From 2898cdccd12c90cf665b9d75ab73be7c298965e3 Mon Sep 17 00:00:00 2001 From: unknown Date: Tue, 25 Feb 2014 12:09:08 -0800 Subject: [PATCH] Use test & set latching instead of file locking calls --- btree2t.c | 2388 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 2388 insertions(+) create mode 100644 btree2t.c diff --git a/btree2t.c b/btree2t.c new file mode 100644 index 0000000..7138712 --- /dev/null +++ b/btree2t.c @@ -0,0 +1,2388 @@ +// btree version 2t +// with reworked bt_deletekey code +// 25 FEB 2014 + +// author: karl malbrain, malbrain@cal.berkeley.edu + +/* +This work, including the source code, documentation +and related data, is placed into the public domain. + +The orginal author is Karl Malbrain. + +THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY +OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF +MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE, +ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE +RESULTING FROM THE USE, MODIFICATION, OR +REDISTRIBUTION OF THIS SOFTWARE. +*/ + +// Please see the project home page for documentation +// code.google.com/p/high-concurrency-btree + +#define _FILE_OFFSET_BITS 64 +#define _LARGEFILE64_SOURCE + +#ifdef linux +#define _GNU_SOURCE +#endif + +#ifdef unix +#include +#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_latchtable 128 // number of latch manager slots + +#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_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; + +// definition for latch implementation + +// exclusive is set for write access +// share is count of read accessors +// grant write lock when share == 0 + +volatile typedef struct { + unsigned char mutex[1]; + unsigned char exclusive:1; + unsigned char pending:1; + ushort share; +} BtSpinLatch; + +// hash table entries + +typedef struct { + BtSpinLatch latch[1]; + volatile ushort slot; // Latch table entry at head of chain +} BtHashEntry; + +// latch manager table structure + +typedef struct { + BtSpinLatch readwr[1]; // read/write page lock + BtSpinLatch access[1]; // Access Intent/Page delete + BtSpinLatch parent[1]; // Posting of fence key in parent + BtSpinLatch busy[1]; // slot is being moved between chains + volatile ushort next; // next entry in hash table chain + volatile ushort prev; // prev entry in hash table chain + volatile ushort pin; // number of outstanding locks + volatile ushort hash; // hash slot entry is under + volatile uid page_no; // latch set page number +} BtLatchSet; + +// Define the length of the page and key pointers + +#define BtId 6 + +// Page key slot definition. + +// If BT_maxbits is 15 or less, you can save 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 BtPage_ { + uint cnt; // count of keys in page + uint act; // count of active keys + uint min; // next key offset + unsigned char bits:7; // page size in bits + unsigned char free:1; // page is on free list + unsigned char lvl:6; // level of page + unsigned char kill:1; // page is being deleted + unsigned char dirty:1; // page is dirty + unsigned char right[BtId]; // page number to right +} *BtPage; + +// The memory mapping hash table entry + +typedef struct { + BtPage page; // mapped page pointer + uid page_no; // mapped page number + void *lruprev; // least recently used previous cache block + void *lrunext; // lru next cache block + void *hashprev; // previous cache block for the same hash idx + void *hashnext; // next cache block for the same hash idx +#ifndef unix + HANDLE hmap; +#endif +}BtHash; + +typedef struct { + struct BtPage_ alloc[2]; // next & free page_nos in right ptr + BtSpinLatch lock[1]; // allocation area lite latch + ushort latchdeployed; // highest number of latch entries deployed + ushort nlatchpage; // number of latch pages at BT_latch + ushort latchtotal; // number of page latch entries + ushort latchhash; // number of latch hash table slots + ushort latchvictim; // next latch entry to examine + BtHashEntry table[0]; // the hash table +} BtLatchMgr; + +// 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 + BtLatchSet *latch; // current page latch + BtLatchMgr *latchmgr; // mapped latch page from allocation page + BtLatchSet *latchsets; // mapped latch set from latch pages +#ifdef unix + int idx; +#else + HANDLE idx; + HANDLE halloc; // allocation and latch table handle +#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 + int found; // last deletekey found key + BtHash *lrufirst; // lru list head + BtHash *lrulast; // lru list tail + ushort *cache; // hash table for cached segments + BtHash *nodes; // segment cache +} BtDb; + +typedef enum { +BTERR_ok = 0, +BTERR_notfound, +BTERR_struct, +BTERR_ovflw, +BTERR_lock, +BTERR_hash, +BTERR_kill, +BTERR_map, +BTERR_wrt, +BTERR_eof +} BTERR; + +// B-Tree functions +extern void bt_close (BtDb *bt); +extern BtDb *bt_open (char *name, uint mode, uint bits, uint cacheblk, uint pgblk, uint hashsize); +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); + +// internal functions +BTERR bt_update (BtDb *bt, BtPage page, uid page_no); +BTERR bt_mappage (BtDb *bt, BtPage *page, uid page_no); +// Helper functions to return slot values + +extern BtKey bt_key (BtDb *bt, uint slot); +extern uid bt_uid (BtDb *bt, uint slot); +extern uint bt_tod (BtDb *bt, uint slot); + +// BTree page number constants +#define ALLOC_page 0 +#define ROOT_page 1 +#define LEAF_page 2 +#define LATCH_page 3 + +// Number of levels to create in a new BTree + +#define MIN_lvl 2 + +// The page is allocated from low and hi ends. +// The key offsets and row-id's are allocated +// from the bottom, while the text of the key +// is allocated from the top. When the two +// areas meet, the page is split into two. + +// A key consists of a length byte, two bytes of +// index number (0 - 65534), and up to 253 bytes +// of key value. Duplicate keys are discarded. +// Associated with each key is a 48 bit row-id. + +// The b-tree root is always located at page 1. +// The first leaf page of level zero is always +// located on page 2. + +// The b-tree pages are linked with right +// pointers to facilitate enumerators, +// and provide for concurrency. + +// When to root page fills, it is split in two and +// the tree height is raised by a new root at page +// one with two keys. + +// Deleted keys are marked with a dead bit until +// page cleanup The fence key for a node is always +// present, even after deletion and cleanup. + +// Deleted leaf pages are reclaimed on a free list. +// The upper levels of the btree are fixed on creation. + +// Groups of pages from the btree are optionally +// cached with memory mapping. A hash table is used to keep +// track of the cached pages. This behaviour is controlled +// by the number of cache blocks parameter and pages per block +// given to bt_open. + +// To achieve maximum concurrency one page is locked at a time +// as the tree is traversed to find leaf key in question. The right +// page numbers are used in cases where the page is being split, +// or consolidated. + +// Page 0 (ALLOC page) is dedicated to lock for new page extensions, +// and chains empty leaf pages together for reuse. + +// Parent locks are obtained to prevent resplitting or deleting a node +// before its fence is posted into its upper level. + +// A special open mode of BT_fl is provided to safely access files on +// WIN32 networks. WIN32 network operations should not use memory mapping. +// This WIN32 mode sets FILE_FLAG_NOBUFFERING and FILE_FLAG_WRITETHROUGH +// to prevent local caching of network file contents. + +// Access macros to address slot and key values from the page. +// Page slots use 1 based indexing. + +#define slotptr(page, slot) (((BtSlot *)(page+1)) + (slot-1)) +#define keyptr(page, slot) ((BtKey)((unsigned char*)(page) + slotptr(page, slot)->off)) + +void bt_putid(unsigned char *dest, uid id) +{ +int i = BtId; + + while( i-- ) + dest[i] = (unsigned char)id, id >>= 8; +} + +uid bt_getid(unsigned char *src) +{ +uid id = 0; +int i; + + for( i = 0; i < BtId; i++ ) + id <<= 8, id |= *src++; + + return id; +} + +BTERR bt_abort (BtDb *bt, BtPage page, uid page_no, BTERR err) +{ +BtKey ptr; + + fprintf(stderr, "\n Btree2 abort, error %d on page %.8x\n", err, page_no); + fprintf(stderr, "level=%d kill=%d free=%d cnt=%x act=%x\n", page->lvl, page->kill, page->free, page->cnt, page->act); + ptr = keyptr(page, page->cnt); + fprintf(stderr, "fence='%.*s'\n", ptr->len, ptr->key); + fprintf(stderr, "right=%.8x\n", bt_getid(page->right)); +} + +// Latch Manager + +// wait until write lock mode is clear +// and add 1 to the share count + +void bt_spinreadlock(BtSpinLatch *latch) +{ +ushort prev; + + do { + // obtain latch mutex +#ifdef unix + if( __sync_lock_test_and_set(latch->mutex, 1) ) + continue; +#else + if( _InterlockedExchange8(latch->mutex, 1) ) + continue; +#endif + // see if exclusive request is granted or pending + + if( prev = !(latch->exclusive | latch->pending) ) + latch->share++; + +#ifdef unix + *latch->mutex = 0; +#else + _InterlockedExchange8(latch->mutex, 0); +#endif + + if( prev ) + return; + +#ifdef unix + } while( sched_yield(), 1 ); +#else + } while( SwitchToThread(), 1 ); +#endif +} + +// wait for other read and write latches to relinquish + +void bt_spinwritelock(BtSpinLatch *latch) +{ +uint prev; + + do { +#ifdef unix + if( __sync_lock_test_and_set(latch->mutex, 1) ) + continue; +#else + if( _InterlockedExchange8(latch->mutex, 1) ) + continue; +#endif + if( prev = !(latch->share | latch->exclusive) ) + latch->exclusive = 1, latch->pending = 0; + else + latch->pending = 1; +#ifdef unix + *latch->mutex = 0; +#else + _InterlockedExchange8(latch->mutex, 0); +#endif + if( prev ) + return; +#ifdef unix + } while( sched_yield(), 1 ); +#else + } while( SwitchToThread(), 1 ); +#endif +} + +// try to obtain write lock + +// return 1 if obtained, +// 0 otherwise + +int bt_spinwritetry(BtSpinLatch *latch) +{ +uint prev; + +#ifdef unix + if( __sync_lock_test_and_set(latch->mutex, 1) ) + return 0; +#else + if( _InterlockedExchange8(latch->mutex, 1) ) + return 0; +#endif + // take write access if all bits are clear + + if( prev = !(latch->exclusive | latch->share) ) + latch->exclusive = 1; + +#ifdef unix + *latch->mutex = 0; +#else + _InterlockedExchange8(latch->mutex, 0); +#endif + return prev; +} + +// clear write mode + +void bt_spinreleasewrite(BtSpinLatch *latch) +{ +#ifdef unix + while( __sync_lock_test_and_set(latch->mutex, 1) ) + sched_yield(); +#else + while( _InterlockedExchange8(latch->mutex, 1) ) + SwitchToThread(); +#endif + latch->exclusive = 0; +#ifdef unix + *latch->mutex = 0; +#else + _InterlockedExchange8(latch->mutex, 0); +#endif +} + +// decrement reader count + +void bt_spinreleaseread(BtSpinLatch *latch) +{ +#ifdef unix + while( __sync_lock_test_and_set(latch->mutex, 1) ) + sched_yield(); +#else + while( _InterlockedExchange8(latch->mutex, 1) ) + SwitchToThread(); +#endif + latch->share--; +#ifdef unix + *latch->mutex = 0; +#else + _InterlockedExchange8(latch->mutex, 0); +#endif +} + +// link latch table entry into latch hash table + +void bt_latchlink (BtDb *bt, ushort hashidx, ushort victim, uid page_no) +{ +BtLatchSet *latch = bt->latchsets + victim; + + if( latch->next = bt->latchmgr->table[hashidx].slot ) + bt->latchsets[latch->next].prev = victim; + + bt->latchmgr->table[hashidx].slot = victim; + latch->page_no = page_no; + latch->hash = hashidx; + latch->prev = 0; +} + +// release latch pin + +void bt_unpinlatch (BtLatchSet *latch) +{ +#ifdef unix + __sync_fetch_and_add(&latch->pin, -1); +#else + _InterlockedDecrement16 (&latch->pin); +#endif +} + +// find existing latchset or inspire new one +// return with latchset pinned + +BtLatchSet *bt_pinlatch (BtDb *bt, uid page_no) +{ +ushort hashidx = page_no % bt->latchmgr->latchhash; +ushort slot, avail = 0, victim, idx; +BtLatchSet *latch; + + // obtain read lock on hash table entry + + bt_spinreadlock(bt->latchmgr->table[hashidx].latch); + + if( slot = bt->latchmgr->table[hashidx].slot ) do + { + latch = bt->latchsets + slot; + if( page_no == latch->page_no ) + break; + } while( slot = latch->next ); + + if( slot ) { +#ifdef unix + __sync_fetch_and_add(&latch->pin, 1); +#else + _InterlockedIncrement16 (&latch->pin); +#endif + } + + bt_spinreleaseread (bt->latchmgr->table[hashidx].latch); + + if( slot ) + return latch; + + // try again, this time with write lock + + bt_spinwritelock(bt->latchmgr->table[hashidx].latch); + + if( slot = bt->latchmgr->table[hashidx].slot ) do + { + latch = bt->latchsets + slot; + if( page_no == latch->page_no ) + break; + if( !latch->pin && !avail ) + avail = slot; + } while( slot = latch->next ); + + // found our entry, or take over an unpinned one + + if( slot || (slot = avail) ) { + latch = bt->latchsets + slot; +#ifdef unix + __sync_fetch_and_add(&latch->pin, 1); +#else + _InterlockedIncrement16 (&latch->pin); +#endif + latch->page_no = page_no; + bt_spinreleasewrite(bt->latchmgr->table[hashidx].latch); + return latch; + } + + // see if there are any unused entries +#ifdef unix + victim = __sync_fetch_and_add (&bt->latchmgr->latchdeployed, 1) + 1; +#else + victim = _InterlockedIncrement16 (&bt->latchmgr->latchdeployed); +#endif + + if( victim < bt->latchmgr->latchtotal ) { + latch = bt->latchsets + victim; +#ifdef unix + __sync_fetch_and_add(&latch->pin, 1); +#else + _InterlockedIncrement16 (&latch->pin); +#endif + bt_latchlink (bt, hashidx, victim, page_no); + bt_spinreleasewrite (bt->latchmgr->table[hashidx].latch); + return latch; + } + +#ifdef unix + victim = __sync_fetch_and_add (&bt->latchmgr->latchdeployed, -1); +#else + victim = _InterlockedDecrement16 (&bt->latchmgr->latchdeployed); +#endif + // find and reuse previous lock entry + + while( 1 ) { +#ifdef unix + victim = __sync_fetch_and_add(&bt->latchmgr->latchvictim, 1); +#else + victim = _InterlockedIncrement16 (&bt->latchmgr->latchvictim) - 1; +#endif + // we don't use slot zero + + if( victim %= bt->latchmgr->latchtotal ) + latch = bt->latchsets + victim; + else + continue; + + // take control of our slot + // from other threads + + if( latch->pin || !bt_spinwritetry (latch->busy) ) + continue; + + idx = latch->hash; + + // try to get write lock on hash chain + // skip entry if not obtained + // or has outstanding locks + + if( !bt_spinwritetry (bt->latchmgr->table[idx].latch) ) { + bt_spinreleasewrite (latch->busy); + continue; + } + + if( latch->pin ) { + bt_spinreleasewrite (latch->busy); + bt_spinreleasewrite (bt->latchmgr->table[idx].latch); + continue; + } + + // unlink our available victim from its hash chain + + if( latch->prev ) + bt->latchsets[latch->prev].next = latch->next; + else + bt->latchmgr->table[idx].slot = latch->next; + + if( latch->next ) + bt->latchsets[latch->next].prev = latch->prev; + + bt_spinreleasewrite (bt->latchmgr->table[idx].latch); +#ifdef unix + __sync_fetch_and_add(&latch->pin, 1); +#else + _InterlockedIncrement16 (&latch->pin); +#endif + bt_latchlink (bt, hashidx, victim, page_no); + bt_spinreleasewrite (bt->latchmgr->table[hashidx].latch); + bt_spinreleasewrite (latch->busy); + return latch; + } +} + +// 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 pool (e.g. 8192) + +BtDb *bt_open (char *name, uint mode, uint bits, uint nodemax, uint segsize, uint hashsize) +{ +uint lvl, attr, cacheblk, last, slot, idx; +uint nlatchpage, latchhash; +BtLatchMgr *latchmgr; +off64_t size; +uint amt[1]; +BtKey key; +BtDb* bt; +int flag; + +#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; + +#ifdef unix + bt = calloc (1, sizeof(BtDb)); + + bt->idx = open ((char*)name, O_RDWR | O_CREAT, 0666); + + if( bt->idx == -1 ) + return free(bt), NULL; + + cacheblk = 4096; // minimum mmap segment size for unix + +#else + bt = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, sizeof(BtDb)); + attr = FILE_ATTRIBUTE_NORMAL; + bt->idx = CreateFile(name, GENERIC_READ| GENERIC_WRITE, FILE_SHARE_READ|FILE_SHARE_WRITE, NULL, OPEN_ALWAYS, attr, NULL); + + if( bt->idx == INVALID_HANDLE_VALUE ) + return GlobalFree(bt), NULL; + + // normalize cacheblk to multiple of sysinfo->dwAllocationGranularity + GetSystemInfo(sysinfo); + cacheblk = sysinfo->dwAllocationGranularity; +#endif + +#ifdef unix + latchmgr = malloc (BT_maxpage); + *amt = 0; + + // read minimum page size to get root info + + if( size = lseek (bt->idx, 0L, 2) ) { + if( pread(bt->idx, latchmgr, BT_minpage, 0) == BT_minpage ) + bits = latchmgr->alloc->bits; + else + return free(bt), free(latchmgr), NULL; + } else if( mode == BT_ro ) + return free(latchmgr), bt_close (bt), NULL; +#else + latchmgr = VirtualAlloc(NULL, BT_maxpage, MEM_COMMIT, PAGE_READWRITE); + size = GetFileSize(bt->idx, amt); + + if( size || *amt ) { + if( !ReadFile(bt->idx, (char *)latchmgr, BT_minpage, amt, NULL) ) + return bt_close (bt), NULL; + bits = latchmgr->alloc->bits; + } else if( mode == BT_ro ) + return bt_close (bt), NULL; +#endif + + bt->page_size = 1 << bits; + bt->page_bits = bits; + + bt->mode = mode; + + if( cacheblk < bt->page_size ) + cacheblk = bt->page_size; + + // mask for partial memmaps + + bt->hashmask = (cacheblk >> bits) - 1; + + // see if requested size of pages per memmap is greater + + if( (1 << segsize) > bt->hashmask ) + bt->hashmask = (1 << segsize) - 1; + + bt->seg_bits = 0; + + while( (1 << bt->seg_bits) <= bt->hashmask ) + bt->seg_bits++; + + bt->hashsize = hashsize; + + if( bt->nodemax = nodemax ) { +#ifdef unix + bt->nodes = calloc (nodemax, sizeof(BtHash)); + bt->cache = calloc (hashsize, sizeof(ushort)); +#else + bt->nodes = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, nodemax * sizeof(BtHash)); + bt->cache = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, hashsize * sizeof(ushort)); +#endif + bt->mapped_io = 1; + } + + if( size || *amt ) + goto btlatch; + + // initialize an empty b-tree with latch page, root page, page of leaves + // and page(s) of latches + + memset (latchmgr, 0, 1 << bits); + nlatchpage = BT_latchtable / (bt->page_size / sizeof(BtLatchSet)) + 1; + bt_putid(latchmgr->alloc->right, MIN_lvl+1+nlatchpage); + latchmgr->alloc->bits = bt->page_bits; + + latchmgr->nlatchpage = nlatchpage; + latchmgr->latchtotal = nlatchpage * (bt->page_size / sizeof(BtLatchSet)); + + // initialize latch manager + + latchhash = (bt->page_size - sizeof(BtLatchMgr)) / sizeof(BtHashEntry); + + // size of hash table = total number of latchsets + + if( latchhash > latchmgr->latchtotal ) + latchhash = latchmgr->latchtotal; + + latchmgr->latchhash = latchhash; + +#ifdef unix + if( write (bt->idx, latchmgr, bt->page_size) < bt->page_size ) + return bt_close (bt), NULL; +#else + if( !WriteFile (bt->idx, (char *)latchmgr, bt->page_size, amt, NULL) ) + return bt_close (bt), NULL; + + if( *amt < bt->page_size ) + return bt_close (bt), NULL; +#endif + + memset (latchmgr, 0, 1 << bits); + latchmgr->alloc->bits = bt->page_bits; + + for( lvl=MIN_lvl; lvl--; ) { + slotptr(latchmgr->alloc, 1)->off = bt->page_size - 3; + bt_putid(slotptr(latchmgr->alloc, 1)->id, lvl ? MIN_lvl - lvl + 1 : 0); // next(lower) page number + key = keyptr(latchmgr->alloc, 1); + key->len = 2; // create stopper key + key->key[0] = 0xff; + key->key[1] = 0xff; + latchmgr->alloc->min = bt->page_size - 3; + latchmgr->alloc->lvl = lvl; + latchmgr->alloc->cnt = 1; + latchmgr->alloc->act = 1; +#ifdef unix + if( write (bt->idx, latchmgr, bt->page_size) < bt->page_size ) + return bt_close (bt), NULL; +#else + if( !WriteFile (bt->idx, (char *)latchmgr, bt->page_size, amt, NULL) ) + return bt_close (bt), NULL; + + if( *amt < bt->page_size ) + return bt_close (bt), NULL; +#endif + } + + // clear out latch manager locks + // and rest of pages to round out segment + + memset(latchmgr, 0, bt->page_size); + last = MIN_lvl + 1; + + while( last <= ((MIN_lvl + 1 + nlatchpage) | bt->hashmask) ) { +#ifdef unix + pwrite(bt->idx, latchmgr, bt->page_size, last << bt->page_bits); +#else + SetFilePointer (bt->idx, last << bt->page_bits, NULL, FILE_BEGIN); + if( !WriteFile (bt->idx, (char *)latchmgr, bt->page_size, amt, NULL) ) + return bt_close (bt), NULL; + if( *amt < bt->page_size ) + return bt_close (bt), NULL; +#endif + last++; + } + +btlatch: +#ifdef unix + flag = PROT_READ | PROT_WRITE; + bt->latchmgr = mmap (0, bt->page_size, flag, MAP_SHARED, bt->idx, ALLOC_page * bt->page_size); + if( bt->latchmgr == MAP_FAILED ) + return bt_close (bt), NULL; + bt->latchsets = (BtLatchSet *)mmap (0, bt->latchmgr->nlatchpage * bt->page_size, flag, MAP_SHARED, bt->idx, LATCH_page * bt->page_size); + if( bt->latchsets == MAP_FAILED ) + return bt_close (bt), NULL; +#else + flag = PAGE_READWRITE; + bt->halloc = CreateFileMapping(bt->idx, NULL, flag, 0, (BT_latchtable / (bt->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * bt->page_size, NULL); + if( !bt->halloc ) + return bt_close (bt), NULL; + + flag = FILE_MAP_WRITE; + bt->latchmgr = MapViewOfFile(bt->halloc, flag, 0, 0, (BT_latchtable / (bt->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * bt->page_size); + if( !bt->latchmgr ) + return GetLastError(), bt_close (bt), NULL; + + bt->latchsets = (void *)((char *)bt->latchmgr + LATCH_page * bt->page_size); +#endif + +#ifdef unix + free (latchmgr); +#else + VirtualFree (latchmgr, 0, MEM_RELEASE); +#endif + +#ifdef unix + bt->mem = malloc (6 * bt->page_size); +#else + bt->mem = VirtualAlloc(NULL, 6 * bt->page_size, MEM_COMMIT, PAGE_READWRITE); +#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); + + memset (bt->zero, 0, bt->page_size); + return bt; +} + +// place write, read, or parent lock on requested page_no. + +void bt_lockpage(BtLock mode, BtLatchSet *latch) +{ + switch( mode ) { + case BtLockRead: + bt_spinreadlock (latch->readwr); + break; + case BtLockWrite: + bt_spinwritelock (latch->readwr); + break; + case BtLockAccess: + bt_spinreadlock (latch->access); + break; + case BtLockDelete: + bt_spinwritelock (latch->access); + break; + case BtLockParent: + bt_spinwritelock (latch->parent); + break; + } +} + +// remove write, read, or parent lock on requested page + +void bt_unlockpage(BtLock mode, BtLatchSet *latch) +{ + switch( mode ) { + case BtLockRead: + bt_spinreleaseread (latch->readwr); + break; + case BtLockWrite: + bt_spinreleasewrite (latch->readwr); + break; + case BtLockAccess: + bt_spinreleaseread (latch->access); + break; + case BtLockDelete: + bt_spinreleasewrite (latch->access); + break; + case BtLockParent: + bt_spinreleasewrite (latch->parent); + break; + } +} + +// allocate a new page and write page into it + +uid bt_newpage(BtDb *bt, BtPage page) +{ +uid new_page; +int reuse; + + // lock allocation page + + bt_spinwritelock(bt->latchmgr->lock); + + // use empty chain first + // else allocate empty page + + if( new_page = bt_getid(bt->latchmgr->alloc[1].right) ) { + if( bt_mappage (bt, &bt->temp, new_page) ) + return 0; + bt_putid(bt->latchmgr->alloc[1].right, bt_getid(bt->temp->right)); + reuse = 1; + } else { + new_page = bt_getid(bt->latchmgr->alloc->right); + bt_putid(bt->latchmgr->alloc->right, new_page+1); + reuse = 0; + } + + bt_spinreleasewrite(bt->latchmgr->lock); + + if( !bt->mapped_io ) + if( bt_update(bt, page, new_page) ) + return 0; //don't unlock on error + else + 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 pool block, zero last page in the block + + if( !reuse && bt->hashmask > 0 && (new_page & bt->hashmask) == 0 ) + { + // use zero buffer to write zeros + 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 pool and copy page. + // this will extend the file into the new pages. + + if( bt_mappage (bt, &bt->temp, new_page) ) + return 0; + + memcpy(bt->temp, page, bt->page_size); +#endif + return new_page; +} + +// 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 +// call with page latched for Writing and Deleting + +BTERR bt_freepage(BtDb *bt, uid page_no, BtPage page, BtLatchSet *latch) +{ + if( bt_mappage (bt, &page, page_no) ) + return bt->err; + + // lock allocation page + + bt_spinwritelock (bt->latchmgr->lock); + + // store chain in second right + bt_putid(page->right, bt_getid(bt->latchmgr->alloc[1].right)); + bt_putid(bt->latchmgr->alloc[1].right, page_no); + page->free = 1; + + if( bt_update(bt, page, page_no) ) + return bt->err; + + // unlock released page + + bt_unlockpage (BtLockDelete, latch); + bt_unlockpage (BtLockWrite, latch); + bt_unpinlatch (latch); + + // unlock allocation page + + bt_spinreleasewrite (bt->latchmgr->lock); + return 0; +} + +// 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 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, 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; +BtLatchSet *prevlatch; +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->latch = bt_pinlatch(bt, page_no); + bt->page_no = page_no; + + // obtain access lock using lock chaining + + if( page_no > ROOT_page ) + bt_lockpage(BtLockAccess, bt->latch); + + if( prevpage ) { + bt_unlockpage(prevmode, prevlatch); + bt_unpinlatch(prevlatch); + prevpage = 0; + } + + // obtain read lock using lock chaining + + bt_lockpage(mode, bt->latch); + + if( page_no > ROOT_page ) + bt_unlockpage(BtLockAccess, bt->latch); + + // 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 != BtLockRead && drill == lvl ) { + bt_unlockpage(mode, bt->latch); + bt_unpinlatch(bt->latch); + continue; + } + } + + prevpage = bt->page_no; + prevlatch = bt->latch; + prevmode = mode; + + // find key on page at this level + // and descend to requested level + + if( !bt->page->kill ) + if( slot = bt_findslot (bt, key, len) ) { + if( drill == lvl ) + return slot; + + while( slotptr(bt->page, slot)->dead ) + if( slot++ < bt->page->cnt ) + continue; + else + goto slideright; + + page_no = bt_getid(slotptr(bt->page, slot)->id); + drill--; + continue; + } + + // or slide right into next page + +slideright: + page_no = bt_getid(bt->page->right); + + } while( page_no ); + + // return error on end of right chain + + bt->err = BTERR_eof; + return 0; // return error +} + +// a fence key was deleted from a page +// push new fence value upwards + +BTERR bt_fixfence (BtDb *bt, uid page_no, uint lvl) +{ +unsigned char leftkey[256], rightkey[256]; +BtLatchSet *latch = bt->latch; +BtKey ptr; + + // remove deleted key, the old fence value + + ptr = keyptr(bt->page, bt->page->cnt); + memcpy(rightkey, ptr, ptr->len + 1); + + memset (slotptr(bt->page, bt->page->cnt--), 0, sizeof(BtSlot)); + bt->page->dirty = 1; + + ptr = keyptr(bt->page, bt->page->cnt); + memcpy(leftkey, ptr, ptr->len + 1); + + if( bt_update (bt, bt->page, page_no) ) + return bt->err; + + bt_lockpage (BtLockParent, latch); + bt_unlockpage (BtLockWrite, latch); + + // insert new (now smaller) fence key + + if( bt_insertkey (bt, leftkey+1, *leftkey, lvl + 1, page_no, time(NULL)) ) + return bt->err; + + // remove old (larger) fence key + + if( bt_deletekey (bt, rightkey+1, *rightkey, lvl + 1) ) + return bt->err; + + bt_unlockpage (BtLockParent, latch); + bt_unpinlatch (latch); + return 0; +} + +// root has a single child +// collapse a level from the btree +// call with root locked in bt->page + +BTERR bt_collapseroot (BtDb *bt, BtPage root) +{ +BtLatchSet *latch; +uid child; +uint idx; + + // find the child entry + // and promote to new root + + do { + for( idx = 0; idx++ < root->cnt; ) + if( !slotptr(root, idx)->dead ) + break; + + child = bt_getid (slotptr(root, idx)->id); + latch = bt_pinlatch (bt, child); + + bt_lockpage (BtLockDelete, latch); + bt_lockpage (BtLockWrite, latch); + + if( bt_mappage (bt, &bt->temp, child) ) + return bt->err; + + memcpy (root, bt->temp, bt->page_size); + + if( bt_update (bt, root, ROOT_page) ) + return bt->err; + + if( bt_freepage (bt, child, bt->temp, latch) ) + return bt->err; + + } while( root->lvl > 1 && root->act == 1 ); + + bt_unlockpage (BtLockWrite, bt->latch); + bt_unpinlatch (bt->latch); + return 0; +} + +// 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, dirty = 0, idx, fence, found; +BtLatchSet *latch, *rlatch; +uid page_no, right; +BtKey ptr; + + if( slot = bt_loadpage (bt, key, len, lvl, BtLockWrite) ) + ptr = keyptr(bt->page, slot); + else + return bt->err; + + // are we deleting a fence slot? + + fence = slot == bt->page->cnt; + + // if key is found delete it, otherwise ignore request + + if( found = !keycmp (ptr, key, len) ) + if( found = slotptr(bt->page, slot)->dead == 0 ) { + dirty = slotptr(bt->page,slot)->dead = 1; + bt->page->dirty = 1; + bt->page->act--; + + // collapse empty slots + + while( idx = bt->page->cnt - 1 ) + if( slotptr(bt->page, idx)->dead ) { + *slotptr(bt->page, idx) = *slotptr(bt->page, idx + 1); + memset (slotptr(bt->page, bt->page->cnt--), 0, sizeof(BtSlot)); + } else + break; + } + + right = bt_getid(bt->page->right); + page_no = bt->page_no; + latch = bt->latch; + + if( !dirty ) { + if( lvl ) + return bt_abort (bt, bt->page, page_no, BTERR_notfound); + bt_unlockpage(BtLockWrite, latch); + bt_unpinlatch (latch); + return bt->found = found, 0; + } + + // did we delete a fence key in an upper level? + + if( lvl && bt->page->act && fence ) + if( bt_fixfence (bt, page_no, lvl) ) + return bt->err; + else + return bt->found = found, 0; + + // is this a collapsed root? + + if( lvl > 1 && page_no == ROOT_page && bt->page->act == 1 ) + if( bt_collapseroot (bt, bt->page) ) + return bt->err; + else + return bt->found = found, 0; + + // return if page is not empty + + if( bt->page->act ) { + if( bt_update(bt, bt->page, page_no) ) + return bt->err; + bt_unlockpage(BtLockWrite, latch); + bt_unpinlatch (latch); + return bt->found = found, 0; + } + + // cache copy of fence key + // in order to find parent + + ptr = keyptr(bt->page, bt->page->cnt); + memcpy(lowerkey, ptr, ptr->len + 1); + + // obtain lock on right page + + rlatch = bt_pinlatch (bt, right); + bt_lockpage(BtLockWrite, rlatch); + + if( bt_mappage (bt, &bt->temp, right) ) + return bt->err; + + if( bt->temp->kill ) { + bt_abort(bt, bt->temp, right, 0); + return bt_abort(bt, bt->page, bt->page_no, BTERR_kill); + } + + // 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; + + if( bt_update(bt, bt->page, page_no) ) + return bt->err; + + if( bt_update(bt, bt->temp, right) ) + return bt->err; + + bt_lockpage(BtLockParent, latch); + bt_unlockpage(BtLockWrite, latch); + + bt_lockpage(BtLockParent, rlatch); + bt_unlockpage(BtLockWrite, rlatch); + + // redirect higher key directly to consolidated node + + if( bt_insertkey (bt, higherkey+1, *higherkey, lvl+1, page_no, time(NULL)) ) + return bt->err; + + // delete old lower key to consolidated node + + if( bt_deletekey (bt, lowerkey + 1, *lowerkey, lvl + 1) ) + return bt->err; + + // obtain write & delete lock on deleted node + // add right block to free chain + + bt_lockpage(BtLockDelete, rlatch); + bt_lockpage(BtLockWrite, rlatch); + bt_unlockpage(BtLockParent, rlatch); + + if( bt_freepage (bt, right, bt->temp, rlatch) ) + return bt->err; + + bt_unlockpage(BtLockParent, latch); + bt_unpinlatch(latch); + 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; + + bt_unlockpage (BtLockRead, bt->latch); + bt_unpinlatch (bt->latch); + return id; +} + +// check page for space available, +// clean if necessary and return +// 0 - page needs splitting +// >0 - go ahead with new slot + +uint bt_cleanpage(BtDb *bt, uint amt, uint slot) +{ +uint nxt = bt->page_size; +BtPage page = bt->page; +uint cnt = 0, idx = 0; +uint max = page->cnt; +uint newslot = slot; +BtKey key; +int ret; + + if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 ) + return slot; + + // skip cleanup if nothing to reclaim + + if( !page->dirty ) + return 0; + + memcpy (bt->frame, page, bt->page_size); + + // skip page info and set rest of page to zero + + memset (page+1, 0, bt->page_size - sizeof(*page)); + page->act = 0; + + while( cnt++ < max ) { + if( cnt == slot ) + newslot = idx + 1; + // always leave fence key in list + if( cnt < max && slotptr(bt->frame,cnt)->dead ) + continue; + + // copy key + key = keyptr(bt->frame, cnt); + nxt -= key->len + 1; + memcpy ((unsigned char *)page + nxt, key, key->len + 1); + + // copy slot + memcpy(slotptr(page, ++idx)->id, slotptr(bt->frame, cnt)->id, BtId); + if( !(slotptr(page, idx)->dead = slotptr(bt->frame, cnt)->dead) ) + page->act++; + slotptr(page, idx)->tod = slotptr(bt->frame, cnt)->tod; + slotptr(page, idx)->off = nxt; + } + + page->min = nxt; + page->cnt = idx; + + if( page->min >= (max+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 ) + return newslot; + + return 0; +} + +// split the root and raise the height of the btree + +BTERR bt_splitroot(BtDb *bt, unsigned char *leftkey, uid page_no2) +{ +uint nxt = bt->page_size; +BtPage root = bt->page; +uid right; + + // Obtain an empty page to use, and copy the current + // root contents into it + + if( !(right = 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 -= *leftkey + 1; + memcpy ((unsigned char *)root + nxt, leftkey, *leftkey + 1); + bt_putid(slotptr(root, 1)->id, right); + slotptr(root, 1)->off = nxt; + + // insert second key on newroot page + // and increase the root height + + nxt -= 3; + ((unsigned char *)root)[nxt] = 2; + ((unsigned char *)root)[nxt+1] = 0xff; + ((unsigned char *)root)[nxt+2] = 0xff; + 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; + + bt_unlockpage(BtLockWrite, bt->latch); + bt_unpinlatch(bt->latch); + return 0; +} + +// split already locked full node +// return unlocked. + +BTERR bt_splitpage (BtDb *bt) +{ +uint cnt = 0, idx = 0, max, nxt = bt->page_size; +unsigned char fencekey[256], rightkey[256]; +uid page_no = bt->page_no, right; +BtLatchSet *latch, *rlatch; +BtPage page = bt->page; +uint lvl = page->lvl; +BtKey key; + + latch = bt->latch; + + // split higher half of keys to bt->frame + // the last key (fence key) might be dead + + memset (bt->frame, 0, bt->page_size); + max = 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 fence key for new right page + + memcpy (rightkey, 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 ) + memcpy (bt->frame->right, page->right, BtId); + + // get new free page and write frame to it. + + if( !(right = 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->dirty = 0; + 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 smaller page + + memcpy (fencekey, key, key->len + 1); + + bt_putid(page->right, right); + page->min = nxt; + page->cnt = idx; + + // if current page is the root page, split it + + if( page_no == ROOT_page ) + return bt_splitroot (bt, fencekey, right); + + // lock right page + + rlatch = bt_pinlatch (bt, right); + bt_lockpage (BtLockParent, rlatch); + + // update left (containing) node + + if( bt_update(bt, page, page_no) ) + return bt->err; + + bt_lockpage (BtLockParent, latch); + bt_unlockpage (BtLockWrite, latch); + + // insert new fence for reformulated left block + + if( bt_insertkey (bt, fencekey+1, *fencekey, lvl+1, page_no, time(NULL)) ) + return bt->err; + + // switch fence for right block of larger keys to new right page + + if( bt_insertkey (bt, rightkey+1, *rightkey, lvl+1, right, time(NULL)) ) + return bt->err; + + bt_unlockpage (BtLockParent, latch); + bt_unlockpage (BtLockParent, rlatch); + + bt_unpinlatch (rlatch); + bt_unpinlatch (latch); + return 0; +} + +// Insert new key into the btree at requested level. +// Pages are unlocked at exit. + +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) ) { + if( slotptr(page, slot)->dead ) + page->act++; + 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; + bt_unlockpage(BtLockWrite, bt->latch); + bt_unpinlatch (bt->latch); + return 0; + } + + // check if page has enough space + + if( slot = bt_cleanpage (bt, len, slot) ) + break; + + if( bt_splitpage (bt) ) + return bt->err; + } + + // calculate next available slot and copy key into page + + page->min -= len + 1; // reset lowest used offset + ((unsigned char *)page)[page->min] = len; + memcpy ((unsigned char *)page + page->min +1, key, len ); + + for( idx = slot; idx < page->cnt; idx++ ) + if( slotptr(page, idx)->dead ) + break; + + // now insert key into array before slot + // preserving the fence slot + + if( idx == page->cnt ) + idx++, page->cnt++; + + page->act++; + + while( idx > slot ) + *slotptr(page, idx) = *slotptr(page, idx -1), idx--; + + bt_putid(slotptr(page,slot)->id, id); + slotptr(page, slot)->off = page->min; + slotptr(page, slot)->tod = tod; + slotptr(page, slot)->dead = 0; + + if( bt_update(bt, bt->page, bt->page_no) ) + return bt->err; + + bt_unlockpage(BtLockWrite, bt->latch); + bt_unpinlatch(bt->latch); + return 0; +} + +// 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); + else + return 0; + + bt_unlockpage(BtLockRead, bt->latch); + bt->cursor_page = bt->page_no; + bt_unpinlatch (bt->latch); + return slot; +} + +// return next slot for cursor page +// or slide cursor right into next page + +uint bt_nextkey (BtDb *bt, uint slot) +{ +BtLatchSet *latch; +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; + latch = bt_pinlatch (bt, right); + bt_lockpage(BtLockRead, latch); + + if( bt_mappage (bt, &bt->page, right) ) + return 0; + + memcpy (bt->cursor, bt->page, bt->page_size); + bt_unlockpage(BtLockRead, latch); + bt_unpinlatch (latch); + 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 + +uint bt_audit (BtDb *bt) +{ +ushort idx, hashidx; +uid next, page_no; +BtLatchSet *latch; +uint cnt = 0; +BtKey ptr; + +#ifdef unix + if( *(uint *)(bt->latchmgr->lock) ) + fprintf(stderr, "Alloc page locked\n"); + *(uint *)(bt->latchmgr->lock) = 0; + + for( idx = 1; idx < bt->latchmgr->latchdeployed; idx++ ) { + latch = bt->latchsets + idx; + if( *(uint *)latch->readwr ) + fprintf(stderr, "latchset %d rwlocked for page %.8x\n", idx, latch->page_no); + *(uint *)latch->readwr = 0; + + if( *(uint *)latch->access ) + fprintf(stderr, "latchset %d accesslocked for page %.8x\n", idx, latch->page_no); + *(uint *)latch->access = 0; + + if( *(uint *)latch->parent ) + fprintf(stderr, "latchset %d parentlocked for page %.8x\n", idx, latch->page_no); + *(uint *)latch->parent = 0; + + if( latch->pin ) { + fprintf(stderr, "latchset %d pinned for page %.8x\n", idx, latch->page_no); + latch->pin = 0; + } + } + + for( hashidx = 0; hashidx < bt->latchmgr->latchhash; hashidx++ ) { + if( *(uint *)(bt->latchmgr->table[hashidx].latch) ) + fprintf(stderr, "hash entry %d locked\n", hashidx); + + *(uint *)(bt->latchmgr->table[hashidx].latch) = 0; + + if( idx = bt->latchmgr->table[hashidx].slot ) do { + latch = bt->latchsets + idx; + if( *(uint *)latch->busy ) + fprintf(stderr, "latchset %d busylocked for page %.8x\n", idx, latch->page_no); + *(uint *)latch->busy = 0; + if( latch->hash != hashidx ) + fprintf(stderr, "latchset %d wrong hashidx\n", idx); + if( latch->pin ) + fprintf(stderr, "latchset %d pinned for page %.8x\n", idx, latch->page_no); + } while( idx = latch->next ); + } + + next = bt->latchmgr->nlatchpage + LATCH_page; + page_no = LEAF_page; + + while( page_no < bt_getid(bt->latchmgr->alloc->right) ) { + pread (bt->idx, bt->frame, bt->page_size, page_no << bt->page_bits); + if( !bt->frame->free ) { + for( idx = 0; idx++ < bt->frame->cnt - 1; ) { + ptr = keyptr(bt->frame, idx+1); + if( keycmp (keyptr(bt->frame, idx), ptr->key, ptr->len) >= 0 ) + fprintf(stderr, "page %.8x idx %.2x out of order\n", page_no, idx); + } + if( !bt->frame->lvl ) + cnt += bt->frame->act; + } + + if( page_no > LEAF_page ) + next = page_no + 1; + page_no = next; + } + return cnt - 1; +#endif +} + +#ifndef unix +double getCpuTime(int type) +{ +FILETIME crtime[1]; +FILETIME xittime[1]; +FILETIME systime[1]; +FILETIME usrtime[1]; +SYSTEMTIME timeconv[1]; +double ans = 0; + + memset (timeconv, 0, sizeof(SYSTEMTIME)); + + switch( type ) { + case 0: + GetSystemTimeAsFileTime (xittime); + FileTimeToSystemTime (xittime, timeconv); + ans = (double)timeconv->wDayOfWeek * 3600 * 24; + break; + case 1: + GetProcessTimes (GetCurrentProcess(), crtime, xittime, systime, usrtime); + FileTimeToSystemTime (usrtime, timeconv); + break; + case 2: + GetProcessTimes (GetCurrentProcess(), crtime, xittime, systime, usrtime); + FileTimeToSystemTime (systime, timeconv); + break; + } + + ans += (double)timeconv->wHour * 3600; + ans += (double)timeconv->wMinute * 60; + ans += (double)timeconv->wSecond; + ans += (double)timeconv->wMilliseconds / 1000; + return ans; +} +#else +#include +#include + +double getCpuTime(int type) +{ +struct rusage used[1]; +struct timeval tv[1]; + + switch( type ) { + case 0: + gettimeofday(tv, NULL); + return (double)tv->tv_sec + (double)tv->tv_usec / 1000000; + + case 1: + getrusage(RUSAGE_SELF, used); + return (double)used->ru_utime.tv_sec + (double)used->ru_utime.tv_usec / 1000000; + + case 2: + getrusage(RUSAGE_SELF, used); + return (double)used->ru_stime.tv_sec + (double)used->ru_stime.tv_usec / 1000000; + } + + return 0; +} +#endif + +// 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 ch, cnt = 0, bits = 12; +unsigned char key[256]; +double done, start; +uid next, page_no; +uint pgblk = 0; +float elapsed; +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 = getCpuTime(0); + 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, map / 8); + + if( !bt ) { + fprintf(stderr, "Index Open Error %s\n", argv[1]); + exit (1); + } + + switch(argv[3][0]| 0x20) + { + case 'a': + fprintf(stderr, "started audit for %s\n", argv[2]); + cnt = bt_audit (bt); + fprintf(stderr, "finished audit for %s, %d keys\n", argv[2], cnt); + break; + + 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 for %s, %d \n", argv[2], 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 for %s, %d \n", argv[2], 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 for %s, found %d\n", line, argv[2], found); + break; + + case 's': + scan++; + + case 'c': + cnt = 0; + + fprintf(stderr, "started reading\n"); + + next = bt->latchmgr->nlatchpage + LATCH_page; + page_no = LEAF_page; + + while( page_no < bt_getid(bt->latchmgr->alloc->right) ) { + uid off = page_no << bt->page_bits; +#ifdef unix + pread (bt->idx, bt->frame, bt->page_size, off); +#else + DWORD amt[1]; + + SetFilePointer (bt->idx, (long)off, (long*)(&off)+1, FILE_BEGIN); + + if( !ReadFile(bt->idx, bt->frame, bt->page_size, amt, NULL)) + return bt->err = BTERR_map; + + if( *amt < bt->page_size ) + return bt->err = BTERR_map; +#endif + if( !bt->frame->free && !bt->frame->lvl ) + cnt += bt->frame->act; + if( page_no > LEAF_page ) + next = page_no + 1; + page_no = next; + } + + cnt--; // remove stopper key + fprintf(stderr, " Total keys read %d\n", cnt); + break; + } + + done = getCpuTime(0); + elapsed = (float)(done - start); + fprintf(stderr, " real %dm%.3fs\n", (int)(elapsed/60), elapsed - (int)(elapsed/60)*60); + elapsed = getCpuTime(1); + fprintf(stderr, " user %dm%.3fs\n", (int)(elapsed/60), elapsed - (int)(elapsed/60)*60); + elapsed = getCpuTime(2); + fprintf(stderr, " sys %dm%.3fs\n", (int)(elapsed/60), elapsed - (int)(elapsed/60)*60); + return 0; +} + +#endif //STANDALONE -- 2.40.0