--- /dev/null
+// btree version 2s
+// 02 FEB 2014
+
+// author: karl malbrain, malbrain@cal.berkeley.edu
+
+/*
+This work, including the source code, documentation
+and related data, is placed into the public domain.
+
+The orginal author is Karl Malbrain.
+
+THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
+OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
+MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
+ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
+RESULTING FROM THE USE, MODIFICATION, OR
+REDISTRIBUTION OF THIS SOFTWARE.
+*/
+
+// Please see the project home page for documentation
+// code.google.com/p/high-concurrency-btree
+
+#define _FILE_OFFSET_BITS 64
+#define _LARGEFILE64_SOURCE
+
+#ifdef linux
+#define _GNU_SOURCE
+#endif
+
+#ifdef unix
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <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 dirty:1; // page is dirty
+ 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
+ int posted; // last loadpage found posted key
+ int found; // last deletekey found key
+ int fence; // last load page used fence position
+} 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
+#define LEAF_page 2
+
+// Number of levels to create in a new BTree
+
+#define MIN_lvl 2
+
+// The page is allocated from low and hi ends.
+// The key offsets and row-id's are allocated
+// from the bottom, while the text of the key
+// is allocated from the top. When the two
+// areas meet, the page is split into two.
+
+// A key consists of a length byte, two bytes of
+// index number (0 - 65534), and up to 253 bytes
+// of key value. Duplicate keys are discarded.
+// Associated with each key is a 48 bit row-id.
+
+// The b-tree root is always located at page 1.
+// The first leaf page of level zero is always
+// located on page 2.
+
+// The b-tree pages are linked with 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.
+
+// Deleted leaf pages are reclaimed on a free list.
+// The upper levels of the btree are fixed on creation.
+
+// 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 (ALLOC page) is dedicated to lock for new page extensions,
+// and chains empty leaf pages together for reuse.
+
+// Parent locks are obtained to prevent resplitting or deleting a node
+// before its fence is posted into its upper level.
+
+// 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
+
+ // unlock page zero
+
+ if ( bt_unlockpage(bt, ALLOC_page, BtLockWrite) )
+ return 0;
+
+ 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;
+
+ // if page is being deleted, send to right
+
+ if( !bt->page->cnt )
+ return 0;
+
+ // if page is an empty fence holder
+
+ if( !bt->page->act )
+ return bt->page->cnt;
+
+ // 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
+
+ bt->posted = 1;
+
+ 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( slot = bt_findslot (bt, key, len) ) {
+ if( drill == lvl )
+ return slot;
+
+ while( slotptr(bt->page, slot)->dead )
+ if( slot++ < bt->page->cnt )
+ continue;
+ else
+ return bt->err = BTERR_struct, 0;
+
+ page_no = bt_getid(slotptr(bt->page, slot)->id);
+ bt->fence = slot == bt->page->cnt;
+ bt->posted = 1;
+ drill--;
+ }
+
+ // or slide right into next page
+ // (slide left from deleted page)
+
+ else {
+ page_no = bt_getid(bt->page->right);
+ bt->posted = 0;
+ }
+
+ // continue down / right using overlapping locks
+ // to protect pages being killed or split.
+
+ 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;
+ if( slot < bt->page->cnt )
+ bt->page->dirty = 1;
+ bt->page->act--;
+ }
+
+ // return if page is not empty, or
+ // if non-leaf level or fence key
+
+ right = bt_getid(bt->page->right);
+ page_no = bt->page_no;
+
+ if( lvl || bt->page->act || bt->fence )
+ 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 fence key
+ // in order to find parent
+
+ 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->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;
+}
+
+// check page for space available,
+// clean if necessary and return
+// 0 - page needs splitting
+// >0 - go ahead with new slot
+
+uint bt_cleanpage(BtDb *bt, uint amt, uint slot)
+{
+uint nxt = bt->page_size;
+BtPage page = bt->page;
+uint cnt = 0, idx = 0;
+uint max = page->cnt;
+uint newslot = slot;
+BtKey key;
+int ret;
+
+ if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return slot;
+
+ // skip cleanup if nothing to reclaim
+
+ if( !page->dirty )
+ return 0;
+
+ memcpy (bt->frame, page, bt->page_size);
+
+ // skip page info and set rest of page to zero
+
+ memset (page+1, 0, bt->page_size - sizeof(*page));
+ page->act = 0;
+
+ while( cnt++ < max ) {
+ if( cnt == slot )
+ newslot = idx + 1;
+ // always leave fence key in list
+ if( cnt < max && slotptr(bt->frame,cnt)->dead )
+ continue;
+
+ // copy key
+ key = keyptr(bt->frame, cnt);
+ nxt -= key->len + 1;
+ memcpy ((unsigned char *)page + nxt, key, key->len + 1);
+
+ // copy slot
+ memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId);
+ if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) )
+ page->act++;
+ slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod;
+ slotptr(page, idx)->off = nxt;
+ }
+
+ page->min = nxt;
+ page->cnt = idx;
+
+ if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 )
+ return newslot;
+
+ return 0;
+}
+
+// split the root and raise the height of the btree
+
+BTERR bt_splitroot(BtDb *bt, unsigned char *newkey, unsigned char *oldkey, uid page_no2)
+{
+uint nxt = bt->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 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;
+
+ // 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( slot = bt_cleanpage (bt, len, slot) )
+ break;
+
+ if( bt_splitpage (bt) )
+ return bt->err;
+ }
+
+ // calculate next available slot and copy key into page
+
+ page->min -= len + 1; // reset lowest used offset
+ ((unsigned char *)page)[page->min] = len;
+ memcpy ((unsigned char *)page + page->min +1, key, len );
+
+ for( idx = slot; idx < page->cnt; idx++ )
+ if( slotptr(page, idx)->dead )
+ break;
+
+ // now insert key into array before slot
+ // preserving the fence slot
+
+ if( idx == page->cnt )
+ idx++, page->cnt++;
+
+ page->act++;
+
+ while( idx > slot )
+ *slotptr(page, idx) = *slotptr(page, idx -1), idx--;
+
+ bt_putid(slotptr(page,slot)->id, id);
+ slotptr(page, slot)->off = page->min;
+ slotptr(page, slot)->tod = tod;
+ slotptr(page, slot)->dead = 0;
+
+ 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);
+ return 0;
+}
+
+#endif //STANDALONE
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