break;
+ case BtLockAccess:
+ bt_releaseread (page->latch->access, 0);
+ break;
+ case BtLockDelete:
+ bt_releasewrite (page->latch->access, 0);
+ break;
+ case BtLockParent:
+ bt_releasewrite (page->latch->parent, 0);
+ 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 subpage;
+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 writing first page of pool block
+ // expand file thru last page in the block
+
+ if( !reuse && (new_page & bt->mgr->poolmask) == 0 )
+ 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;
+#endif
+ // unlock page allocation page
+
+ if( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
+ return 0;
+
+ // bring new page into pool and copy page.
+ // on Windows, this will extend the file into the new page.
+
+ if( bt_lockpage(bt, new_page, BtLockWrite, &pmap) )
+ return 0;
+
+ // copy source page but leave latch area intact
+
+ memcpy((char *)pmap + sizeof(BtLatchSet), (char *)page + sizeof(BtLatchSet), bt->mgr->page_size - sizeof(BtLatchSet));
+
+ if( bt_unlockpage (bt, new_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;
+uint good = 0;
+
+ // make stopper key an infinite fence value
+
+ if( bt_getid (bt->page->right) )
+ higher++;
+ else
+ good++;
+
+ // low is the next 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, good++;
+ }
+
+ // return zero if key is on right link page
+
+ return good ? higher : 0;
+}
+
+// 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->lvl != drill) {
+ if ( bt->page_no != ROOT_page )
+ return bt->err = BTERR_struct, 0;
+
+ drill = bt->page->lvl;
+
+ if( lock == BtLockWrite && drill == lvl )
+ if( bt_unlockpage(bt, page_no, mode) )
+ return 0;
+ else
+ continue;
+ }
+
+ // find key on page at this level
+ // and descend to requested level
+
+ if( !bt->page->kill && (slot = bt_findslot (bt, key, len)) ) {
+ if( drill == lvl )
+ return slot;
+
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else {
+ page_no = bt_getid(bt->page->right);
+ goto slideright;
+ }
+
+ page_no = bt_getid(slotptr(bt->page, slot)->id);
+ drill--;
+ }
+
+ // or slide right into next page
+ // (slide left from deleted page)
+
+ else
+ page_no = bt_getid(bt->page->right);
+
+ // continue down / right using overlapping locks
+ // to protect pages being killed or split.
+
+slideright:
+ prevpage = bt->page_no;
+ prevmode = mode;
+ } while( page_no );
+
+ // return error on end of right 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
+
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl)
+{
+unsigned char lowerkey[256], higherkey[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;
+
+ // keep copy of key to delete
+
+ ptr = keyptr(bt->page, bt->page->cnt);
+ memcpy(lowerkey, 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((char *)bt->page + sizeof(BtLatchSet), (char *)bt->temp + sizeof(BtLatchSet), bt->mgr->page_size - sizeof(BtLatchSet));
+
+ // keep copy of key to update
+ ptr = keyptr(bt->temp, bt->temp->cnt);
+ memcpy(higherkey, 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, lowerkey + 1, *lowerkey, lvl + 1) )
+ return bt->err;
+
+ // redirect higher key directly to consolidated node
+
+ tod = (uint)time(NULL);
+
+ if( bt_insertkey (bt, higherkey+1, *higherkey, lvl + 1, page_no, tod) )
+ return bt->err;
+
+ // 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 >= (page->cnt+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;
+
+ 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 >= (page->cnt+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return 1;
+
+ return 0;
+}
+
+// split the root and raise the height of the btree
+
+BTERR bt_splitroot(BtDb *bt, unsigned char *newkey, unsigned char *oldkey, uid page_no2)
+{
+uint nxt = bt->mgr->page_size;
+BtPage root = bt->page;
+uid new_page;
+
+ // Obtain an empty page to use, and copy the current
+ // root contents into it which is the lower half of
+ // the old root.
+
+ if( !(new_page = bt_newpage(bt, root)) )
+ 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 first key on newroot page
+
+ nxt -= *newkey + 1;
+ memcpy ((unsigned char *)root + nxt, newkey, *newkey + 1);
+ bt_putid(slotptr(root, 1)->id, new_page);
+ slotptr(root, 1)->off = nxt;
+
+ // insert second key on newroot page
+ // and increase the root height
+
+ nxt -= *oldkey + 1;
+ memcpy ((unsigned char *)root + nxt, oldkey, *oldkey + 1);
+ bt_putid(slotptr(root, 2)->id, page_no2);
+ 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 cnt = 0, idx = 0, max, nxt = bt->mgr->page_size;
+unsigned char oldkey[256], lowerkey[256];
+uid page_no = bt->page_no, right;
+BtPage page = bt->page;
+uint lvl = page->lvl;
+uid new_page;
+BtKey key;
+uint tod;
+
+ // split higher half of keys to bt->frame
+ // the last key (fence key) might be dead
+
+ tod = (uint)time(NULL);
+
+ memset (bt->frame, 0, bt->mgr->page_size);
+ max = (int)page->cnt;
+ cnt = max / 2;
+ idx = 0;
+
+ 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;
+ }
+
+ // remember existing fence key for new page to the right
+
+ memcpy (oldkey, key, key->len + 1);
+
+ bt->frame->bits = bt->mgr->page_bits;
+ bt->frame->min = nxt;
+ bt->frame->cnt = idx;
+ bt->frame->lvl = lvl;
+
+ // link right node
+
+ if( page_no > ROOT_page ) {
+ right = bt_getid (page->right);
+ bt_putid(bt->frame->right, right);
+ }
+
+ // get new free page and write frame to it.
+
+ if( !(new_page = bt_newpage(bt, bt->frame)) )
+ return bt->err;
+
+ // update lower keys 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
+ // (they're all active keys)
+
+ 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++;
+ }
+
+ // remember fence key for old page
+
+ memcpy(lowerkey, key, key->len + 1);
+ bt_putid(page->right, new_page);
+ page->min = nxt;
+ page->cnt = idx;
+
+ // if current page is the root page, split it
+
+ if( page_no == ROOT_page )
+ return bt_splitroot (bt, lowerkey, oldkey, new_page);
+
+ // obtain Parent/Write locks
+ // for left and right node pages
+
+ if( bt_lockpage (bt, new_page, BtLockParent, NULL) )
+ return bt->err;
+
+ if( bt_lockpage (bt, page_no, BtLockParent, NULL) )
+ return bt->err;
+
+ // release wr lock on left page
+
+ if( bt_unlockpage (bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ // insert new fence for reformulated left block
+
+ if( bt_insertkey (bt, lowerkey+1, *lowerkey, lvl + 1, page_no, tod) )
+ return bt->err;
+
+ // fix old fence for newly allocated right block page
+
+ if( bt_insertkey (bt, oldkey+1, *oldkey, lvl + 1, new_page, tod) )
+ return bt->err;
+
+ // release Parent & Write locks
+
+ if( bt_unlockpage (bt, new_page, BtLockParent) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, page_no, BtLockParent) )
+ return bt->err;
+
+ return 0;
+}
+
+// Insert new key into the btree at requested level.
+// Level zero pages are leaf pages and are unlocked at exit.
+// Interior pages remain locked.
+
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uint lvl, uid id, uint tod)
+{
+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) ) {
+ 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;
+ }
+
+ // calculate next available slot and copy key into page
+
+ page->min -= len + 1; // reset lowest used offset
+ ((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);
+}
+
+// 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)
+{
+off64_t right;
+
+ do {
+ right = bt_getid(bt->cursor->right);
+ while( slot++ < bt->cursor->cnt )
+ if( slotptr(bt->cursor,slot)->dead )
+ continue;
+ else if( right || (slot < bt->cursor->cnt))
+ return slot;
+ else
+ break;
+
+ if( !right )
+ break;
+
+ bt->cursor_page = right;
+
+ if( bt_lockpage(bt, right, BtLockRead, &bt->page) )
+ return 0;
+
+ memcpy (bt->cursor, bt->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, 0, 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 set to 1 to append line numbers to input lines\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: mapped_pool has no segments\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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