--- /dev/null
+// btree version 2p
+// 26 APR 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 <time.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <errno.h>
+#else
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <fcntl.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_fl 0x6c66 // fl
+
+#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
+
+/*
+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;
+
+// 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 2 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 if dead.
+
+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[0];
+} *BtKey;
+
+// The first part of an index page.
+// It is immediately followed
+// by the BtSlot array of keys.
+
+typedef struct {
+ 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:7; // level of page
+ unsigned char kill:1; // page is being deleted
+ unsigned char right[BtId]; // page number to right
+} *BtPage;
+
+// The memory mapping hash table entry
+
+typedef struct {
+ BtPage page; // mapped page pointer
+ uid page_no; // mapped page number
+ void *lruprev; // least recently used previous cache block
+ void *lrunext; // lru next cache block
+ 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
+}BtHash;
+
+// The object structure for Btree access
+
+typedef struct _BtDb {
+ uint page_size; // each page size
+ uint page_bits; // each page size in bits
+ uint seg_bits; // segment size in pages in bits
+ uid page_no; // current page number
+ uid cursor_page; // current cursor page number
+ int err;
+ uint mode; // read-write mode
+ uint mapped_io; // use memory mapping
+ 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; // zeroes frame buffer (never mapped)
+ BtPage page; // current page
+#ifdef unix
+ int idx;
+#else
+ HANDLE idx;
+#endif
+ unsigned char *mem; // frame, cursor, page memory buffer
+ int nodecnt; // highest page cache segment in use
+ int nodemax; // highest page cache segment allocated
+ int hashmask; // number of pages in segments - 1
+ int hashsize; // size of hash table
+ BtHash *lrufirst; // lru list head
+ BtHash *lrulast; // lru list tail
+ ushort *cache; // hash table for cached segments
+ BtHash nodes[1]; // segment cache follows
+} 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 (char *name, uint mode, uint bits, uint cacheblk, uint pgblk);
+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);
+
+// 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
+
+// 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 right
+// 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 from the btree are optionally
+// cached with memory mapping. A hash table is used to keep
+// track of the cached pages. This behaviour is controlled
+// by the number of cache blocks parameter and pages per block
+// given 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.
+
+// Parent locks are obtained to prevent resplitting or deleting a node
+// before its fence is posted into its upper level.
+
+// Empty nodes are chained together through the ALLOC page and reused.
+
+// A special open mode of BT_fl is provided to safely access files on
+// WIN32 networks. WIN32 network operations should not use memory mapping.
+// This WIN32 mode sets FILE_FLAG_NOBUFFERING and FILE_FLAG_WRITETHROUGH
+// to prevent local caching of network file contents.
+
+// Access macros to address slot and key values from the page.
+// Page slots use 1 based indexing.
+
+#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;
+}
+
+// place write, read, or parent lock on requested page_no.
+
+BTERR bt_lockpage(BtDb *bt, uid page_no, BtLock mode)
+{
+off64_t off = page_no << bt->page_bits;
+#ifdef unix
+int flag = PROT_READ | ( bt->mode == BT_ro ? 0 : PROT_WRITE );
+struct flock lock[1];
+#else
+uint flags = 0, len;
+OVERLAPPED ovl[1];
+#endif
+
+ if( mode == BtLockRead || mode == BtLockWrite )
+ off += sizeof(*bt->page); // use second segment
+
+ if( mode == BtLockParent )
+ off += 2 * sizeof(*bt->page); // use third segment
+
+#ifdef unix
+ memset (lock, 0, sizeof(lock));
+
+ lock->l_start = off;
+ lock->l_type = (mode == BtLockDelete || mode == BtLockWrite || mode == BtLockParent) ? F_WRLCK : F_RDLCK;
+ lock->l_len = sizeof(*bt->page);
+ lock->l_whence = 0;
+
+ if( fcntl (bt->idx, F_SETLKW, lock) < 0 )
+ return bt->err = BTERR_lock;
+
+ return 0;
+#else
+ memset (ovl, 0, sizeof(ovl));
+ ovl->OffsetHigh = (uint)(off >> 32);
+ ovl->Offset = (uint)off;
+ len = sizeof(*bt->page);
+
+ // use large offsets to
+ // simulate advisory locking
+
+ ovl->OffsetHigh |= 0x80000000;
+
+ if( mode == BtLockDelete || mode == BtLockWrite || mode == BtLockParent )
+ flags |= LOCKFILE_EXCLUSIVE_LOCK;
+
+ if( LockFileEx (bt->idx, flags, 0, len, 0L, ovl) )
+ return bt->err = 0;
+
+ return bt->err = BTERR_lock;
+#endif
+}
+
+// remove write, read, or parent lock on requested page_no.
+
+BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode)
+{
+off64_t off = page_no << bt->page_bits;
+#ifdef unix
+struct flock lock[1];
+#else
+OVERLAPPED ovl[1];
+uint len;
+#endif
+
+ if( mode == BtLockRead || mode == BtLockWrite )
+ off += sizeof(*bt->page); // use second segment
+
+ if( mode == BtLockParent )
+ off += 2 * sizeof(*bt->page); // use third segment
+
+#ifdef unix
+ memset (lock, 0, sizeof(lock));
+
+ lock->l_start = off;
+ lock->l_type = F_UNLCK;
+ lock->l_len = sizeof(*bt->page);
+ lock->l_whence = 0;
+
+ if( fcntl (bt->idx, F_SETLK, lock) < 0 )
+ return bt->err = BTERR_lock;
+#else
+ memset (ovl, 0, sizeof(ovl));
+ ovl->OffsetHigh = (uint)(off >> 32);
+ ovl->Offset = (uint)off;
+ len = sizeof(*bt->page);
+
+ // use large offsets to
+ // simulate advisory locking
+
+ ovl->OffsetHigh |= 0x80000000;
+
+ if( !UnlockFileEx (bt->idx, 0, len, 0, ovl) )
+ return GetLastError(), bt->err = BTERR_lock;
+#endif
+
+ return bt->err = 0;
+}
+
+// close and release memory
+
+void bt_close (BtDb *bt)
+{
+BtHash *hash;
+#ifdef unix
+ // release mapped pages
+
+ if( hash = bt->lrufirst )
+ do munmap (hash->page, (bt->hashmask+1) << bt->page_bits);
+ while(hash = hash->lrunext);
+
+ if ( bt->mem )
+ free (bt->mem);
+ close (bt->idx);
+ free (bt->cache);
+ free (bt);
+#else
+ if( hash = bt->lrufirst )
+ do
+ {
+ FlushViewOfFile(hash->page, 0);
+ UnmapViewOfFile(hash->page);
+ CloseHandle(hash->hmap);
+ } while(hash = hash->lrunext);
+
+ if ( bt->mem)
+ VirtualFree (bt->mem, 0, MEM_RELEASE);
+ FlushFileBuffers(bt->idx);
+ CloseHandle(bt->idx);
+ GlobalFree (bt->cache);
+ GlobalFree (bt);
+#endif
+}
+
+// open/create new btree
+// call with file_name, BT_openmode, bits in page size (e.g. 16),
+// size of mapped page cache (e.g. 8192) or zero for no mapping.
+
+BtDb *bt_open (char *name, uint mode, uint bits, uint nodemax, uint pgblk)
+{
+uint lvl, attr, cacheblk, last;
+BtLock lockmode = BtLockWrite;
+BtPage alloc;
+off64_t size;
+uint amt[1];
+BtKey key;
+BtDb* bt;
+
+#ifndef unix
+SYSTEM_INFO sysinfo[1];
+#endif
+
+#ifdef unix
+ bt = malloc (sizeof(BtDb) + nodemax * sizeof(BtHash));
+ memset (bt, 0, sizeof(BtDb));
+
+ switch (mode & 0x7fff)
+ {
+ case BT_fl:
+ case BT_rw:
+ bt->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
+ break;
+
+ case BT_ro:
+ default:
+ bt->idx = open ((char*)name, O_RDONLY);
+ lockmode = BtLockRead;
+ break;
+ }
+ if( bt->idx == -1 )
+ return free(bt), NULL;
+
+ if( nodemax )
+ cacheblk = 4096; // page size for unix
+ else
+ cacheblk = 0;
+
+#else
+ bt = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtDb) + nodemax * sizeof(BtHash));
+ attr = FILE_ATTRIBUTE_NORMAL;
+ switch (mode & 0x7fff)
+ {
+ case BT_fl:
+ attr |= FILE_FLAG_WRITE_THROUGH | FILE_FLAG_NO_BUFFERING;
+
+ case BT_rw:
+ bt->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
+ break;
+
+ case BT_ro:
+ default:
+ bt->idx = CreateFile(name, GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, attr, NULL);
+ lockmode = BtLockRead;
+ break;
+ }
+ if( bt->idx == INVALID_HANDLE_VALUE )
+ return GlobalFree(bt), NULL;
+
+ // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity
+ GetSystemInfo(sysinfo);
+
+ if( nodemax )
+ cacheblk = sysinfo->dwAllocationGranularity;
+ else
+ cacheblk = 0;
+#endif
+
+ // determine sanity of page size
+
+ if( bits > BT_maxbits )
+ bits = BT_maxbits;
+ else if( bits < BT_minbits )
+ bits = BT_minbits;
+
+ if ( bt_lockpage(bt, ALLOC_page, lockmode) )
+ return bt_close (bt), NULL;
+
+#ifdef unix
+ *amt = 0;
+
+ // read minimum page size to get root info
+
+ if( size = lseek (bt->idx, 0L, 2) ) {
+ alloc = malloc (BT_minpage);
+ pread(bt->idx, alloc, BT_minpage, 0);
+ bits = alloc->bits;
+ free (alloc);
+ } else if( mode == BT_ro )
+ return bt_close (bt), NULL;
+#else
+ size = GetFileSize(bt->idx, amt);
+
+ if( size || *amt ) {
+ alloc = VirtualAlloc(NULL, BT_minpage, MEM_COMMIT, PAGE_READWRITE);
+ if( !ReadFile(bt->idx, (char *)alloc, BT_minpage, amt, NULL) )
+ return bt_close (bt), NULL;
+ bits = alloc->bits;
+ VirtualFree (alloc, 0, MEM_RELEASE);
+ } else if( mode == BT_ro )
+ return bt_close (bt), NULL;
+#endif
+
+ bt->page_size = 1 << bits;
+ bt->page_bits = bits;
+
+ bt->nodemax = nodemax;
+ bt->mode = mode;
+
+ // setup cache mapping
+
+ if( cacheblk ) {
+ if( cacheblk < bt->page_size )
+ cacheblk = bt->page_size;
+
+ bt->hashsize = nodemax / 8;
+ bt->hashmask = (cacheblk >> bits) - 1;
+ bt->mapped_io = 1;
+ }
+
+ // requested number of pages per memmap segment
+
+ if( cacheblk )
+ if( (1 << pgblk) > bt->hashmask )
+ bt->hashmask = (1 << pgblk) - 1;
+
+ bt->seg_bits = 0;
+
+ while( (1 << bt->seg_bits) <= bt->hashmask )
+ bt->seg_bits++;
+
+#ifdef unix
+ bt->mem = malloc (6 *bt->page_size);
+ bt->cache = calloc (bt->hashsize, sizeof(ushort));
+#else
+ bt->mem = VirtualAlloc(NULL, 6 * bt->page_size, MEM_COMMIT, PAGE_READWRITE);
+ bt->cache = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, bt->hashsize * sizeof(ushort));
+#endif
+ bt->frame = (BtPage)bt->mem;
+ bt->cursor = (BtPage)(bt->mem + bt->page_size);
+ bt->page = (BtPage)(bt->mem + 2 * bt->page_size);
+ bt->alloc = (BtPage)(bt->mem + 3 * bt->page_size);
+ bt->temp = (BtPage)(bt->mem + 4 * bt->page_size);
+ bt->zero = (BtPage)(bt->mem + 5 * bt->page_size);
+
+ if( size || *amt ) {
+ if ( bt_unlockpage(bt, ALLOC_page, lockmode) )
+ return bt_close (bt), NULL;
+
+ return bt;
+ }
+
+ // initializes an empty b-tree with root page and page of leaves
+
+ memset (bt->alloc, 0, bt->page_size);
+ bt_putid(bt->alloc->right, MIN_lvl+1);
+ bt->alloc->bits = bt->page_bits;
+
+#ifdef unix
+ if( write (bt->idx, bt->alloc, bt->page_size) < bt->page_size )
+ return bt_close (bt), NULL;
+#else
+ if( !WriteFile (bt->idx, (char *)bt->alloc, bt->page_size, amt, NULL) )
+ return bt_close (bt), NULL;
+
+ if( *amt < bt->page_size )
+ return bt_close (bt), NULL;
+#endif
+
+ memset (bt->frame, 0, bt->page_size);
+ bt->frame->bits = bt->page_bits;
+
+ for( lvl=MIN_lvl; lvl--; ) {
+ slotptr(bt->frame, 1)->off = bt->page_size - 3;
+ bt_putid(slotptr(bt->frame, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number
+ key = keyptr(bt->frame, 1);
+ key->len = 2; // create stopper key
+ key->key[0] = 0xff;
+ key->key[1] = 0xff;
+ bt->frame->min = bt->page_size - 3;
+ bt->frame->lvl = lvl;
+ bt->frame->cnt = 1;
+ bt->frame->act = 1;
+#ifdef unix
+ if( write (bt->idx, bt->frame, bt->page_size) < bt->page_size )
+ return bt_close (bt), NULL;
+#else
+ if( !WriteFile (bt->idx, (char *)bt->frame, bt->page_size, amt, NULL) )
+ return bt_close (bt), NULL;
+
+ if( *amt < bt->page_size )
+ return bt_close (bt), NULL;
+#endif
+ }
+
+ // create empty page area by writing last page of first
+ // cache area (other pages are zeroed by O/S)
+
+ if( bt->mapped_io && bt->hashmask ) {
+ memset(bt->frame, 0, bt->page_size);
+ last = bt->hashmask;
+
+ while( last < MIN_lvl + 1 )
+ last += bt->hashmask + 1;
+#ifdef unix
+ pwrite(bt->idx, bt->frame, bt->page_size, last << bt->page_bits);
+#else
+ SetFilePointer (bt->idx, last << bt->page_bits, NULL, FILE_BEGIN);
+ if( !WriteFile (bt->idx, (char *)bt->frame, bt->page_size, amt, NULL) )
+ return bt_close (bt), NULL;
+ if( *amt < bt->page_size )
+ return bt_close (bt), NULL;
+#endif
+ }
+
+ if( bt_unlockpage(bt, ALLOC_page, lockmode) )
+ return bt_close (bt), NULL;
+
+ 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;
+}
+
+// Update current page of btree by writing file contents
+// or flushing mapped area to disk.
+
+BTERR bt_update (BtDb *bt, BtPage page, uid page_no)
+{
+off64_t off = page_no << bt->page_bits;
+
+#ifdef unix
+ if ( !bt->mapped_io )
+ if ( pwrite(bt->idx, page, bt->page_size, off) != bt->page_size )
+ return bt->err = BTERR_wrt;
+#else
+uint amt[1];
+ if ( !bt->mapped_io )
+ {
+ SetFilePointer (bt->idx, (long)off, (long*)(&off)+1, FILE_BEGIN);
+ if( !WriteFile (bt->idx, (char *)page, bt->page_size, amt, NULL) )
+ return GetLastError(), bt->err = BTERR_wrt;
+
+ if( *amt < bt->page_size )
+ return GetLastError(), bt->err = BTERR_wrt;
+ }
+ else if ( bt->mode == BT_fl ) {
+ FlushViewOfFile(page, bt->page_size);
+ FlushFileBuffers(bt->idx);
+ }
+#endif
+ return 0;
+}
+
+// find page in cache
+
+BtHash *bt_findhash(BtDb *bt, uid page_no)
+{
+BtHash *hash;
+uint idx;
+
+ // compute cache block first page and hash idx
+
+ page_no &= ~bt->hashmask;
+ idx = (uint)(page_no >> bt->seg_bits) % bt->hashsize;
+
+ if( bt->cache[idx] )
+ hash = bt->nodes + bt->cache[idx];
+ else
+ return NULL;
+
+ do if( hash->page_no == page_no )
+ break;
+ while(hash = hash->hashnext );
+
+ return hash;
+}
+
+// add page cache entry to hash index
+
+void bt_linkhash(BtDb *bt, BtHash *node, uid page_no)
+{
+uint idx = (uint)(page_no >> bt->seg_bits) % bt->hashsize;
+BtHash *hash;
+
+ if( bt->cache[idx] ) {
+ node->hashnext = hash = bt->nodes + bt->cache[idx];
+ hash->hashprev = node;
+ }
+
+ node->hashprev = NULL;
+ bt->cache[idx] = (ushort)(node - bt->nodes);
+}
+
+// remove cache entry from hash table
+
+void bt_unlinkhash(BtDb *bt, BtHash *node)
+{
+uint idx = (uint)(node->page_no >> bt->seg_bits) % bt->hashsize;
+BtHash *hash;
+
+ // unlink node
+ if( hash = node->hashprev )
+ hash->hashnext = node->hashnext;
+ else if( hash = node->hashnext )
+ bt->cache[idx] = (ushort)(hash - bt->nodes);
+ else
+ bt->cache[idx] = 0;
+
+ if( hash = node->hashnext )
+ hash->hashprev = node->hashprev;
+}
+
+// add cache page to lru chain and map pages
+
+BtPage bt_linklru(BtDb *bt, BtHash *hash, uid page_no)
+{
+int flag;
+off64_t off = (page_no & ~bt->hashmask) << bt->page_bits;
+off64_t limit = off + ((bt->hashmask+1) << bt->page_bits);
+BtHash *node;
+
+ memset(hash, 0, sizeof(BtHash));
+ hash->page_no = (page_no & ~bt->hashmask);
+ bt_linkhash(bt, hash, page_no);
+
+ if( node = hash->lrunext = bt->lrufirst )
+ node->lruprev = hash;
+ else
+ bt->lrulast = hash;
+
+ bt->lrufirst = hash;
+
+#ifdef unix
+ flag = PROT_READ | ( bt->mode == BT_ro ? 0 : PROT_WRITE );
+ hash->page = (BtPage)mmap (0, (bt->hashmask+1) << bt->page_bits, flag, MAP_SHARED, bt->idx, off);
+ if( hash->page == MAP_FAILED )
+ return bt->err = BTERR_map, (BtPage)NULL;
+
+#else
+ flag = ( bt->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE );
+ hash->hmap = CreateFileMapping(bt->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL);
+ if( !hash->hmap )
+ return bt->err = BTERR_map, NULL;
+
+ flag = ( bt->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE );
+ hash->page = MapViewOfFile(hash->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->hashmask+1) << bt->page_bits);
+ if( !hash->page )
+ return bt->err = BTERR_map, NULL;
+#endif
+
+ return (BtPage)((char*)hash->page + ((uint)(page_no & bt->hashmask) << bt->page_bits));
+}
+
+// find or place requested page in page-cache
+// return memory address where page is located.
+
+BtPage bt_hashpage(BtDb *bt, uid page_no)
+{
+BtHash *hash, *node, *next;
+BtPage page;
+
+ // find page in cache and move to top of lru list
+
+ if( hash = bt_findhash(bt, page_no) ) {
+ page = (BtPage)((char*)hash->page + ((uint)(page_no & bt->hashmask) << bt->page_bits));
+ // swap node in lru list
+ if( node = hash->lruprev ) {
+ if( next = node->lrunext = hash->lrunext )
+ next->lruprev = node;
+ else
+ bt->lrulast = node;
+
+ if( next = hash->lrunext = bt->lrufirst )
+ next->lruprev = hash;
+ else
+ return bt->err = BTERR_hash, (BtPage)NULL;
+
+ hash->lruprev = NULL;
+ bt->lrufirst = hash;
+ }
+ return page;
+ }
+
+ // map pages and add to cache entry
+
+ if( bt->nodecnt < bt->nodemax ) {
+ hash = bt->nodes + ++bt->nodecnt;
+ return bt_linklru(bt, hash, page_no);
+ }
+
+ // hash table is already full, replace last lru entry from the cache
+
+ if( hash = bt->lrulast ) {
+ // unlink from lru list
+ if( node = bt->lrulast = hash->lruprev )
+ node->lrunext = NULL;
+ else
+ return bt->err = BTERR_hash, (BtPage)NULL;
+
+#ifdef unix
+ munmap (hash->page, (bt->hashmask+1) << bt->page_bits);
+#else
+ FlushViewOfFile(hash->page, 0);
+ UnmapViewOfFile(hash->page);
+ CloseHandle(hash->hmap);
+#endif
+ // unlink from hash table
+
+ bt_unlinkhash(bt, hash);
+
+ // map and add to cache
+
+ return bt_linklru(bt, hash, page_no);
+ }
+
+ return bt->err = BTERR_hash, (BtPage)NULL;
+}
+
+// map a btree page onto current page
+
+BTERR bt_mappage (BtDb *bt, BtPage *page, uid page_no)
+{
+off64_t off = page_no << bt->page_bits;
+#ifndef unix
+int amt[1];
+#endif
+
+ if( bt->mapped_io ) {
+ bt->err = 0;
+ *page = bt_hashpage(bt, page_no);
+ return bt->err;
+ }
+#ifdef unix
+ if ( pread(bt->idx, *page, bt->page_size, off) < bt->page_size )
+ return bt->err = BTERR_map;
+#else
+ SetFilePointer (bt->idx, (long)off, (long*)(&off)+1, FILE_BEGIN);
+
+ if( !ReadFile(bt->idx, *page, bt->page_size, amt, NULL) )
+ return bt->err = BTERR_map;
+
+ if( *amt < bt->page_size )
+ return bt->err = BTERR_map;
+#endif
+ return 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 node
+
+ if( bt_lockpage(bt, page_no, BtLockDelete) )
+ return bt->err;
+
+ // obtain write lock on deleted node
+
+ if( bt_lockpage(bt, page_no, BtLockWrite) )
+ return bt->err;
+
+ if( bt_mappage (bt, &bt->temp, page_no) )
+ return bt->err;
+
+ // lock allocation page
+
+ if ( bt_lockpage(bt, ALLOC_page, BtLockWrite) )
+ return bt->err;
+
+ if( bt_mappage (bt, &bt->alloc, ALLOC_page) )
+ 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);
+
+ if( bt_update(bt, bt->alloc, ALLOC_page) )
+ return bt->err;
+ if( bt_update(bt, bt->temp, page_no) )
+ return bt->err;
+
+ // 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;
+char *pmap;
+int reuse;
+
+ // lock page zero
+
+ if ( bt_lockpage(bt, ALLOC_page, BtLockWrite) )
+ return 0;
+
+ if( bt_mappage (bt, &bt->alloc, ALLOC_page) )
+ return 0;
+
+ // use empty chain first
+ // else allocate empty page
+
+ if( new_page = bt_getid(bt->alloc[1].right) ) {
+ if( bt_mappage (bt, &bt->temp, new_page) )
+ return 0; // don't unlock on error
+ bt_putid(bt->alloc[1].right, bt_getid(bt->temp->right));
+ reuse = 1;
+ } else {
+ new_page = bt_getid(bt->alloc->right);
+ bt_putid(bt->alloc->right, new_page+1);
+ reuse = 0;
+ }
+
+ if( bt_update(bt, bt->alloc, ALLOC_page) )
+ return 0; // don't unlock on error
+
+ if( !bt->mapped_io ) {
+ if( bt_update(bt, page, new_page) )
+ return 0; //don't unlock on error
+
+ return new_page;
+ }
+
+#ifdef unix
+ if ( pwrite(bt->idx, page, bt->page_size, new_page << bt->page_bits) < bt->page_size )
+ return bt->err = BTERR_wrt, 0;
+
+ // if writing first page of hash block, zero last page in the block
+
+ if ( !reuse && bt->hashmask > 0 && (new_page & bt->hashmask) == 0 )
+ {
+ // use temp buffer to write zeros
+ memset(bt->zero, 0, bt->page_size);
+ if ( pwrite(bt->idx,bt->zero, bt->page_size, (new_page | bt->hashmask) << bt->page_bits) < bt->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( !(pmap = (char*)bt_hashpage(bt, new_page & ~bt->hashmask)) )
+ return 0;
+
+ memcpy(pmap+((new_page & bt->hashmask) << bt->page_bits), page, bt->page_size);
+#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;
+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
+
+ if( page_no > ROOT_page )
+ if( bt_lockpage(bt, bt->page_no, BtLockAccess) )
+ return 0;
+
+ if( prevpage )
+ if( bt_unlockpage(bt, prevpage, prevmode) )
+ return 0;
+
+ // obtain read lock using lock chaining
+
+ if( bt_lockpage(bt, bt->page_no, mode) )
+ return 0;
+
+ if( page_no > ROOT_page )
+ if( bt_unlockpage(bt, bt->page_no, BtLockAccess) )
+ return 0;
+
+ // map/obtain page contents
+
+ if( bt_mappage (bt, &bt->page, page_no) )
+ 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];
+uint slot, tod, dirty = 0;
+uid page_no, right;
+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 )
+ dirty = slotptr(bt->page,slot)->dead = 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 )
+ if ( dirty && bt_update(bt, bt->page, page_no) )
+ return bt->err;
+ else
+ return bt_unlockpage(bt, page_no, BtLockWrite);
+
+ // obtain Parent lock over write lock
+
+ if( bt_lockpage(bt, page_no, BtLockParent) )
+ return bt->err;
+
+ // cache 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) )
+ return bt->err;
+
+ if( bt_mappage (bt, &bt->temp, right) )
+ return bt->err;
+
+ // pull contents of next page into current empty page
+ memcpy (bt->page, bt->temp, bt->page_size);
+
+ // cache 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_update(bt, bt->page, page_no) )
+ return bt->err;
+
+ if ( bt_update(bt, bt->temp, right) )
+ return bt->err;
+
+ 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;
+}
+
+void bt_cleanpage(BtDb *bt)
+{
+uint nxt = bt->page_size;
+BtPage page = bt->page;
+uint cnt = 0, idx = 0;
+uint max = page->cnt;
+BtKey key;
+
+ memcpy (bt->frame, page, bt->page_size);
+
+ // skip page info and set rest of page to zero
+ memset (page+1, 0, bt->page_size - sizeof(*page));
+ 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;
+}
+
+// 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->page_size;
+BtPage root = bt->page;
+uid new_page;
+
+ // Obtain an empty page to use, and copy the current
+ // root contents into it
+
+ 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->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++;
+
+ // update and release root (bt->page)
+
+ if( bt_update(bt, root, bt->page_no) )
+ return bt->err;
+
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+}
+
+// split already locked full node
+// return unlocked.
+
+BTERR bt_splitpage (BtDb *bt, uint len)
+{
+uint cnt = 0, idx = 0, max, nxt = bt->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;
+
+ // perform cleanup
+
+ bt_cleanpage(bt);
+
+ // return if enough space now
+
+ if( page->min >= (page->cnt + 1) * sizeof(BtSlot) + sizeof(*page) + len + 1)
+ {
+ if ( bt_update(bt, page, page_no) )
+ return bt->err;
+
+ return bt_unlockpage(bt, page_no, BtLockWrite);
+ }
+
+ // 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->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->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->page_size);
+ memset (page+1, 0, bt->page_size - sizeof(*page));
+ nxt = bt->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);
+
+ // update left (containing) node
+
+ if( bt_update(bt, page, page_no) )
+ return bt->err;
+
+ // obtain Parent/Write locks
+ // for left and right node pages
+
+ if( bt_lockpage (bt, new_page, BtLockParent) )
+ return bt->err;
+
+ if( bt_lockpage (bt, page_no, BtLockParent) )
+ 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 nodes 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);
+ if ( bt_update(bt, bt->page, bt->page_no) )
+ return bt->err;
+ return bt_unlockpage(bt, bt->page_no, BtLockWrite);
+ }
+
+ // check if page has enough space
+
+ if( page->min >= (page->cnt + 1) * sizeof(BtSlot) + sizeof(*page) + len + 1)
+ break;
+
+ if( bt_splitpage (bt, len) )
+ 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;
+
+ if ( bt_update(bt, bt->page, bt->page_no) )
+ return bt->err;
+
+ 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->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) )
+ return 0;
+
+ if( bt_mappage (bt, &bt->page, right) )
+ break;
+
+ memcpy (bt->cursor, bt->page, bt->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
+// standalone program to index file of keys
+// then list them onto std-out
+
+int main (int argc, char **argv)
+{
+uint slot, line = 0, off = 0, found = 0;
+int dead, ch, cnt = 0, bits = 12;
+unsigned char key[256];
+clock_t done, start;
+uint pgblk = 0;
+time_t tod[1];
+uint scan = 0;
+uint len = 0;
+uint map = 0;
+BtKey ptr;
+BtDb *bt;
+FILE *in;
+
+ if( argc < 4 ) {
+ fprintf (stderr, "Usage: %s idx_file src_file Read/Write/Scan/Delete/Find [page_bits mapped_pool_segments pages_per_segment start_line_number]\n", argv[0]);
+ fprintf (stderr, " page_bits: size of btree page in bits\n");
+ fprintf (stderr, " mapped_pool_segments: size of buffer pool in segments\n");
+ fprintf (stderr, " pages_per_segment: size of buffer pool segment in pages in bits\n");
+ exit(0);
+ }
+
+ start = clock();
+ time(tod);
+
+ if( argc > 4 )
+ bits = atoi(argv[4]);
+
+ if( argc > 5 )
+ map = atoi(argv[5]);
+
+ if( map > 65536 )
+ fprintf (stderr, "Warning: buffer_pool > 65536 segments\n");
+
+ if( map && map < 8 )
+ fprintf (stderr, "Buffer_pool too small\n");
+
+ if( argc > 6 )
+ pgblk = atoi(argv[6]);
+
+ if( bits + pgblk > 30 )
+ fprintf (stderr, "Warning: very large buffer pool segment size\n");
+
+ if( argc > 7 )
+ off = atoi(argv[7]);
+
+ bt = bt_open ((argv[1]), BT_rw, bits, map, pgblk);
+
+ if( !bt ) {
+ fprintf(stderr, "Index Open Error %s\n", argv[1]);
+ exit (1);
+ }
+
+ switch(argv[3][0]| 0x20)
+ {
+ case 'w':
+ fprintf(stderr, "started indexing for %s\n", argv[2]);
+ if( argc > 2 && (in = fopen (argv[2], "rb")) )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ if( off )
+ sprintf((char *)key+len, "%.9d", line + off), 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 < 245 )
+ key[len++] = ch;
+ fprintf(stderr, "finished adding keys, %d \n", line);
+ break;
+
+ case 'd':
+ fprintf(stderr, "started deleting keys for %s\n", argv[2]);
+ if( argc > 2 && (in = fopen (argv[2], "rb")) )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ if( off )
+ sprintf((char *)key+len, "%.9d", line + off), len += 9;
+ 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 < 245 )
+ key[len++] = ch;
+ fprintf(stderr, "finished deleting keys, %d \n", line);
+ break;
+
+ case 'f':
+ fprintf(stderr, "started finding keys for %s\n", argv[2]);
+ if( argc > 2 && (in = fopen (argv[2], "rb")) )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ if( off )
+ sprintf((char *)key+len, "%.9d", line + off), len += 9;
+ 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 < 245 )
+ key[len++] = ch;
+ fprintf(stderr, "finished search of %d keys, found %d\n", line, found);
+ break;
+
+ case 's':
+ scan++;
+ break;
+
+ }
+
+ done = clock();
+ fprintf(stderr, " Time to complete: %.2f seconds\n", (float)(done - start) / CLOCKS_PER_SEC);
+
+ dead = cnt = 0;
+ 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) )
+ if( cnt++, scan ) {
+ ptr = bt_key(bt, slot);
+ fwrite (ptr->key, ptr->len, 1, stdout);
+ fputc ('\n', stdout);
+ }
+
+ fprintf(stderr, " Total keys read %d\n", cnt);
+}
+
+#endif //STANDALONE
--- /dev/null
+// foster btree
+// 26 MAY 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:7; // page size in bits
+ 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 (cacheblk, (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, 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;
+}
+
+void bt_cleanpage(BtDb *bt)
+{
+uint nxt = bt->mgr->page_size;
+BtPage page = bt->page;
+uint cnt = 0, idx = 0;
+uint max = page->cnt;
+BtKey key;
+
+ 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->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;
+}
+
+// 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 len)
+{
+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;
+
+ // perform cleanup
+
+ bt_cleanpage(bt);
+
+ // return if enough space now
+
+ if( page->min >= (page->cnt + 1) * sizeof(BtSlot) + sizeof(*page) + len + 1)
+ return bt_unlockpage(bt, page_no, BtLockWrite);
+
+ // 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->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);
+
+ // get our new fence key length
+
+ key = keyptr(page, page->cnt - 1);
+ len = key->len;
+
+ 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
+
+ if( bt->page->min < (bt->page->cnt + 1) * sizeof(BtSlot) + sizeof(*bt->page) + len + 1)
+ if( bt_splitpage (bt, len) )
+ return bt->err;
+ else
+ continue;
+ else
+ break;
+ } while( 1 );
+
+ // wait for 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--;
+ 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( page->min >= (page->cnt + 1) * sizeof(BtSlot) + sizeof(*page) + len + 1)
+ break;
+
+ if( bt_splitpage (bt, len) )
+ 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 *infile;
+ char type;
+ 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' )
+ {
+ 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;
+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 hash_size 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, " hash_size is the size of buffer pool hash table\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
+
+ cnt = argc - 6;
+#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 + 6];
+ args[idx].type = argv[2][0];
+ args[idx].mgr = mgr;
+#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
+// jaluta's balanced B-Link tree algorithms
+// 26 APR 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
+// http://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 <time.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <errno.h>
+#else
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <fcntl.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_fl 0x6c66 // fl
+
+#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_hashsize 512 // size of hash index for page cache
+#define BT_hashprime 8191 // prime number for hashing
+
+typedef enum{
+ BtLockShared = 1,
+ BtLockUpdate = 2,
+ BtLockXclusive = 3,
+ BtLockUpgrade = 4,
+}BtLock;
+
+// Define the length of the page and key pointers
+
+#define BtId 6
+
+// Page key slot definition.
+
+// If BT_maxbits is 16 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.
+
+typedef struct {
+ uint off; // page offset for key start
+ 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 up to
+// 255 value bytes.
+
+typedef struct {
+ unsigned char len;
+ unsigned char key[255];
+} *BtKey;
+
+// The first part of an index page.
+// It is immediately followed
+// by the BtSlot array of keys.
+
+typedef struct {
+ uint cnt; // count of keys in page
+ uint min; // next key offset
+ unsigned char lvl:3; // level of page
+ unsigned char bits:5; // page size in bits
+ unsigned char fence; // len of fence key at top of page
+ unsigned char right[BtId]; // page number to right
+ BtSlot slots[0]; // page slots
+} *BtPage;
+
+// The memory mapping hash table entry
+
+typedef struct {
+ BtPage page; // mapped page pointer
+ uid page_no; // mapped page number
+ void *lruprev; // least recently used previous cache block
+ void *lrunext; // lru next cache block
+ 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
+}BtHash;
+
+// The object structure for Btree access
+
+typedef struct {
+ uint page_size; // each page size
+ uint page_bits; // each page size in bits
+ uid parentpage; // current parent page number
+ uid cursorpage; // current cursor page number
+ uid childpage; // current child page number
+ int err;
+ uint mode; // read-write mode
+ uint mapped_io; // use memory mapping
+ 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 parent; // current parent page
+ BtPage child; // current child page
+ BtPage sibling; // current sibling page
+ BtPage sibling2; // current sibling2 page
+#ifdef unix
+ int idx;
+#else
+ HANDLE idx;
+#endif
+ unsigned char *mem; // frame, cursor, page memory buffer
+ int nodecnt; // highest page cache node in use
+ int nodemax; // highest page cache node allocated
+ int hashmask; // number of hash headers in cache - 1
+ BtHash *lrufirst; // lru list head
+ BtHash *lrulast; // lru list tail
+ ushort cache[BT_hashsize]; // hash index for cache
+ BtHash nodes[1]; // page cache follows
+} BtDb;
+
+typedef enum {
+BTERR_ok = 0,
+BTERR_struct,
+BTERR_ovflw,
+BTERR_lock,
+BTERR_map,
+BTERR_wrt,
+BTERR_hash,
+BTERR_restart
+} BTERR;
+
+// B-Tree functions
+extern void bt_close (BtDb *bt);
+extern BtDb *bt_open (char *name, uint mode, uint bits, uint cacheblk);
+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);
+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);
+
+// 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
+
+// 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 overflowns.
+
+// A key consists of a length byte, two bytes of
+// index number (0 - 65535), 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 at each level are linked
+// with next page to right to facilitate
+// cursors and provide for concurrency.
+
+// When to root page overflows, it is split in two and
+// the tree height is raised by a new root at page
+// one with two keys.
+
+// Groups of pages from the btree are optionally
+// cached with memory mapping. A hash table is used to keep
+// track of the cached pages. 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.
+
+// Empty nodes are chained together through the ALLOC page and reused.
+
+// A special open mode of BT_fl is provided to safely access files on
+// WIN32 networks. WIN32 network operations should not use memory mapping.
+// This WIN32 mode sets FILE_FLAG_NOBUFFERING and FILE_FLAG_WRITETHROUGH
+// to prevent local caching of network file contents.
+
+// Access macros to address slot and key values from the page
+
+#define slotptr(page, slot) ((page)->slots + 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;
+}
+
+// place requested latch on requested page_no.
+// the Shared latch is a read lock over segment 0
+// the Update latch is a write lock over segment 1
+// the Xclusive latch is a write lock over segment 0 & 1
+// the Upgrade latch upgrades Update to Xclusive
+
+BTERR bt_lockpage(BtDb *bt, uid page_no, BtLock mode)
+{
+off64_t off = page_no << bt->page_bits;
+uint len = sizeof(*bt->parent);
+uint type;
+#ifdef unix
+int flag = PROT_READ | ( bt->mode == BT_ro ? 0 : PROT_WRITE );
+struct flock lock[1];
+#else
+uint flags = 0;
+OVERLAPPED ovl[1];
+#endif
+
+ switch( mode ) {
+ case BtLockShared: // lock segment 0 w/read lock
+ type = 0;
+ break;
+
+ case BtLockUpdate: // lock segment 1 w/write lock
+ off += sizeof(*bt->parent);
+ type = 1;
+ break;
+
+ case BtLockXclusive:// lock both segments w/write lock
+ len += sizeof(*bt->parent);
+ type = 1;
+ break;
+
+ case BtLockUpgrade: // lock segment 0 w/write lock
+ type = 1;
+ break;
+ }
+
+#ifdef unix
+ memset (lock, 0, sizeof(lock));
+
+ lock->l_start = off;
+ lock->l_type = type ? F_WRLCK : F_RDLCK;
+ lock->l_len = len;
+ lock->l_whence = 0;
+
+ if( fcntl (bt->idx, F_SETLKW, lock) < 0 )
+ return bt->err = BTERR_lock;
+
+ return 0;
+#else
+ memset (ovl, 0, sizeof(ovl));
+ ovl->OffsetHigh = (uint)(off >> 32);
+ ovl->Offset = (uint)off;
+
+ // use large offsets to
+ // simulate advisory locking
+
+ ovl->OffsetHigh |= 0x80000000;
+
+ if( type = 1 )
+ flags |= LOCKFILE_EXCLUSIVE_LOCK;
+
+ if( LockFileEx (bt->idx, flags, 0, len, 0L, ovl) )
+ return bt->err = 0;
+
+ return bt->err = BTERR_lock;
+#endif
+}
+
+// remove lock on requested page_no.
+
+BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode)
+{
+off64_t off = page_no << bt->page_bits;
+uint len = sizeof(*bt->parent);
+#ifdef unix
+struct flock lock[1];
+#else
+OVERLAPPED ovl[1];
+#endif
+
+ switch( mode ) {
+ case BtLockShared: // unlock segment 0
+ break;
+
+ case BtLockUpdate: // unlock segment 1
+ off += sizeof(*bt->parent);
+ break;
+
+ case BtLockXclusive:// unlock both segments
+ len += sizeof(*bt->parent);
+ break;
+
+ case BtLockUpgrade: // unlock segment 0
+ break;
+ }
+
+#ifdef unix
+ memset (lock, 0, sizeof(lock));
+
+ lock->l_start = off;
+ lock->l_type = F_UNLCK;
+ lock->l_len = len;
+ lock->l_whence = 0;
+
+ if( fcntl (bt->idx, F_SETLK, lock) < 0 )
+ return bt->err = BTERR_lock;
+#else
+ memset (ovl, 0, sizeof(ovl));
+ ovl->OffsetHigh = (uint)(off >> 32);
+ ovl->Offset = (uint)off;
+
+ // use large offsets to
+ // simulate advisory locking
+
+ ovl->OffsetHigh |= 0x80000000;
+
+ if( !UnlockFileEx (bt->idx, 0, len, 0, ovl) )
+ return GetLastError(), bt->err = BTERR_lock;
+#endif
+
+ return bt->err = 0;
+}
+
+// close and release memory
+
+void bt_close (BtDb *bt)
+{
+BtHash *hash;
+#ifdef unix
+ // release mapped pages
+
+ if( hash = bt->lrufirst )
+ do munmap (hash->page, (bt->hashmask+1) << bt->page_bits);
+ while(hash = hash->lrunext);
+
+ if ( bt->mem )
+ free (bt->mem);
+ close (bt->idx);
+ free (bt);
+#else
+ if( hash = bt->lrufirst )
+ do
+ {
+ FlushViewOfFile(hash->page, 0);
+ UnmapViewOfFile(hash->page);
+ CloseHandle(hash->hmap);
+ } while(hash = hash->lrunext);
+
+ if ( bt->mem)
+ VirtualFree (bt->mem, 0, MEM_RELEASE);
+ FlushFileBuffers(bt->idx);
+ CloseHandle(bt->idx);
+ GlobalFree (bt);
+#endif
+}
+
+// open/create new btree
+// call with file_name, BT_openmode, bits in page size (e.g. 16),
+// size of mapped page cache (e.g. 8192) or zero for no mapping.
+
+BtDb *bt_open (char *name, uint mode, uint bits, uint nodemax)
+{
+BtLock lockmode = BtLockXclusive;
+uint lvl, attr, cacheblk;
+BtPage alloc;
+off64_t size;
+uint amt[1];
+BtKey key;
+BtDb* bt;
+
+#ifndef unix
+SYSTEM_INFO sysinfo[1];
+#endif
+
+#ifdef unix
+ bt = malloc (sizeof(BtDb) + nodemax * sizeof(BtHash));
+ memset (bt, 0, sizeof(BtDb));
+
+ switch (mode & 0x7fff)
+ {
+ case BT_fl:
+ case BT_rw:
+ bt->idx = open ((char*)name, O_RDWR | O_CREAT, 0666);
+ break;
+
+ case BT_ro:
+ default:
+ bt->idx = open ((char*)name, O_RDONLY);
+ lockmode = BtLockShared;
+ break;
+ }
+ if( bt->idx == -1 )
+ return free(bt), NULL;
+
+ if( nodemax )
+ cacheblk = 4096; // page size for unix
+ else
+ cacheblk = 0;
+
+#else
+ bt = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtDb) + nodemax * sizeof(BtHash));
+ attr = FILE_ATTRIBUTE_NORMAL;
+ switch (mode & 0x7fff)
+ {
+ case BT_fl:
+ attr |= FILE_FLAG_WRITE_THROUGH | FILE_FLAG_NO_BUFFERING;
+
+ case BT_rw:
+ bt->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL);
+ break;
+
+ case BT_ro:
+ default:
+ bt->idx = CreateFile(name, GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, attr, NULL);
+ lockmode = BtLockShared;
+ break;
+ }
+ if( bt->idx == INVALID_HANDLE_VALUE )
+ return GlobalFree(bt), NULL;
+
+ // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity
+ GetSystemInfo(sysinfo);
+
+ if( nodemax )
+ cacheblk = sysinfo->dwAllocationGranularity;
+ else
+ cacheblk = 0;
+#endif
+
+ // determine sanity of page size
+
+ if( bits > BT_maxbits )
+ bits = BT_maxbits;
+ else if( bits < BT_minbits )
+ bits = BT_minbits;
+
+ if ( bt_lockpage(bt, ALLOC_page, lockmode) )
+ return bt_close (bt), NULL;
+
+#ifdef unix
+ *amt = 0;
+
+ // read minimum page size to get root info
+
+ if( size = lseek (bt->idx, 0L, 2) ) {
+ alloc = malloc (BT_minpage);
+ pread(bt->idx, alloc, BT_minpage, 0);
+ bits = alloc->bits;
+ free (alloc);
+ } else if( mode == BT_ro )
+ return bt_close (bt), NULL;
+#else
+ size = GetFileSize(bt->idx, amt);
+
+ if( size || *amt ) {
+ alloc = VirtualAlloc(NULL, BT_minpage, MEM_COMMIT, PAGE_READWRITE);
+ if( !ReadFile(bt->idx, (char *)alloc, BT_minpage, amt, NULL) )
+ return bt_close (bt), NULL;
+ bits = alloc->bits;
+ VirtualFree (alloc, 0, MEM_RELEASE);
+ } else if( mode == BT_ro )
+ return bt_close (bt), NULL;
+#endif
+
+ bt->page_size = 1 << bits;
+ bt->page_bits = bits;
+
+ bt->nodemax = nodemax;
+ bt->mode = mode;
+
+ // setup cache mapping
+
+ if( cacheblk ) {
+ if( cacheblk < bt->page_size )
+ cacheblk = bt->page_size;
+
+ bt->hashmask = (cacheblk >> bits) - 1;
+ bt->mapped_io = 1;
+ }
+
+#ifdef unix
+ bt->mem = malloc (8 *bt->page_size);
+#else
+ bt->mem = VirtualAlloc(NULL, 8 * bt->page_size, MEM_COMMIT, PAGE_READWRITE);
+#endif
+ bt->frame = (BtPage)bt->mem;
+ bt->cursor = (BtPage)(bt->mem + bt->page_size);
+ bt->alloc = (BtPage)(bt->mem + 2 * bt->page_size);
+ bt->parent = (BtPage)(bt->mem + 3 * bt->page_size);
+ bt->child = (BtPage)(bt->mem + 4 * bt->page_size);
+ bt->temp = (BtPage)(bt->mem + 5 * bt->page_size);
+ bt->sibling = (BtPage)(bt->mem + 6 * bt->page_size);
+ bt->sibling2 = (BtPage)(bt->mem + 7 * bt->page_size);
+
+ if( size || *amt ) {
+ if ( bt_unlockpage(bt, ALLOC_page, lockmode) )
+ return bt_close (bt), NULL;
+
+ return bt;
+ }
+
+ // initialize an empty b-tree with alloc page & root page
+
+ memset (bt->alloc, 0, bt->page_size);
+ bt_putid(bt->alloc->right, ROOT_page + 1);
+ bt->alloc->bits = bt->page_bits;
+
+#ifdef unix
+ if( write (bt->idx, bt->alloc, bt->page_size) < bt->page_size )
+ return bt_close (bt), NULL;
+#else
+ if( !WriteFile (bt->idx, (char *)bt->alloc, bt->page_size, amt, NULL) )
+ return bt_close (bt), NULL;
+
+ if( *amt < bt->page_size )
+ return bt_close (bt), NULL;
+#endif
+
+ // write root page
+
+ memset (bt->frame, 0, bt->page_size);
+ bt->frame->bits = bt->page_bits;
+
+ bt->frame->min = bt->page_size;
+#ifdef unix
+ if( write (bt->idx, bt->frame, bt->page_size) < bt->page_size )
+ return bt_close (bt), NULL;
+#else
+ if( !WriteFile (bt->idx, (char *)bt->frame, bt->page_size, amt, NULL) )
+ return bt_close (bt), NULL;
+
+ if( *amt < bt->page_size )
+ return bt_close (bt), NULL;
+#endif
+
+ // create initial empty page area by writing last page of first
+ // cache area (other pages are zeroed by O/S)
+
+ if( bt->mapped_io && bt->hashmask > 2 ) {
+ memset(bt->frame, 0, bt->page_size);
+
+#ifdef unix
+ pwrite(bt->idx, bt->frame, bt->page_size, bt->hashmask << bt->page_bits);
+#else
+ SetFilePointer (bt->idx, bt->hashmask << bt->page_bits, NULL, FILE_BEGIN);
+ if( !WriteFile (bt->idx, (char *)bt->frame, bt->page_size, amt, NULL) )
+ return bt_close (bt), NULL;
+ if( *amt < bt->page_size )
+ return bt_close (bt), NULL;
+#endif
+ }
+
+ if( bt_unlockpage(bt, ALLOC_page, lockmode) )
+ return bt_close (bt), NULL;
+
+ return bt;
+}
+
+// reset parent/child page pointers
+
+void bt_resetpages (BtDb *bt)
+{
+ if( bt->mapped_io )
+ return;
+
+ bt->frame = (BtPage)bt->mem;
+ bt->cursor = (BtPage)(bt->mem + bt->page_size);
+ bt->alloc = (BtPage)(bt->mem + 2 * bt->page_size);
+ bt->parent = (BtPage)(bt->mem + 3 * bt->page_size);
+ bt->child = (BtPage)(bt->mem + 4 * bt->page_size);
+ bt->temp = (BtPage)(bt->mem + 5 * bt->page_size);
+ bt->sibling = (BtPage)(bt->mem + 6 * bt->page_size);
+ bt->sibling2 = (BtPage)(bt->mem + 7 * bt->page_size);
+}
+
+// return pointer to high key
+// or NULL if infinite value
+
+BtKey bt_highkey (BtDb *bt, BtPage page)
+{
+ if( page->lvl )
+ if( bt_getid (page->right) )
+ return keyptr(page, page->cnt);
+ else
+ return NULL;
+
+ if( bt_getid (page->right) )
+ return ((BtKey)((unsigned char*)(page) + bt->page_size - page->fence));
+
+ return NULL;
+}
+
+// return pointer to slot key in index page
+// or NULL if infinite value
+
+BtKey bt_slotkey (BtPage page, uint slot)
+{
+ if( slot < page->cnt || bt_getid (page->right) )
+ return keyptr(page, slot);
+ else
+ return NULL;
+}
+
+// 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;
+}
+
+// Update current page of btree by writing file contents
+// or flushing mapped area to disk.
+
+BTERR bt_update (BtDb *bt, BtPage page, uid page_no)
+{
+off64_t off = page_no << bt->page_bits;
+
+#ifdef unix
+ if ( !bt->mapped_io )
+ if ( pwrite(bt->idx, page, bt->page_size, off) != bt->page_size )
+ return bt->err = BTERR_wrt;
+#else
+uint amt[1];
+ if ( !bt->mapped_io )
+ {
+ SetFilePointer (bt->idx, (long)off, (long*)(&off)+1, FILE_BEGIN);
+ if( !WriteFile (bt->idx, (char *)page, bt->page_size, amt, NULL) )
+ return GetLastError(), bt->err = BTERR_wrt;
+
+ if( *amt < bt->page_size )
+ return GetLastError(), bt->err = BTERR_wrt;
+ }
+ else if ( bt->mode == BT_fl ) {
+ FlushViewOfFile(page, bt->page_size);
+ FlushFileBuffers(bt->idx);
+ }
+#endif
+ return 0;
+}
+
+// find page in cache
+
+BtHash *bt_findhash(BtDb *bt, uid page_no)
+{
+BtHash *hash;
+uint idx;
+
+ // compute cache block first page and hash idx
+
+ page_no &= ~bt->hashmask;
+ idx = (uint)(page_no * BT_hashprime % BT_hashsize);
+
+ if( bt->cache[idx] )
+ hash = bt->nodes + bt->cache[idx];
+ else
+ return NULL;
+
+ do if( hash->page_no == page_no )
+ break;
+ while(hash = hash->hashnext );
+
+ return hash;
+}
+
+// add page cache entry to hash index
+
+void bt_linkhash(BtDb *bt, BtHash *node, uid page_no)
+{
+uint idx = (uint)((page_no & ~bt->hashmask) * BT_hashprime % BT_hashsize);
+BtHash *hash;
+
+ if( bt->cache[idx] ) {
+ node->hashnext = hash = bt->nodes + bt->cache[idx];
+ hash->hashprev = node;
+ }
+
+ node->hashprev = NULL;
+ bt->cache[idx] = (ushort)(node - bt->nodes);
+}
+
+// remove cache entry from hash table
+
+void bt_unlinkhash(BtDb *bt, BtHash *node)
+{
+uint idx = (uint)((node->page_no & ~bt->hashmask) * BT_hashprime % BT_hashsize);
+BtHash *hash;
+
+ // unlink node
+ if( hash = node->hashprev )
+ hash->hashnext = node->hashnext;
+ else if( hash = node->hashnext )
+ bt->cache[idx] = (ushort)(hash - bt->nodes);
+ else
+ bt->cache[idx] = 0;
+
+ if( hash = node->hashnext )
+ hash->hashprev = node->hashprev;
+}
+
+// add cache page to lru chain and map pages
+
+BtPage bt_linklru(BtDb *bt, BtHash *hash, uid page_no)
+{
+int flag;
+off64_t off = (page_no & ~bt->hashmask) << bt->page_bits;
+off64_t limit = off + ((bt->hashmask+1) << bt->page_bits);
+BtHash *node;
+
+ memset(hash, 0, sizeof(BtHash));
+ hash->page_no = (page_no & ~bt->hashmask);
+ bt_linkhash(bt, hash, page_no);
+
+ if( node = hash->lrunext = bt->lrufirst )
+ node->lruprev = hash;
+ else
+ bt->lrulast = hash;
+
+ bt->lrufirst = hash;
+
+#ifdef unix
+ flag = PROT_READ | ( bt->mode == BT_ro ? 0 : PROT_WRITE );
+ hash->page = (BtPage)mmap (0, (bt->hashmask+1) << bt->page_bits, flag, MAP_SHARED, bt->idx, off);
+ if( (long long int)hash->page == -1LL )
+ return bt->err = BTERR_map, (BtPage)NULL;
+
+#else
+ flag = ( bt->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE );
+ hash->hmap = CreateFileMapping(bt->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL);
+ if( !hash->hmap )
+ return bt->err = BTERR_map, NULL;
+
+ flag = ( bt->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE );
+ hash->page = MapViewOfFile(hash->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->hashmask+1) << bt->page_bits);
+ if( !hash->page )
+ return bt->err = BTERR_map, NULL;
+#endif
+
+ return (BtPage)((char*)hash->page + ((uint)(page_no & bt->hashmask) << bt->page_bits));
+}
+
+// find or place requested page in page-cache
+// return memory address where page is located.
+
+BtPage bt_hashpage(BtDb *bt, uid page_no)
+{
+BtHash *hash, *node, *next;
+BtPage page;
+
+ // find page in cache and move to top of lru list
+
+ if( hash = bt_findhash(bt, page_no) ) {
+ page = (BtPage)((char*)hash->page + ((uint)(page_no & bt->hashmask) << bt->page_bits));
+ // swap node in lru list
+ if( node = hash->lruprev ) {
+ if( next = node->lrunext = hash->lrunext )
+ next->lruprev = node;
+ else
+ bt->lrulast = node;
+
+ if( next = hash->lrunext = bt->lrufirst )
+ next->lruprev = hash;
+ else
+ return bt->err = BTERR_hash, (BtPage)NULL;
+
+ hash->lruprev = NULL;
+ bt->lrufirst = hash;
+ }
+ return page;
+ }
+
+ // map pages and add to cache entry
+
+ if( bt->nodecnt < bt->nodemax ) {
+ hash = bt->nodes + ++bt->nodecnt;
+ return bt_linklru(bt, hash, page_no);
+ }
+
+ // hash table is already full, replace last lru entry from the cache
+
+ if( hash = bt->lrulast ) {
+ // unlink from lru list
+ if( node = bt->lrulast = hash->lruprev )
+ node->lrunext = NULL;
+ else
+ return bt->err = BTERR_hash, (BtPage)NULL;
+
+#ifdef unix
+ munmap (hash->page, (bt->hashmask+1) << bt->page_bits);
+#else
+ FlushViewOfFile(hash->page, 0);
+ UnmapViewOfFile(hash->page);
+ CloseHandle(hash->hmap);
+#endif
+ // unlink from hash table
+
+ bt_unlinkhash(bt, hash);
+
+ // map and add to cache
+
+ return bt_linklru(bt, hash, page_no);
+ }
+
+ return bt->err = BTERR_hash, (BtPage)NULL;
+}
+
+// map a btree page onto current page
+
+BTERR bt_mappage (BtDb *bt, BtPage *page, uid page_no)
+{
+off64_t off = page_no << bt->page_bits;
+#ifndef unix
+int amt[1];
+#endif
+
+ if( bt->mapped_io ) {
+ bt->err = 0;
+ *page = bt_hashpage(bt, page_no);
+ return bt->err;
+ }
+#ifdef unix
+ if ( pread(bt->idx, *page, bt->page_size, off) < bt->page_size )
+ return bt->err = BTERR_map;
+#else
+ SetFilePointer (bt->idx, (long)off, (long*)(&off)+1, FILE_BEGIN);
+
+ if( !ReadFile(bt->idx, *page, bt->page_size, amt, NULL) )
+ return bt->err = BTERR_map;
+
+ if( *amt < bt->page_size )
+ return bt->err = BTERR_map;
+#endif
+ return 0;
+}
+
+// deallocate a deleted page
+// place on free chain out of allocator page
+// page must already be BtLockXclusive and mapped
+
+BTERR bt_freepage (BtDb *bt, BtPage page, uid page_no)
+{
+ // lock allocation page
+
+ if ( bt_lockpage(bt, ALLOC_page, BtLockUpdate) )
+ return bt->err;
+
+ if( bt_mappage (bt, &bt->alloc, ALLOC_page) )
+ return bt->err;
+
+ // store chain in second right
+ bt_putid(page->right, bt_getid(bt->alloc[1].right));
+ bt_putid(bt->alloc[1].right, page_no);
+
+ if( bt_update(bt, bt->alloc, ALLOC_page) )
+ return bt->err;
+ if( bt_update(bt, page, page_no) )
+ return bt->err;
+
+ // unlock page zero
+
+ if( bt_unlockpage(bt, ALLOC_page, BtLockUpdate) )
+ return bt->err;
+
+ return 0;
+}
+
+// allocate a new page and write page into it
+
+uid bt_newpage(BtDb *bt, BtPage page)
+{
+uid new_page;
+char *pmap;
+int reuse;
+
+ // lock page zero
+
+ if ( bt_lockpage(bt, ALLOC_page, BtLockUpdate) )
+ return 0;
+
+ if( bt_mappage (bt, &bt->alloc, ALLOC_page) )
+ return 0;
+
+ // use empty chain first
+ // else allocate empty page
+
+ if( new_page = bt_getid(bt->alloc[1].right) ) {
+ if( bt_mappage (bt, &bt->temp, new_page) )
+ return 0; // don't unlock on error
+ bt_putid(bt->alloc[1].right, bt_getid(bt->temp->right));
+ reuse = 1;
+ } else {
+ new_page = bt_getid(bt->alloc->right);
+ bt_putid(bt->alloc->right, new_page+1);
+ reuse = 0;
+ }
+
+ if( bt_update(bt, bt->alloc, ALLOC_page) )
+ return 0; // don't unlock on error
+
+ // unlock page zero
+
+ if ( bt_unlockpage(bt, ALLOC_page, BtLockUpdate) )
+ return 0;
+
+ if( !bt->mapped_io ) {
+ if( bt_update(bt, page, new_page) )
+ return 0; //don't unlock on error
+
+ return new_page;
+ }
+
+#ifdef unix
+ if ( pwrite(bt->idx, page, bt->page_size, new_page << bt->page_bits) < bt->page_size )
+ return bt->err = BTERR_wrt, 0;
+
+ // if writing first page of hash block, zero last page in the block
+
+ if ( !reuse && bt->hashmask > 0 && (new_page & bt->hashmask) == 0 )
+ {
+ // use temp buffer to write zeros
+ memset(bt->temp, 0, bt->page_size);
+ if ( pwrite(bt->idx,bt->temp, bt->page_size, (new_page | bt->hashmask) << bt->page_bits) < bt->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( !(pmap = (char*)bt_hashpage(bt, new_page & ~bt->hashmask)) )
+ return 0;
+
+ memcpy(pmap+((new_page & bt->hashmask) << bt->page_bits), page, bt->page_size);
+#endif
+
+ return new_page;
+}
+
+// find slot in given page for given key
+
+int bt_findslot (BtPage page, unsigned char *key, uint len)
+{
+uint diff, higher = page->cnt, low = 1, slot;
+uint good = 0;
+
+ // make last key an infinite fence value
+
+ if( !page->lvl || bt_getid (page->right) )
+ higher++;
+ else
+ good++;
+
+ // low is the next candidate, higher is already
+ // tested as .ge. the given key, loop ends when they meet
+
+ if( higher )
+ while( diff = higher - low ) {
+ slot = low + ( diff >> 1 );
+ if( keycmp (keyptr(page, slot), key, len) < 0 )
+ low = slot + 1;
+ else
+ higher = slot, good++;
+ }
+
+ // return zero if key is beyond highkey value
+ // or page is empty
+
+ return good ? higher : 0;
+}
+
+// split full parent node
+
+BTERR bt_splitparent (BtDb *bt, unsigned char *key, uint len)
+{
+uint cnt = 0, idx = 0, max, nxt = bt->page_size;
+uid parentpage = bt->parentpage, right;
+BtPage page = bt->parent;
+uid new_page;
+BtKey ptr;
+
+ // upgrade parent latch to Xclusive
+
+ if( bt_lockpage (bt, bt->parentpage, BtLockUpgrade) )
+ return bt->err;
+
+ // split higher half of keys to bt->frame
+
+ memset (bt->frame, 0, bt->page_size);
+ max = (int)page->cnt;
+ cnt = max / 2;
+ idx = 0;
+
+ // link right sibling node into new right page
+
+ right = bt_getid (page->right);
+ bt_putid(bt->frame->right, right);
+
+ // record higher fence key in new right leaf page
+
+ if( bt->frame->fence = page->fence ) {
+ memcpy ((unsigned char *)bt->frame + bt->page_size - bt->frame->fence, (unsigned char *)(page) + bt->page_size - bt->frame->fence, bt->frame->fence);
+ nxt -= page->fence;
+ }
+
+ while( cnt++ < max ) {
+
+ // copy key, but not infinite values
+
+ if( cnt < max || !page->lvl || right ) {
+ ptr = keyptr(page, cnt);
+ nxt -= ptr->len + 1;
+ memcpy ((unsigned char *)bt->frame + nxt, ptr, ptr->len + 1);
+ }
+
+ // copy slot
+
+ 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->bits = bt->page_bits;
+ bt->frame->lvl = page->lvl;
+ bt->frame->min = nxt;
+ bt->frame->cnt = idx;
+
+ // get new free page and write right 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->page_size);
+ memset (page+1, 0, bt->page_size - sizeof(*page));
+ nxt = bt->page_size;
+ max /= 2;
+ cnt = 0;
+ idx = 0;
+
+ // record fence key in left leaf page
+
+ if( !page->lvl ) {
+ ptr = keyptr(bt->frame, max);
+ nxt -= ptr->len + 1;
+ memcpy ((unsigned char *)page + nxt, ptr, ptr->len + 1);
+ page->fence = ptr->len + 1;
+ }
+
+ // assemble page of smaller keys
+ // no infinite value to deal with
+
+ while( cnt++ < max ) {
+ ptr = keyptr(bt->frame, cnt);
+ nxt -= ptr->len + 1;
+ memcpy ((unsigned char *)page + nxt, ptr, ptr->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;
+ }
+
+ bt_putid(page->right, new_page);
+ page->min = nxt;
+ page->cnt = idx;
+
+ // update left node
+
+ if( bt_update(bt, page, parentpage) )
+ return bt->err;
+
+ // decide to move to new right
+ // node or stay on left node
+
+ ptr = bt_highkey (bt, page);
+
+ if( keycmp (ptr, key, len) >= 0 )
+ return bt_unlockpage (bt, parentpage, BtLockUpgrade);
+
+ bt->parentpage = new_page;
+
+ if( bt_mappage (bt, &bt->parent, new_page) )
+ return bt->err;
+ if( bt_lockpage (bt, new_page, BtLockUpdate) )
+ return bt->err;
+ if( bt_unlockpage (bt, parentpage, BtLockUpgrade) )
+ return bt->err;
+
+ return bt_unlockpage (bt, parentpage, BtLockUpdate);
+}
+
+// add unlinked node key into parent
+// childpage is existing record
+// siblingpage is right record
+
+BTERR bt_parentlink (BtDb *bt, BtPage left, uid leftpage, BtKey rightkey, uid rightpage)
+{
+BtKey leftkey = bt_highkey (bt, left);
+BtPage page = bt->parent;
+uint slot, idx;
+
+ // upgrade parent latch to exclusive
+
+ if( bt_lockpage (bt, bt->parentpage, BtLockUpgrade) )
+ return bt->err;
+
+ // find the existing right high key in the parent
+ // and fix the downlink to point to right page
+
+ if( rightkey ) {
+ if( !(slot = bt_findslot (page, rightkey->key, rightkey->len)) )
+ return bt->err = BTERR_struct;
+ } else
+ slot = page->cnt;
+
+ bt_putid(slotptr(page,slot)->id, rightpage);
+
+ // calculate next available slot and copy left key onto page
+
+ page->min -= leftkey->len + 1; // reset lowest used offset
+ memcpy ((unsigned char *)page + page->min, leftkey, leftkey->len + 1);
+
+ // now insert key into array before slot
+
+ idx = ++page->cnt;
+
+ while( idx > slot )
+ *slotptr(page, idx) = *slotptr(page, idx -1), idx--;
+
+ bt_putid(slotptr(page,slot)->id, leftpage);
+ slotptr(page, slot)->off = page->min;
+
+ if ( bt_update(bt, page, bt->parentpage) )
+ return bt->err;
+
+ // downgrade parent page lock to BtLockUpdate
+
+ if( bt_unlockpage(bt, bt->parentpage, BtLockUpgrade) )
+ return bt->err;
+
+ return 0;
+}
+
+// remove slot from parent
+
+void bt_removeslot(BtDb *bt, uint slot)
+{
+uint nxt = bt->page_size, amt;
+BtPage page = bt->parent;
+uint cnt = 0, idx = 0;
+uint max = page->cnt;
+uid right;
+BtKey key;
+
+ memcpy (bt->frame, page, bt->page_size);
+
+ // skip page info and set rest of page to zero
+ memset (page+1, 0, bt->page_size - sizeof(*page));
+
+ // copy fence key onto new page
+ if( amt = page->fence ) {
+ nxt -= amt;
+ memcpy ((unsigned char *)page + nxt, (unsigned char *)(bt->frame) + nxt, amt);
+ }
+
+ right = bt_getid (page->right);
+
+ while( cnt++ < max ) {
+
+ // skip key to delete
+
+ if( cnt == slot )
+ continue;
+
+ // copy key, but not infinite value
+
+ if( cnt < max || !page->lvl || right ) {
+ 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);
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ }
+ page->min = nxt;
+ page->cnt = idx;
+}
+
+// unlink sibling node
+
+BTERR bt_parentunlink (BtDb *bt, BtPage child, uid childpage)
+{
+BtKey parentkey = bt_highkey (bt, child);
+uint slot;
+
+ if( bt_lockpage (bt, bt->parentpage, BtLockUpgrade) )
+ return bt->err;
+
+ // delete child's slot from parent
+
+ if( slot = bt_findslot (bt->parent, parentkey->key, parentkey->len) )
+ bt_removeslot (bt, slot);
+ else
+ return bt->err + BTERR_struct;
+
+ // sibling now in the slot
+
+ bt_putid(slotptr(bt->parent,slot)->id, childpage);
+
+ if ( bt_update(bt, bt->parent, bt->parentpage) )
+ return bt->err;
+
+ // unlock parent page completely
+
+ if( bt_unlockpage (bt, bt->parentpage, BtLockUpgrade) )
+ return bt->err;
+
+ return bt_unlockpage(bt, bt->parentpage, BtLockUpdate);
+}
+
+// merge right sibling page into child page
+
+BTERR bt_mergepages (BtDb *bt, BtPage *right, uid rightpage)
+{
+BtPage *left = &bt->child;
+uint idx, amt;
+BtKey ptr;
+
+ if( bt_lockpage (bt, bt->childpage, BtLockUpgrade) )
+ return bt->err;
+ if( bt_lockpage (bt, rightpage, BtLockUpgrade) )
+ return bt->err;
+
+ // initialize empty frame
+
+ memset (bt->frame, 0, bt->page_size);
+ *bt->frame = **right;
+
+ // copy right fence key
+
+ if( amt = (*right)->fence )
+ memcpy ((unsigned char *)bt->frame + bt->page_size - amt, (unsigned char *)(*right) + bt->page_size - amt, amt);
+
+ bt->frame->min = bt->page_size - amt;
+
+ // copy lowerkey key/values from left page
+
+ for( idx = 1; idx <= (*left)->cnt; idx++ ) {
+ ptr = keyptr(*left, idx);
+ bt->frame->min -= ptr->len + 1;
+ memcpy ((unsigned char *)bt->frame + bt->frame->min, ptr, ptr->len + 1);
+ memcpy (slotptr(bt->frame, idx)->id, slotptr(*left, idx)->id, BtId);
+ slotptr(bt->frame, idx)->tod = slotptr(*left, idx)->tod;
+ slotptr(bt->frame, idx)->off = bt->frame->min;
+ }
+
+ bt->frame->cnt = (*left)->cnt;
+
+ // copy higherkey key/values from right page
+
+ for( idx = 1; idx <= (*right)->cnt; idx++ ) {
+
+ // copy key but not infinite value
+
+ if( idx < (*right)->cnt || !(*right)->lvl || right ) {
+ ptr = keyptr(*right, idx);
+ bt->frame->min -= ptr->len + 1;
+ memcpy ((unsigned char *)bt->frame + bt->frame->min, ptr, ptr->len + 1);
+ }
+
+ // copy slot
+ memcpy (slotptr(bt->frame, bt->frame->cnt + idx)->id, slotptr(*right, idx)->id, BtId);
+ slotptr(bt->frame, bt->frame->cnt + idx)->tod = slotptr(*right, idx)->tod;
+ slotptr(bt->frame, bt->frame->cnt + idx)->off = bt->frame->min;
+ }
+
+ bt->frame->cnt += (*right)->cnt;
+ memcpy (*left, bt->frame, bt->page_size);
+
+ if( bt_update (bt, *left, bt->childpage) )
+ return bt->err;
+ if( bt_freepage (bt, *right, rightpage) )
+ return bt->err;
+ if( bt_unlockpage (bt, rightpage, BtLockUpgrade) )
+ return bt->err;
+ if( bt_unlockpage (bt, rightpage, BtLockUpdate) )
+ return bt->err;
+
+ return bt_unlockpage (bt, bt->childpage, BtLockUpgrade);
+}
+
+// redistribute right sibling page with child page
+// switch child page to containing page
+
+BTERR bt_redistribute (BtDb *bt, BtPage *right, uid rightpage, unsigned char *key, uint len)
+{
+uid siblingpage = bt_getid((*right)->right);
+BtPage *left = &bt->child;
+uint idx, cnt = 0, amt = 0;
+uint leftmax, rightmin;
+BtPage swap;
+BtKey ptr;
+
+ if( bt_lockpage (bt, bt->childpage, BtLockUpgrade) )
+ return bt->err;
+ if( bt_lockpage (bt, rightpage, BtLockUpgrade) )
+ return bt->err;
+
+ // initialize empty frames to contain redistributed pages
+
+ memset (bt->frame, 0, bt->page_size); // new left page
+ memset (bt->temp, 0, bt->page_size); // new right page
+
+ *bt->frame = **left;
+ *bt->temp = **right;
+
+ bt->frame->min = bt->page_size;
+ bt->temp->min = bt->page_size;
+ bt->frame->cnt = 0;
+ bt->temp->cnt = 0;
+
+ // find new left fence index
+ // and copy left fence key
+
+ if( (*left)->cnt > (*right)->cnt ) {
+ rightmin = 0;
+ leftmax = (*left)->cnt / 2;
+ if( !bt->frame->lvl ) {
+ ptr = keyptr(*left, leftmax);
+ bt->frame->fence = ptr->len + 1;
+ bt->frame->min -= ptr->len + 1;
+ memcpy ((unsigned char *)bt->frame + bt->frame->min, ptr, ptr->len + 1);
+ }
+ } else {
+ leftmax = (*left)->cnt;
+ rightmin = (*right)->cnt / 2;
+ if( !bt->frame->lvl ) {
+ ptr = keyptr(*right, rightmin);
+ bt->frame->fence = ptr->len + 1;
+ bt->frame->min -= ptr->len + 1;
+ memcpy ((unsigned char *)bt->frame + bt->frame->min, ptr, ptr->len + 1);
+ }
+ }
+
+ // right fence stays the same, if any
+
+ if( amt = (*right)->fence ) {
+ bt->temp->min -= amt;
+ memcpy ((unsigned char *)bt->temp + bt->temp->min, (unsigned char *)(*right) + bt->temp->min, amt);
+ }
+
+ // copy first set of lowerkey key/values from left page
+
+ for( idx = 1; idx <= leftmax; idx++ ) {
+ bt->frame->cnt++;
+ ptr = keyptr(*left, idx);
+ bt->frame->min -= ptr->len + 1;
+ memcpy ((unsigned char *)bt->frame + bt->frame->min, ptr, ptr->len + 1);
+ memcpy (slotptr(bt->frame, idx)->id, slotptr(*left, idx)->id, BtId);
+ slotptr(bt->frame, idx)->tod = slotptr(*left, idx)->tod;
+ slotptr(bt->frame, idx)->off = bt->frame->min;
+ }
+
+ // copy remaining left page key/values from right page, if any
+
+ for( idx = 1; idx <= rightmin; idx++ ) {
+ bt->frame->cnt++;
+ ptr = keyptr(*right, idx);
+ bt->frame->min -= ptr->len + 1;
+ memcpy ((unsigned char *)bt->frame + bt->frame->min, ptr, ptr->len + 1);
+ memcpy (slotptr(bt->frame, bt->frame->cnt)->id, slotptr(*right, idx)->id, BtId);
+ slotptr(bt->frame, bt->frame->cnt)->tod = slotptr(*right, idx)->tod;
+ slotptr(bt->frame, bt->frame->cnt)->off = bt->frame->min;
+ }
+
+ // copy remaining left page key/values into new right page, if any
+
+ for( idx = leftmax; idx <= (*left)->cnt; idx++ ) {
+ bt->temp->cnt++;
+ ptr = keyptr(*left, idx);
+ bt->temp->min -= ptr->len + 1;
+ memcpy ((unsigned char *)bt->temp + bt->temp->min, ptr, ptr->len + 1);
+ memcpy (slotptr(bt->temp, bt->temp->cnt)->id, slotptr(*left, idx)->id, BtId);
+ slotptr(bt->temp, bt->temp->cnt)->tod = slotptr(*left, idx)->tod;
+ slotptr(bt->temp, bt->temp->cnt)->off = bt->temp->min;
+ }
+
+ // copy rest of higherkey key/values from right page
+
+ for( idx = rightmin; idx <= (*right)->cnt; idx++ ) {
+
+ // copy key, but not infinite value
+
+ if( idx < (*right)->cnt || !(*right)->lvl || siblingpage ) {
+ ptr = keyptr(*right, idx);
+ bt->temp->min -= ptr->len + 1;
+ memcpy ((unsigned char *)bt->temp + bt->temp->min, ptr, ptr->len + 1);
+ }
+
+ // copy slot
+
+ bt->temp->cnt++;
+ memcpy (slotptr(bt->temp, bt->temp->cnt)->id, slotptr(*right, idx)->id, BtId);
+ slotptr(bt->temp, bt->temp->cnt)->tod = slotptr(*right, idx)->tod;
+ slotptr(bt->temp, bt->temp->cnt)->off = bt->temp->min;
+ }
+
+ memcpy (*left, bt->frame, bt->page_size);
+ memcpy (*right, bt->temp, bt->page_size);
+
+ if( bt_update (bt, *left, bt->childpage) )
+ return bt->err;
+ if( bt_update (bt, *right, rightpage) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, rightpage, BtLockUpgrade) )
+ return bt->err;
+ if( bt_unlockpage (bt, rightpage, BtLockUpdate) )
+ return bt->err;
+
+ ptr = bt_highkey (bt, *left);
+
+ // decide which page is the child page
+ // if leftkey >= our key, go with left
+
+ if( keycmp (ptr, key, len) >= 0 ) {
+ if( bt_unlockpage (bt, bt->childpage, BtLockUpgrade) )
+ return bt->err;
+ if( bt_unlockpage (bt, rightpage, BtLockUpgrade) )
+ return bt->err;
+ if( bt_unlockpage (bt, rightpage, BtLockUpdate) )
+ return bt->err;
+ } else {
+ if( bt_unlockpage (bt, rightpage, BtLockUpgrade) )
+ return bt->err;
+ if( bt_unlockpage (bt, bt->childpage, BtLockUpgrade) )
+ return bt->err;
+ if( bt_unlockpage (bt, bt->childpage, BtLockUpdate) )
+ return bt->err;
+ swap = bt->child;
+ bt->child = *right;
+ *left = swap;
+ bt->childpage = rightpage;
+ }
+
+ return 0;
+}
+
+// lower the root level by removing the child node
+
+BTERR bt_lowerroot(BtDb *bt)
+{
+ if( bt_lockpage (bt, ROOT_page, BtLockUpgrade) )
+ return bt->err;
+
+ if( bt_lockpage (bt, bt->childpage, BtLockUpgrade) )
+ return bt->err;
+
+ memcpy (bt->parent, bt->child, bt->page_size);
+
+ if( bt_update(bt, bt->parent, ROOT_page) )
+ return bt->err;
+
+ if( bt_freepage(bt, bt->child, bt->childpage) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, bt->childpage, BtLockUpgrade) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, bt->childpage, BtLockUpdate) )
+ return bt->err;
+
+ return bt_unlockpage (bt, ROOT_page, BtLockUpgrade);
+}
+
+// split the root and raise the height of the btree
+// return with parent page set to appropriate sibling
+
+BTERR bt_raiseroot(BtDb *bt, uid sibling, unsigned char *key, uint len)
+{
+unsigned char lowerkey[256];
+uint nxt = bt->page_size;
+BtPage root = bt->parent;
+uid new_page;
+BtKey ptr;
+
+ // upgrade root page lock to exclusive
+
+ if( bt_lockpage (bt, ROOT_page, BtLockUpgrade) )
+ return bt->err;
+
+ // Obtain an empty page to use, and copy the current
+ // root (lower half) contents into it
+
+ if( !(new_page = bt_newpage(bt, root)) )
+ return bt->err;
+
+ if( bt_lockpage (bt, new_page, BtLockUpdate) )
+ return bt->err;
+
+ // save high fence key for left page
+
+ ptr = bt_highkey(bt, root);
+ memcpy (lowerkey, ptr, ptr->len + 1);
+
+ // preserve the page info at the bottom
+ // and set rest to zero to initialize new root page
+
+ memset(root+1, 0, bt->page_size - sizeof(*root));
+
+ // insert left key in newroot page
+
+ nxt -= *lowerkey + 1;
+ memcpy ((unsigned char *)root + nxt, lowerkey, *lowerkey + 1);
+ bt_putid(slotptr(root, 1)->id, new_page);
+ slotptr(root, 1)->off = nxt;
+
+ // insert second (infinite) key on newroot page that's never examined
+ // and increase the root level
+
+ bt_putid(slotptr(root, 2)->id, sibling);
+ bt_putid(root->right, 0);
+
+ root->min = nxt; // reset lowest used offset and key count
+ root->fence = 0;
+ root->cnt = 2;
+ root->lvl++;
+
+ if( bt_update(bt, root, bt->parentpage) )
+ return bt->err;
+
+ if( bt_unlockpage(bt, ROOT_page, BtLockUpgrade) )
+ return bt->err;
+
+ if( bt_unlockpage(bt, ROOT_page, BtLockUpdate) )
+ return bt->err;
+
+ // decide which root node to continue with
+ // sibling has upper keys, newpage the lower ones
+
+ if( keycmp((BtKey)lowerkey, key, len) < 0 ) {
+ bt->parentpage = sibling; // go with the upper ones
+
+ if( bt_unlockpage (bt, new_page, BtLockUpdate) )
+ return bt->err;
+
+ return bt_mappage (bt, &bt->parent, sibling);
+ }
+
+ bt->parentpage = new_page; // go with the lower ones
+
+ if( bt_unlockpage (bt, sibling, BtLockUpdate) )
+ return bt->err;
+
+ return bt_mappage (bt, &bt->parent, new_page);
+}
+
+// handle underflowing child node
+
+BTERR bt_repairchild (BtDb *bt, uint parentslot, unsigned char *key, uint len)
+{
+BtKey parentkey = bt_slotkey(bt->parent, parentslot);
+BtKey fencekey = bt_highkey (bt, bt->child);
+BtKey highkey = bt_highkey(bt, bt->parent);
+BtKey siblingkey, siblingkey2;
+uid siblingpage, siblingpage2;
+uid swappage;
+BtPage swap;
+uint slot;
+
+ // high key is never NULL
+ // fence key is null on right end
+
+ if( fencekey )
+ if( !highkey || keycmp (fencekey, highkey->key, highkey->len) < 0 ) {
+
+ // childpage is not rightmost child of parent page
+
+ siblingpage = bt_getid(bt->child->right);
+
+ if( bt_lockpage (bt, siblingpage, BtLockUpdate) )
+ return bt->err;
+
+ if( bt_mappage (bt, &bt->sibling, siblingpage) )
+ return bt->err;
+
+ if( !parentkey || keycmp (fencekey, parentkey->key, parentkey->len) < 0 ) {
+
+ // sibling is not linked in parent, so we can merge it
+
+ if( bt_unlockpage (bt, bt->parentpage, BtLockUpdate) )
+ return bt->err;
+
+ // calculate size of merged page by adding single child key to sibling
+
+ fencekey = keyptr(bt->child, 1);
+
+ if( bt->sibling->min < (bt->sibling->cnt + 1) * sizeof(BtSlot) + sizeof(*bt->sibling) + fencekey->len + 1)
+ return bt_redistribute (bt, &bt->sibling, siblingpage, key, len);
+ else
+ return bt_mergepages (bt, &bt->sibling, siblingpage);
+ }
+
+ // sibling has a key in the parent node
+ // find its slot in parent
+
+ if( siblingkey = bt_highkey (bt, bt->sibling) )
+ slot = bt_findslot (bt->parent, siblingkey->key, siblingkey->len);
+ else
+ slot = bt->parent->cnt;
+
+ parentkey = bt_slotkey (bt->parent, slot);
+ siblingpage2 = bt_getid(bt->sibling->right);
+
+ if( siblingkey && parentkey && keycmp (siblingkey, parentkey->key, parentkey->len) < 0 ) {
+
+ // sibling2 is not linked in P, its key is parentkey
+ // can parent support its insertion?
+ // if not, split parent node first.
+
+ if( bt->parent->min < (bt->parent->cnt + 1) * sizeof(BtSlot) + sizeof(*bt->parent) + parentkey->len + 1) {
+ if( bt_splitparent (bt, key, len) )
+ return bt->err;
+
+ // are we in the correct half of new parent nodes?
+ // if not, restart the function.
+
+ if( slot = bt_findslot (bt->parent, siblingkey->key, siblingkey->len) )
+ parentkey = keyptr(bt->parent, slot);
+ else
+ return BTERR_restart;
+ }
+
+ // link right of sibling into parent
+
+ if( bt_parentlink (bt, bt->sibling, siblingpage, parentkey, siblingpage2) )
+ return bt->err;
+
+ // unlink sibling from parent
+
+ if( bt_parentunlink (bt, bt->child, bt->childpage) )
+ return bt->err;
+
+ fencekey = keyptr(bt->child, 1);
+
+ if( bt->sibling->min < (bt->sibling->cnt + 1) * sizeof(BtSlot) + sizeof(*bt->sibling) + fencekey->len + 1)
+ return bt_redistribute (bt, &bt->sibling, siblingpage, key, len);
+ else
+ return bt_mergepages (bt, &bt->sibling, siblingpage);
+ } else {
+
+ // unlink sibling from parent and merge
+
+ if( bt_parentunlink (bt, bt->child, bt->childpage) )
+ return bt->err;
+
+ fencekey = keyptr(bt->child, 1);
+
+ if( bt->sibling->min < (bt->sibling->cnt + 1) * sizeof(BtSlot) + sizeof(*bt->sibling) + fencekey->len + 1)
+ return bt_redistribute (bt, &bt->sibling, siblingpage, key, len);
+ else
+ return bt_mergepages (bt, &bt->sibling, siblingpage);
+ }
+ }
+
+ // child is rightmost key in the parent,
+ // work with nodes to left.
+
+ siblingpage = bt_getid(slotptr(bt->parent, parentslot - 1)->id);
+ siblingkey = keyptr(bt->parent, parentslot - 1);
+
+ if( bt_unlockpage (bt, bt->childpage, BtLockUpdate) )
+ return bt->err;
+ if( bt_lockpage (bt, siblingpage, BtLockUpdate) )
+ return bt->err;
+ if( bt_mappage (bt, &bt->sibling, siblingpage) )
+ return bt->err;
+
+ siblingpage2 = bt_getid(bt->sibling->right);
+ siblingkey2 = bt_highkey (bt, bt->sibling);
+
+ if( bt_lockpage (bt, siblingpage2, BtLockUpdate) )
+ return bt->err;
+ if( bt_mappage (bt, &bt->sibling2, siblingpage2) )
+ return bt->err;
+
+ if( keycmp (siblingkey, siblingkey2->key, siblingkey2->len) == 0 ) {
+
+ // left sibling right (mapped into sibling2) is our child node
+
+ swap = bt->sibling2;
+ bt->sibling2 = bt->child;
+ bt->child = swap;
+
+ // does child still need to merge/redistribute?
+
+ if( bt->child->cnt > 1 ) {
+ if( bt_unlockpage (bt, bt->parentpage, BtLockUpdate) )
+ return bt->err;
+
+ return bt_unlockpage (bt, siblingpage, BtLockUpdate);
+ }
+
+ swap = bt->sibling;
+ bt->sibling = bt->child;
+ bt->child = swap;
+
+ bt->childpage = siblingpage;
+ siblingpage = siblingpage2;
+
+ // unlink sibling node from parent and merge with child
+
+ if( bt_parentunlink (bt, bt->child, bt->childpage) )
+ return bt->err;
+
+ fencekey = keyptr(bt->sibling, 1);
+
+ if( bt->child->min < (bt->child->cnt + 1) * sizeof(BtSlot) + sizeof(*bt->sibling) + fencekey->len + 1)
+ return bt_redistribute (bt, &bt->sibling, siblingpage, key, len);
+ else
+ return bt_mergepages (bt, &bt->sibling, siblingpage);
+ }
+
+ // currently unlinked sibling2 merges with child
+
+ fencekey = bt_highkey (bt, bt->sibling2);
+
+ if( bt->parent->min < (bt->parent->cnt + 1) * sizeof(BtSlot) + sizeof(*bt->parent) + fencekey->len + 1)
+ if( bt_splitparent (bt, key, len) )
+ return bt->err;
+
+ if( bt_parentlink (bt, bt->sibling, siblingpage, fencekey, siblingpage2) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, siblingpage, BtLockUpdate) )
+ return bt->err;
+ if( bt_lockpage (bt, bt->childpage, BtLockUpdate) )
+ return bt->err;
+ if( bt_mappage (bt, &bt->child, bt->childpage) )
+ return bt->err;
+
+ if( bt->child->cnt > 1 ) {
+ if( bt_unlockpage (bt, bt->parentpage, BtLockUpdate) )
+ return bt->err;
+ return bt_unlockpage (bt, siblingpage2, BtLockUpdate);
+ }
+
+ // unlink child from parent node leaving immediate
+ // left sibling2 to accept merge/redistribution
+
+ if( bt_parentunlink (bt, bt->sibling2, siblingpage2) )
+ return bt->err;
+
+ swap = bt->sibling2;
+ bt->sibling2 = bt->child;
+ bt->child = swap;
+ bt->childpage = siblingpage2;
+
+ fencekey = keyptr(bt->sibling2, 1);
+
+ if( bt->child->min < (bt->child->cnt + 1) * sizeof(BtSlot) + sizeof(*bt->child) + fencekey->len + 1)
+ return bt_redistribute (bt, &bt->sibling2, siblingpage2, key, len);
+ else
+ return bt_mergepages (bt, &bt->sibling2, siblingpage2);
+}
+
+// find and load leaf page for given key
+// leave page BtLockShared, return with key's slot
+
+int bt_loadpageread (BtDb *bt, unsigned char *key, uint len)
+{
+uid page_no = ROOT_page, prevpage = 0;
+uint slot, mode;
+
+ // start at root of btree and drill down
+
+ do {
+ bt->parentpage = page_no;
+
+ if( bt_lockpage(bt, bt->parentpage, BtLockShared) )
+ return 0;
+
+ if( prevpage )
+ if( bt_unlockpage(bt, prevpage, BtLockShared) )
+ return 0;
+
+ // map/obtain page contents
+
+ if( bt_mappage (bt, &bt->parent, page_no) )
+ return 0;
+
+ // find key on page at this level
+ // return if leaf page
+
+ if( (slot = bt_findslot (bt->parent, key, len)) ) {
+ if( !bt->parent->lvl )
+ return slot;
+
+ // continue down to next level
+
+ page_no = bt_getid(slotptr(bt->parent, slot)->id);
+ }
+
+ // or slide right into next page
+
+ else
+ page_no = bt_getid(bt->parent->right);
+
+ prevpage = bt->parentpage;
+ } while( page_no );
+
+ // return EOF on end of right chain
+
+ if( bt_unlockpage(bt, bt->parentpage, BtLockShared) )
+ return 0;
+
+ return 0; // return EOF
+}
+
+// find and load leaf page for given key
+// return w/slot # on leaf page
+// leave page BtLockUpdate
+
+int bt_loadpageupdate (BtDb *bt, unsigned char *key, uint len)
+{
+uid parentpage = 0, nextpage;
+BtKey fencekey, parentkey;
+uint slot, mode;
+BtPage swap;
+
+ // start at root of btree and drill down
+
+ if( bt_lockpage(bt, ROOT_page, BtLockUpdate) )
+ return 0;
+
+ // map/obtain page contents
+
+ if( bt_mappage (bt, &bt->parent, ROOT_page) )
+ return 0;
+
+ bt->parentpage = ROOT_page;
+
+ do {
+ // if root page, check for tree level growth
+ // by existence of right pointer
+
+ if( bt->parentpage == ROOT_page )
+ if( nextpage = bt_getid(bt->parent->right) ) {
+ if( bt_lockpage (bt, nextpage, BtLockUpdate) )
+ return 0;
+
+ if( bt_raiseroot (bt, nextpage, key, len) )
+ return 0;
+ }
+
+ // find key on page at this level
+ // return if leaf page
+
+ slot = bt_findslot (bt->parent, key, len);
+
+ if( !bt->parent->lvl )
+ return slot;
+
+ // lock & map the child
+
+ bt->childpage = bt_getid(slotptr(bt->parent, slot)->id);
+
+ if( bt_lockpage(bt, bt->childpage, BtLockUpdate) )
+ return 0;
+
+ if( bt_mappage (bt, &bt->child, bt->childpage) )
+ return 0;
+
+ // check child for underflow
+
+ if( bt->parentpage == ROOT_page )
+ if( bt->parent->cnt == 1 )
+ if( !bt_getid(bt->child->right) ) {
+ if( bt_lowerroot (bt) )
+ return 0;
+ nextpage = ROOT_page;
+ continue;
+ }
+
+ if( bt->child->cnt == 1 ) {
+ while( bt_repairchild (bt, slot, key, len) == BTERR_restart );
+ if( bt->err )
+ return 0;
+
+ swap = bt->child;
+ bt->child = bt->parent;
+ bt->parent = swap;
+ nextpage = bt->childpage;
+ continue;
+ }
+
+ fencekey = bt_highkey (bt, bt->child);
+ parentkey = bt_slotkey(bt->parent, slot);
+
+ // if right sibling is not linked,
+ // fix links in parent node
+
+ if( fencekey )
+ if( !parentkey || keycmp (fencekey, parentkey->key, parentkey->len) < 0 ) {
+
+ if( bt->parent->min < (bt->parent->cnt + 1) * sizeof(BtSlot) + sizeof(*bt->parent) + fencekey->len + 1)
+ if( bt_splitparent (bt, key, len) ) {
+ return 0;
+ } else {
+ slot = bt_findslot (bt->parent, key, len);
+ parentkey = bt_slotkey(bt->parent, slot);
+ }
+
+ // add key to parent for child page
+ // and fix downlink for childpage
+
+ nextpage = bt_getid(bt->child->right);
+
+ if( bt_parentlink (bt, bt->child, bt->childpage, parentkey, nextpage) )
+ return 0;
+ }
+
+ // unlock the parent page
+
+ if( bt_unlockpage (bt, bt->parentpage, BtLockUpdate) )
+ return 0;
+
+ // is our key on this child page?
+ // is fencekey infinite, or .ge. our key
+
+ if( !fencekey || keycmp (fencekey, key, len) >= 0 ) {
+ swap = bt->child;
+ bt->child = bt->parent;
+ bt->parent = swap;
+ nextpage = bt->childpage;
+ continue;
+ }
+
+ // otherwise slide right into next page
+
+ nextpage = bt_getid(bt->child->right);
+
+ if( bt_lockpage (bt, nextpage, BtLockUpdate) )
+ return 0;
+
+ if( bt_unlockpage (bt, bt->childpage, BtLockUpdate) )
+ return 0;
+
+ if( bt_mappage (bt, &bt->parent, nextpage) )
+ return 0;
+
+ } while( bt->parentpage = nextpage );
+
+ // return error on end of right chain
+
+ bt->err = BTERR_struct;
+ return 0; // return error
+}
+
+// find and delete key on leaf page
+
+BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len)
+{
+uid page_no, right;
+uint slot, tod;
+BtKey ptr;
+
+ bt_resetpages (bt);
+
+ if( slot = bt_loadpageupdate (bt, key, len) )
+ ptr = keyptr(bt->parent, slot);
+ else if( bt->err )
+ return bt->err;
+
+ // if key is found delete it, otherwise ignore request
+
+ if( slot && !keycmp (ptr, key, len) ) {
+ if( bt_lockpage (bt, bt->parentpage, BtLockUpgrade) )
+ return bt->err;
+
+ bt_removeslot (bt, slot);
+
+ if( bt_update(bt, bt->parent, bt->parentpage) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, bt->parentpage, BtLockUpgrade) )
+ return bt->err;
+ }
+
+ return bt_unlockpage (bt, bt->parentpage, BtLockUpdate);
+}
+
+// find key in leaf page and return row-id
+// or zero if key is not found.
+
+uid bt_findkey (BtDb *bt, unsigned char *key, uint len)
+{
+uint slot;
+BtKey ptr;
+uid id;
+
+ bt_resetpages (bt);
+
+ if( slot = bt_loadpageread (bt, key, len) )
+ ptr = keyptr(bt->parent, 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->parent,slot)->id);
+ else
+ id = 0;
+
+ if ( bt_unlockpage(bt, bt->parentpage, BtLockShared) )
+ return 0;
+
+ return id;
+}
+
+// Insert new key into the btree leaf page
+
+BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod)
+{
+uint slot, idx;
+BtKey ptr;
+
+ if( slot = bt_loadpageupdate (bt, key, len) )
+ ptr = keyptr(bt->parent, slot);
+ else if( bt->err )
+ return bt->err;
+
+ if( bt->parent->lvl )
+ abort();
+ if( bt->parent->lvl )
+ abort();
+
+
+ // if key already exists, update id and return
+
+ if( slot )
+ if( !keycmp (ptr, key, len) ) {
+ if( bt_lockpage (bt, bt->parentpage, BtLockUpgrade) )
+ return bt->err;
+ slotptr(bt->parent, slot)->tod = tod;
+ bt_putid(slotptr(bt->parent,slot)->id, id);
+ if ( bt_update(bt, bt->parent, bt->parentpage) )
+ return bt->err;
+ if( bt_unlockpage (bt, bt->parentpage, BtLockUpgrade) )
+ return bt->err;
+ return bt_unlockpage(bt, bt->parentpage, BtLockUpdate);
+ }
+
+ // check if leaf page has enough space
+
+ if( bt->parent->min < (bt->parent->cnt + 1) * sizeof(BtSlot) + sizeof(*bt->parent) + len + 1) {
+ if( bt_splitparent (bt, key, len) )
+ return bt->err;
+
+ slot = bt_findslot (bt->parent, key, len);
+ }
+
+ // calculate next available slot and copy key into page
+
+ if( bt_lockpage (bt, bt->parentpage, BtLockUpgrade) )
+ return bt->err;
+
+ bt->parent->min -= len + 1; // reset lowest used offset
+ ((unsigned char *)bt->parent)[bt->parent->min] = len;
+ memcpy ((unsigned char *)bt->parent + bt->parent->min +1, key, len );
+
+ // now insert key into array before slot
+
+ idx = ++bt->parent->cnt;
+
+ if( slot )
+ while( idx > slot )
+ *slotptr(bt->parent, idx) = *slotptr(bt->parent, idx -1), idx--;
+
+ bt_putid(slotptr(bt->parent,idx)->id, id);
+ slotptr(bt->parent, idx)->off = bt->parent->min;
+ slotptr(bt->parent, idx)->tod = tod;
+
+ if ( bt_update(bt, bt->parent, bt->parentpage) )
+ return bt->err;
+
+ if( bt_unlockpage (bt, bt->parentpage, BtLockUpgrade) )
+ return bt->err;
+
+ return bt_unlockpage(bt, bt->parentpage, BtLockUpdate);
+}
+
+// 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_loadpageread (bt, key, len) )
+ memcpy (bt->cursor, bt->parent, bt->page_size);
+ bt->cursorpage = bt->parentpage;
+ if ( bt_unlockpage(bt, bt->parentpage, BtLockShared) )
+ 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 {
+ if( slot++ < bt->cursor->cnt )
+ return slot;
+
+ right = bt_getid(bt->cursor->right);
+
+ if( !right )
+ break;
+
+ bt->cursorpage = right;
+
+ if( bt_lockpage(bt, right,BtLockShared) )
+ return 0;
+
+ if( bt_mappage (bt, &bt->parent, right) )
+ break;
+
+ memcpy (bt->cursor, bt->parent, bt->page_size);
+ if ( bt_unlockpage(bt, right, BtLockShared) )
+ 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
+// standalone program to index file of keys
+// then list them onto std-out
+
+int main (int argc, char **argv)
+{
+uint slot, found = 0, line = 0, off = 0;
+int ch, cnt = 0, bits = 12;
+unsigned char key[256];
+clock_t done, start;
+time_t tod[1];
+uint scan = 0;
+uint len = 0;
+uint map = 0;
+BtKey ptr;
+BtDb *bt;
+FILE *in;
+
+ if( argc < 4 ) {
+ fprintf (stderr, "Usage: %s idx_file src_file Read/Write/Scan/Delete/Find [page_bits mapped_pool_pages start_line_number]", argv[0]);
+ exit(0);
+ }
+
+ start = clock();
+ time (tod);
+
+ if( argc > 4 )
+ bits = atoi(argv[4]);
+
+ if( argc > 5 )
+ map = atoi(argv[5]);
+
+ if( map > 65536 )
+ fprintf (stderr, "Warning: mapped_pool > 65536 pages\n");
+
+ if( argc > 6 )
+ off = atoi(argv[6]);
+
+ bt = bt_open ((argv[1]), BT_rw, bits, map);
+
+ if( !bt ) {
+ fprintf(stderr, "Index Open Error %s\n", argv[1]);
+ exit (1);
+ }
+
+ switch(argv[3][0]| 0x20)
+ {
+ case 'w':
+ fprintf(stderr, "started indexing for %s\n", argv[2]);
+ if( argc > 2 && (in = fopen (argv[2], "rb")) )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ if( off )
+ sprintf((char *)key+len, "%.9d", line + off), len += 9;
+
+ if( bt_insertkey (bt, key, len, ++line, *tod) )
+ fprintf(stderr, "Error %d Syserr %d Line: %d\n", bt->err, errno, line), exit(0);
+ len = 0;
+ }
+ else if( len < 245 )
+ key[len++] = ch;
+ fprintf(stderr, "finished adding keys, %d \n", line);
+ break;
+
+ case 'd':
+ fprintf(stderr, "started deleting keys for %s\n", argv[2]);
+ if( argc > 2 && (in = fopen (argv[2], "rb")) )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ if( off )
+ sprintf((char *)key+len, "%.9d", line + off), len += 9;
+ line++;
+ if( bt_deletekey (bt, key, len) )
+ fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0);
+ len = 0;
+ }
+ else if( len < 245 )
+ key[len++] = ch;
+ fprintf(stderr, "finished deleting keys, %d\n", line);
+ break;
+
+ case 'f':
+ fprintf(stderr, "started finding keys for %s\n", argv[2]);
+ if( argc > 2 && (in = fopen (argv[2], "rb")) )
+ while( ch = getc(in), ch != EOF )
+ if( ch == '\n' )
+ {
+ if( off )
+ sprintf((char *)key+len, "%.9d", line + off), len += 9;
+ 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 < 245 )
+ key[len++] = ch;
+ fprintf(stderr, "finished search of %d keys, found %d\n", line, found);
+ break;
+
+ case 's':
+ scan++;
+ break;
+
+ }
+
+ done = clock();
+ fprintf(stderr, " Time to complete: %.2f seconds\n", (float)(done - start) / CLOCKS_PER_SEC);
+
+ cnt = 0;
+ len = key[0] = 0;
+
+ fprintf(stderr, "started reading\n");
+
+ slot = bt_startkey (bt, key, len);
+
+ if( bt->err )
+ fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0);
+
+ if( slot-- )
+ while( slot = bt_nextkey (bt, slot) )
+ if( cnt++, scan ) {
+ ptr = bt_key(bt, slot);
+ fwrite (ptr->key, ptr->len, 1, stdout);
+ fputc ('\n', stdout);
+ }
+
+ fprintf(stderr, " Total keys read %d\n", cnt);
+}
+
+#endif //STANDALONE
--- /dev/null
+// btree version threads2d sched_yield version
+// 26 APR 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
+// http://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) ParentModification: Exclusive. Change the node's parent keys. Incompatible with another ParentModification.
+*/
+
+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
+ unsigned char bits; // page size in bits
+ unsigned char lvl:7; // level of page
+ unsigned char kill:1; // page is being deleted
+ 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]; // Parent modification
+} 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_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 cacheblk, 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
+
+// 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 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. 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)
+{
+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 (cacheblk, (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(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
+ // 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
+// 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 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;
+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];
+uint slot, tod, dirty = 0;
+uid page_no, right;
+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 )
+ dirty = slotptr(bt->page,slot)->dead = 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(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 (bt->page, bt->temp, bt->mgr->page_size);
+
+ // cache 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;
+}
+
+void bt_cleanpage(BtDb *bt)
+{
+uint nxt = bt->mgr->page_size;
+BtPage page = bt->page;
+uint cnt = 0, idx = 0;
+uint max = page->cnt;
+BtKey key;
+
+ 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->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;
+}
+
+// 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
+
+ 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 len)
+{
+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;
+
+ // perform cleanup
+
+ bt_cleanpage(bt);
+
+ // return if enough space now
+
+ if( page->min >= (page->cnt + 1) * sizeof(BtSlot) + sizeof(*page) + len + 1)
+ return bt_unlockpage(bt, page_no, BtLockWrite);
+
+ // 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( page->min >= (page->cnt + 1) * sizeof(BtSlot) + sizeof(*page) + len + 1)
+ break;
+
+ if( bt_splitpage (bt, len) )
+ 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 *infile;
+ char type;
+ 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' )
+ {
+ 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( 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;
+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 hash_size 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, " hash_size is the size of buffer pool hash table\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
+
+ cnt = argc - 6;
+#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 + 6];
+ args[idx].type = argv[2][0];
+ args[idx].mgr = mgr;
+#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
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