From 7ff742ab3d1df6bada156a746cb3205969f3c3d1 Mon Sep 17 00:00:00 2001 From: unknown Date: Wed, 12 Jun 2013 13:46:02 -0700 Subject: [PATCH] Initial release of B-tree programs. --- btree2p.c | 1781 +++++++++++++++++++++++++++++++++++++ fosterbtree.c | 2054 ++++++++++++++++++++++++++++++++++++++++++ jaluta.c | 2369 +++++++++++++++++++++++++++++++++++++++++++++++++ threads2e.c | 1980 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 8184 insertions(+) create mode 100644 btree2p.c create mode 100644 fosterbtree.c create mode 100644 jaluta.c create mode 100644 threads2e.c diff --git a/btree2p.c b/btree2p.c new file mode 100644 index 0000000..94602ee --- /dev/null +++ b/btree2p.c @@ -0,0 +1,1781 @@ +// btree version 2p +// 26 APR 2013 + +// author: karl malbrain, malbrain@cal.berkeley.edu + +/* +This work, including the source code, documentation +and related data, is placed into the public domain. + +The orginal author is Karl Malbrain. + +THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY +OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF +MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE, +ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE +RESULTING FROM THE USE, MODIFICATION, OR +REDISTRIBUTION OF THIS SOFTWARE. +*/ + +// Please see the project home page for documentation +// code.google.com/p/high-concurrency-btree + +#define _FILE_OFFSET_BITS 64 +#define _LARGEFILE64_SOURCE + +#ifdef linux +#define _GNU_SOURCE +#endif + +#ifdef unix +#include +#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 + +/* +There are five lock types for each node in three independent sets: +1. (set 1) AccessIntent: Sharable. Going to Read the node. Incompatible with NodeDelete. +2. (set 1) NodeDelete: Exclusive. About to release the node. Incompatible with AccessIntent. +3. (set 2) ReadLock: Sharable. Read the node. Incompatible with WriteLock. +4. (set 2) WriteLock: Exclusive. Modify the node. Incompatible with ReadLock and other WriteLocks. +5. (set 3) ParentModification: Exclusive. Change the node's parent keys. Incompatible with another ParentModification. +*/ + +typedef enum{ + BtLockAccess, + BtLockDelete, + BtLockRead, + BtLockWrite, + BtLockParent +}BtLock; + +// Define the length of the page and key pointers + +#define BtId 6 + +// Page key slot definition. + +// If BT_maxbits is 15 or less, you can save 2 bytes +// for each key stored by making the first two uints +// into ushorts. You can also save 4 bytes by removing +// the tod field from the key. + +// Keys are marked dead, but remain on the page until +// cleanup is called. The fence key (highest key) for +// the page is always present, even if dead. + +typedef struct { + uint off:BT_maxbits; // page offset for key start + uint dead:1; // set for deleted key + uint tod; // time-stamp for key + unsigned char id[BtId]; // id associated with key +} BtSlot; + +// The key structure occupies space at the upper end of +// each page. It's a length byte followed by the value +// bytes. + +typedef struct { + unsigned char len; + unsigned char key[0]; +} *BtKey; + +// The first part of an index page. +// It is immediately followed +// by the BtSlot array of keys. + +typedef struct { + uint cnt; // count of keys in page + uint act; // count of active keys + uint min; // next key offset + unsigned char bits; // page size in bits + unsigned char lvl:7; // level of page + unsigned char kill:1; // page is being deleted + unsigned char right[BtId]; // page number to right +} *BtPage; + +// The memory mapping hash table entry + +typedef struct { + BtPage page; // mapped page pointer + uid page_no; // mapped page number + void *lruprev; // least recently used previous cache block + void *lrunext; // lru next cache block + void *hashprev; // previous cache block for the same hash idx + void *hashnext; // next cache block for the same hash idx +#ifndef unix + HANDLE hmap; +#endif +}BtHash; + +// The object structure for Btree access + +typedef struct _BtDb { + uint page_size; // each page size + uint page_bits; // each page size in bits + uint seg_bits; // segment size in pages in bits + uid page_no; // current page number + uid cursor_page; // current cursor page number + int err; + uint mode; // read-write mode + uint mapped_io; // use memory mapping + BtPage temp; // temporary frame buffer (memory mapped/file IO) + BtPage alloc; // frame buffer for alloc page ( page 0 ) + BtPage cursor; // cached frame for start/next (never mapped) + BtPage frame; // spare frame for the page split (never mapped) + BtPage zero; // zeroes frame buffer (never mapped) + BtPage page; // current page +#ifdef unix + int idx; +#else + HANDLE idx; +#endif + unsigned char *mem; // frame, cursor, page memory buffer + int nodecnt; // highest page cache segment in use + int nodemax; // highest page cache segment allocated + int hashmask; // number of pages in segments - 1 + int hashsize; // size of hash table + BtHash *lrufirst; // lru list head + BtHash *lrulast; // lru list tail + ushort *cache; // hash table for cached segments + BtHash nodes[1]; // segment cache follows +} BtDb; + +typedef enum { +BTERR_ok = 0, +BTERR_struct, +BTERR_ovflw, +BTERR_lock, +BTERR_map, +BTERR_wrt, +BTERR_hash +} BTERR; + +// B-Tree functions +extern void bt_close (BtDb *bt); +extern BtDb *bt_open (char *name, uint mode, uint bits, uint cacheblk, uint pgblk); +extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uint lvl, uid id, uint tod); +extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl); +extern uid bt_findkey (BtDb *bt, unsigned char *key, uint len); +extern uint bt_startkey (BtDb *bt, unsigned char *key, uint len); +extern uint bt_nextkey (BtDb *bt, uint slot); + +// Helper functions to return slot values + +extern BtKey bt_key (BtDb *bt, uint slot); +extern uid bt_uid (BtDb *bt, uint slot); +extern uint bt_tod (BtDb *bt, uint slot); + +// BTree page number constants +#define ALLOC_page 0 +#define ROOT_page 1 + +// Number of levels to create in a new BTree + +#define MIN_lvl 2 + +// The page is allocated from low and hi ends. +// The key offsets and row-id's are allocated +// from the bottom, while the text of the key +// is allocated from the top. When the two +// areas meet, the page is split into two. + +// A key consists of a length byte, two bytes of +// index number (0 - 65534), and up to 253 bytes +// of key value. Duplicate keys are discarded. +// Associated with each key is a 48 bit row-id. + +// The b-tree root is always located at page 1. +// The first leaf page of level zero is always +// located on page 2. + +// The b-tree pages are linked with right +// pointers to facilitate enumerators, +// and provide for concurrency. + +// When to root page fills, it is split in two and +// the tree height is raised by a new root at page +// one with two keys. + +// Deleted keys are marked with a dead bit until +// page cleanup The fence key for a node is always +// present, even after deletion and cleanup. + +// Groups of pages from the btree are optionally +// cached with memory mapping. A hash table is used to keep +// track of the cached pages. This behaviour is controlled +// by the number of cache blocks parameter and pages per block +// given to bt_open. + +// To achieve maximum concurrency one page is locked at a time +// as the tree is traversed to find leaf key in question. The right +// page numbers are used in cases where the page is being split, +// or consolidated. + +// Page 0 is dedicated to lock for new page extensions, +// and chains empty pages together for reuse. + +// Parent locks are obtained to prevent resplitting or deleting a node +// before its fence is posted into its upper level. + +// Empty nodes are chained together through the ALLOC page and reused. + +// A special open mode of BT_fl is provided to safely access files on +// WIN32 networks. WIN32 network operations should not use memory mapping. +// This WIN32 mode sets FILE_FLAG_NOBUFFERING and FILE_FLAG_WRITETHROUGH +// to prevent local caching of network file contents. + +// Access macros to address slot and key values from the page. +// Page slots use 1 based indexing. + +#define slotptr(page, slot) (((BtSlot *)(page+1)) + (slot-1)) +#define keyptr(page, slot) ((BtKey)((unsigned char*)(page) + slotptr(page, slot)->off)) + +void bt_putid(unsigned char *dest, uid id) +{ +int i = BtId; + + while( i-- ) + dest[i] = (unsigned char)id, id >>= 8; +} + +uid bt_getid(unsigned char *src) +{ +uid id = 0; +int i; + + for( i = 0; i < BtId; i++ ) + id <<= 8, id |= *src++; + + return id; +} + +// place write, read, or parent lock on requested page_no. + +BTERR bt_lockpage(BtDb *bt, uid page_no, BtLock mode) +{ +off64_t off = page_no << bt->page_bits; +#ifdef unix +int flag = PROT_READ | ( bt->mode == BT_ro ? 0 : PROT_WRITE ); +struct flock lock[1]; +#else +uint flags = 0, len; +OVERLAPPED ovl[1]; +#endif + + if( mode == BtLockRead || mode == BtLockWrite ) + off += sizeof(*bt->page); // use second segment + + if( mode == BtLockParent ) + off += 2 * sizeof(*bt->page); // use third segment + +#ifdef unix + memset (lock, 0, sizeof(lock)); + + lock->l_start = off; + lock->l_type = (mode == BtLockDelete || mode == BtLockWrite || mode == BtLockParent) ? F_WRLCK : F_RDLCK; + lock->l_len = sizeof(*bt->page); + lock->l_whence = 0; + + if( fcntl (bt->idx, F_SETLKW, lock) < 0 ) + return bt->err = BTERR_lock; + + return 0; +#else + memset (ovl, 0, sizeof(ovl)); + ovl->OffsetHigh = (uint)(off >> 32); + ovl->Offset = (uint)off; + len = sizeof(*bt->page); + + // use large offsets to + // simulate advisory locking + + ovl->OffsetHigh |= 0x80000000; + + if( mode == BtLockDelete || mode == BtLockWrite || mode == BtLockParent ) + flags |= LOCKFILE_EXCLUSIVE_LOCK; + + if( LockFileEx (bt->idx, flags, 0, len, 0L, ovl) ) + return bt->err = 0; + + return bt->err = BTERR_lock; +#endif +} + +// remove write, read, or parent lock on requested page_no. + +BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode) +{ +off64_t off = page_no << bt->page_bits; +#ifdef unix +struct flock lock[1]; +#else +OVERLAPPED ovl[1]; +uint len; +#endif + + if( mode == BtLockRead || mode == BtLockWrite ) + off += sizeof(*bt->page); // use second segment + + if( mode == BtLockParent ) + off += 2 * sizeof(*bt->page); // use third segment + +#ifdef unix + memset (lock, 0, sizeof(lock)); + + lock->l_start = off; + lock->l_type = F_UNLCK; + lock->l_len = sizeof(*bt->page); + lock->l_whence = 0; + + if( fcntl (bt->idx, F_SETLK, lock) < 0 ) + return bt->err = BTERR_lock; +#else + memset (ovl, 0, sizeof(ovl)); + ovl->OffsetHigh = (uint)(off >> 32); + ovl->Offset = (uint)off; + len = sizeof(*bt->page); + + // use large offsets to + // simulate advisory locking + + ovl->OffsetHigh |= 0x80000000; + + if( !UnlockFileEx (bt->idx, 0, len, 0, ovl) ) + return GetLastError(), bt->err = BTERR_lock; +#endif + + return bt->err = 0; +} + +// close and release memory + +void bt_close (BtDb *bt) +{ +BtHash *hash; +#ifdef unix + // release mapped pages + + if( hash = bt->lrufirst ) + do munmap (hash->page, (bt->hashmask+1) << bt->page_bits); + while(hash = hash->lrunext); + + if ( bt->mem ) + free (bt->mem); + close (bt->idx); + free (bt->cache); + free (bt); +#else + if( hash = bt->lrufirst ) + do + { + FlushViewOfFile(hash->page, 0); + UnmapViewOfFile(hash->page); + CloseHandle(hash->hmap); + } while(hash = hash->lrunext); + + if ( bt->mem) + VirtualFree (bt->mem, 0, MEM_RELEASE); + FlushFileBuffers(bt->idx); + CloseHandle(bt->idx); + GlobalFree (bt->cache); + GlobalFree (bt); +#endif +} + +// open/create new btree +// call with file_name, BT_openmode, bits in page size (e.g. 16), +// size of mapped page cache (e.g. 8192) or zero for no mapping. + +BtDb *bt_open (char *name, uint mode, uint bits, uint nodemax, uint pgblk) +{ +uint lvl, attr, cacheblk, last; +BtLock lockmode = BtLockWrite; +BtPage alloc; +off64_t size; +uint amt[1]; +BtKey key; +BtDb* bt; + +#ifndef unix +SYSTEM_INFO sysinfo[1]; +#endif + +#ifdef unix + bt = malloc (sizeof(BtDb) + nodemax * sizeof(BtHash)); + memset (bt, 0, sizeof(BtDb)); + + switch (mode & 0x7fff) + { + case BT_fl: + case BT_rw: + bt->idx = open ((char*)name, O_RDWR | O_CREAT, 0666); + break; + + case BT_ro: + default: + bt->idx = open ((char*)name, O_RDONLY); + lockmode = BtLockRead; + break; + } + if( bt->idx == -1 ) + return free(bt), NULL; + + if( nodemax ) + cacheblk = 4096; // page size for unix + else + cacheblk = 0; + +#else + bt = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtDb) + nodemax * sizeof(BtHash)); + attr = FILE_ATTRIBUTE_NORMAL; + switch (mode & 0x7fff) + { + case BT_fl: + attr |= FILE_FLAG_WRITE_THROUGH | FILE_FLAG_NO_BUFFERING; + + case BT_rw: + bt->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL); + break; + + case BT_ro: + default: + bt->idx = CreateFile(name, GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, attr, NULL); + lockmode = BtLockRead; + break; + } + if( bt->idx == INVALID_HANDLE_VALUE ) + return GlobalFree(bt), NULL; + + // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity + GetSystemInfo(sysinfo); + + if( nodemax ) + cacheblk = sysinfo->dwAllocationGranularity; + else + cacheblk = 0; +#endif + + // determine sanity of page size + + if( bits > BT_maxbits ) + bits = BT_maxbits; + else if( bits < BT_minbits ) + bits = BT_minbits; + + if ( bt_lockpage(bt, ALLOC_page, lockmode) ) + return bt_close (bt), NULL; + +#ifdef unix + *amt = 0; + + // read minimum page size to get root info + + if( size = lseek (bt->idx, 0L, 2) ) { + alloc = malloc (BT_minpage); + pread(bt->idx, alloc, BT_minpage, 0); + bits = alloc->bits; + free (alloc); + } else if( mode == BT_ro ) + return bt_close (bt), NULL; +#else + size = GetFileSize(bt->idx, amt); + + if( size || *amt ) { + alloc = VirtualAlloc(NULL, BT_minpage, MEM_COMMIT, PAGE_READWRITE); + if( !ReadFile(bt->idx, (char *)alloc, BT_minpage, amt, NULL) ) + return bt_close (bt), NULL; + bits = alloc->bits; + VirtualFree (alloc, 0, MEM_RELEASE); + } else if( mode == BT_ro ) + return bt_close (bt), NULL; +#endif + + bt->page_size = 1 << bits; + bt->page_bits = bits; + + bt->nodemax = nodemax; + bt->mode = mode; + + // setup cache mapping + + if( cacheblk ) { + if( cacheblk < bt->page_size ) + cacheblk = bt->page_size; + + bt->hashsize = nodemax / 8; + bt->hashmask = (cacheblk >> bits) - 1; + bt->mapped_io = 1; + } + + // requested number of pages per memmap segment + + if( cacheblk ) + if( (1 << pgblk) > bt->hashmask ) + bt->hashmask = (1 << pgblk) - 1; + + bt->seg_bits = 0; + + while( (1 << bt->seg_bits) <= bt->hashmask ) + bt->seg_bits++; + +#ifdef unix + bt->mem = malloc (6 *bt->page_size); + bt->cache = calloc (bt->hashsize, sizeof(ushort)); +#else + bt->mem = VirtualAlloc(NULL, 6 * bt->page_size, MEM_COMMIT, PAGE_READWRITE); + bt->cache = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, bt->hashsize * sizeof(ushort)); +#endif + bt->frame = (BtPage)bt->mem; + bt->cursor = (BtPage)(bt->mem + bt->page_size); + bt->page = (BtPage)(bt->mem + 2 * bt->page_size); + bt->alloc = (BtPage)(bt->mem + 3 * bt->page_size); + bt->temp = (BtPage)(bt->mem + 4 * bt->page_size); + bt->zero = (BtPage)(bt->mem + 5 * bt->page_size); + + if( size || *amt ) { + if ( bt_unlockpage(bt, ALLOC_page, lockmode) ) + return bt_close (bt), NULL; + + return bt; + } + + // initializes an empty b-tree with root page and page of leaves + + memset (bt->alloc, 0, bt->page_size); + bt_putid(bt->alloc->right, MIN_lvl+1); + bt->alloc->bits = bt->page_bits; + +#ifdef unix + if( write (bt->idx, bt->alloc, bt->page_size) < bt->page_size ) + return bt_close (bt), NULL; +#else + if( !WriteFile (bt->idx, (char *)bt->alloc, bt->page_size, amt, NULL) ) + return bt_close (bt), NULL; + + if( *amt < bt->page_size ) + return bt_close (bt), NULL; +#endif + + memset (bt->frame, 0, bt->page_size); + bt->frame->bits = bt->page_bits; + + for( lvl=MIN_lvl; lvl--; ) { + slotptr(bt->frame, 1)->off = bt->page_size - 3; + bt_putid(slotptr(bt->frame, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number + key = keyptr(bt->frame, 1); + key->len = 2; // create stopper key + key->key[0] = 0xff; + key->key[1] = 0xff; + bt->frame->min = bt->page_size - 3; + bt->frame->lvl = lvl; + bt->frame->cnt = 1; + bt->frame->act = 1; +#ifdef unix + if( write (bt->idx, bt->frame, bt->page_size) < bt->page_size ) + return bt_close (bt), NULL; +#else + if( !WriteFile (bt->idx, (char *)bt->frame, bt->page_size, amt, NULL) ) + return bt_close (bt), NULL; + + if( *amt < bt->page_size ) + return bt_close (bt), NULL; +#endif + } + + // create empty page area by writing last page of first + // cache area (other pages are zeroed by O/S) + + if( bt->mapped_io && bt->hashmask ) { + memset(bt->frame, 0, bt->page_size); + last = bt->hashmask; + + while( last < MIN_lvl + 1 ) + last += bt->hashmask + 1; +#ifdef unix + pwrite(bt->idx, bt->frame, bt->page_size, last << bt->page_bits); +#else + SetFilePointer (bt->idx, last << bt->page_bits, NULL, FILE_BEGIN); + if( !WriteFile (bt->idx, (char *)bt->frame, bt->page_size, amt, NULL) ) + return bt_close (bt), NULL; + if( *amt < bt->page_size ) + return bt_close (bt), NULL; +#endif + } + + if( bt_unlockpage(bt, ALLOC_page, lockmode) ) + return bt_close (bt), NULL; + + return bt; +} + +// compare two keys, returning > 0, = 0, or < 0 +// as the comparison value + +int keycmp (BtKey key1, unsigned char *key2, uint len2) +{ +uint len1 = key1->len; +int ans; + + if( ans = memcmp (key1->key, key2, len1 > len2 ? len2 : len1) ) + return ans; + + if( len1 > len2 ) + return 1; + if( len1 < len2 ) + return -1; + + return 0; +} + +// Update current page of btree by writing file contents +// or flushing mapped area to disk. + +BTERR bt_update (BtDb *bt, BtPage page, uid page_no) +{ +off64_t off = page_no << bt->page_bits; + +#ifdef unix + if ( !bt->mapped_io ) + if ( pwrite(bt->idx, page, bt->page_size, off) != bt->page_size ) + return bt->err = BTERR_wrt; +#else +uint amt[1]; + if ( !bt->mapped_io ) + { + SetFilePointer (bt->idx, (long)off, (long*)(&off)+1, FILE_BEGIN); + if( !WriteFile (bt->idx, (char *)page, bt->page_size, amt, NULL) ) + return GetLastError(), bt->err = BTERR_wrt; + + if( *amt < bt->page_size ) + return GetLastError(), bt->err = BTERR_wrt; + } + else if ( bt->mode == BT_fl ) { + FlushViewOfFile(page, bt->page_size); + FlushFileBuffers(bt->idx); + } +#endif + return 0; +} + +// find page in cache + +BtHash *bt_findhash(BtDb *bt, uid page_no) +{ +BtHash *hash; +uint idx; + + // compute cache block first page and hash idx + + page_no &= ~bt->hashmask; + idx = (uint)(page_no >> bt->seg_bits) % bt->hashsize; + + if( bt->cache[idx] ) + hash = bt->nodes + bt->cache[idx]; + else + return NULL; + + do if( hash->page_no == page_no ) + break; + while(hash = hash->hashnext ); + + return hash; +} + +// add page cache entry to hash index + +void bt_linkhash(BtDb *bt, BtHash *node, uid page_no) +{ +uint idx = (uint)(page_no >> bt->seg_bits) % bt->hashsize; +BtHash *hash; + + if( bt->cache[idx] ) { + node->hashnext = hash = bt->nodes + bt->cache[idx]; + hash->hashprev = node; + } + + node->hashprev = NULL; + bt->cache[idx] = (ushort)(node - bt->nodes); +} + +// remove cache entry from hash table + +void bt_unlinkhash(BtDb *bt, BtHash *node) +{ +uint idx = (uint)(node->page_no >> bt->seg_bits) % bt->hashsize; +BtHash *hash; + + // unlink node + if( hash = node->hashprev ) + hash->hashnext = node->hashnext; + else if( hash = node->hashnext ) + bt->cache[idx] = (ushort)(hash - bt->nodes); + else + bt->cache[idx] = 0; + + if( hash = node->hashnext ) + hash->hashprev = node->hashprev; +} + +// add cache page to lru chain and map pages + +BtPage bt_linklru(BtDb *bt, BtHash *hash, uid page_no) +{ +int flag; +off64_t off = (page_no & ~bt->hashmask) << bt->page_bits; +off64_t limit = off + ((bt->hashmask+1) << bt->page_bits); +BtHash *node; + + memset(hash, 0, sizeof(BtHash)); + hash->page_no = (page_no & ~bt->hashmask); + bt_linkhash(bt, hash, page_no); + + if( node = hash->lrunext = bt->lrufirst ) + node->lruprev = hash; + else + bt->lrulast = hash; + + bt->lrufirst = hash; + +#ifdef unix + flag = PROT_READ | ( bt->mode == BT_ro ? 0 : PROT_WRITE ); + hash->page = (BtPage)mmap (0, (bt->hashmask+1) << bt->page_bits, flag, MAP_SHARED, bt->idx, off); + if( hash->page == MAP_FAILED ) + return bt->err = BTERR_map, (BtPage)NULL; + +#else + flag = ( bt->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE ); + hash->hmap = CreateFileMapping(bt->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL); + if( !hash->hmap ) + return bt->err = BTERR_map, NULL; + + flag = ( bt->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE ); + hash->page = MapViewOfFile(hash->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->hashmask+1) << bt->page_bits); + if( !hash->page ) + return bt->err = BTERR_map, NULL; +#endif + + return (BtPage)((char*)hash->page + ((uint)(page_no & bt->hashmask) << bt->page_bits)); +} + +// find or place requested page in page-cache +// return memory address where page is located. + +BtPage bt_hashpage(BtDb *bt, uid page_no) +{ +BtHash *hash, *node, *next; +BtPage page; + + // find page in cache and move to top of lru list + + if( hash = bt_findhash(bt, page_no) ) { + page = (BtPage)((char*)hash->page + ((uint)(page_no & bt->hashmask) << bt->page_bits)); + // swap node in lru list + if( node = hash->lruprev ) { + if( next = node->lrunext = hash->lrunext ) + next->lruprev = node; + else + bt->lrulast = node; + + if( next = hash->lrunext = bt->lrufirst ) + next->lruprev = hash; + else + return bt->err = BTERR_hash, (BtPage)NULL; + + hash->lruprev = NULL; + bt->lrufirst = hash; + } + return page; + } + + // map pages and add to cache entry + + if( bt->nodecnt < bt->nodemax ) { + hash = bt->nodes + ++bt->nodecnt; + return bt_linklru(bt, hash, page_no); + } + + // hash table is already full, replace last lru entry from the cache + + if( hash = bt->lrulast ) { + // unlink from lru list + if( node = bt->lrulast = hash->lruprev ) + node->lrunext = NULL; + else + return bt->err = BTERR_hash, (BtPage)NULL; + +#ifdef unix + munmap (hash->page, (bt->hashmask+1) << bt->page_bits); +#else + FlushViewOfFile(hash->page, 0); + UnmapViewOfFile(hash->page); + CloseHandle(hash->hmap); +#endif + // unlink from hash table + + bt_unlinkhash(bt, hash); + + // map and add to cache + + return bt_linklru(bt, hash, page_no); + } + + return bt->err = BTERR_hash, (BtPage)NULL; +} + +// map a btree page onto current page + +BTERR bt_mappage (BtDb *bt, BtPage *page, uid page_no) +{ +off64_t off = page_no << bt->page_bits; +#ifndef unix +int amt[1]; +#endif + + if( bt->mapped_io ) { + bt->err = 0; + *page = bt_hashpage(bt, page_no); + return bt->err; + } +#ifdef unix + if ( pread(bt->idx, *page, bt->page_size, off) < bt->page_size ) + return bt->err = BTERR_map; +#else + SetFilePointer (bt->idx, (long)off, (long*)(&off)+1, FILE_BEGIN); + + if( !ReadFile(bt->idx, *page, bt->page_size, amt, NULL) ) + return bt->err = BTERR_map; + + if( *amt < bt->page_size ) + return bt->err = BTERR_map; +#endif + return 0; +} + +// deallocate a deleted page +// place on free chain out of allocator page + +BTERR bt_freepage(BtDb *bt, uid page_no) +{ + // obtain delete lock on deleted node + + if( bt_lockpage(bt, page_no, BtLockDelete) ) + return bt->err; + + // obtain write lock on deleted node + + if( bt_lockpage(bt, page_no, BtLockWrite) ) + return bt->err; + + if( bt_mappage (bt, &bt->temp, page_no) ) + return bt->err; + + // lock allocation page + + if ( bt_lockpage(bt, ALLOC_page, BtLockWrite) ) + return bt->err; + + if( bt_mappage (bt, &bt->alloc, ALLOC_page) ) + return bt->err; + + // store chain in second right + bt_putid(bt->temp->right, bt_getid(bt->alloc[1].right)); + bt_putid(bt->alloc[1].right, page_no); + + if( bt_update(bt, bt->alloc, ALLOC_page) ) + return bt->err; + if( bt_update(bt, bt->temp, page_no) ) + return bt->err; + + // unlock page zero + + if( bt_unlockpage(bt, ALLOC_page, BtLockWrite) ) + return bt->err; + + // remove write lock on deleted node + + if( bt_unlockpage(bt, page_no, BtLockWrite) ) + return bt->err; + + // remove delete lock on deleted node + + if( bt_unlockpage(bt, page_no, BtLockDelete) ) + return bt->err; + + return 0; +} + +// allocate a new page and write page into it + +uid bt_newpage(BtDb *bt, BtPage page) +{ +uid new_page; +char *pmap; +int reuse; + + // lock page zero + + if ( bt_lockpage(bt, ALLOC_page, BtLockWrite) ) + return 0; + + if( bt_mappage (bt, &bt->alloc, ALLOC_page) ) + return 0; + + // use empty chain first + // else allocate empty page + + if( new_page = bt_getid(bt->alloc[1].right) ) { + if( bt_mappage (bt, &bt->temp, new_page) ) + return 0; // don't unlock on error + bt_putid(bt->alloc[1].right, bt_getid(bt->temp->right)); + reuse = 1; + } else { + new_page = bt_getid(bt->alloc->right); + bt_putid(bt->alloc->right, new_page+1); + reuse = 0; + } + + if( bt_update(bt, bt->alloc, ALLOC_page) ) + return 0; // don't unlock on error + + if( !bt->mapped_io ) { + if( bt_update(bt, page, new_page) ) + return 0; //don't unlock on error + + return new_page; + } + +#ifdef unix + if ( pwrite(bt->idx, page, bt->page_size, new_page << bt->page_bits) < bt->page_size ) + return bt->err = BTERR_wrt, 0; + + // if writing first page of hash block, zero last page in the block + + if ( !reuse && bt->hashmask > 0 && (new_page & bt->hashmask) == 0 ) + { + // use temp buffer to write zeros + memset(bt->zero, 0, bt->page_size); + if ( pwrite(bt->idx,bt->zero, bt->page_size, (new_page | bt->hashmask) << bt->page_bits) < bt->page_size ) + return bt->err = BTERR_wrt, 0; + } +#else + // bring new page into page-cache and copy page. + // this will extend the file into the new pages. + + if( !(pmap = (char*)bt_hashpage(bt, new_page & ~bt->hashmask)) ) + return 0; + + memcpy(pmap+((new_page & bt->hashmask) << bt->page_bits), page, bt->page_size); +#endif + + // unlock page zero + + if ( bt_unlockpage(bt, ALLOC_page, BtLockWrite) ) + return 0; + + return new_page; +} + +// find slot in page for given key at a given level + +int bt_findslot (BtDb *bt, unsigned char *key, uint len) +{ +uint diff, higher = bt->page->cnt, low = 1, slot; +uint good = 0; + + // make stopper key an infinite fence value + + if( bt_getid (bt->page->right) ) + higher++; + else + good++; + + // low is the next candidate, higher is already + // tested as .ge. the given key, loop ends when they meet + + while( diff = higher - low ) { + slot = low + ( diff >> 1 ); + if( keycmp (keyptr(bt->page, slot), key, len) < 0 ) + low = slot + 1; + else + higher = slot, good++; + } + + // return zero if key is on right link page + + return good ? higher : 0; +} + +// find and load page at given level for given key +// leave page rd or wr locked as requested + +int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, uint lock) +{ +uid page_no = ROOT_page, prevpage = 0; +uint drill = 0xff, slot; +uint mode, prevmode; + + // start at root of btree and drill down + + do { + // determine lock mode of drill level + mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead; + + bt->page_no = page_no; + + // obtain access lock using lock chaining + + if( page_no > ROOT_page ) + if( bt_lockpage(bt, bt->page_no, BtLockAccess) ) + return 0; + + if( prevpage ) + if( bt_unlockpage(bt, prevpage, prevmode) ) + return 0; + + // obtain read lock using lock chaining + + if( bt_lockpage(bt, bt->page_no, mode) ) + return 0; + + if( page_no > ROOT_page ) + if( bt_unlockpage(bt, bt->page_no, BtLockAccess) ) + return 0; + + // map/obtain page contents + + if( bt_mappage (bt, &bt->page, page_no) ) + return 0; + + // re-read and re-lock root after determining actual level of root + + if( bt->page->lvl != drill) { + if ( bt->page_no != ROOT_page ) + return bt->err = BTERR_struct, 0; + + drill = bt->page->lvl; + + if( lock == BtLockWrite && drill == lvl ) + if( bt_unlockpage(bt, page_no, mode) ) + return 0; + else + continue; + } + + // find key on page at this level + // and descend to requested level + + if( !bt->page->kill && (slot = bt_findslot (bt, key, len)) ) { + if( drill == lvl ) + return slot; + + while( slotptr(bt->page, slot)->dead ) + if( slot++ < bt->page->cnt ) + continue; + else { + page_no = bt_getid(bt->page->right); + goto slideright; + } + + page_no = bt_getid(slotptr(bt->page, slot)->id); + drill--; + } + + // or slide right into next page + // (slide left from deleted page) + + else + page_no = bt_getid(bt->page->right); + + // continue down / right using overlapping locks + // to protect pages being killed or split. + +slideright: + prevpage = bt->page_no; + prevmode = mode; + } while( page_no ); + + // return error on end of right chain + + bt->err = BTERR_struct; + return 0; // return error +} + +// find and delete key on page by marking delete flag bit +// when page becomes empty, delete it + +BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl) +{ +unsigned char lowerkey[256], higherkey[256]; +uint slot, tod, dirty = 0; +uid page_no, right; +BtKey ptr; + + if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) ) + ptr = keyptr(bt->page, slot); + else + return bt->err; + + // if key is found delete it, otherwise ignore request + + if( !keycmp (ptr, key, len) ) + if( slotptr(bt->page, slot)->dead == 0 ) + dirty = slotptr(bt->page,slot)->dead = 1, bt->page->act--; + + // return if page is not empty, or it has no right sibling + + right = bt_getid(bt->page->right); + page_no = bt->page_no; + + if( !right || bt->page->act ) + if ( dirty && bt_update(bt, bt->page, page_no) ) + return bt->err; + else + return bt_unlockpage(bt, page_no, BtLockWrite); + + // obtain Parent lock over write lock + + if( bt_lockpage(bt, page_no, BtLockParent) ) + return bt->err; + + // cache copy of key to delete + + ptr = keyptr(bt->page, bt->page->cnt); + memcpy(lowerkey, ptr, ptr->len + 1); + + // lock and map right page + + if ( bt_lockpage(bt, right, BtLockWrite) ) + return bt->err; + + if( bt_mappage (bt, &bt->temp, right) ) + return bt->err; + + // pull contents of next page into current empty page + memcpy (bt->page, bt->temp, bt->page_size); + + // cache copy of key to update + ptr = keyptr(bt->temp, bt->temp->cnt); + memcpy(higherkey, ptr, ptr->len + 1); + + // Mark right page as deleted and point it to left page + // until we can post updates at higher level. + + bt_putid(bt->temp->right, page_no); + bt->temp->kill = 1; + bt->temp->cnt = 0; + + if ( bt_update(bt, bt->page, page_no) ) + return bt->err; + + if ( bt_update(bt, bt->temp, right) ) + return bt->err; + + if( bt_unlockpage(bt, right, BtLockWrite) ) + return bt->err; + if( bt_unlockpage(bt, page_no, BtLockWrite) ) + return bt->err; + + // delete old lower key to consolidated node + + if( bt_deletekey (bt, lowerkey + 1, *lowerkey, lvl + 1) ) + return bt->err; + + // redirect higher key directly to consolidated node + + tod = (uint)time(NULL); + + if( bt_insertkey (bt, higherkey+1, *higherkey, lvl + 1, page_no, tod) ) + return bt->err; + + // obtain write lock and + // add right block to free chain + + if( bt_freepage (bt, right) ) + return bt->err; + + // remove ParentModify lock + + if( bt_unlockpage(bt, page_no, BtLockParent) ) + return bt->err; + + return 0; +} + +// find key in leaf level and return row-id + +uid bt_findkey (BtDb *bt, unsigned char *key, uint len) +{ +uint slot; +BtKey ptr; +uid id; + + if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) ) + ptr = keyptr(bt->page, slot); + else + return 0; + + // if key exists, return row-id + // otherwise return 0 + + if( ptr->len == len && !memcmp (ptr->key, key, len) ) + id = bt_getid(slotptr(bt->page,slot)->id); + else + id = 0; + + if ( bt_unlockpage(bt, bt->page_no, BtLockRead) ) + return 0; + + return id; +} + +void bt_cleanpage(BtDb *bt) +{ +uint nxt = bt->page_size; +BtPage page = bt->page; +uint cnt = 0, idx = 0; +uint max = page->cnt; +BtKey key; + + memcpy (bt->frame, page, bt->page_size); + + // skip page info and set rest of page to zero + memset (page+1, 0, bt->page_size - sizeof(*page)); + page->act = 0; + + // try cleaning up page first + + while( cnt++ < max ) { + // always leave fence key in list + if( cnt < max && slotptr(bt->frame,cnt)->dead ) + continue; + + // copy key + key = keyptr(bt->frame, cnt); + nxt -= key->len + 1; + memcpy ((unsigned char *)page + nxt, key, key->len + 1); + + // copy slot + memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId); + if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) ) + page->act++; + slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod; + slotptr(page, idx)->off = nxt; + } + page->min = nxt; + page->cnt = idx; +} + +// split the root and raise the height of the btree + +BTERR bt_splitroot(BtDb *bt, unsigned char *newkey, unsigned char *oldkey, uid page_no2) +{ +uint nxt = bt->page_size; +BtPage root = bt->page; +uid new_page; + + // Obtain an empty page to use, and copy the current + // root contents into it + + if( !(new_page = bt_newpage(bt, root)) ) + return bt->err; + + // preserve the page info at the bottom + // and set rest to zero + + memset(root+1, 0, bt->page_size - sizeof(*root)); + + // insert first key on newroot page + + nxt -= *newkey + 1; + memcpy ((unsigned char *)root + nxt, newkey, *newkey + 1); + bt_putid(slotptr(root, 1)->id, new_page); + slotptr(root, 1)->off = nxt; + + // insert second key on newroot page + // and increase the root height + + nxt -= *oldkey + 1; + memcpy ((unsigned char *)root + nxt, oldkey, *oldkey + 1); + bt_putid(slotptr(root, 2)->id, page_no2); + slotptr(root, 2)->off = nxt; + + bt_putid(root->right, 0); + root->min = nxt; // reset lowest used offset and key count + root->cnt = 2; + root->act = 2; + root->lvl++; + + // update and release root (bt->page) + + if( bt_update(bt, root, bt->page_no) ) + return bt->err; + + return bt_unlockpage(bt, bt->page_no, BtLockWrite); +} + +// split already locked full node +// return unlocked. + +BTERR bt_splitpage (BtDb *bt, uint len) +{ +uint cnt = 0, idx = 0, max, nxt = bt->page_size; +unsigned char oldkey[256], lowerkey[256]; +uid page_no = bt->page_no, right; +BtPage page = bt->page; +uint lvl = page->lvl; +uid new_page; +BtKey key; +uint tod; + + // perform cleanup + + bt_cleanpage(bt); + + // return if enough space now + + if( page->min >= (page->cnt + 1) * sizeof(BtSlot) + sizeof(*page) + len + 1) + { + if ( bt_update(bt, page, page_no) ) + return bt->err; + + return bt_unlockpage(bt, page_no, BtLockWrite); + } + + // split higher half of keys to bt->frame + // the last key (fence key) might be dead + + tod = (uint)time(NULL); + + memset (bt->frame, 0, bt->page_size); + max = (int)page->cnt; + cnt = max / 2; + idx = 0; + + while( cnt++ < max ) { + key = keyptr(page, cnt); + nxt -= key->len + 1; + memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1); + memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId); + if( !(slotptr(bt->frame, idx)->dead = slotptr(page, cnt)->dead) ) + bt->frame->act++; + slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod; + slotptr(bt->frame, idx)->off = nxt; + } + + // remember existing fence key for new page to the right + + memcpy (oldkey, key, key->len + 1); + + bt->frame->bits = bt->page_bits; + bt->frame->min = nxt; + bt->frame->cnt = idx; + bt->frame->lvl = lvl; + + // link right node + + if( page_no > ROOT_page ) { + right = bt_getid (page->right); + bt_putid(bt->frame->right, right); + } + + // get new free page and write frame to it. + + if( !(new_page = bt_newpage(bt, bt->frame)) ) + return bt->err; + + // update lower keys to continue in old page + + memcpy (bt->frame, page, bt->page_size); + memset (page+1, 0, bt->page_size - sizeof(*page)); + nxt = bt->page_size; + page->act = 0; + cnt = 0; + idx = 0; + + // assemble page of smaller keys + // (they're all active keys) + + while( cnt++ < max / 2 ) { + key = keyptr(bt->frame, cnt); + nxt -= key->len + 1; + memcpy ((unsigned char *)page + nxt, key, key->len + 1); + memcpy(slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId); + slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod; + slotptr(page, idx)->off = nxt; + page->act++; + } + + // remember fence key for old page + + memcpy(lowerkey, key, key->len + 1); + bt_putid(page->right, new_page); + page->min = nxt; + page->cnt = idx; + + // if current page is the root page, split it + + if( page_no == ROOT_page ) + return bt_splitroot (bt, lowerkey, oldkey, new_page); + + // update left (containing) node + + if( bt_update(bt, page, page_no) ) + return bt->err; + + // obtain Parent/Write locks + // for left and right node pages + + if( bt_lockpage (bt, new_page, BtLockParent) ) + return bt->err; + + if( bt_lockpage (bt, page_no, BtLockParent) ) + return bt->err; + + // release wr lock on left page + + if( bt_unlockpage (bt, page_no, BtLockWrite) ) + return bt->err; + + // insert new fence for reformulated left block + + if( bt_insertkey (bt, lowerkey+1, *lowerkey, lvl + 1, page_no, tod) ) + return bt->err; + + // fix old fence for newly allocated right block page + + if( bt_insertkey (bt, oldkey+1, *oldkey, lvl + 1, new_page, tod) ) + return bt->err; + + // release Parent & Write locks + + if( bt_unlockpage (bt, new_page, BtLockParent) ) + return bt->err; + + if( bt_unlockpage (bt, page_no, BtLockParent) ) + return bt->err; + + return 0; +} + +// Insert new key into the btree at requested level. +// Level zero pages are leaf pages and are unlocked at exit. +// Interior nodes remain locked. + +BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uint lvl, uid id, uint tod) +{ +uint slot, idx; +BtPage page; +BtKey ptr; + + while( 1 ) { + if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) ) + ptr = keyptr(bt->page, slot); + else + { + if ( !bt->err ) + bt->err = BTERR_ovflw; + return bt->err; + } + + // if key already exists, update id and return + + page = bt->page; + + if( !keycmp (ptr, key, len) ) { + slotptr(page, slot)->dead = 0; + slotptr(page, slot)->tod = tod; + bt_putid(slotptr(page,slot)->id, id); + if ( bt_update(bt, bt->page, bt->page_no) ) + return bt->err; + return bt_unlockpage(bt, bt->page_no, BtLockWrite); + } + + // check if page has enough space + + if( page->min >= (page->cnt + 1) * sizeof(BtSlot) + sizeof(*page) + len + 1) + break; + + if( bt_splitpage (bt, len) ) + return bt->err; + } + + // calculate next available slot and copy key into page + + page->min -= len + 1; // reset lowest used offset + ((unsigned char *)page)[page->min] = len; + memcpy ((unsigned char *)page + page->min +1, key, len ); + + for( idx = slot; idx < page->cnt; idx++ ) + if( slotptr(page, idx)->dead ) + break; + + // now insert key into array before slot + // preserving the fence slot + + if( idx == page->cnt ) + idx++, page->cnt++; + + page->act++; + + while( idx > slot ) + *slotptr(page, idx) = *slotptr(page, idx -1), idx--; + + bt_putid(slotptr(page,slot)->id, id); + slotptr(page, slot)->off = page->min; + slotptr(page, slot)->tod = tod; + slotptr(page, slot)->dead = 0; + + if ( bt_update(bt, bt->page, bt->page_no) ) + return bt->err; + + return bt_unlockpage(bt, bt->page_no, BtLockWrite); +} + +// cache page of keys into cursor and return starting slot for given key + +uint bt_startkey (BtDb *bt, unsigned char *key, uint len) +{ +uint slot; + + // cache page for retrieval + if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) ) + memcpy (bt->cursor, bt->page, bt->page_size); + bt->cursor_page = bt->page_no; + if ( bt_unlockpage(bt, bt->page_no, BtLockRead) ) + return 0; + + return slot; +} + +// return next slot for cursor page +// or slide cursor right into next page + +uint bt_nextkey (BtDb *bt, uint slot) +{ +off64_t right; + + do { + right = bt_getid(bt->cursor->right); + while( slot++ < bt->cursor->cnt ) + if( slotptr(bt->cursor,slot)->dead ) + continue; + else if( right || (slot < bt->cursor->cnt)) + return slot; + else + break; + + if( !right ) + break; + + bt->cursor_page = right; + + if( bt_lockpage(bt, right,BtLockRead) ) + return 0; + + if( bt_mappage (bt, &bt->page, right) ) + break; + + memcpy (bt->cursor, bt->page, bt->page_size); + if ( bt_unlockpage(bt, right, BtLockRead) ) + return 0; + + slot = 0; + } while( 1 ); + + return bt->err = 0; +} + +BtKey bt_key(BtDb *bt, uint slot) +{ + return keyptr(bt->cursor, slot); +} + +uid bt_uid(BtDb *bt, uint slot) +{ + return bt_getid(slotptr(bt->cursor,slot)->id); +} + +uint bt_tod(BtDb *bt, uint slot) +{ + return slotptr(bt->cursor,slot)->tod; +} + + +#ifdef STANDALONE +// standalone program to index file of keys +// then list them onto std-out + +int main (int argc, char **argv) +{ +uint slot, line = 0, off = 0, found = 0; +int dead, ch, cnt = 0, bits = 12; +unsigned char key[256]; +clock_t done, start; +uint pgblk = 0; +time_t tod[1]; +uint scan = 0; +uint len = 0; +uint map = 0; +BtKey ptr; +BtDb *bt; +FILE *in; + + if( argc < 4 ) { + fprintf (stderr, "Usage: %s idx_file src_file Read/Write/Scan/Delete/Find [page_bits mapped_pool_segments pages_per_segment start_line_number]\n", argv[0]); + fprintf (stderr, " page_bits: size of btree page in bits\n"); + fprintf (stderr, " mapped_pool_segments: size of buffer pool in segments\n"); + fprintf (stderr, " pages_per_segment: size of buffer pool segment in pages in bits\n"); + exit(0); + } + + start = clock(); + time(tod); + + if( argc > 4 ) + bits = atoi(argv[4]); + + if( argc > 5 ) + map = atoi(argv[5]); + + if( map > 65536 ) + fprintf (stderr, "Warning: buffer_pool > 65536 segments\n"); + + if( map && map < 8 ) + fprintf (stderr, "Buffer_pool too small\n"); + + if( argc > 6 ) + pgblk = atoi(argv[6]); + + if( bits + pgblk > 30 ) + fprintf (stderr, "Warning: very large buffer pool segment size\n"); + + if( argc > 7 ) + off = atoi(argv[7]); + + bt = bt_open ((argv[1]), BT_rw, bits, map, pgblk); + + if( !bt ) { + fprintf(stderr, "Index Open Error %s\n", argv[1]); + exit (1); + } + + switch(argv[3][0]| 0x20) + { + case 'w': + fprintf(stderr, "started indexing for %s\n", argv[2]); + if( argc > 2 && (in = fopen (argv[2], "rb")) ) + while( ch = getc(in), ch != EOF ) + if( ch == '\n' ) + { + if( off ) + sprintf((char *)key+len, "%.9d", line + off), len += 9; + + if( bt_insertkey (bt, key, len, 0, ++line, *tod) ) + fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0); + len = 0; + } + else if( len < 245 ) + key[len++] = ch; + fprintf(stderr, "finished adding keys, %d \n", line); + break; + + case 'd': + fprintf(stderr, "started deleting keys for %s\n", argv[2]); + if( argc > 2 && (in = fopen (argv[2], "rb")) ) + while( ch = getc(in), ch != EOF ) + if( ch == '\n' ) + { + if( off ) + sprintf((char *)key+len, "%.9d", line + off), len += 9; + line++; + if( bt_deletekey (bt, key, len, 0) ) + fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0); + len = 0; + } + else if( len < 245 ) + key[len++] = ch; + fprintf(stderr, "finished deleting keys, %d \n", line); + break; + + case 'f': + fprintf(stderr, "started finding keys for %s\n", argv[2]); + if( argc > 2 && (in = fopen (argv[2], "rb")) ) + while( ch = getc(in), ch != EOF ) + if( ch == '\n' ) + { + if( off ) + sprintf((char *)key+len, "%.9d", line + off), len += 9; + line++; + if( bt_findkey (bt, key, len) ) + found++; + else if( bt->err ) + fprintf(stderr, "Error %d Syserr %d Line: %d\n", bt->err, errno, line), exit(0); + len = 0; + } + else if( len < 245 ) + key[len++] = ch; + fprintf(stderr, "finished search of %d keys, found %d\n", line, found); + break; + + case 's': + scan++; + break; + + } + + done = clock(); + fprintf(stderr, " Time to complete: %.2f seconds\n", (float)(done - start) / CLOCKS_PER_SEC); + + dead = cnt = 0; + len = key[0] = 0; + + fprintf(stderr, "started reading\n"); + + if( slot = bt_startkey (bt, key, len) ) + slot--; + else + fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0); + + while( slot = bt_nextkey (bt, slot) ) + if( cnt++, scan ) { + ptr = bt_key(bt, slot); + fwrite (ptr->key, ptr->len, 1, stdout); + fputc ('\n', stdout); + } + + fprintf(stderr, " Total keys read %d\n", cnt); +} + +#endif //STANDALONE diff --git a/fosterbtree.c b/fosterbtree.c new file mode 100644 index 0000000..1b9735e --- /dev/null +++ b/fosterbtree.c @@ -0,0 +1,2054 @@ +// foster btree +// 26 MAY 2013 + +// author: karl malbrain, malbrain@cal.berkeley.edu + +/* +This work, including the source code, documentation +and related data, is placed into the public domain. + +The orginal author is Karl Malbrain. + +THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY +OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF +MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE, +ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE +RESULTING FROM THE USE, MODIFICATION, OR +REDISTRIBUTION OF THIS SOFTWARE. +*/ + +// Please see the project home page for documentation +// code.google.com/p/high-concurrency-btree + +#define _FILE_OFFSET_BITS 64 +#define _LARGEFILE64_SOURCE + +#ifdef linux +#define _GNU_SOURCE +#endif + +#ifdef unix +#include +#include +#include +#include +#include +#include +#include +#include +#else +#define WIN32_LEAN_AND_MEAN +#include +#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_maxbits 24 // maximum page size in bits +#define BT_minbits 9 // minimum page size in bits +#define BT_minpage (1 << BT_minbits) // minimum page size +#define BT_maxpage (1 << BT_maxbits) // maximum page size + +/* +There are five lock types for each node in three independent sets: +1. (set 1) AccessIntent: Sharable. Going to Read the node. Incompatible with NodeDelete. +2. (set 1) NodeDelete: Exclusive. About to release the node. Incompatible with AccessIntent. +3. (set 2) ReadLock: Sharable. Read the node. Incompatible with WriteLock. +4. (set 2) WriteLock: Exclusive. Modify the node. Incompatible with ReadLock and other WriteLocks. +5. (set 3) ParentLock: Exclusive. Have parent adopt/delete maximum foster child from the node. +*/ + +typedef enum{ + BtLockAccess, + BtLockDelete, + BtLockRead, + BtLockWrite, + BtLockParent +}BtLock; + +// Define the length of the page and key pointers + +#define BtId 6 + +// Page key slot definition. + +// If BT_maxbits is 15 or less, you can save 4 bytes +// for each key stored by making the first two uints +// into ushorts. You can also save 4 bytes by removing +// the tod field from the key. + +// Keys are marked dead, but remain on the page until +// it cleanup is called. The fence key (highest key) for +// the page is always present, even after cleanup. + +typedef struct { + uint off:BT_maxbits; // page offset for key start + uint dead:1; // set for deleted key + uint tod; // time-stamp for key + unsigned char id[BtId]; // id associated with key +} BtSlot; + +// The key structure occupies space at the upper end of +// each page. It's a length byte followed by the value +// bytes. + +typedef struct { + unsigned char len; + unsigned char key[1]; +} *BtKey; + +// The first part of an index page. +// It is immediately followed +// by the BtSlot array of keys. + +typedef struct Page { + uint cnt; // count of keys in page + uint act; // count of active keys + uint min; // next key offset + uint foster; // count of foster children + unsigned char bits:7; // page size in bits + unsigned char kill:1; // page is being deleted + unsigned char lvl; // level of page + unsigned char right[BtId]; // page number to right +} *BtPage; + +// mode & definition for latch table implementation + +enum { + Write = 1, + Share = 2 +} LockMode; + +// latch table lock structure + +// mode is set for write access +// share is count of read accessors +// grant write lock when share == 0 + +typedef struct { + int mode:1; + int share:31; +} BtLatch; + +typedef struct { + BtLatch readwr[1]; // read/write page lock + BtLatch access[1]; // Access Intent/Page delete + BtLatch parent[1]; // adoption of foster children +} BtLatchSet; + +// The memory mapping hash table buffer manager entry + +typedef struct { + unsigned long long int lru; // number of times accessed + uid basepage; // mapped base page number + char *map; // mapped memory pointer + uint pin; // mapped page pin counter + uint slot; // slot index in this array + void *hashprev; // previous cache block for the same hash idx + void *hashnext; // next cache block for the same hash idx +#ifndef unix + HANDLE hmap; +#endif +// array of page latch sets, one for each page in map segment + BtLatchSet pagelatch[0]; +} BtHash; + +// The object structure for Btree access + +typedef struct { + uint page_size; // page size + uint page_bits; // page size in bits + uint seg_bits; // seg size in pages in bits + uint mode; // read-write mode +#ifdef unix + int idx; +#else + HANDLE idx; +#endif + uint nodecnt; // highest page cache node in use + uint nodemax; // highest page cache node allocated + uint hashmask; // number of pages in mmap segment + uint hashsize; // size of Hash Table + uint evicted; // last evicted hash slot + ushort *cache; // hash index for memory pool + BtLatch *latch; // latches for hash table slots + char *nodes; // memory pool page hash nodes +} BtMgr; + +typedef struct { + BtMgr *mgr; // buffer manager for thread + BtPage temp; // temporary frame buffer (memory mapped/file IO) + BtPage alloc; // frame buffer for alloc page ( page 0 ) + BtPage cursor; // cached frame for start/next (never mapped) + BtPage frame; // spare frame for the page split (never mapped) + BtPage zero; // page frame for zeroes at end of file + BtPage page; // current page + uid page_no; // current page number + uid cursor_page; // current cursor page number + unsigned char *mem; // frame, cursor, page memory buffer + int err; // last error +} BtDb; + +typedef enum { + BTERR_ok = 0, + BTERR_again, + BTERR_struct, + BTERR_ovflw, + BTERR_lock, + BTERR_map, + BTERR_wrt, + BTERR_hash +} BTERR; + +// B-Tree functions +extern void bt_close (BtDb *bt); +extern BtDb *bt_open (BtMgr *mgr); +extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod); +extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl); +extern uid bt_findkey (BtDb *bt, unsigned char *key, uint len); +extern uint bt_startkey (BtDb *bt, unsigned char *key, uint len); +extern uint bt_nextkey (BtDb *bt, uint slot); + +// manager functions +extern BtMgr *bt_mgr (char *name, uint mode, uint bits, uint cacheblk, uint segsize, uint hashsize); +void bt_mgrclose (BtMgr *mgr); + +// Helper functions to return cursor slot values + +extern BtKey bt_key (BtDb *bt, uint slot); +extern uid bt_uid (BtDb *bt, uint slot); +extern uint bt_tod (BtDb *bt, uint slot); + +// BTree page number constants +#define ALLOC_page 0 +#define ROOT_page 1 + +// Number of levels to create in a new BTree + +#define MIN_lvl 2 + +// The page is allocated from low and hi ends. +// The key offsets and row-id's are allocated +// from the bottom, while the text of the key +// is allocated from the top. When the two +// areas meet, the page is split into two. + +// A key consists of a length byte, two bytes of +// index number (0 - 65534), and up to 253 bytes +// of key value. Duplicate keys are discarded. +// Associated with each key is a 48 bit row-id. + +// The b-tree root is always located at page 1. +// The first leaf page of level zero is always +// located on page 2. + +// When to root page fills, it is split in two and +// the tree height is raised by a new root at page +// one with two keys. + +// Deleted keys are marked with a dead bit until +// page cleanup The fence key for a node is always +// present, even after deletion and cleanup. + +// Groups of pages called segments from the btree are +// cached with memory mapping. A hash table is used to keep +// track of the cached segments. This behaviour is controlled +// by the cache block size parameter to bt_open. + +// To achieve maximum concurrency one page is locked at a time +// as the tree is traversed to find leaf key in question. + +// An adoption traversal leaves the parent node locked as the +// tree is traversed to the level in quesiton. + +// Page 0 is dedicated to lock for new page extensions, +// and chains empty pages together for reuse. + +// Empty pages are chained together through the ALLOC page and reused. + +// Access macros to address slot and key values from the page + +#define slotptr(page, slot) (((BtSlot *)(page+1)) + (slot-1)) +#define keyptr(page, slot) ((BtKey)((unsigned char*)(page) + slotptr(page, slot)->off)) + +void bt_putid(unsigned char *dest, uid id) +{ +int i = BtId; + + while( i-- ) + dest[i] = (unsigned char)id, id >>= 8; +} + +uid bt_getid(unsigned char *src) +{ +uid id = 0; +int i; + + for( i = 0; i < BtId; i++ ) + id <<= 8, id |= *src++; + + return id; +} + +void bt_mgrclose (BtMgr *mgr) +{ +BtHash *hash; +uint slot; + + // release mapped pages + + for( slot = 0; slot < mgr->nodemax; slot++ ) { + hash = (BtHash *)(mgr->nodes + slot * (sizeof(BtHash) + (mgr->hashmask + 1) * sizeof(BtLatchSet))); + if( hash->slot ) +#ifdef unix + munmap (hash->map, (mgr->hashmask+1) << mgr->page_bits); +#else + { + FlushViewOfFile(hash->map, 0); + UnmapViewOfFile(hash->map); + CloseHandle(hash->hmap); + } +#endif + } + +#ifdef unix + close (mgr->idx); + free (mgr->nodes); + free (mgr->cache); + free (mgr->latch); +#else + FlushFileBuffers(mgr->idx); + CloseHandle(mgr->idx); + GlobalFree (mgr->nodes); + GlobalFree (mgr->cache); + GlobalFree (mgr->latch); +#endif +} + +// close and release memory + +void bt_close (BtDb *bt) +{ +#ifdef unix + if ( bt->mem ) + free (bt->mem); + free (bt); +#else + if ( bt->mem) + VirtualFree (bt->mem, 0, MEM_RELEASE); + GlobalFree (bt); +#endif +} + +// open/create new btree buffer manager + +// call with file_name, BT_openmode, bits in page size (e.g. 16), +// size of mapped page cache (e.g. 8192) + +BtMgr *bt_mgr (char *name, uint mode, uint bits, uint nodemax, uint segsize, uint hashsize) +{ +uint lvl, attr, cacheblk, last; +BtPage alloc; +int lockmode; +off64_t size; +uint amt[1]; +BtMgr* mgr; +BtKey key; + +#ifndef unix +SYSTEM_INFO sysinfo[1]; +#endif + + // determine sanity of page size and buffer pool + + if( bits > BT_maxbits ) + bits = BT_maxbits; + else if( bits < BT_minbits ) + bits = BT_minbits; + + if( !nodemax ) + return NULL; // must have buffer pool + +#ifdef unix + mgr = calloc (1, sizeof(BtMgr)); + + switch (mode & 0x7fff) + { + case BT_rw: + mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666); + lockmode = 1; + break; + + case BT_ro: + default: + mgr->idx = open ((char*)name, O_RDONLY); + lockmode = 0; + break; + } + if( mgr->idx == -1 ) + return free(mgr), NULL; + + cacheblk = 4096; // minimum mmap segment size for unix + +#else + mgr = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtMgr)); + attr = FILE_ATTRIBUTE_NORMAL; + switch (mode & 0x7fff) + { + case BT_rw: + mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL); + lockmode = 1; + break; + + case BT_ro: + default: + mgr->idx = CreateFile(name, GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, attr, NULL); + lockmode = 0; + break; + } + if( mgr->idx == INVALID_HANDLE_VALUE ) + return GlobalFree(mgr), NULL; + + // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity + GetSystemInfo(sysinfo); + cacheblk = sysinfo->dwAllocationGranularity; +#endif + +#ifdef unix + alloc = malloc (BT_maxpage); + *amt = 0; + + // read minimum page size to get root info + + if( size = lseek (mgr->idx, 0L, 2) ) { + if( pread(mgr->idx, alloc, BT_minpage, 0) == BT_minpage ) + bits = alloc->bits; + else + return free(mgr), free(alloc), NULL; + } else if( mode == BT_ro ) + return bt_mgrclose (mgr), NULL; +#else + alloc = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE); + size = GetFileSize(mgr->idx, amt); + + if( size || *amt ) { + if( !ReadFile(mgr->idx, (char *)alloc, BT_minpage, amt, NULL) ) + return bt_mgrclose (mgr), NULL; + bits = alloc->bits; + } else if( mode == BT_ro ) + return bt_mgrclose (mgr), NULL; +#endif + + mgr->page_size = 1 << bits; + mgr->page_bits = bits; + + mgr->nodemax = nodemax; + mgr->mode = mode; + + if( cacheblk < mgr->page_size ) + cacheblk = mgr->page_size; + + // mask for partial memmaps + + mgr->hashmask = (cacheblk >> bits) - 1; + + // see if requested number of pages per memmap is greater + + if( (1 << segsize) > mgr->hashmask ) + mgr->hashmask = (1 << segsize) - 1; + + mgr->seg_bits = 0; + + while( (1 << mgr->seg_bits) <= mgr->hashmask ) + mgr->seg_bits++; + + mgr->hashsize = hashsize; + +#ifdef unix + mgr->nodes = calloc (cacheblk, (sizeof(BtHash) + (mgr->hashmask + 1) * sizeof(BtLatchSet))); + mgr->cache = calloc (hashsize, sizeof(ushort)); + mgr->latch = calloc (hashsize, sizeof(BtLatch)); +#else + mgr->nodes = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, cacheblk * (sizeof(BtHash) + (mgr->hashmask + 1) * sizeof(BtLatchSet))); + mgr->cache = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(ushort)); + mgr->latch = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(BtLatch)); +#endif + + if( size || *amt ) + goto mgrxit; + + // initializes an empty b-tree with root page and page of leaves + + memset (alloc, 0, 1 << bits); + bt_putid(slotptr(alloc, 2)->id, MIN_lvl+1); + alloc->bits = mgr->page_bits; + +#ifdef unix + if( write (mgr->idx, alloc, mgr->page_size) < mgr->page_size ) + return bt_mgrclose (mgr), NULL; +#else + if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) ) + return bt_mgrclose (mgr), NULL; + + if( *amt < mgr->page_size ) + return bt_mgrclose (mgr), NULL; +#endif + + memset (alloc, 0, 1 << bits); + alloc->bits = mgr->page_bits; + + for( lvl=MIN_lvl; lvl--; ) { + slotptr(alloc, 1)->off = mgr->page_size - 3; + bt_putid(slotptr(alloc, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number + key = keyptr(alloc, 1); + key->len = 2; // create stopper key + key->key[0] = 0xff; + key->key[1] = 0xff; + alloc->min = mgr->page_size - 3; + alloc->lvl = lvl; + alloc->cnt = 1; + alloc->act = 1; +#ifdef unix + if( write (mgr->idx, alloc, mgr->page_size) < mgr->page_size ) + return bt_mgrclose (mgr), NULL; +#else + if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) ) + return bt_mgrclose (mgr), NULL; + + if( *amt < mgr->page_size ) + return bt_mgrclose (mgr), NULL; +#endif + } + + // create empty page area by writing last page of first + // cache area (other pages are zeroed by O/S) + + if( mgr->hashmask ) { + memset(alloc, 0, mgr->page_size); + last = mgr->hashmask; + + while( last < MIN_lvl + 1 ) + last += mgr->hashmask + 1; + +#ifdef unix + pwrite(mgr->idx, alloc, mgr->page_size, last << mgr->page_bits); +#else + SetFilePointer (mgr->idx, last << mgr->page_bits, NULL, FILE_BEGIN); + if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) ) + return bt_mgrclose (mgr), NULL; + if( *amt < mgr->page_size ) + return bt_mgrclose (mgr), NULL; +#endif + } + +mgrxit: +#ifdef unix + free (alloc); +#else + VirtualFree (alloc, 0, MEM_RELEASE); +#endif + return mgr; +} + +// open BTree access method +// based on buffer manager + +BtDb *bt_open (BtMgr *mgr) +{ +BtDb *bt = malloc (sizeof(*bt)); + + memset (bt, 0, sizeof(*bt)); + bt->mgr = mgr; +#ifdef unix + bt->mem = malloc (3 *mgr->page_size); +#else + bt->mem = VirtualAlloc(NULL, 3 * mgr->page_size, MEM_COMMIT, PAGE_READWRITE); +#endif + bt->frame = (BtPage)bt->mem; + bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size); + bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size); + return bt; +} + +// compare two keys, returning > 0, = 0, or < 0 +// as the comparison value + +int keycmp (BtKey key1, unsigned char *key2, uint len2) +{ +uint len1 = key1->len; +int ans; + + if( ans = memcmp (key1->key, key2, len1 > len2 ? len2 : len1) ) + return ans; + + if( len1 > len2 ) + return 1; + if( len1 < len2 ) + return -1; + + return 0; +} + +// Latch Manager + +// wait until write lock mode is clear +// and add 1 to the share count + +void bt_readlock(BtLatch *latch) +{ + do { + // add one to counter, check write bit + +#ifdef unix + if( ~__sync_fetch_and_add((int *)latch, Share) & Write ) + return; +#else + if( ~InterlockedAdd((int *)latch, Share) & Write ) + return; +#endif + // didn't get latch, reset counter by one + +#ifdef unix + __sync_fetch_and_add((int *)latch, -Share); +#else + InterlockedAdd ((int *)latch, -Share); +#endif + + // and yield +#ifdef unix + sched_yield(); +#else + SwitchToThread(); +#endif + } while( 1 ); +} + +// wait for other read and write latches to relinquish + +void bt_writelock(BtLatch *latch) +{ +int prev, ours = 0; + + do { + // see if we can get write access + // with no readers +#ifdef unix + prev = __sync_fetch_and_or((int *)latch, Write); +#else + prev = InterlockedOr((int *)latch, Write); +#endif + + if( ~prev & 1 ) + ours++; // it's ours + + if( !(prev >> 1) && ours ) + return; + + // otherwise yield + +#ifdef unix + sched_yield(); +#else + SwitchToThread(); +#endif + } while( 1 ); +} + +// try to obtain write lock + +// return 1 if obtained, +// 0 if already write locked + +int bt_writetry(BtLatch *latch) +{ +int prev, ours = 0; + + do { + // see if we can get write access + // with no readers +#ifdef unix + prev = __sync_fetch_and_or((int *)latch, Write); +#else + prev = InterlockedOr((int *)latch, Write); +#endif + + if( ~prev & 1 ) + ours++; // it's ours + + if( !ours ) + return 0; + + if( !(prev >> 1) && ours ) + return 1; + + // otherwise yield +#ifdef unix + sched_yield(); +#else + SwitchToThread(); +#endif + } while( 1 ); +} + +// clear write mode + +void bt_releasewrite(BtLatch *latch) +{ +#ifdef unix + __sync_fetch_and_and((int *)latch, ~Write); +#else + InterlockedAnd ((int *)latch, ~Write); +#endif +} + +// decrement reader count + +void bt_releaseread(BtLatch *latch) +{ +#ifdef unix + __sync_fetch_and_add((int *)latch, -Share); +#else + InterlockedAdd((int *)latch, -Share); +#endif +} + +// Buffer Pool mgr + +// find segment in cache +// return NULL if not there +// otherwise return node + +BtHash *bt_findhash(BtDb *bt, uid page_no, uint idx) +{ +BtHash *hash; +uint slot; + + // compute cache block first page and hash idx + + if( slot = bt->mgr->cache[idx] ) + hash = (BtHash *)(bt->mgr->nodes + slot * (sizeof(BtHash) + (bt->mgr->hashmask + 1) * sizeof(BtLatchSet))); + else + return NULL; + + page_no &= ~bt->mgr->hashmask; + + while( hash->basepage != page_no ) + if( hash = hash->hashnext ) + continue; + else + return NULL; + + return hash; +} + +// add segment to hash table + +void bt_linkhash(BtDb *bt, BtHash *hash, uid page_no, int idx) +{ +BtHash *node; +uint slot; + + hash->hashprev = hash->hashnext = NULL; + hash->basepage = page_no & ~bt->mgr->hashmask; + hash->pin = 1; + hash->lru = 1; + + if( slot = bt->mgr->cache[idx] ) { + node = (BtHash *)(bt->mgr->nodes + slot * (sizeof(BtHash) + (bt->mgr->hashmask + 1) * sizeof(BtLatchSet))); + hash->hashnext = node; + node->hashprev = hash; + } + + bt->mgr->cache[idx] = hash->slot; +} + +// find best segment to evict from buffer pool + +BtHash *bt_findlru (BtDb *bt, uint slot) +{ +unsigned long long int target = ~0LL; +BtHash *hash = NULL, *node; + + if( !slot ) + return NULL; + + node = (BtHash *)(bt->mgr->nodes + slot * (sizeof(BtHash) + (bt->mgr->hashmask + 1) * sizeof(BtLatchSet))); + + do { + if( node->pin ) + continue; + if( node->lru > target ) + continue; + target = node->lru; + hash = node; + } while( node = node->hashnext ); + + return hash; +} + +// map new segment to virtual memory + +BTERR bt_mapsegment(BtDb *bt, BtHash *hash, uid page_no) +{ +off64_t off = (page_no & ~bt->mgr->hashmask) << bt->mgr->page_bits; +off64_t limit = off + ((bt->mgr->hashmask+1) << bt->mgr->page_bits); +int flag; + +#ifdef unix + flag = PROT_READ | ( bt->mgr->mode == BT_ro ? 0 : PROT_WRITE ); + hash->map = mmap (0, (bt->mgr->hashmask+1) << bt->mgr->page_bits, flag, MAP_SHARED, bt->mgr->idx, off); + if( hash->map == MAP_FAILED ) + return bt->err = BTERR_map; +#else + flag = ( bt->mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE ); + hash->hmap = CreateFileMapping(bt->mgr->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL); + if( !hash->hmap ) + return bt->err = BTERR_map; + + flag = ( bt->mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE ); + hash->map = MapViewOfFile(hash->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->mgr->hashmask+1) << bt->mgr->page_bits); + if( !hash->map ) + return bt->err = BTERR_map; +#endif + return bt->err = 0; +} + +// find or place requested page in segment-cache +// return hash table entry + +BtHash *bt_hashpage(BtDb *bt, uid page_no) +{ +BtHash *hash, *node, *next; +uint slot, idx, victim; +BtLatchSet *set; + + // lock hash table chain + + idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize; + bt_readlock (&bt->mgr->latch[idx]); + + // look up in hash table + + if( hash = bt_findhash(bt, page_no, idx) ) { +#ifdef unix + __sync_fetch_and_add(&hash->pin, 1); +#else + InterlockedIncrement (&hash->pin); +#endif + bt_releaseread (&bt->mgr->latch[idx]); + hash->lru++; + return hash; + } + + // upgrade to write lock + + bt_releaseread (&bt->mgr->latch[idx]); + bt_writelock (&bt->mgr->latch[idx]); + + // try to find page in cache with write lock + + if( hash = bt_findhash(bt, page_no, idx) ) { +#ifdef unix + __sync_fetch_and_add(&hash->pin, 1); +#else + InterlockedIncrement (&hash->pin); +#endif + bt_releasewrite (&bt->mgr->latch[idx]); + hash->lru++; + return hash; + } + + // allocate a new hash node + // and add to hash table + +#ifdef unix + slot = __sync_fetch_and_add(&bt->mgr->nodecnt, 1); +#else + slot = InterlockedIncrement (&bt->mgr->nodecnt) - 1; +#endif + + if( ++slot < bt->mgr->nodemax ) { + hash = (BtHash *)(bt->mgr->nodes + slot * (sizeof(BtHash) + (bt->mgr->hashmask + 1) * sizeof(BtLatchSet))); + hash->slot = slot; + + if( bt_mapsegment(bt, hash, page_no) ) + return NULL; + + bt_linkhash(bt, hash, page_no, idx); + bt_releasewrite (&bt->mgr->latch[idx]); + return hash; + } + + // hash table is full + // find best cache entry to evict + +#ifdef unix + __sync_fetch_and_add(&bt->mgr->nodecnt, -1); +#else + InterlockedDecrement (&bt->mgr->nodecnt); +#endif + + while( 1 ) { +#ifdef unix + victim = __sync_fetch_and_add(&bt->mgr->evicted, 1); +#else + victim = InterlockedIncrement (&bt->mgr->evicted) - 1; +#endif + victim %= bt->mgr->hashsize; + + // try to get write lock + // skip entry if not obtained + + if( !bt_writetry (&bt->mgr->latch[victim]) ) + continue; + + // if cache entry is empty + // or no slots are unpinned + // skip this entry + + if( !(hash = bt_findlru(bt, bt->mgr->cache[victim])) ) { + bt_releasewrite (&bt->mgr->latch[victim]); + continue; + } + + // unlink victim hash node from hash table + + if( node = hash->hashprev ) + node->hashnext = hash->hashnext; + else if( node = hash->hashnext ) + bt->mgr->cache[victim] = node->slot; + else + bt->mgr->cache[victim] = 0; + + if( node = hash->hashnext ) + node->hashprev = hash->hashprev; + + // remove old file mapping +#ifdef unix + munmap (hash->map, (bt->mgr->hashmask+1) << bt->mgr->page_bits); +#else + FlushViewOfFile(hash->map, 0); + UnmapViewOfFile(hash->map); + CloseHandle(hash->hmap); +#endif + hash->map = NULL; + bt_releasewrite (&bt->mgr->latch[victim]); + + // create new file mapping + // and link into hash table + + if( bt_mapsegment(bt, hash, page_no) ) + return NULL; + + bt_linkhash(bt, hash, page_no, idx); + bt_releasewrite (&bt->mgr->latch[idx]); + return hash; + } +} + +// place write, read, or parent lock on requested page_no. +// pin to buffer pool + +BTERR bt_lockpage(BtDb *bt, uid page_no, BtLock mode, BtPage *page) +{ +BtLatchSet *set; +BtHash *hash; +uint subpage; + + // find/create maping in hash table + + if( hash = bt_hashpage(bt, page_no) ) + subpage = (uint)(page_no & bt->mgr->hashmask); // page within mapping + else + return bt->err; + + set = hash->pagelatch + subpage; + + switch( mode ) { + case BtLockRead: + bt_readlock (set->readwr); + break; + case BtLockWrite: + bt_writelock (set->readwr); + break; + case BtLockAccess: + bt_readlock (set->access); + break; + case BtLockDelete: + bt_writelock (set->access); + break; + case BtLockParent: + bt_writelock (set->parent); + break; + default: + return bt->err = BTERR_lock; + } + + if( page ) + *page = (BtPage)(hash->map + (subpage << bt->mgr->page_bits)); + + return bt->err = 0; +} + +// remove write, read, or parent lock on requested page_no. + +BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode) +{ +uint subpage, idx; +BtLatchSet *set; +BtHash *hash; + + // since page is pinned + // it should still be in the buffer pool + + idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize; + bt_readlock (&bt->mgr->latch[idx]); + + if( hash = bt_findhash(bt, page_no, idx) ) + subpage = (uint)(page_no & bt->mgr->hashmask); + else + return bt->err = BTERR_hash; + + bt_releaseread (&bt->mgr->latch[idx]); + set = hash->pagelatch + subpage; + + switch( mode ) { + case BtLockRead: + bt_releaseread (set->readwr); + break; + case BtLockWrite: + bt_releasewrite (set->readwr); + break; + case BtLockAccess: + bt_releaseread (set->access); + break; + case BtLockDelete: + bt_releasewrite (set->access); + break; + case BtLockParent: + bt_releasewrite (set->parent); + break; + default: + return bt->err = BTERR_lock; + } + +#ifdef unix + __sync_fetch_and_add(&hash->pin, -1); +#else + InterlockedDecrement (&hash->pin); +#endif + return bt->err = 0; +} + +// deallocate a deleted page that has no tree pointers +// place on free chain out of allocator page + +BTERR bt_freepage(BtDb *bt, uid page_no) +{ + // obtain delete lock on deleted page + + if( bt_lockpage(bt, page_no, BtLockDelete, NULL) ) + return bt->err; + + // obtain write lock on deleted page + + if( bt_lockpage(bt, page_no, BtLockWrite, &bt->temp) ) + return bt->err; + + // lock allocation page + + if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) ) + return bt->err; + + // store chain in first key + bt_putid(slotptr(bt->temp, 1)->id, bt_getid(slotptr(bt->alloc, 1)->id)); + bt_putid(slotptr(bt->alloc, 1)->id, page_no); + + // unlock page zero + + if( bt_unlockpage(bt, ALLOC_page, BtLockWrite) ) + return bt->err; + + // remove write lock on deleted node + + if( bt_unlockpage(bt, page_no, BtLockWrite) ) + return bt->err; + + // remove delete lock on deleted node + + if( bt_unlockpage(bt, page_no, BtLockDelete) ) + return bt->err; + + return 0; +} + +// allocate a new page and write page into it + +uid bt_newpage(BtDb *bt, BtPage page) +{ +uid new_page; +BtPage pmap; +int reuse; + + // lock page zero + + if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) ) + return 0; + + // use empty chain first + // else allocate empty page + + if( new_page = bt_getid(slotptr(bt->alloc, 1)->id) ) { + if( bt_lockpage (bt, new_page, BtLockWrite, &bt->temp) ) + return 0; + bt_putid(slotptr(bt->alloc, 1)->id, bt_getid(slotptr(bt->temp, 1)->id)); + if( bt_unlockpage (bt, new_page, BtLockWrite) ) + return 0; + reuse = 1; + } else { + new_page = bt_getid(slotptr(bt->alloc, 2)->id); + bt_putid(slotptr(bt->alloc, 2)->id, new_page+1); + reuse = 0; + } +#ifdef unix + if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size ) + return bt->err = BTERR_wrt, 0; + + // if writing first page of hash block, zero last page in the block + + if ( !reuse && bt->mgr->hashmask > 0 && (new_page & bt->mgr->hashmask) == 0 ) + { + // use zero buffer to write zeros + memset(bt->zero, 0, bt->mgr->page_size); + if ( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->hashmask) << bt->mgr->page_bits) < bt->mgr->page_size ) + return bt->err = BTERR_wrt, 0; + } +#else + // bring new page into page-cache and copy page. + // this will extend the file into the new pages. + + if( bt_lockpage(bt, new_page, BtLockWrite, &pmap) ) + return 0; + + memcpy(pmap, page, bt->mgr->page_size); + + if( bt_unlockpage (bt, new_page, BtLockWrite) ) + return 0; +#endif + // unlock page zero + + if ( bt_unlockpage(bt, ALLOC_page, BtLockWrite) ) + return 0; + + return new_page; +} + +// find slot in page for given key at a given level + +int bt_findslot (BtDb *bt, unsigned char *key, uint len) +{ +uint diff, higher = bt->page->cnt, low = 1, slot; + + // low is the lowest candidate, higher is already + // tested as .ge. the given key, loop ends when they meet + + while( diff = higher - low ) { + slot = low + ( diff >> 1 ); + if( keycmp (keyptr(bt->page, slot), key, len) < 0 ) + low = slot + 1; + else + higher = slot; + } + + return higher; +} + +// find and load page at given level for given key +// leave page rd or wr locked as requested + +int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, uint lock) +{ +uid page_no = ROOT_page, prevpage = 0; +uint drill = 0xff, slot; +uint mode, prevmode; + + // start at root of btree and drill down + + do { + // determine lock mode of drill level + mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead; + + bt->page_no = page_no; + + // obtain access lock using lock chaining with Access mode + + if( page_no > ROOT_page ) + if( bt_lockpage(bt, page_no, BtLockAccess, NULL) ) + return 0; + + if( prevpage ) + if( bt_unlockpage(bt, prevpage, prevmode) ) + return 0; + + // obtain read lock using lock chaining + // and pin page contents + + if( bt_lockpage(bt, page_no, mode, &bt->page) ) + return 0; + + if( page_no > ROOT_page ) + if( bt_unlockpage(bt, page_no, BtLockAccess) ) + return 0; + + // re-read and re-lock root after determining actual level of root + + if( bt->page_no == ROOT_page ) + if( bt->page->lvl != drill) { + drill = bt->page->lvl; + + if( lock == BtLockWrite && drill == lvl ) + if( bt_unlockpage(bt, page_no, mode) ) + return 0; + else + continue; + } + + // if page is being deleted, + // move back to preceeding page + + if( bt->page->kill ) { + page_no = bt_getid (bt->page->right); + continue; + } + + // find key on page at this level + // and descend to requested level + + slot = bt_findslot (bt, key, len); + + // is this slot a foster child? + + if( slot <= bt->page->cnt - bt->page->foster ) + if( drill == lvl ) + return slot; + else + drill--; + + while( slotptr(bt->page, slot)->dead ) + if( slot++ < bt->page->cnt ) + continue; + else + return bt->err = BTERR_struct, 0; + + // continue down / right using overlapping locks + // to protect pages being killed or split. + + prevmode = mode; + prevpage = bt->page_no; + page_no = bt_getid(slotptr(bt->page, slot)->id); + } while( page_no ); + + // return error on end of chain + + bt->err = BTERR_struct; + return 0; // return error +} + +// find and delete key on page by marking delete flag bit +// when page becomes empty, delete it from the btree + +BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl) +{ +unsigned char leftkey[256], rightkey[256]; +uid page_no, right; +uint slot, tod; +BtKey ptr; + + if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) ) + ptr = keyptr(bt->page, slot); + else + return bt->err; + + // if key is found delete it, otherwise ignore request + + if( !keycmp (ptr, key, len) ) + if( slotptr(bt->page, slot)->dead == 0 ) + slotptr(bt->page,slot)->dead = 1, bt->page->act--; + + // return if page is not empty, or it has no right sibling + + right = bt_getid(bt->page->right); + page_no = bt->page_no; + + if( !right || bt->page->act ) + return bt_unlockpage(bt, page_no, BtLockWrite); + + // obtain Parent lock over write lock + + if( bt_lockpage(bt, page_no, BtLockParent, NULL) ) + return bt->err; + + // cache copy of key to delete + + ptr = keyptr(bt->page, bt->page->cnt); + memcpy(leftkey, ptr, ptr->len + 1); + + // lock and map right page + + if ( bt_lockpage(bt, right, BtLockWrite, &bt->temp) ) + return bt->err; + + // pull contents of next page into current empty page + memcpy (bt->page, bt->temp, bt->mgr->page_size); + + // cache copy of key to update + ptr = keyptr(bt->temp, bt->temp->cnt); + memcpy(rightkey, ptr, ptr->len + 1); + + // Mark right page as deleted and point it to left page + // until we can post updates at higher level. + + bt_putid(bt->temp->right, page_no); + bt->temp->kill = 1; + bt->temp->cnt = 0; + + if( bt_unlockpage(bt, right, BtLockWrite) ) + return bt->err; + if( bt_unlockpage(bt, page_no, BtLockWrite) ) + return bt->err; + + // delete old lower key to consolidated node + + if( bt_deletekey (bt, leftkey + 1, *leftkey, lvl + 1) ) + return bt->err; + + // redirect higher key directly to consolidated node + + if( slot = bt_loadpage (bt, rightkey+1, *rightkey, lvl+1, BtLockWrite) ) + ptr = keyptr(bt->page, slot); + else + return bt->err; + + // since key already exists, update id + + if( keycmp (ptr, rightkey+1, *rightkey) ) + return bt->err = BTERR_struct; + + slotptr(bt->page, slot)->dead = 0; + bt_putid(slotptr(bt->page,slot)->id, page_no); + bt_unlockpage(bt, bt->page_no, BtLockWrite); + + // obtain write lock and + // add right block to free chain + + if( bt_freepage (bt, right) ) + return bt->err; + + // remove ParentModify lock + + if( bt_unlockpage(bt, page_no, BtLockParent) ) + return bt->err; + + return 0; +} + +// find key in leaf level and return row-id + +uid bt_findkey (BtDb *bt, unsigned char *key, uint len) +{ +uint slot; +BtKey ptr; +uid id; + + if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) ) + ptr = keyptr(bt->page, slot); + else + return 0; + + // if key exists, return row-id + // otherwise return 0 + + if( ptr->len == len && !memcmp (ptr->key, key, len) ) + id = bt_getid(slotptr(bt->page,slot)->id); + else + id = 0; + + if ( bt_unlockpage(bt, bt->page_no, BtLockRead) ) + return 0; + + return id; +} + +void bt_cleanpage(BtDb *bt) +{ +uint nxt = bt->mgr->page_size; +BtPage page = bt->page; +uint cnt = 0, idx = 0; +uint max = page->cnt; +BtKey key; + + memcpy (bt->frame, page, bt->mgr->page_size); + + // skip page info and set rest of page to zero + memset (page+1, 0, bt->mgr->page_size - sizeof(*page)); + page->act = 0; + + // try cleaning up page first + + while( cnt++ < max ) { + // always leave fence key in list + if( cnt < max && slotptr(bt->frame,cnt)->dead ) + continue; + + // copy key + key = keyptr(bt->frame, cnt); + nxt -= key->len + 1; + memcpy ((unsigned char *)page + nxt, key, key->len + 1); + + // copy slot + memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId); + if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) ) + page->act++; + slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod; + slotptr(page, idx)->off = nxt; + } + page->min = nxt; + page->cnt = idx; +} + +// add key to page +// return with page unlocked + +BTERR bt_addkeytopage (BtDb *bt, uint slot, unsigned char *key, uint len, uid id, uint tod) +{ +BtPage page = bt->page; +uint idx; + + // calculate next available slot and copy key into page + + page->min -= len + 1; + ((unsigned char *)page)[page->min] = len; + memcpy ((unsigned char *)page + page->min +1, key, len ); + + for( idx = slot; idx < page->cnt; idx++ ) + if( slotptr(page, idx)->dead ) + break; + + // now insert key into array before slot + // preserving the fence slot + + if( idx == page->cnt ) + idx++, page->cnt++; + + page->act++; + + while( idx > slot ) + *slotptr(page, idx) = *slotptr(page, idx -1), idx--; + + bt_putid(slotptr(page,slot)->id, id); + slotptr(page, slot)->off = page->min; + slotptr(page, slot)->tod = tod; + slotptr(page, slot)->dead = 0; + + return bt_unlockpage(bt, bt->page_no, BtLockWrite); +} + +// split the root and raise the height of the btree + +BTERR bt_splitroot(BtDb *bt, uid right) +{ +uint nxt = bt->mgr->page_size; +unsigned char fencekey[256]; +BtPage root = bt->page; +uid new_page; +BtKey key; + + // Obtain an empty page to use, and copy the left page + // contents into it. Strip foster child key. + // Save left fence key. + + bt->page->act--; + bt->page->cnt--; + bt->page->foster--; + key = keyptr(bt->page, bt->page->cnt); + memcpy (fencekey, key, key->len + 1); + + if( !(new_page = bt_newpage(bt, bt->page)) ) + return bt->err; + + // preserve the page info at the bottom + // and set rest to zero + + memset (root+1, 0, bt->mgr->page_size - sizeof(*root)); + + // insert left fence key on newroot page + + nxt -= *fencekey + 1; + memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1); + bt_putid(slotptr(root, 1)->id, new_page); + slotptr(root, 1)->off = nxt; + + // insert stopper key on newroot page + // and increase the root height + + nxt -= 3; + fencekey[0] = 2; + fencekey[1] = 0xff; + fencekey[2] = 0xff; + memcpy ((unsigned char *)root + nxt, fencekey, *fencekey + 1); + bt_putid(slotptr(root, 2)->id, right); + slotptr(root, 2)->off = nxt; + + bt_putid(root->right, 0); + root->min = nxt; // reset lowest used offset and key count + root->cnt = 2; + root->act = 2; + root->lvl++; + + // release root (bt->page) + + return bt_unlockpage(bt, bt->page_no, BtLockWrite); +} + +// split already locked full node +// return unlocked. + +BTERR bt_splitpage (BtDb *bt, uint len) +{ +uint slot, cnt, idx, max, nxt = bt->mgr->page_size; +unsigned char fencekey[256]; +uid page_no = bt->page_no; +BtPage page = bt->page; +uint tod = time(NULL); +uint lvl = page->lvl; +uid new_page, right; +BtKey key; + + // perform cleanup + + bt_cleanpage(bt); + + // return if enough space now + + if( page->min >= (page->cnt + 1) * sizeof(BtSlot) + sizeof(*page) + len + 1) + return bt_unlockpage(bt, page_no, BtLockWrite); + + // initialize frame buffer + + memset (bt->frame, 0, bt->mgr->page_size); + max = page->cnt - page->foster; + tod = (uint)time(NULL); + cnt = max / 2; + idx = 0; + + // split higher half of keys to bt->frame + // leaving foster children in the left node. + + while( cnt++ < max ) { + key = keyptr(page, cnt); + nxt -= key->len + 1; + memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1); + memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId); + slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod; + slotptr(bt->frame, idx)->off = nxt; + bt->frame->act++; + } + + // transfer right link node + + if( page_no > ROOT_page ) { + right = bt_getid (page->right); + bt_putid(bt->frame->right, right); + } + + bt->frame->bits = bt->mgr->page_bits; + bt->frame->min = nxt; + bt->frame->cnt = idx; + bt->frame->lvl = lvl; + + // get new free page and write frame to it. + + if( !(new_page = bt_newpage(bt, bt->frame)) ) + return bt->err; + + // update lower keys and foster children to continue in old page + + memcpy (bt->frame, page, bt->mgr->page_size); + memset (page+1, 0, bt->mgr->page_size - sizeof(*page)); + nxt = bt->mgr->page_size; + page->act = 0; + cnt = 0; + idx = 0; + + // assemble page of smaller keys + // to remain in the old page + + while( cnt++ < max / 2 ) { + key = keyptr(bt->frame, cnt); + nxt -= key->len + 1; + memcpy ((unsigned char *)page + nxt, key, key->len + 1); + memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId); + slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod; + slotptr(page, idx)->off = nxt; + page->act++; + } + + // assemble old foster child keys + // add new foster child fence + + cnt = bt->frame->cnt - bt->frame->foster - 1; + + while( cnt++ < bt->frame->cnt ) { + key = keyptr(bt->frame, cnt); + nxt -= key->len + 1; + memcpy ((unsigned char *)page + nxt, key, key->len + 1); + memcpy (slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId); + slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod; + slotptr(page, idx)->off = nxt; + page->act++; + } + + // link new right page + + bt_putid (page->right, new_page); + + // put new page as smallest foster child key + + page->cnt = idx; + cnt = page->cnt - page->foster++; + bt_putid (slotptr(page,cnt)->id, new_page); + + // if current page is the root page, split it + + if( page_no == ROOT_page ) + return bt_splitroot (bt, new_page); + + // release wr lock on page + + if( bt_unlockpage (bt, page_no, BtLockWrite) ) + return bt->err; + + // obtain ParentModification lock for current page + // to fix highest foster child on page + + if( bt_lockpage (bt, page_no, BtLockParent, NULL) ) + return bt->err; + + if( bt_lockpage (bt, page_no, BtLockRead, &page) ) + return bt->err; + + // get our old fence key + + key = keyptr(page, page->cnt); + memcpy (fencekey, key, key->len+1); + + // get our new fence key length + + key = keyptr(page, page->cnt - 1); + len = key->len; + + if( bt_unlockpage (bt, page_no, BtLockRead) ) + return bt->err; + + do { + slot = bt_loadpage (bt, fencekey + 1, *fencekey, lvl + 1, BtLockWrite); + + if( !slot ) + return bt->err; + + // check if parent page has enough space + + if( bt->page->min < (bt->page->cnt + 1) * sizeof(BtSlot) + sizeof(*bt->page) + len + 1) + if( bt_splitpage (bt, len) ) + return bt->err; + else + continue; + else + break; + } while( 1 ); + + // wait for readers from parent get their locks + + if( bt_lockpage (bt, page_no, BtLockDelete, NULL) ) + return bt->err; + + if( bt_lockpage (bt, page_no, BtLockWrite, &page) ) + return bt->err; + + // switch parent fence key to foster child + + if( slotptr(page, page->cnt)->dead ) + slotptr(bt->page, slot)->dead = 1; + else + bt_putid (slotptr(bt->page, slot)->id, bt_getid(slotptr(page, page->cnt)->id)); + + // remove foster child from our page + // add our new fence key to parent + + page->cnt--; + page->act--; + page->foster--; + key = keyptr(page, page->cnt); + + if( bt_addkeytopage (bt, slot, key->key, key->len, page_no, tod) ) + return bt->err; + + if( bt_unlockpage (bt, page_no, BtLockDelete) ) + return bt->err; + + if( bt_unlockpage (bt, page_no, BtLockParent) ) + return bt->err; + + return bt_unlockpage (bt, page_no, BtLockWrite); +} + +// Insert new key into the btree at leaf level. + +BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uid id, uint tod) +{ +uint slot, idx; +BtPage page; +BtKey ptr; + + while( 1 ) { + if( slot = bt_loadpage (bt, key, len, 0, BtLockWrite) ) + ptr = keyptr(bt->page, slot); + else + { + if ( !bt->err ) + bt->err = BTERR_ovflw; + return bt->err; + } + + // if key already exists, update id and return + + page = bt->page; + + if( !keycmp (ptr, key, len) ) { + slotptr(page, slot)->dead = 0; + slotptr(page, slot)->tod = tod; + bt_putid(slotptr(page,slot)->id, id); + return bt_unlockpage(bt, bt->page_no, BtLockWrite); + } + + // check if page has enough space + + if( page->min >= (page->cnt + 1) * sizeof(BtSlot) + sizeof(*page) + len + 1) + break; + + if( bt_splitpage (bt, len) ) + return bt->err; + } + + return bt_addkeytopage (bt, slot, key, len, id, tod); +} + +// cache page of keys into cursor and return starting slot for given key + +uint bt_startkey (BtDb *bt, unsigned char *key, uint len) +{ +uint slot; + + // cache page for retrieval + if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) ) + memcpy (bt->cursor, bt->page, bt->mgr->page_size); + bt->cursor_page = bt->page_no; + if ( bt_unlockpage(bt, bt->page_no, BtLockRead) ) + return 0; + + return slot; +} + +// return next slot for cursor page +// or slide cursor right into next page + +uint bt_nextkey (BtDb *bt, uint slot) +{ +BtPage page; +uid right; + + do { + right = bt_getid(bt->cursor->right); + while( slot++ < bt->cursor->cnt - bt->cursor->foster ) + if( slotptr(bt->cursor,slot)->dead ) + continue; + else if( right || (slot < bt->cursor->cnt - bt->cursor->foster) ) + return slot; + else + break; + + if( !right ) + break; + + bt->cursor_page = right; + + if( bt_lockpage(bt, right, BtLockRead, &page) ) + return 0; + + memcpy (bt->cursor, page, bt->mgr->page_size); + + if ( bt_unlockpage(bt, right, BtLockRead) ) + return 0; + + slot = 0; + } while( 1 ); + + return bt->err = 0; +} + +BtKey bt_key(BtDb *bt, uint slot) +{ + return keyptr(bt->cursor, slot); +} + +uid bt_uid(BtDb *bt, uint slot) +{ + return bt_getid(slotptr(bt->cursor,slot)->id); +} + +uint bt_tod(BtDb *bt, uint slot) +{ + return slotptr(bt->cursor,slot)->tod; +} + + +#ifdef STANDALONE + +typedef struct { + char *infile; + char type; + BtMgr *mgr; +} ThreadArg; + +// standalone program to index file of keys +// then list them onto std-out + +#ifdef unix +void *index_file (void *arg) +#else +uint __stdcall index_file (void *arg) +#endif +{ +int line = 0, found = 0; +unsigned char key[256]; +ThreadArg *args = arg; +int ch, len = 0, slot; +time_t tod[1]; +BtKey ptr; +BtDb *bt; +FILE *in; + + bt = bt_open (args->mgr); + time (tod); + + switch(args->type | 0x20) + { + case 'w': + fprintf(stderr, "started indexing for %s\n", args->infile); + if( in = fopen (args->infile, "rb") ) + while( ch = getc(in), ch != EOF ) + if( ch == '\n' ) + { + if( bt_insertkey (bt, key, len, ++line, *tod) ) + fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0); + len = 0; + } + else if( len < 255 ) + key[len++] = ch; + fprintf(stderr, "finished %s for %d keys\n", args->infile, line); + break; + + case 'd': + fprintf(stderr, "started deleting keys for %s\n", args->infile); + if( in = fopen (args->infile, "rb") ) + while( ch = getc(in), ch != EOF ) + if( ch == '\n' ) + { + line++; + if( bt_deletekey (bt, key, len, 0) ) + fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0); + len = 0; + } + else if( len < 255 ) + key[len++] = ch; + fprintf(stderr, "finished %s for keys, %d \n", args->infile, line); + break; + + case 'f': + fprintf(stderr, "started finding keys for %s\n", args->infile); + if( in = fopen (args->infile, "rb") ) + while( ch = getc(in), ch != EOF ) + if( ch == '\n' ) + { + line++; + if( bt_findkey (bt, key, len) ) + found++; + else if( bt->err ) + fprintf(stderr, "Error %d Syserr %d Line: %d\n", bt->err, errno, line), exit(0); + len = 0; + } + else if( len < 255 ) + key[len++] = ch; + fprintf(stderr, "finished %s for %d keys, found %d\n", args->infile, line, found); + break; + + case 's': + len = key[0] = 0; + + fprintf(stderr, "started reading\n"); + + if( slot = bt_startkey (bt, key, len) ) + slot--; + else + fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0); + + while( slot = bt_nextkey (bt, slot) ) { + ptr = bt_key(bt, slot); + fwrite (ptr->key, ptr->len, 1, stdout); + fputc ('\n', stdout); + } + } + + bt_close (bt); +#ifdef unix + return NULL; +#else + return 0; +#endif +} + +typedef struct timeval timer; + +int main (int argc, char **argv) +{ +int idx, cnt, len, slot, err; +int segsize, bits = 16; +#ifdef unix +pthread_t *threads; +timer start, stop; +#else +time_t start[1], stop[1]; +HANDLE *threads; +#endif +double real_time; +ThreadArg *args; +uint map = 0; +char key[1]; +BtMgr *mgr; +BtKey ptr; +BtDb *bt; + + if( argc < 3 ) { + fprintf (stderr, "Usage: %s idx_file Read/Write/Scan/Delete/Find [page_bits mapped_segments seg_bits hash_size src_file1 src_file2 ... ]\n", argv[0]); + fprintf (stderr, " where page_bits is the page size in bits\n"); + fprintf (stderr, " mapped_segments is the number of mmap segments in buffer pool\n"); + fprintf (stderr, " seg_bits is the size of individual segments in buffer pool in pages in bits\n"); + fprintf (stderr, " hash_size is the size of buffer pool hash table\n"); + fprintf (stderr, " src_file1 thru src_filen are files of keys separated by newline\n"); + exit(0); + } + +#ifdef unix + gettimeofday(&start, NULL); +#else + time(start); +#endif + + if( argc > 3 ) + bits = atoi(argv[3]); + + if( argc > 4 ) + map = atoi(argv[4]); + + if( map > 65536 ) + fprintf (stderr, "Warning: mapped_pool > 65536 segments\n"); + + if( argc > 5 ) + segsize = atoi(argv[5]); + else + segsize = 4; // 16 pages per mmap segment + + cnt = argc - 6; +#ifdef unix + threads = malloc (cnt * sizeof(pthread_t)); +#else + threads = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, cnt * sizeof(HANDLE)); +#endif + args = malloc (cnt * sizeof(ThreadArg)); + + mgr = bt_mgr ((argv[1]), BT_rw, bits, map, segsize, map / 8); + + if( !mgr ) { + fprintf(stderr, "Index Open Error %s\n", argv[1]); + exit (1); + } + + // fire off threads + + for( idx = 0; idx < cnt; idx++ ) { + args[idx].infile = argv[idx + 6]; + args[idx].type = argv[2][0]; + args[idx].mgr = mgr; +#ifdef unix + if( err = pthread_create (threads + idx, NULL, index_file, args + idx) ) + fprintf(stderr, "Error creating thread %d\n", err); +#else + threads[idx] = (HANDLE)_beginthreadex(NULL, 65536, index_file, args + idx, 0, NULL); +#endif + } + + // wait for termination + +#ifdef unix + for( idx = 0; idx < cnt; idx++ ) + pthread_join (threads[idx], NULL); + gettimeofday(&stop, NULL); + real_time = 1000.0 * ( stop.tv_sec - start.tv_sec ) + 0.001 * (stop.tv_usec - start.tv_usec ); +#else + WaitForMultipleObjects (cnt, threads, TRUE, INFINITE); + + for( idx = 0; idx < cnt; idx++ ) + CloseHandle(threads[idx]); + + time (stop); + real_time = 1000 * (*stop - *start); +#endif + fprintf(stderr, " Time to complete: %.2f seconds\n", real_time/1000); + + cnt = 0; + len = key[0] = 0; + bt = bt_open (mgr); + + fprintf(stderr, "started reading\n"); + + if( slot = bt_startkey (bt, key, len) ) + slot--; + else + fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0); + + while( slot = bt_nextkey (bt, slot) ) + cnt++; + + fprintf(stderr, " Total keys read %d\n", cnt); + + bt_close (bt); + bt_mgrclose (mgr); +} + +#endif //STANDALONE diff --git a/jaluta.c b/jaluta.c new file mode 100644 index 0000000..66596c0 --- /dev/null +++ b/jaluta.c @@ -0,0 +1,2369 @@ +// jaluta's balanced B-Link tree algorithms +// 26 APR 2013 + +// author: karl malbrain, malbrain@cal.berkeley.edu + +/* +This work, including the source code, documentation +and related data, is placed into the public domain. + +The orginal author is Karl Malbrain. + +THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY +OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF +MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE, +ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE +RESULTING FROM THE USE, MODIFICATION, OR +REDISTRIBUTION OF THIS SOFTWARE. +*/ + +// Please see the project home page for documentation +// http://code.google.com/p/high-concurrency-btree + +#define _FILE_OFFSET_BITS 64 +#define _LARGEFILE64_SOURCE + +#ifdef linux +#define _GNU_SOURCE +#endif + +#ifdef unix +#include +#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 + + 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 diff --git a/threads2e.c b/threads2e.c new file mode 100644 index 0000000..d6c57db --- /dev/null +++ b/threads2e.c @@ -0,0 +1,1980 @@ +// btree version threads2d sched_yield version +// 26 APR 2013 + +// author: karl malbrain, malbrain@cal.berkeley.edu + +/* +This work, including the source code, documentation +and related data, is placed into the public domain. + +The orginal author is Karl Malbrain. + +THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY +OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF +MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE, +ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE +RESULTING FROM THE USE, MODIFICATION, OR +REDISTRIBUTION OF THIS SOFTWARE. +*/ + +// Please see the project home page for documentation +// http://code.google.com/p/high-concurrency-btree + +#define _FILE_OFFSET_BITS 64 +#define _LARGEFILE64_SOURCE + +#ifdef linux +#define _GNU_SOURCE +#endif + +#ifdef unix +#include +#include +#include +#include +#include +#include +#include +#include +#else +#define WIN32_LEAN_AND_MEAN +#include +#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_maxbits 24 // maximum page size in bits +#define BT_minbits 9 // minimum page size in bits +#define BT_minpage (1 << BT_minbits) // minimum page size +#define BT_maxpage (1 << BT_maxbits) // maximum page size + +/* +There are five lock types for each node in three independent sets: +1. (set 1) AccessIntent: Sharable. Going to Read the node. Incompatible with NodeDelete. +2. (set 1) NodeDelete: Exclusive. About to release the node. Incompatible with AccessIntent. +3. (set 2) ReadLock: Sharable. Read the node. Incompatible with WriteLock. +4. (set 2) WriteLock: Exclusive. Modify the node. Incompatible with ReadLock and other WriteLocks. +5. (set 3) ParentModification: Exclusive. Change the node's parent keys. Incompatible with another ParentModification. +*/ + +typedef enum{ + BtLockAccess, + BtLockDelete, + BtLockRead, + BtLockWrite, + BtLockParent +}BtLock; + +// Define the length of the page and key pointers + +#define BtId 6 + +// Page key slot definition. + +// If BT_maxbits is 15 or less, you can save 4 bytes +// for each key stored by making the first two uints +// into ushorts. You can also save 4 bytes by removing +// the tod field from the key. + +// Keys are marked dead, but remain on the page until +// it cleanup is called. The fence key (highest key) for +// the page is always present, even after cleanup. + +typedef struct { + uint off:BT_maxbits; // page offset for key start + uint dead:1; // set for deleted key + uint tod; // time-stamp for key + unsigned char id[BtId]; // id associated with key +} BtSlot; + +// The key structure occupies space at the upper end of +// each page. It's a length byte followed by the value +// bytes. + +typedef struct { + unsigned char len; + unsigned char key[1]; +} *BtKey; + +// The first part of an index page. +// It is immediately followed +// by the BtSlot array of keys. + +typedef struct Page { + uint cnt; // count of keys in page + uint act; // count of active keys + uint min; // next key offset + unsigned char bits; // page size in bits + unsigned char lvl:7; // level of page + unsigned char kill:1; // page is being deleted + unsigned char right[BtId]; // page number to right +} *BtPage; + +// mode & definition for latch table implementation + +enum { + Write = 1, + Share = 2 +} LockMode; + +// latch table lock structure + +// mode is set for write access +// share is count of read accessors +// grant write lock when share == 0 + +typedef struct { + int mode:1; + int share:31; +} BtLatch; + +typedef struct { + BtLatch readwr[1]; // read/write page lock + BtLatch access[1]; // Access Intent/Page delete + BtLatch parent[1]; // Parent modification +} BtLatchSet; + +// The memory mapping hash table buffer manager entry + +typedef struct { + unsigned long long int lru; // number of times accessed + uid basepage; // mapped base page number + char *map; // mapped memory pointer + uint pin; // mapped page pin counter + uint slot; // slot index in this array + void *hashprev; // previous cache block for the same hash idx + void *hashnext; // next cache block for the same hash idx +#ifndef unix + HANDLE hmap; +#endif +// array of page latch sets, one for each page in map segment + BtLatchSet pagelatch[0]; +} BtHash; + +// The object structure for Btree access + +typedef struct { + uint page_size; // page size + uint page_bits; // page size in bits + uint seg_bits; // seg size in pages in bits + uint mode; // read-write mode +#ifdef unix + int idx; +#else + HANDLE idx; +#endif + uint nodecnt; // highest page cache node in use + uint nodemax; // highest page cache node allocated + uint hashmask; // number of pages in mmap segment + uint hashsize; // size of Hash Table + uint evicted; // last evicted hash slot + ushort *cache; // hash index for memory pool + BtLatch *latch; // latches for hash table slots + char *nodes; // memory pool page hash nodes +} BtMgr; + +typedef struct { + BtMgr *mgr; // buffer manager for thread + BtPage temp; // temporary frame buffer (memory mapped/file IO) + BtPage alloc; // frame buffer for alloc page ( page 0 ) + BtPage cursor; // cached frame for start/next (never mapped) + BtPage frame; // spare frame for the page split (never mapped) + BtPage zero; // page frame for zeroes at end of file + BtPage page; // current page + uid page_no; // current page number + uid cursor_page; // current cursor page number + unsigned char *mem; // frame, cursor, page memory buffer + int err; // last error +} BtDb; + +typedef enum { + BTERR_ok = 0, + BTERR_struct, + BTERR_ovflw, + BTERR_lock, + BTERR_map, + BTERR_wrt, + BTERR_hash +} BTERR; + +// B-Tree functions +extern void bt_close (BtDb *bt); +extern BtDb *bt_open (BtMgr *mgr); +extern BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uint lvl, uid id, uint tod); +extern BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl); +extern uid bt_findkey (BtDb *bt, unsigned char *key, uint len); +extern uint bt_startkey (BtDb *bt, unsigned char *key, uint len); +extern uint bt_nextkey (BtDb *bt, uint slot); + +// manager functions +extern BtMgr *bt_mgr (char *name, uint mode, uint bits, uint cacheblk, uint segsize, uint hashsize); +void bt_mgrclose (BtMgr *mgr); + +// Helper functions to return slot values + +extern BtKey bt_key (BtDb *bt, uint slot); +extern uid bt_uid (BtDb *bt, uint slot); +extern uint bt_tod (BtDb *bt, uint slot); + +// BTree page number constants +#define ALLOC_page 0 +#define ROOT_page 1 + +// Number of levels to create in a new BTree + +#define MIN_lvl 2 + +// The page is allocated from low and hi ends. +// The key offsets and row-id's are allocated +// from the bottom, while the text of the key +// is allocated from the top. When the two +// areas meet, the page is split into two. + +// A key consists of a length byte, two bytes of +// index number (0 - 65534), and up to 253 bytes +// of key value. Duplicate keys are discarded. +// Associated with each key is a 48 bit row-id. + +// The b-tree root is always located at page 1. +// The first leaf page of level zero is always +// located on page 2. + +// The b-tree pages are linked with next +// pointers to facilitate enumerators, +// and provide for concurrency. + +// When to root page fills, it is split in two and +// the tree height is raised by a new root at page +// one with two keys. + +// Deleted keys are marked with a dead bit until +// page cleanup The fence key for a node is always +// present, even after deletion and cleanup. + +// Groups of pages called segments from the btree are optionally +// cached with memory mapping. A hash table is used to keep +// track of the cached segments. This behaviour is controlled +// by the cache block size parameter to bt_open. + +// To achieve maximum concurrency one page is locked at a time +// as the tree is traversed to find leaf key in question. The right +// page numbers are used in cases where the page is being split, +// or consolidated. + +// Page 0 is dedicated to lock for new page extensions, +// and chains empty pages together for reuse. + +// The ParentModification lock on a node is obtained to prevent resplitting +// or deleting a node before its fence is posted into its upper level. + +// Empty pages are chained together through the ALLOC page and reused. + +// Access macros to address slot and key values from the page + +#define slotptr(page, slot) (((BtSlot *)(page+1)) + (slot-1)) +#define keyptr(page, slot) ((BtKey)((unsigned char*)(page) + slotptr(page, slot)->off)) + +void bt_putid(unsigned char *dest, uid id) +{ +int i = BtId; + + while( i-- ) + dest[i] = (unsigned char)id, id >>= 8; +} + +uid bt_getid(unsigned char *src) +{ +uid id = 0; +int i; + + for( i = 0; i < BtId; i++ ) + id <<= 8, id |= *src++; + + return id; +} + +void bt_mgrclose (BtMgr *mgr) +{ +BtHash *hash; +uint slot; + + // release mapped pages + + for( slot = 0; slot < mgr->nodemax; slot++ ) { + hash = (BtHash *)(mgr->nodes + slot * (sizeof(BtHash) + (mgr->hashmask + 1) * sizeof(BtLatchSet))); + if( hash->slot ) +#ifdef unix + munmap (hash->map, (mgr->hashmask+1) << mgr->page_bits); +#else + { + FlushViewOfFile(hash->map, 0); + UnmapViewOfFile(hash->map); + CloseHandle(hash->hmap); + } +#endif + } + +#ifdef unix + close (mgr->idx); + free (mgr->nodes); + free (mgr->cache); + free (mgr->latch); +#else + FlushFileBuffers(mgr->idx); + CloseHandle(mgr->idx); + GlobalFree (mgr->nodes); + GlobalFree (mgr->cache); + GlobalFree (mgr->latch); +#endif +} + +// close and release memory + +void bt_close (BtDb *bt) +{ +#ifdef unix + if ( bt->mem ) + free (bt->mem); + free (bt); +#else + if ( bt->mem) + VirtualFree (bt->mem, 0, MEM_RELEASE); + GlobalFree (bt); +#endif +} + +// open/create new btree buffer manager + +// call with file_name, BT_openmode, bits in page size (e.g. 16), +// size of mapped page cache (e.g. 8192) + +BtMgr *bt_mgr (char *name, uint mode, uint bits, uint nodemax, uint segsize, uint hashsize) +{ +uint lvl, attr, cacheblk, last; +BtPage alloc; +int lockmode; +off64_t size; +uint amt[1]; +BtMgr* mgr; +BtKey key; + +#ifndef unix +SYSTEM_INFO sysinfo[1]; +#endif + + // determine sanity of page size and buffer pool + + if( bits > BT_maxbits ) + bits = BT_maxbits; + else if( bits < BT_minbits ) + bits = BT_minbits; + + if( !nodemax ) + return NULL; // must have buffer pool + +#ifdef unix + mgr = calloc (1, sizeof(BtMgr)); + + switch (mode & 0x7fff) + { + case BT_rw: + mgr->idx = open ((char*)name, O_RDWR | O_CREAT, 0666); + lockmode = 1; + break; + + case BT_ro: + default: + mgr->idx = open ((char*)name, O_RDONLY); + lockmode = 0; + break; + } + if( mgr->idx == -1 ) + return free(mgr), NULL; + + cacheblk = 4096; // minimum mmap segment size for unix + +#else + mgr = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtMgr)); + attr = FILE_ATTRIBUTE_NORMAL; + switch (mode & 0x7fff) + { + case BT_rw: + mgr->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL); + lockmode = 1; + break; + + case BT_ro: + default: + mgr->idx = CreateFile(name, GENERIC_READ, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_EXISTING, attr, NULL); + lockmode = 0; + break; + } + if( mgr->idx == INVALID_HANDLE_VALUE ) + return GlobalFree(mgr), NULL; + + // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity + GetSystemInfo(sysinfo); + cacheblk = sysinfo->dwAllocationGranularity; +#endif + +#ifdef unix + alloc = malloc (BT_maxpage); + *amt = 0; + + // read minimum page size to get root info + + if( size = lseek (mgr->idx, 0L, 2) ) { + if( pread(mgr->idx, alloc, BT_minpage, 0) == BT_minpage ) + bits = alloc->bits; + else + return free(mgr), free(alloc), NULL; + } else if( mode == BT_ro ) + return bt_mgrclose (mgr), NULL; +#else + alloc = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE); + size = GetFileSize(mgr->idx, amt); + + if( size || *amt ) { + if( !ReadFile(mgr->idx, (char *)alloc, BT_minpage, amt, NULL) ) + return bt_mgrclose (mgr), NULL; + bits = alloc->bits; + } else if( mode == BT_ro ) + return bt_mgrclose (mgr), NULL; +#endif + + mgr->page_size = 1 << bits; + mgr->page_bits = bits; + + mgr->nodemax = nodemax; + mgr->mode = mode; + + if( cacheblk < mgr->page_size ) + cacheblk = mgr->page_size; + + // mask for partial memmaps + + mgr->hashmask = (cacheblk >> bits) - 1; + + // see if requested number of pages per memmap is greater + + if( (1 << segsize) > mgr->hashmask ) + mgr->hashmask = (1 << segsize) - 1; + + mgr->seg_bits = 0; + + while( (1 << mgr->seg_bits) <= mgr->hashmask ) + mgr->seg_bits++; + + mgr->hashsize = hashsize; + +#ifdef unix + mgr->nodes = calloc (cacheblk, (sizeof(BtHash) + (mgr->hashmask + 1) * sizeof(BtLatchSet))); + mgr->cache = calloc (hashsize, sizeof(ushort)); + mgr->latch = calloc (hashsize, sizeof(BtLatch)); +#else + mgr->nodes = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, cacheblk * (sizeof(BtHash) + (mgr->hashmask + 1) * sizeof(BtLatchSet))); + mgr->cache = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(ushort)); + mgr->latch = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(BtLatch)); +#endif + + if( size || *amt ) + goto mgrxit; + + // initializes an empty b-tree with root page and page of leaves + + memset (alloc, 0, 1 << bits); + bt_putid(alloc->right, MIN_lvl+1); + alloc->bits = mgr->page_bits; + +#ifdef unix + if( write (mgr->idx, alloc, mgr->page_size) < mgr->page_size ) + return bt_mgrclose (mgr), NULL; +#else + if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) ) + return bt_mgrclose (mgr), NULL; + + if( *amt < mgr->page_size ) + return bt_mgrclose (mgr), NULL; +#endif + + memset (alloc, 0, 1 << bits); + alloc->bits = mgr->page_bits; + + for( lvl=MIN_lvl; lvl--; ) { + slotptr(alloc, 1)->off = mgr->page_size - 3; + bt_putid(slotptr(alloc, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number + key = keyptr(alloc, 1); + key->len = 2; // create stopper key + key->key[0] = 0xff; + key->key[1] = 0xff; + alloc->min = mgr->page_size - 3; + alloc->lvl = lvl; + alloc->cnt = 1; + alloc->act = 1; +#ifdef unix + if( write (mgr->idx, alloc, mgr->page_size) < mgr->page_size ) + return bt_mgrclose (mgr), NULL; +#else + if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) ) + return bt_mgrclose (mgr), NULL; + + if( *amt < mgr->page_size ) + return bt_mgrclose (mgr), NULL; +#endif + } + + // create empty page area by writing last page of first + // cache area (other pages are zeroed by O/S) + + if( mgr->hashmask ) { + memset(alloc, 0, mgr->page_size); + last = mgr->hashmask; + + while( last < MIN_lvl + 1 ) + last += mgr->hashmask + 1; + +#ifdef unix + pwrite(mgr->idx, alloc, mgr->page_size, last << mgr->page_bits); +#else + SetFilePointer (mgr->idx, last << mgr->page_bits, NULL, FILE_BEGIN); + if( !WriteFile (mgr->idx, (char *)alloc, mgr->page_size, amt, NULL) ) + return bt_mgrclose (mgr), NULL; + if( *amt < mgr->page_size ) + return bt_mgrclose (mgr), NULL; +#endif + } + +mgrxit: +#ifdef unix + free (alloc); +#else + VirtualFree (alloc, 0, MEM_RELEASE); +#endif + return mgr; +} + +// open BTree access method +// based on buffer manager + +BtDb *bt_open (BtMgr *mgr) +{ +BtDb *bt = malloc (sizeof(*bt)); + + memset (bt, 0, sizeof(*bt)); + bt->mgr = mgr; +#ifdef unix + bt->mem = malloc (3 *mgr->page_size); +#else + bt->mem = VirtualAlloc(NULL, 3 * mgr->page_size, MEM_COMMIT, PAGE_READWRITE); +#endif + bt->frame = (BtPage)bt->mem; + bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size); + bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size); + return bt; +} + +// compare two keys, returning > 0, = 0, or < 0 +// as the comparison value + +int keycmp (BtKey key1, unsigned char *key2, uint len2) +{ +uint len1 = key1->len; +int ans; + + if( ans = memcmp (key1->key, key2, len1 > len2 ? len2 : len1) ) + return ans; + + if( len1 > len2 ) + return 1; + if( len1 < len2 ) + return -1; + + return 0; +} + +// Latch Manager + +// wait until write lock mode is clear +// and add 1 to the share count + +void bt_readlock(BtLatch *latch) +{ + do { + // add one to counter, check write bit + +#ifdef unix + if( ~__sync_fetch_and_add((int *)latch, Share) & Write ) + return; +#else + if( ~InterlockedAdd((int *)latch, Share) & Write ) + return; +#endif + // didn't get latch, reset counter by one + +#ifdef unix + __sync_fetch_and_add((int *)latch, -Share); +#else + InterlockedAdd ((int *)latch, -Share); +#endif + + // and yield +#ifdef unix + sched_yield(); +#else + SwitchToThread(); +#endif + } while( 1 ); +} + +// wait for other read and write latches to relinquish + +void bt_writelock(BtLatch *latch) +{ +int prev, ours = 0; + + do { + // see if we can get write access + // with no readers +#ifdef unix + prev = __sync_fetch_and_or((int *)latch, Write); +#else + prev = InterlockedOr((int *)latch, Write); +#endif + + if( ~prev & 1 ) + ours++; // it's ours + + if( !(prev >> 1) && ours ) + return; + + // otherwise yield + +#ifdef unix + sched_yield(); +#else + SwitchToThread(); +#endif + } while( 1 ); +} + +// try to obtain write lock + +// return 1 if obtained, +// 0 if already write locked + +int bt_writetry(BtLatch *latch) +{ +int prev, ours = 0; + + do { + // see if we can get write access + // with no readers +#ifdef unix + prev = __sync_fetch_and_or((int *)latch, Write); +#else + prev = InterlockedOr((int *)latch, Write); +#endif + + if( ~prev & 1 ) + ours++; // it's ours + + if( !ours ) + return 0; + + if( !(prev >> 1) && ours ) + return 1; + + // otherwise yield +#ifdef unix + sched_yield(); +#else + SwitchToThread(); +#endif + } while( 1 ); +} + +// clear write mode + +void bt_releasewrite(BtLatch *latch) +{ +#ifdef unix + __sync_fetch_and_and((int *)latch, ~Write); +#else + InterlockedAnd ((int *)latch, ~Write); +#endif +} + +// decrement reader count + +void bt_releaseread(BtLatch *latch) +{ +#ifdef unix + __sync_fetch_and_add((int *)latch, -Share); +#else + InterlockedAdd((int *)latch, -Share); +#endif +} + +// Buffer Pool mgr + +// find segment in cache +// return NULL if not there +// otherwise return node + +BtHash *bt_findhash(BtDb *bt, uid page_no, uint idx) +{ +BtHash *hash; +uint slot; + + // compute cache block first page and hash idx + + if( slot = bt->mgr->cache[idx] ) + hash = (BtHash *)(bt->mgr->nodes + slot * (sizeof(BtHash) + (bt->mgr->hashmask + 1) * sizeof(BtLatchSet))); + else + return NULL; + + page_no &= ~bt->mgr->hashmask; + + while( hash->basepage != page_no ) + if( hash = hash->hashnext ) + continue; + else + return NULL; + + return hash; +} + +// add segment to hash table + +void bt_linkhash(BtDb *bt, BtHash *hash, uid page_no, int idx) +{ +BtHash *node; +uint slot; + + hash->hashprev = hash->hashnext = NULL; + hash->basepage = page_no & ~bt->mgr->hashmask; + hash->pin = 1; + hash->lru = 1; + + if( slot = bt->mgr->cache[idx] ) { + node = (BtHash *)(bt->mgr->nodes + slot * (sizeof(BtHash) + (bt->mgr->hashmask + 1) * sizeof(BtLatchSet))); + hash->hashnext = node; + node->hashprev = hash; + } + + bt->mgr->cache[idx] = hash->slot; +} + +// find best segment to evict from buffer pool + +BtHash *bt_findlru (BtDb *bt, uint slot) +{ +unsigned long long int target = ~0LL; +BtHash *hash = NULL, *node; + + if( !slot ) + return NULL; + + node = (BtHash *)(bt->mgr->nodes + slot * (sizeof(BtHash) + (bt->mgr->hashmask + 1) * sizeof(BtLatchSet))); + + do { + if( node->pin ) + continue; + if( node->lru > target ) + continue; + target = node->lru; + hash = node; + } while( node = node->hashnext ); + + return hash; +} + +// map new segment to virtual memory + +BTERR bt_mapsegment(BtDb *bt, BtHash *hash, uid page_no) +{ +off64_t off = (page_no & ~bt->mgr->hashmask) << bt->mgr->page_bits; +off64_t limit = off + ((bt->mgr->hashmask+1) << bt->mgr->page_bits); +int flag; + +#ifdef unix + flag = PROT_READ | ( bt->mgr->mode == BT_ro ? 0 : PROT_WRITE ); + hash->map = mmap (0, (bt->mgr->hashmask+1) << bt->mgr->page_bits, flag, MAP_SHARED, bt->mgr->idx, off); + if( hash->map == MAP_FAILED ) + return bt->err = BTERR_map; +#else + flag = ( bt->mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE ); + hash->hmap = CreateFileMapping(bt->mgr->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL); + if( !hash->hmap ) + return bt->err = BTERR_map; + + flag = ( bt->mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE ); + hash->map = MapViewOfFile(hash->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->mgr->hashmask+1) << bt->mgr->page_bits); + if( !hash->map ) + return bt->err = BTERR_map; +#endif + return bt->err = 0; +} + +// find or place requested page in segment-cache +// return hash table entry + +BtHash *bt_hashpage(BtDb *bt, uid page_no) +{ +BtHash *hash, *node, *next; +uint slot, idx, victim; +BtLatchSet *set; + + // lock hash table chain + + idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize; + bt_readlock (&bt->mgr->latch[idx]); + + // look up in hash table + + if( hash = bt_findhash(bt, page_no, idx) ) { +#ifdef unix + __sync_fetch_and_add(&hash->pin, 1); +#else + InterlockedIncrement (&hash->pin); +#endif + bt_releaseread (&bt->mgr->latch[idx]); + hash->lru++; + return hash; + } + + // upgrade to write lock + + bt_releaseread (&bt->mgr->latch[idx]); + bt_writelock (&bt->mgr->latch[idx]); + + // try to find page in cache with write lock + + if( hash = bt_findhash(bt, page_no, idx) ) { +#ifdef unix + __sync_fetch_and_add(&hash->pin, 1); +#else + InterlockedIncrement (&hash->pin); +#endif + bt_releasewrite (&bt->mgr->latch[idx]); + hash->lru++; + return hash; + } + + // allocate a new hash node + // and add to hash table + +#ifdef unix + slot = __sync_fetch_and_add(&bt->mgr->nodecnt, 1); +#else + slot = InterlockedIncrement (&bt->mgr->nodecnt) - 1; +#endif + + if( ++slot < bt->mgr->nodemax ) { + hash = (BtHash *)(bt->mgr->nodes + slot * (sizeof(BtHash) + (bt->mgr->hashmask + 1) * sizeof(BtLatchSet))); + hash->slot = slot; + + if( bt_mapsegment(bt, hash, page_no) ) + return NULL; + + bt_linkhash(bt, hash, page_no, idx); + bt_releasewrite (&bt->mgr->latch[idx]); + return hash; + } + + // hash table is full + // find best cache entry to evict + +#ifdef unix + __sync_fetch_and_add(&bt->mgr->nodecnt, -1); +#else + InterlockedDecrement (&bt->mgr->nodecnt); +#endif + + while( 1 ) { +#ifdef unix + victim = __sync_fetch_and_add(&bt->mgr->evicted, 1); +#else + victim = InterlockedIncrement (&bt->mgr->evicted) - 1; +#endif + victim %= bt->mgr->hashsize; + + // try to get write lock + // skip entry if not obtained + + if( !bt_writetry (&bt->mgr->latch[victim]) ) + continue; + + // if cache entry is empty + // or no slots are unpinned + // skip this entry + + if( !(hash = bt_findlru(bt, bt->mgr->cache[victim])) ) { + bt_releasewrite (&bt->mgr->latch[victim]); + continue; + } + + // unlink victim hash node from hash table + + if( node = hash->hashprev ) + node->hashnext = hash->hashnext; + else if( node = hash->hashnext ) + bt->mgr->cache[victim] = node->slot; + else + bt->mgr->cache[victim] = 0; + + if( node = hash->hashnext ) + node->hashprev = hash->hashprev; + + // remove old file mapping +#ifdef unix + munmap (hash->map, (bt->mgr->hashmask+1) << bt->mgr->page_bits); +#else + FlushViewOfFile(hash->map, 0); + UnmapViewOfFile(hash->map); + CloseHandle(hash->hmap); +#endif + hash->map = NULL; + bt_releasewrite (&bt->mgr->latch[victim]); + + // create new file mapping + // and link into hash table + + if( bt_mapsegment(bt, hash, page_no) ) + return NULL; + + bt_linkhash(bt, hash, page_no, idx); + bt_releasewrite (&bt->mgr->latch[idx]); + return hash; + } +} + +// place write, read, or parent lock on requested page_no. +// pin to buffer pool + +BTERR bt_lockpage(BtDb *bt, uid page_no, BtLock mode, BtPage *page) +{ +BtLatchSet *set; +BtHash *hash; +uint subpage; + + // find/create maping in hash table + + if( hash = bt_hashpage(bt, page_no) ) + subpage = (uint)(page_no & bt->mgr->hashmask); // page within mapping + else + return bt->err; + + set = hash->pagelatch + subpage; + + switch( mode ) { + case BtLockRead: + bt_readlock (set->readwr); + break; + case BtLockWrite: + bt_writelock (set->readwr); + break; + case BtLockAccess: + bt_readlock (set->access); + break; + case BtLockDelete: + bt_writelock (set->access); + break; + case BtLockParent: + bt_writelock (set->parent); + break; + default: + return bt->err = BTERR_lock; + } + + if( page ) + *page = (BtPage)(hash->map + (subpage << bt->mgr->page_bits)); + + return bt->err = 0; +} + +// remove write, read, or parent lock on requested page_no. + +BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode) +{ +uint subpage, idx; +BtLatchSet *set; +BtHash *hash; + + // since page is pinned + // it should still be in the buffer pool + + idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize; + bt_readlock (&bt->mgr->latch[idx]); + + if( hash = bt_findhash(bt, page_no, idx) ) + subpage = (uint)(page_no & bt->mgr->hashmask); + else + return bt->err = BTERR_hash; + + bt_releaseread (&bt->mgr->latch[idx]); + set = hash->pagelatch + subpage; + + switch( mode ) { + case BtLockRead: + bt_releaseread (set->readwr); + break; + case BtLockWrite: + bt_releasewrite (set->readwr); + break; + case BtLockAccess: + bt_releaseread (set->access); + break; + case BtLockDelete: + bt_releasewrite (set->access); + break; + case BtLockParent: + bt_releasewrite (set->parent); + break; + default: + return bt->err = BTERR_lock; + } + +#ifdef unix + __sync_fetch_and_add(&hash->pin, -1); +#else + InterlockedDecrement (&hash->pin); +#endif + return bt->err = 0; +} + +// deallocate a deleted page +// place on free chain out of allocator page + +BTERR bt_freepage(BtDb *bt, uid page_no) +{ + // obtain delete lock on deleted page + + if( bt_lockpage(bt, page_no, BtLockDelete, NULL) ) + return bt->err; + + // obtain write lock on deleted page + + if( bt_lockpage(bt, page_no, BtLockWrite, &bt->temp) ) + return bt->err; + + // lock allocation page + + if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) ) + return bt->err; + + // store chain in second right + bt_putid(bt->temp->right, bt_getid(bt->alloc[1].right)); + bt_putid(bt->alloc[1].right, page_no); + + // unlock page zero + + if( bt_unlockpage(bt, ALLOC_page, BtLockWrite) ) + return bt->err; + + // remove write lock on deleted node + + if( bt_unlockpage(bt, page_no, BtLockWrite) ) + return bt->err; + + // remove delete lock on deleted node + + if( bt_unlockpage(bt, page_no, BtLockDelete) ) + return bt->err; + + return 0; +} + +// allocate a new page and write page into it + +uid bt_newpage(BtDb *bt, BtPage page) +{ +uid new_page; +BtPage pmap; +int reuse; + + // lock page zero + + if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) ) + return 0; + + // use empty chain first + // else allocate empty page + + if( new_page = bt_getid(bt->alloc[1].right) ) { + if( bt_lockpage (bt, new_page, BtLockWrite, &bt->temp) ) + return 0; + bt_putid(bt->alloc[1].right, bt_getid(bt->temp->right)); + if( bt_unlockpage (bt, new_page, BtLockWrite) ) + return 0; + reuse = 1; + } else { + new_page = bt_getid(bt->alloc->right); + bt_putid(bt->alloc->right, new_page+1); + reuse = 0; + } + +#ifdef unix + if ( pwrite(bt->mgr->idx, page, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size ) + return bt->err = BTERR_wrt, 0; + + // if writing first page of hash block, zero last page in the block + + if ( !reuse && bt->mgr->hashmask > 0 && (new_page & bt->mgr->hashmask) == 0 ) + { + // use zero buffer to write zeros + memset(bt->zero, 0, bt->mgr->page_size); + if ( pwrite(bt->mgr->idx,bt->zero, bt->mgr->page_size, (new_page | bt->mgr->hashmask) << bt->mgr->page_bits) < bt->mgr->page_size ) + return bt->err = BTERR_wrt, 0; + } +#else + // bring new page into page-cache and copy page. + // this will extend the file into the new pages. + + if( bt_lockpage(bt, new_page, BtLockWrite, &pmap) ) + return 0; + + memcpy(pmap, page, bt->mgr->page_size); + + if( bt_unlockpage (bt, new_page, BtLockWrite) ) + return 0; +#endif + // unlock page zero + + if ( bt_unlockpage(bt, ALLOC_page, BtLockWrite) ) + return 0; + + return new_page; +} + +// find slot in page for given key at a given level + +int bt_findslot (BtDb *bt, unsigned char *key, uint len) +{ +uint diff, higher = bt->page->cnt, low = 1, slot; +uint good = 0; + + // make stopper key an infinite fence value + + if( bt_getid (bt->page->right) ) + higher++; + else + good++; + + // low is the next candidate, higher is already + // tested as .ge. the given key, loop ends when they meet + + while( diff = higher - low ) { + slot = low + ( diff >> 1 ); + if( keycmp (keyptr(bt->page, slot), key, len) < 0 ) + low = slot + 1; + else + higher = slot, good++; + } + + // return zero if key is on right link page + + return good ? higher : 0; +} + +// find and load page at given level for given key +// leave page rd or wr locked as requested + +int bt_loadpage (BtDb *bt, unsigned char *key, uint len, uint lvl, uint lock) +{ +uid page_no = ROOT_page, prevpage = 0; +uint drill = 0xff, slot; +uint mode, prevmode; + + // start at root of btree and drill down + + do { + // determine lock mode of drill level + mode = (lock == BtLockWrite) && (drill == lvl) ? BtLockWrite : BtLockRead; + + bt->page_no = page_no; + + // obtain access lock using lock chaining with Access mode + + if( page_no > ROOT_page ) + if( bt_lockpage(bt, page_no, BtLockAccess, NULL) ) + return 0; + + if( prevpage ) + if( bt_unlockpage(bt, prevpage, prevmode) ) + return 0; + + // obtain read lock using lock chaining + // and pin page contents + + if( bt_lockpage(bt, page_no, mode, &bt->page) ) + return 0; + + if( page_no > ROOT_page ) + if( bt_unlockpage(bt, page_no, BtLockAccess) ) + return 0; + + // re-read and re-lock root after determining actual level of root + + if( bt->page->lvl != drill) { + if ( bt->page_no != ROOT_page ) + return bt->err = BTERR_struct, 0; + + drill = bt->page->lvl; + + if( lock == BtLockWrite && drill == lvl ) + if( bt_unlockpage(bt, page_no, mode) ) + return 0; + else + continue; + } + + // find key on page at this level + // and descend to requested level + + if( !bt->page->kill && (slot = bt_findslot (bt, key, len)) ) { + if( drill == lvl ) + return slot; + + while( slotptr(bt->page, slot)->dead ) + if( slot++ < bt->page->cnt ) + continue; + else { + page_no = bt_getid(bt->page->right); + goto slideright; + } + + page_no = bt_getid(slotptr(bt->page, slot)->id); + drill--; + } + + // or slide right into next page + // (slide left from deleted page) + + else + page_no = bt_getid(bt->page->right); + + // continue down / right using overlapping locks + // to protect pages being killed or split. + +slideright: + prevpage = bt->page_no; + prevmode = mode; + } while( page_no ); + + // return error on end of right chain + + bt->err = BTERR_struct; + return 0; // return error +} + +// find and delete key on page by marking delete flag bit +// when page becomes empty, delete it + +BTERR bt_deletekey (BtDb *bt, unsigned char *key, uint len, uint lvl) +{ +unsigned char lowerkey[256], higherkey[256]; +uint slot, tod, dirty = 0; +uid page_no, right; +BtKey ptr; + + if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) ) + ptr = keyptr(bt->page, slot); + else + return bt->err; + + // if key is found delete it, otherwise ignore request + + if( !keycmp (ptr, key, len) ) + if( slotptr(bt->page, slot)->dead == 0 ) + dirty = slotptr(bt->page,slot)->dead = 1, bt->page->act--; + + // return if page is not empty, or it has no right sibling + + right = bt_getid(bt->page->right); + page_no = bt->page_no; + + if( !right || bt->page->act ) + return bt_unlockpage(bt, page_no, BtLockWrite); + + // obtain Parent lock over write lock + + if( bt_lockpage(bt, page_no, BtLockParent, NULL) ) + return bt->err; + + // cache copy of key to delete + + ptr = keyptr(bt->page, bt->page->cnt); + memcpy(lowerkey, ptr, ptr->len + 1); + + // lock and map right page + + if ( bt_lockpage(bt, right, BtLockWrite, &bt->temp) ) + return bt->err; + + // pull contents of next page into current empty page + memcpy (bt->page, bt->temp, bt->mgr->page_size); + + // cache copy of key to update + ptr = keyptr(bt->temp, bt->temp->cnt); + memcpy(higherkey, ptr, ptr->len + 1); + + // Mark right page as deleted and point it to left page + // until we can post updates at higher level. + + bt_putid(bt->temp->right, page_no); + bt->temp->kill = 1; + bt->temp->cnt = 0; + + if( bt_unlockpage(bt, right, BtLockWrite) ) + return bt->err; + if( bt_unlockpage(bt, page_no, BtLockWrite) ) + return bt->err; + + // delete old lower key to consolidated node + + if( bt_deletekey (bt, lowerkey + 1, *lowerkey, lvl + 1) ) + return bt->err; + + // redirect higher key directly to consolidated node + + tod = (uint)time(NULL); + + if( bt_insertkey (bt, higherkey+1, *higherkey, lvl + 1, page_no, tod) ) + return bt->err; + + // obtain write lock and + // add right block to free chain + + if( bt_freepage (bt, right) ) + return bt->err; + + // remove ParentModify lock + + if( bt_unlockpage(bt, page_no, BtLockParent) ) + return bt->err; + + return 0; +} + +// find key in leaf level and return row-id + +uid bt_findkey (BtDb *bt, unsigned char *key, uint len) +{ +uint slot; +BtKey ptr; +uid id; + + if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) ) + ptr = keyptr(bt->page, slot); + else + return 0; + + // if key exists, return row-id + // otherwise return 0 + + if( ptr->len == len && !memcmp (ptr->key, key, len) ) + id = bt_getid(slotptr(bt->page,slot)->id); + else + id = 0; + + if ( bt_unlockpage(bt, bt->page_no, BtLockRead) ) + return 0; + + return id; +} + +void bt_cleanpage(BtDb *bt) +{ +uint nxt = bt->mgr->page_size; +BtPage page = bt->page; +uint cnt = 0, idx = 0; +uint max = page->cnt; +BtKey key; + + memcpy (bt->frame, page, bt->mgr->page_size); + + // skip page info and set rest of page to zero + memset (page+1, 0, bt->mgr->page_size - sizeof(*page)); + page->act = 0; + + // try cleaning up page first + + while( cnt++ < max ) { + // always leave fence key in list + if( cnt < max && slotptr(bt->frame,cnt)->dead ) + continue; + + // copy key + key = keyptr(bt->frame, cnt); + nxt -= key->len + 1; + memcpy ((unsigned char *)page + nxt, key, key->len + 1); + + // copy slot + memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId); + if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) ) + page->act++; + slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod; + slotptr(page, idx)->off = nxt; + } + page->min = nxt; + page->cnt = idx; +} + +// split the root and raise the height of the btree + +BTERR bt_splitroot(BtDb *bt, unsigned char *newkey, unsigned char *oldkey, uid page_no2) +{ +uint nxt = bt->mgr->page_size; +BtPage root = bt->page; +uid new_page; + + // Obtain an empty page to use, and copy the current + // root contents into it + + if( !(new_page = bt_newpage(bt, root)) ) + return bt->err; + + // preserve the page info at the bottom + // and set rest to zero + + memset(root+1, 0, bt->mgr->page_size - sizeof(*root)); + + // insert first key on newroot page + + nxt -= *newkey + 1; + memcpy ((unsigned char *)root + nxt, newkey, *newkey + 1); + bt_putid(slotptr(root, 1)->id, new_page); + slotptr(root, 1)->off = nxt; + + // insert second key on newroot page + // and increase the root height + + nxt -= *oldkey + 1; + memcpy ((unsigned char *)root + nxt, oldkey, *oldkey + 1); + bt_putid(slotptr(root, 2)->id, page_no2); + slotptr(root, 2)->off = nxt; + + bt_putid(root->right, 0); + root->min = nxt; // reset lowest used offset and key count + root->cnt = 2; + root->act = 2; + root->lvl++; + + // release root (bt->page) + + return bt_unlockpage(bt, bt->page_no, BtLockWrite); +} + +// split already locked full node +// return unlocked. + +BTERR bt_splitpage (BtDb *bt, uint len) +{ +uint cnt = 0, idx = 0, max, nxt = bt->mgr->page_size; +unsigned char oldkey[256], lowerkey[256]; +uid page_no = bt->page_no, right; +BtPage page = bt->page; +uint lvl = page->lvl; +uid new_page; +BtKey key; +uint tod; + + // perform cleanup + + bt_cleanpage(bt); + + // return if enough space now + + if( page->min >= (page->cnt + 1) * sizeof(BtSlot) + sizeof(*page) + len + 1) + return bt_unlockpage(bt, page_no, BtLockWrite); + + // split higher half of keys to bt->frame + // the last key (fence key) might be dead + + tod = (uint)time(NULL); + + memset (bt->frame, 0, bt->mgr->page_size); + max = (int)page->cnt; + cnt = max / 2; + idx = 0; + + while( cnt++ < max ) { + key = keyptr(page, cnt); + nxt -= key->len + 1; + memcpy ((unsigned char *)bt->frame + nxt, key, key->len + 1); + memcpy(slotptr(bt->frame,++idx)->id, slotptr(page,cnt)->id, BtId); + if( !(slotptr(bt->frame, idx)->dead = slotptr(page, cnt)->dead) ) + bt->frame->act++; + slotptr(bt->frame, idx)->tod = slotptr(page, cnt)->tod; + slotptr(bt->frame, idx)->off = nxt; + } + + // remember existing fence key for new page to the right + + memcpy (oldkey, key, key->len + 1); + + bt->frame->bits = bt->mgr->page_bits; + bt->frame->min = nxt; + bt->frame->cnt = idx; + bt->frame->lvl = lvl; + + // link right node + + if( page_no > ROOT_page ) { + right = bt_getid (page->right); + bt_putid(bt->frame->right, right); + } + + // get new free page and write frame to it. + + if( !(new_page = bt_newpage(bt, bt->frame)) ) + return bt->err; + + // update lower keys to continue in old page + + memcpy (bt->frame, page, bt->mgr->page_size); + memset (page+1, 0, bt->mgr->page_size - sizeof(*page)); + nxt = bt->mgr->page_size; + page->act = 0; + cnt = 0; + idx = 0; + + // assemble page of smaller keys + // (they're all active keys) + + while( cnt++ < max / 2 ) { + key = keyptr(bt->frame, cnt); + nxt -= key->len + 1; + memcpy ((unsigned char *)page + nxt, key, key->len + 1); + memcpy(slotptr(page,++idx)->id, slotptr(bt->frame,cnt)->id, BtId); + slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod; + slotptr(page, idx)->off = nxt; + page->act++; + } + + // remember fence key for old page + + memcpy(lowerkey, key, key->len + 1); + bt_putid(page->right, new_page); + page->min = nxt; + page->cnt = idx; + + // if current page is the root page, split it + + if( page_no == ROOT_page ) + return bt_splitroot (bt, lowerkey, oldkey, new_page); + + // obtain Parent/Write locks + // for left and right node pages + + if( bt_lockpage (bt, new_page, BtLockParent, NULL) ) + return bt->err; + + if( bt_lockpage (bt, page_no, BtLockParent, NULL) ) + return bt->err; + + // release wr lock on left page + + if( bt_unlockpage (bt, page_no, BtLockWrite) ) + return bt->err; + + // insert new fence for reformulated left block + + if( bt_insertkey (bt, lowerkey+1, *lowerkey, lvl + 1, page_no, tod) ) + return bt->err; + + // fix old fence for newly allocated right block page + + if( bt_insertkey (bt, oldkey+1, *oldkey, lvl + 1, new_page, tod) ) + return bt->err; + + // release Parent & Write locks + + if( bt_unlockpage (bt, new_page, BtLockParent) ) + return bt->err; + + if( bt_unlockpage (bt, page_no, BtLockParent) ) + return bt->err; + + return 0; +} + +// Insert new key into the btree at requested level. +// Level zero pages are leaf pages and are unlocked at exit. +// Interior pages remain locked. + +BTERR bt_insertkey (BtDb *bt, unsigned char *key, uint len, uint lvl, uid id, uint tod) +{ +uint slot, idx; +BtPage page; +BtKey ptr; + + while( 1 ) { + if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) ) + ptr = keyptr(bt->page, slot); + else + { + if ( !bt->err ) + bt->err = BTERR_ovflw; + return bt->err; + } + + // if key already exists, update id and return + + page = bt->page; + + if( !keycmp (ptr, key, len) ) { + slotptr(page, slot)->dead = 0; + slotptr(page, slot)->tod = tod; + bt_putid(slotptr(page,slot)->id, id); + return bt_unlockpage(bt, bt->page_no, BtLockWrite); + } + + // check if page has enough space + + if( page->min >= (page->cnt + 1) * sizeof(BtSlot) + sizeof(*page) + len + 1) + break; + + if( bt_splitpage (bt, len) ) + return bt->err; + } + + // calculate next available slot and copy key into page + + page->min -= len + 1; // reset lowest used offset + ((unsigned char *)page)[page->min] = len; + memcpy ((unsigned char *)page + page->min +1, key, len ); + + for( idx = slot; idx < page->cnt; idx++ ) + if( slotptr(page, idx)->dead ) + break; + + // now insert key into array before slot + // preserving the fence slot + + if( idx == page->cnt ) + idx++, page->cnt++; + + page->act++; + + while( idx > slot ) + *slotptr(page, idx) = *slotptr(page, idx -1), idx--; + + bt_putid(slotptr(page,slot)->id, id); + slotptr(page, slot)->off = page->min; + slotptr(page, slot)->tod = tod; + slotptr(page, slot)->dead = 0; + + return bt_unlockpage(bt, bt->page_no, BtLockWrite); +} + +// cache page of keys into cursor and return starting slot for given key + +uint bt_startkey (BtDb *bt, unsigned char *key, uint len) +{ +uint slot; + + // cache page for retrieval + if( slot = bt_loadpage (bt, key, len, 0, BtLockRead) ) + memcpy (bt->cursor, bt->page, bt->mgr->page_size); + bt->cursor_page = bt->page_no; + if ( bt_unlockpage(bt, bt->page_no, BtLockRead) ) + return 0; + + return slot; +} + +// return next slot for cursor page +// or slide cursor right into next page + +uint bt_nextkey (BtDb *bt, uint slot) +{ +off64_t right; + + do { + right = bt_getid(bt->cursor->right); + while( slot++ < bt->cursor->cnt ) + if( slotptr(bt->cursor,slot)->dead ) + continue; + else if( right || (slot < bt->cursor->cnt)) + return slot; + else + break; + + if( !right ) + break; + + bt->cursor_page = right; + + if( bt_lockpage(bt, right, BtLockRead, &bt->page) ) + return 0; + + memcpy (bt->cursor, bt->page, bt->mgr->page_size); + + if ( bt_unlockpage(bt, right, BtLockRead) ) + return 0; + + slot = 0; + } while( 1 ); + + return bt->err = 0; +} + +BtKey bt_key(BtDb *bt, uint slot) +{ + return keyptr(bt->cursor, slot); +} + +uid bt_uid(BtDb *bt, uint slot) +{ + return bt_getid(slotptr(bt->cursor,slot)->id); +} + +uint bt_tod(BtDb *bt, uint slot) +{ + return slotptr(bt->cursor,slot)->tod; +} + + +#ifdef STANDALONE + +typedef struct { + char *infile; + char type; + BtMgr *mgr; +} ThreadArg; + +// standalone program to index file of keys +// then list them onto std-out + +#ifdef unix +void *index_file (void *arg) +#else +uint __stdcall index_file (void *arg) +#endif +{ +int line = 0, found = 0; +unsigned char key[256]; +ThreadArg *args = arg; +int ch, len = 0, slot; +time_t tod[1]; +BtKey ptr; +BtDb *bt; +FILE *in; + + bt = bt_open (args->mgr); + time (tod); + + switch(args->type | 0x20) + { + case 'w': + fprintf(stderr, "started indexing for %s\n", args->infile); + if( in = fopen (args->infile, "rb") ) + while( ch = getc(in), ch != EOF ) + if( ch == '\n' ) + { + if( bt_insertkey (bt, key, len, 0, ++line, *tod) ) + fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0); + len = 0; + } + else if( len < 255 ) + key[len++] = ch; + fprintf(stderr, "finished %s for %d keys\n", args->infile, line); + break; + + case 'd': + fprintf(stderr, "started deleting keys for %s\n", args->infile); + if( in = fopen (args->infile, "rb") ) + while( ch = getc(in), ch != EOF ) + if( ch == '\n' ) + { + line++; + if( bt_deletekey (bt, key, len, 0) ) + fprintf(stderr, "Error %d Line: %d\n", bt->err, line), exit(0); + len = 0; + } + else if( len < 255 ) + key[len++] = ch; + fprintf(stderr, "finished %s for keys, %d \n", args->infile, line); + break; + + case 'f': + fprintf(stderr, "started finding keys for %s\n", args->infile); + if( in = fopen (args->infile, "rb") ) + while( ch = getc(in), ch != EOF ) + if( ch == '\n' ) + { + line++; + if( bt_findkey (bt, key, len) ) + found++; + else if( bt->err ) + fprintf(stderr, "Error %d Syserr %d Line: %d\n", bt->err, errno, line), exit(0); + len = 0; + } + else if( len < 255 ) + key[len++] = ch; + fprintf(stderr, "finished %s for %d keys, found %d\n", args->infile, line, found); + break; + + case 's': + len = key[0] = 0; + + fprintf(stderr, "started reading\n"); + + if( slot = bt_startkey (bt, key, len) ) + slot--; + else + fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0); + + while( slot = bt_nextkey (bt, slot) ) { + ptr = bt_key(bt, slot); + fwrite (ptr->key, ptr->len, 1, stdout); + fputc ('\n', stdout); + } + } + + bt_close (bt); +#ifdef unix + return NULL; +#else + return 0; +#endif +} + +typedef struct timeval timer; + +int main (int argc, char **argv) +{ +int idx, cnt, len, slot, err; +int segsize, bits = 16; +#ifdef unix +pthread_t *threads; +timer start, stop; +#else +time_t start[1], stop[1]; +HANDLE *threads; +#endif +double real_time; +ThreadArg *args; +uint map = 0; +char key[1]; +BtMgr *mgr; +BtKey ptr; +BtDb *bt; + + if( argc < 3 ) { + fprintf (stderr, "Usage: %s idx_file Read/Write/Scan/Delete/Find [page_bits mapped_segments seg_bits hash_size src_file1 src_file2 ... ]\n", argv[0]); + fprintf (stderr, " where page_bits is the page size in bits\n"); + fprintf (stderr, " mapped_segments is the number of mmap segments in buffer pool\n"); + fprintf (stderr, " seg_bits is the size of individual segments in buffer pool in pages in bits\n"); + fprintf (stderr, " hash_size is the size of buffer pool hash table\n"); + fprintf (stderr, " src_file1 thru src_filen are files of keys separated by newline\n"); + exit(0); + } + +#ifdef unix + gettimeofday(&start, NULL); +#else + time(start); +#endif + + if( argc > 3 ) + bits = atoi(argv[3]); + + if( argc > 4 ) + map = atoi(argv[4]); + + if( map > 65536 ) + fprintf (stderr, "Warning: mapped_pool > 65536 segments\n"); + + if( argc > 5 ) + segsize = atoi(argv[5]); + else + segsize = 4; // 16 pages per mmap segment + + cnt = argc - 6; +#ifdef unix + threads = malloc (cnt * sizeof(pthread_t)); +#else + threads = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, cnt * sizeof(HANDLE)); +#endif + args = malloc (cnt * sizeof(ThreadArg)); + + mgr = bt_mgr ((argv[1]), BT_rw, bits, map, segsize, map / 8); + + if( !mgr ) { + fprintf(stderr, "Index Open Error %s\n", argv[1]); + exit (1); + } + + // fire off threads + + for( idx = 0; idx < cnt; idx++ ) { + args[idx].infile = argv[idx + 6]; + args[idx].type = argv[2][0]; + args[idx].mgr = mgr; +#ifdef unix + if( err = pthread_create (threads + idx, NULL, index_file, args + idx) ) + fprintf(stderr, "Error creating thread %d\n", err); +#else + threads[idx] = (HANDLE)_beginthreadex(NULL, 65536, index_file, args + idx, 0, NULL); +#endif + } + + // wait for termination + +#ifdef unix + for( idx = 0; idx < cnt; idx++ ) + pthread_join (threads[idx], NULL); + gettimeofday(&stop, NULL); + real_time = 1000.0 * ( stop.tv_sec - start.tv_sec ) + 0.001 * (stop.tv_usec - start.tv_usec ); +#else + WaitForMultipleObjects (cnt, threads, TRUE, INFINITE); + + for( idx = 0; idx < cnt; idx++ ) + CloseHandle(threads[idx]); + + time (stop); + real_time = 1000 * (*stop - *start); +#endif + fprintf(stderr, " Time to complete: %.2f seconds\n", real_time/1000); + + cnt = 0; + len = key[0] = 0; + bt = bt_open (mgr); + + fprintf(stderr, "started reading\n"); + + if( slot = bt_startkey (bt, key, len) ) + slot--; + else + fprintf(stderr, "Error %d in StartKey. Syserror: %d\n", bt->err, errno), exit(0); + + while( slot = bt_nextkey (bt, slot) ) + cnt++; + + fprintf(stderr, " Total keys read %d\n", cnt); + + bt_close (bt); + bt_mgrclose (mgr); +} + +#endif //STANDALONE -- 2.40.0