From 717d222a9b8f1c9a1765aebb0fa15d723baa5b8a Mon Sep 17 00:00:00 2001 From: Karl Malbrain Date: Thu, 21 Nov 2013 15:47:12 -0800 Subject: [PATCH] Fix bt_newpage unlock of allocation page for fileio --- jaluta2.c | 2374 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 2374 insertions(+) create mode 100644 jaluta2.c diff --git a/jaluta2.c b/jaluta2.c new file mode 100644 index 0000000..9e2f6cd --- /dev/null +++ b/jaluta2.c @@ -0,0 +1,2374 @@ +// jaluta's balanced B-Link tree algorithms +// 26 NOV 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 +#include +#include +#include +#include +#include +#include +#else +#define WIN32_LEAN_AND_MEAN +#include +#include +#include +#include +#include +#endif + +#include +#include + +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 + + // 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->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 -- 2.40.0