From: unknown Date: Mon, 13 Jan 2014 21:50:01 +0000 (-0800) Subject: new linux futex calls to manage contention X-Git-Url: https://pd.if.org/git/?p=btree;a=commitdiff_plain;h=52f68bc6737d5afee8a12dbba7cece08f115547e new linux futex calls to manage contention --- diff --git a/fosterbtreee.c b/fosterbtreee.c index c9c4ffa..8d18fed 100644 --- a/fosterbtreee.c +++ b/fosterbtreee.c @@ -234,7 +234,7 @@ typedef struct { BtLatchMgr *latchmgr; // mapped latch page from allocation page BtLatchSet *latchset; // first mapped latch set from latch pages #ifndef unix - HANDLE halloc, hlatch; // allocation and latch table handles + HANDLE halloc; // allocation and latch table handle #endif } BtMgr; @@ -363,20 +363,27 @@ ushort prev; do { #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, Mutex); - while( prev & Mutex ); + while( __sync_fetch_and_or((ushort *)latch, Mutex) & Mutex ) + sched_yield(); #else - do prev = _InterlockedOr16((ushort *)latch, Mutex); - while( prev & Mutex ); + while( _InterlockedOr16((ushort *)latch, Mutex) & Mutex ) + SwitchToThread(); #endif - // see if exclusive request is pending, or granted + // see if exclusive request is granted or pending if( prev = !(latch->exclusive | latch->pending) ) - latch->share++; - - latch->mutex = 0; +#ifdef unix + __sync_fetch_and_add((ushort *)latch, Share); +#else + _InterlockedExchangeAdd16 ((ushort *)latch, Share); +#endif +#ifdef unix + __sync_fetch_and_and ((ushort *)latch, ~Mutex); +#else + _InterlockedAnd16((ushort *)latch, ~Mutex); +#endif if( prev ) return; #ifdef unix @@ -394,17 +401,24 @@ ushort prev; do { #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, (Pending | Mutex)); - while( prev & Mutex ); + while( __sync_fetch_and_or((ushort *)latch, Mutex | Pending) & Mutex ) + sched_yield(); #else - do prev = _InterlockedOr16((ushort *)latch, (Pending | Mutex)); - while( prev & Mutex ); + while( _InterlockedOr16((ushort *)latch, Mutex | Pending) & Mutex ) + SwitchToThread(); #endif if( prev = !(latch->share | latch->exclusive) ) - latch->exclusive = 1, latch->pending = 0; - - latch->mutex = 0; +#ifdef unix + __sync_fetch_and_or((ushort *)latch, Write); +#else + _InterlockedOr16((ushort *)latch, Write); +#endif +#ifdef unix + __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending)); +#else + _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending)); +#endif if( prev ) return; #ifdef unix @@ -425,18 +439,26 @@ int bt_spinwritetry(BtSpinLatch *latch) ushort prev; #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, Mutex); - while( prev & Mutex ); + if( prev = __sync_fetch_and_or((ushort *)latch, Mutex), prev & Mutex ) + return 0; #else - do prev = _InterlockedOr16((ushort *)latch, Mutex); - while( prev & Mutex ); + if( prev = _InterlockedOr16((ushort *)latch, Mutex), prev & Mutex ) + return 0; #endif // take write access if all bits are clear if( !prev ) - latch->exclusive = 1; +#ifdef unix + __sync_fetch_and_or ((ushort *)latch, Write); +#else + _InterlockedOr16((ushort *)latch, Write); +#endif - latch->mutex = 0; +#ifdef unix + __sync_fetch_and_and ((ushort *)latch, ~Mutex); +#else + _InterlockedAnd16((ushort *)latch, ~Mutex); +#endif return !prev; } @@ -444,36 +466,22 @@ ushort prev; void bt_spinreleasewrite(BtSpinLatch *latch) { -ushort prev; - #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, Mutex); - while( prev & Mutex ); + __sync_fetch_and_and ((ushort *)latch, ~Write); #else - do prev = _InterlockedOr16((ushort *)latch, Mutex); - while( prev & Mutex ); + _InterlockedAnd16((ushort *)latch, ~Write); #endif - - latch->exclusive = 0; - latch->mutex = 0; } // decrement reader count void bt_spinreleaseread(BtSpinLatch *latch) { -ushort prev; - #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, Mutex); - while( prev & Mutex ); + __sync_fetch_and_add((ushort *)latch, -Share); #else - do prev = _InterlockedOr16((ushort *)latch, Mutex); - while( prev & Mutex ); + _InterlockedExchangeAdd16 ((ushort *)latch, -Share); #endif - - latch->share--; - latch->mutex = 0; } void bt_initlockset (BtLatchSet *set) @@ -944,23 +952,16 @@ mgrlatch: return bt_mgrclose (mgr), NULL; #else flag = ( mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE ); - mgr->halloc = CreateFileMapping(mgr->idx, NULL, flag, 0, mgr->page_size, NULL); + mgr->halloc = CreateFileMapping(mgr->idx, NULL, flag, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size, NULL); if( !mgr->halloc ) return bt_mgrclose (mgr), NULL; flag = ( mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE ); - mgr->latchmgr = MapViewOfFile(mgr->halloc, flag, 0, ALLOC_page * mgr->page_size, mgr->page_size); + mgr->latchmgr = MapViewOfFile(mgr->halloc, flag, 0, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size); if( !mgr->latchmgr ) - return bt_mgrclose (mgr), NULL; - flag = ( mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE ); - mgr->hlatch = CreateFileMapping(mgr->idx, NULL, flag, 0, (mgr->latchmgr->nlatchpage + LATCH_page) * mgr->page_size, NULL); - if( !mgr->hlatch ) - return bt_mgrclose (mgr), NULL; + return GetLastError(), bt_mgrclose (mgr), NULL; - flag = ( mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE ); - mgr->latchset = MapViewOfFile(mgr->halloc, flag, 0, LATCH_page * mgr->page_size, mgr->page_size * mgr->latchmgr->nlatchpage); - if( !mgr->latchmgr ) - return bt_mgrclose (mgr), NULL; + mgr->latchset = (void *)((char *)mgr->latchmgr + LATCH_page * mgr->page_size); #endif #ifdef unix diff --git a/fosterbtreef.c b/fosterbtreef.c index 5182bff..2b3eecb 100644 --- a/fosterbtreef.c +++ b/fosterbtreef.c @@ -223,7 +223,7 @@ typedef struct { BtLatchMgr *latchmgr; // mapped latch page from allocation page BtLatchSet *latchset; // first mapped latch set from latch pages #ifndef unix - HANDLE halloc, hlatch; // allocation and latch table handles + HANDLE halloc; // allocation and latch table #endif } BtMgr; @@ -352,19 +352,27 @@ ushort prev; do { #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, Mutex); - while( prev & Mutex ); + while( __sync_fetch_and_or((ushort *)latch, Mutex) & Mutex ) + sched_yield(); #else - do prev = _InterlockedOr16((ushort *)latch, Mutex); - while( prev & Mutex ); + while( _InterlockedOr16((ushort *)latch, Mutex) & Mutex ) + SwitchToThread(); #endif - // see if exclusive request is pending, or granted + // see if exclusive request is granted or pending if( prev = !(latch->exclusive | latch->pending) ) - latch->share++; +#ifdef unix + __sync_fetch_and_add((ushort *)latch, Share); +#else + _InterlockedExchangeAdd16 ((ushort *)latch, Share); +#endif - latch->mutex = 0; +#ifdef unix + __sync_fetch_and_and ((ushort *)latch, ~Mutex); +#else + _InterlockedAnd16((ushort *)latch, ~Mutex); +#endif if( prev ) return; @@ -383,17 +391,24 @@ ushort prev; do { #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, (Pending | Mutex)); - while( prev & Mutex ); + while( __sync_fetch_and_or((ushort *)latch, Mutex | Pending) & Mutex ) + sched_yield(); #else - do prev = _InterlockedOr16((ushort *)latch, (Pending | Mutex)); - while( prev & Mutex ); + while( _InterlockedOr16((ushort *)latch, Mutex | Pending) & Mutex ) + SwitchToThread(); #endif if( prev = !(latch->share | latch->exclusive) ) - latch->exclusive = 1, latch->pending = 0; - - latch->mutex = 0; +#ifdef unix + __sync_fetch_and_or((ushort *)latch, Write); +#else + _InterlockedOr16((ushort *)latch, Write); +#endif +#ifdef unix + __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending)); +#else + _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending)); +#endif if( prev ) return; #ifdef unix @@ -414,18 +429,26 @@ int bt_spinwritetry(BtSpinLatch *latch) ushort prev; #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, Mutex); - while( prev & Mutex ); + if( prev = __sync_fetch_and_or((ushort *)latch, Mutex), prev & Mutex ) + return 0; #else - do prev = _InterlockedOr16((ushort *)latch, Mutex); - while( prev & Mutex ); + if( prev = _InterlockedOr16((ushort *)latch, Mutex), prev & Mutex ) + return 0; #endif // take write access if all bits are clear if( !prev ) - latch->exclusive = 1; +#ifdef unix + __sync_fetch_and_or ((ushort *)latch, Write); +#else + _InterlockedOr16((ushort *)latch, Write); +#endif - latch->mutex = 0; +#ifdef unix + __sync_fetch_and_and ((ushort *)latch, ~Mutex); +#else + _InterlockedAnd16((ushort *)latch, ~Mutex); +#endif return !prev; } @@ -433,36 +456,22 @@ ushort prev; void bt_spinreleasewrite(BtSpinLatch *latch) { -ushort prev; - #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, Mutex); - while( prev & Mutex ); + __sync_fetch_and_and ((ushort *)latch, ~Write); #else - do prev = _InterlockedOr16((ushort *)latch, Mutex); - while( prev & Mutex ); + _InterlockedAnd16((ushort *)latch, ~Write); #endif - - latch->exclusive = 0; - latch->mutex = 0; } // decrement reader count void bt_spinreleaseread(BtSpinLatch *latch) { -ushort prev; - #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, Mutex); - while( prev & Mutex ); + __sync_fetch_and_add((ushort *)latch, -Share); #else - do prev = _InterlockedOr16((ushort *)latch, Mutex); - while( prev & Mutex ); + _InterlockedExchangeAdd16 ((ushort *)latch, -Share); #endif - - latch->share--; - latch->mutex = 0; } // link latch table entry into latch hash table @@ -908,23 +917,16 @@ mgrlatch: return bt_mgrclose (mgr), NULL; #else flag = ( mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE ); - mgr->halloc = CreateFileMapping(mgr->idx, NULL, flag, 0, mgr->page_size, NULL); + mgr->halloc = CreateFileMapping(mgr->idx, NULL, flag, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size, NULL); if( !mgr->halloc ) return bt_mgrclose (mgr), NULL; flag = ( mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE ); - mgr->latchmgr = MapViewOfFile(mgr->halloc, flag, 0, ALLOC_page * mgr->page_size, mgr->page_size); + mgr->latchmgr = MapViewOfFile(mgr->halloc, flag, 0, 0, (BT_latchtable / (mgr->page_size / sizeof(BtLatchSet)) + 1 + LATCH_page) * mgr->page_size); if( !mgr->latchmgr ) - return bt_mgrclose (mgr), NULL; - flag = ( mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE ); - mgr->hlatch = CreateFileMapping(mgr->idx, NULL, flag, 0, (mgr->latchmgr->nlatchpage + LATCH_page) * mgr->page_size, NULL); - if( !mgr->hlatch ) - return bt_mgrclose (mgr), NULL; + return GetLastError(), bt_mgrclose (mgr), NULL; - flag = ( mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE ); - mgr->latchset = MapViewOfFile(mgr->halloc, flag, 0, LATCH_page * mgr->page_size, mgr->page_size * mgr->latchmgr->nlatchpage); - if( !mgr->latchmgr ) - return bt_mgrclose (mgr), NULL; + mgr->latchset = (void *)((char *)mgr->latchmgr + LATCH_page * mgr->page_size); #endif #ifdef unix diff --git a/fosterbtreeg.c b/fosterbtreeg.c index 1652450..fdd42be 100644 --- a/fosterbtreeg.c +++ b/fosterbtreeg.c @@ -142,10 +142,10 @@ typedef struct Page { BtSpinLatch readwr[1]; // read/write lock BtSpinLatch access[1]; // access intent lock BtSpinLatch parent[1]; // parent SMO lock + ushort foster; // count of foster children 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; // page size in bits unsigned char lvl:6; // level of page unsigned char kill:1; // page is being deleted @@ -159,7 +159,7 @@ typedef struct { unsigned long long int lru; // number of times accessed uid basepage; // mapped base page number char *map; // mapped memory pointer - ushort pin; // mapped page pin counter + volatile ushort pin; // mapped page pin counter ushort slot; // slot index in this array void *hashprev; // previous pool entry for the same hash idx void *hashnext; // next pool entry for the same hash idx @@ -181,11 +181,11 @@ typedef struct { #else HANDLE idx; #endif - ushort poolcnt; // highest page pool node in use + volatile ushort poolcnt; // highest page pool node in use + volatile ushort evicted; // last evicted hash table slot ushort poolmax; // highest page pool node allocated ushort poolmask; // total size of pages in mmap segment - 1 ushort hashsize; // size of Hash Table for pool entries - ushort evicted; // last evicted hash table slot ushort *hash; // hash table of pool entries BtPool *pool; // memory pool page segments BtSpinLatch *latch; // latches for pool hash slots @@ -319,19 +319,26 @@ ushort prev; do { #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, Mutex); - while( prev & Mutex ); + while( __sync_fetch_and_or((ushort *)latch, Mutex) & Mutex ) + sched_yield(); #else - do prev = _InterlockedOr16((ushort *)latch, Mutex); - while( prev & Mutex ); + while( _InterlockedOr16((ushort *)latch, Mutex) & Mutex ) + SwitchToThread(); #endif - - // see if exclusive request is pending, or granted + // see if exclusive request is granted or pending if( prev = !(latch->exclusive | latch->pending) ) - latch->share++; +#ifdef unix + __sync_fetch_and_add((ushort *)latch, Share); +#else + _InterlockedExchangeAdd16 ((ushort *)latch, Share); +#endif - latch->mutex = 0; +#ifdef unix + __sync_fetch_and_and ((ushort *)latch, ~Mutex); +#else + _InterlockedAnd16((ushort *)latch, ~Mutex); +#endif if( prev ) return; @@ -350,16 +357,24 @@ ushort prev; do { #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, (Pending | Mutex)); - while( prev & Mutex ); + while( __sync_fetch_and_or((ushort *)latch, Mutex | Pending) & Mutex ) + sched_yield(); #else - do prev = _InterlockedOr16((ushort *)latch, (Pending | Mutex)); - while( prev & Mutex ); + while( _InterlockedOr16((ushort *)latch, Mutex | Pending) & Mutex ) + SwitchToThread(); #endif if( prev = !(latch->share | latch->exclusive) ) - latch->exclusive = 1, latch->pending = 0; +#ifdef unix + __sync_fetch_and_or((ushort *)latch, Write); +#else + _InterlockedOr16((ushort *)latch, Write); +#endif - latch->mutex = 0; +#ifdef unix + __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending)); +#else + _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending)); +#endif if( prev ) return; @@ -381,18 +396,20 @@ int bt_spinwritetry(BtSpinLatch *latch) ushort prev; #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, Mutex); - while( prev & Mutex ); + if( prev = __sync_fetch_and_or((ushort *)latch, Mutex), prev & Mutex ) + return 0; #else - do prev = _InterlockedOr16((ushort *)latch, Mutex); - while( prev & Mutex ); + if( prev = _InterlockedOr16((ushort *)latch, Mutex), prev & Mutex ) + return 0; #endif // take write access if all bits are clear if( !prev ) - latch->exclusive = 1; - - latch->mutex = 0; +#ifdef unix + __sync_fetch_and_or ((ushort *)latch, Write); +#else + _InterlockedOr16((ushort *)latch, Write); +#endif return !prev; } @@ -400,36 +417,22 @@ ushort prev; void bt_spinreleasewrite(BtSpinLatch *latch) { -ushort prev; - #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, Mutex); - while( prev & Mutex ); + __sync_fetch_and_and ((ushort *)latch, ~Write); #else - do prev = _InterlockedOr16((ushort *)latch, Mutex); - while( prev & Mutex ); + _InterlockedAnd16((ushort *)latch, ~Write); #endif - - latch->exclusive = 0; - latch->mutex = 0; } // decrement reader count void bt_spinreleaseread(BtSpinLatch *latch) { -ushort prev; - #ifdef unix - do prev = __sync_fetch_and_or((ushort *)latch, Mutex); - while( prev & Mutex ); + __sync_fetch_and_add((ushort *)latch, -Share); #else - do prev = _InterlockedOr16((ushort *)latch, Mutex); - while( prev & Mutex ); + _InterlockedExchangeAdd16 ((ushort *)latch, -Share); #endif - - latch->share--; - latch->mutex = 0; } void bt_mgrclose (BtMgr *mgr) @@ -1138,11 +1141,12 @@ uid bt_newpage(BtDb *bt, BtPage page) { uid new_page; BtPage pmap; +int subpage; int reuse; - // lock allocation page + // lock page zero - if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) ) + if( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) ) return 0; // use empty chain first @@ -1160,6 +1164,7 @@ int reuse; bt_putid(bt->alloc->right, new_page+1); reuse = 0; } + #ifdef unix memset(bt->zero, 0, 3 * sizeof(BtSpinLatch)); // clear locks memcpy((char *)bt->zero + 3 * sizeof(BtSpinLatch), (char *)page + 3 * sizeof(BtSpinLatch), bt->mgr->page_size - 3 * sizeof(BtSpinLatch)); @@ -1182,7 +1187,9 @@ int reuse; if( bt_lockpage(bt, new_page, BtLockWrite, &pmap) ) return 0; - memcpy(pmap, page, bt->mgr->page_size); + // copy source page, but leave latch area intact + + memcpy((char *)pmap + 3 * sizeof(BtSpinLatch), (char *)page + 3 * sizeof(BtSpinLatch), bt->mgr->page_size - 3 * sizeof(BtSpinLatch)); if( bt_unlockpage (bt, new_page, BtLockWrite) ) return 0; diff --git a/threads2h.c b/threads2h.c index 1b4d630..2c4deaa 100644 --- a/threads2h.c +++ b/threads2h.c @@ -86,9 +86,10 @@ typedef enum{ // mode & definition for latch implementation enum { - Write = 1, - Pending = 2, - Share = 4 + Mutex = 1, + Write = 2, + Pending = 4, + Share = 8 } LockMode; // exclusive is set for write access @@ -96,9 +97,10 @@ enum { // grant write lock when share == 0 typedef struct { - volatile uint exclusive:1; - volatile uint request:1; - volatile uint share:30; + volatile ushort mutex:1; + volatile ushort exclusive:1; + volatile ushort pending:1; + volatile ushort share:13; } BtLatch; typedef struct { @@ -594,6 +596,8 @@ BtDb *bt = malloc (sizeof(*bt)); bt->frame = (BtPage)bt->mem; bt->zero = (BtPage)(bt->mem + 1 * mgr->page_size); bt->cursor = (BtPage)(bt->mem + 2 * mgr->page_size); + + memset (bt->zero, 0, mgr->page_size); return bt; } @@ -623,89 +627,75 @@ int ans; void bt_readlock(BtLatch *latch) { +ushort prev; + do { - // see if exclusive request is pending, or granted + // obtain latch mutex +#ifdef unix + if( __sync_fetch_and_or((ushort *)latch, Mutex) & Mutex ) + continue; +#else + if( prev = _InterlockedOr16((ushort *)latch, Mutex) & Mutex ) + continue; +#endif + // see if exclusive request is granted or pending - if( !(volatile int)latch->request && !(volatile int)latch->exclusive ) { - // add one to counter, check write bit + if( prev = !(latch->exclusive | latch->pending) ) #ifdef unix - if( ~__sync_fetch_and_add((volatile int *)latch, Share) & Write ) - return; + __sync_fetch_and_add((ushort *)latch, Share); #else - if( ~_InterlockedExchangeAdd((volatile int *)latch, Share) & Write ) - return; + _InterlockedExchangeAdd16 ((ushort *)latch, Share); #endif - // didn't get latch, reduce counter by one #ifdef unix - __sync_fetch_and_add((volatile int *)latch, -Share); + __sync_fetch_and_and ((ushort *)latch, ~Mutex); #else - _InterlockedExchangeAdd ((volatile int *)latch, -Share); + _InterlockedAnd16((ushort *)latch, ~Mutex); #endif - } - // and yield + if( prev ) + return; #ifdef unix - sched_yield(); + } while( sched_yield(), 1 ); #else - SwitchToThread(); + } while( SwitchToThread(), 1 ); #endif - } while( 1 ); } // wait for other read and write latches to relinquish void bt_writelock(BtLatch *latch) { -int prev; +ushort prev; do { - // set exclusive access pending - -#ifdef unix - __sync_fetch_and_or((int *)latch, Pending); +#ifdef unix + if( __sync_fetch_and_or((ushort *)latch, Mutex | Pending) & Mutex ) + continue; #else - _InterlockedOr((int *)latch, Pending); + if( _InterlockedOr16((ushort *)latch, Mutex | Pending) & Mutex ) + continue; #endif - - // see if we can get write access - // with no readers + if( prev = !(latch->share | latch->exclusive) ) #ifdef unix - prev = __sync_fetch_and_or((volatile int *)latch, Write); + __sync_fetch_and_or((ushort *)latch, Write); #else - prev = _InterlockedOr((volatile int *)latch, Write); + _InterlockedOr16((ushort *)latch, Write); #endif - // did we get exclusive access? - // if so, clear write pending - - if( !(prev & ~Pending) ) { #ifdef unix - __sync_fetch_and_and((volatile int *)latch, ~Pending); + __sync_fetch_and_and ((ushort *)latch, ~(Mutex | Pending)); #else - _InterlockedAnd((volatile int *)latch, ~Pending); + _InterlockedAnd16((ushort *)latch, ~(Mutex | Pending)); #endif - return; - } - - // reset our Write mode if it was clear before - - if( !(prev & Write) ) { -#ifdef unix - __sync_fetch_and_and((volatile int *)latch, ~Write); -#else - _InterlockedAnd((volatile int *)latch, ~Write); -#endif - } - - // otherwise yield + if( prev ) + return; #ifdef unix - sched_yield(); + } while( sched_yield(), 1 ); #else - SwitchToThread(); + } while( SwitchToThread(), 1 ); #endif - } while( 1 ); } // try to obtain write lock @@ -715,32 +705,30 @@ int prev; int bt_writetry(BtLatch *latch) { -int prev; +ushort prev; - // see if we can get write access - // with no readers #ifdef unix - prev = __sync_fetch_and_or((volatile int *)latch, Write); + if( prev = __sync_fetch_and_or((ushort *)latch, Mutex), prev & Mutex ) + return 0; #else - prev = _InterlockedOr((volatile int *)latch, Write); + if( prev = _InterlockedOr16((ushort *)latch, Mutex), prev & Mutex ) + return 0; #endif + // take write access if all bits are clear - // did we get exclusive access? - // if so, return OK - - if( !(prev & ~Pending) ) - return 1; - - // reset our Write mode if it was clear before + if( !prev ) +#ifdef unix + __sync_fetch_and_or ((ushort *)latch, Write); +#else + _InterlockedOr16((ushort *)latch, Write); +#endif - if( !(prev & Write) ) { #ifdef unix - __sync_fetch_and_and((volatile int *)latch, ~Write); + __sync_fetch_and_and ((ushort *)latch, ~Mutex); #else - _InterlockedAnd((volatile int *)latch, ~Write); + _InterlockedAnd16((ushort *)latch, ~Mutex); #endif - } - return 0; + return !prev; } // clear write mode @@ -748,9 +736,9 @@ int prev; void bt_releasewrite(BtLatch *latch) { #ifdef unix - __sync_fetch_and_and((int *)latch, ~Write); + __sync_fetch_and_and ((ushort *)latch, ~Write); #else - _InterlockedAnd ((int *)latch, ~Write); + _InterlockedAnd16((ushort *)latch, ~Write); #endif } @@ -759,9 +747,9 @@ void bt_releasewrite(BtLatch *latch) void bt_releaseread(BtLatch *latch) { #ifdef unix - __sync_fetch_and_add((int *)latch, -Share); + __sync_fetch_and_add((ushort *)latch, -Share); #else - _InterlockedExchangeAdd((int *)latch, -Share); + _InterlockedExchangeAdd16 ((ushort *)latch, -Share); #endif } @@ -1166,7 +1154,6 @@ BTERR bt_freepage(BtDb *bt, uid page_no) uid bt_newpage(BtDb *bt, BtPage page) { -BtPool *pool; uid new_page; BtPage pmap; int subpage; @@ -1174,7 +1161,7 @@ int reuse; // lock page zero - if ( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) ) + if( bt_lockpage(bt, ALLOC_page, BtLockWrite, &bt->alloc) ) return 0; // use empty chain first @@ -1194,36 +1181,29 @@ int reuse; } #ifdef unix - memset(bt->zero, 0, sizeof(BtLatchSet)); // clear locks - memcpy((char *)bt->zero + sizeof(BtLatchSet), (char *)page + sizeof(BtLatchSet), bt->mgr->page_size - sizeof(BtLatchSet)); + // if writing first page of pool block + // expand file thru last page in the block - if ( pwrite(bt->mgr->idx, bt->zero, bt->mgr->page_size, new_page << bt->mgr->page_bits) < bt->mgr->page_size ) + if( !reuse && (new_page & bt->mgr->poolmask) == 0 ) + if( pwrite(bt->mgr->idx, bt->zero, bt->mgr->page_size, (new_page | bt->mgr->poolmask) << bt->mgr->page_bits) < bt->mgr->page_size ) return bt->err = BTERR_wrt, 0; +#endif + // unlock page allocation page - // if writing first page of pool block, zero last page in the block + if( bt_unlockpage(bt, ALLOC_page, BtLockWrite) ) + return 0; - if ( !reuse && bt->mgr->poolmask > 0 && (new_page & bt->mgr->poolmask) == 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->poolmask) << bt->mgr->page_bits) < bt->mgr->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. + // on Windows, this will extend the file into the new page. if( bt_lockpage(bt, new_page, BtLockWrite, &pmap) ) return 0; - memcpy(pmap, page, bt->mgr->page_size); + // copy source page but leave latch area intact - if( bt_unlockpage (bt, new_page, BtLockWrite) ) - return 0; -#endif - // unlock page allocation page + memcpy((char *)pmap + sizeof(BtLatchSet), (char *)page + sizeof(BtLatchSet), bt->mgr->page_size - sizeof(BtLatchSet)); - if ( bt_unlockpage(bt, ALLOC_page, BtLockWrite) ) + if( bt_unlockpage (bt, new_page, BtLockWrite) ) return 0; return new_page; diff --git a/threads2i.c b/threads2i.c new file mode 100644 index 0000000..25a26fd --- /dev/null +++ b/threads2i.c @@ -0,0 +1,2103 @@ +// btree version threads2i linux futex concurrency version +// 09 JAN 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 +#include +#define SYS_futex 202 +#endif + +#ifdef unix +#include +#include +#include +#include +#include +#include +#include +#include +#include +#else +#define WIN32_LEAN_AND_MEAN +#include +#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; + +// mode & definition for latch implementation + +enum { + Mutex = 1 << 0, // the mutex bit + Write = 1 << 1, // the writers bit + Share = 1 << 2, // reader count + PendRd = 1 << 12, // reader contended count + PendWr = 1 << 22 // writer contended count +} LockMode; + +enum { + QueRd = 1, // reader queue + QueWr = 2 // writer queue +} RWQueue; + +// share is count of read accessors +// grant write lock when share == 0 + +typedef struct { + volatile uint mutex:1; // 1 = busy + volatile uint write:1; // 1 = exclusive + volatile uint share:10; // count of readers holding locks + volatile uint readwait:10; // count of readers waiting + volatile uint writewait:10; // count of writers waiting +} BtLatch; + +typedef struct { + BtLatch readwr[1]; // read/write page lock + BtLatch access[1]; // Access Intent/Page delete + BtLatch parent[1]; // Parent modification +} 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 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 { + BtLatchSet latch[1]; // Set of three latches + 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:6; // level of page + unsigned char kill:1; // page is being deleted + unsigned char dirty:1; // page has deleted keys + unsigned char right[BtId]; // page number to right +} *BtPage; + +// The memory mapping pool 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 slot; // slot index in this array + volatile uint pin; // mapped page pin counter + void *hashprev; // previous pool entry for the same hash idx + void *hashnext; // next pool entry for the same hash idx +#ifndef unix + HANDLE hmap; +#endif +} BtPool; + +// 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 + char *pooladvise; // bit maps for pool page advisements + int idx; +#else + HANDLE idx; +#endif + volatile uint poolcnt; // highest page pool node in use + volatile uint evicted; // last evicted hash table slot + uint poolmax; // highest page pool node allocated + uint poolmask; // total size of pages in mmap segment - 1 + uint hashsize; // size of Hash Table for pool entries + ushort *hash; // pool index for hash entries + BtLatch *latch; // latches for hash table slots + BtPool *pool; // memory pool page segments +} 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 ( mapped to page 0 ) + BtPage cursor; // cached frame for start/next (never mapped) + BtPage frame; // spare frame for the page split (never mapped) + BtPage zero; // page of zeroes to extend the file (never mapped) + BtPage page; // current page mapped from file + 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 poolsize, 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 +#define LEAF_page 2 + +// Number of levels to create in a new BTree + +#define MIN_lvl 2 + +// The page is allocated from low and hi ends. +// The key offsets and row-id's are allocated +// from the bottom, while the text of the key +// is allocated from the top. When the two +// areas meet, the page is split into two. + +// A key consists of a length byte, two bytes of +// index number (0 - 65534), and up to 253 bytes +// of key value. Duplicate keys are discarded. +// Associated with each key is a 48 bit row-id. + +// The b-tree root is always located at page 1. +// The first leaf page of level zero is always +// located on page 2. + +// The b-tree pages are linked with 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 a memory mapped pool. 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) +{ +BtPool *pool; +uint slot; + + // release mapped pages + // note that slot zero is never used + + for( slot = 1; slot < mgr->poolmax; slot++ ) { + pool = mgr->pool + slot; + if( pool->slot ) +#ifdef unix + munmap (pool->map, (mgr->poolmask+1) << mgr->page_bits); +#else + { + FlushViewOfFile(pool->map, 0); + UnmapViewOfFile(pool->map); + CloseHandle(pool->hmap); + } +#endif + } + +#ifdef unix + close (mgr->idx); + free (mgr->pool); + free (mgr->hash); + free (mgr->latch); + free (mgr->pooladvise); + free (mgr); +#else + FlushFileBuffers(mgr->idx); + CloseHandle(mgr->idx); + GlobalFree (mgr->pool); + GlobalFree (mgr->hash); + GlobalFree (mgr->latch); + GlobalFree (mgr); +#endif +} + +// close and release memory + +void bt_close (BtDb *bt) +{ +#ifdef unix + if ( bt->mem ) + free (bt->mem); +#else + if ( bt->mem) + VirtualFree (bt->mem, 0, MEM_RELEASE); +#endif + free (bt); +} + +// open/create new btree buffer manager + +// call with file_name, BT_openmode, bits in page size (e.g. 16), +// size of mapped page pool (e.g. 8192) + +BtMgr *bt_mgr (char *name, uint mode, uint bits, uint poolmax, 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( !poolmax ) + 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->poolmax = poolmax; + mgr->mode = mode; + + if( cacheblk < mgr->page_size ) + cacheblk = mgr->page_size; + + // mask for partial memmaps + + mgr->poolmask = (cacheblk >> bits) - 1; + + // see if requested size of pages per memmap is greater + + if( (1 << segsize) > mgr->poolmask ) + mgr->poolmask = (1 << segsize) - 1; + + mgr->seg_bits = 0; + + while( (1 << mgr->seg_bits) <= mgr->poolmask ) + mgr->seg_bits++; + + mgr->hashsize = hashsize; + +#ifdef unix + mgr->pool = calloc (poolmax, sizeof(BtPool)); + mgr->hash = calloc (hashsize, sizeof(ushort)); + mgr->latch = calloc (hashsize, sizeof(BtLatch)); + mgr->pooladvise = calloc (poolmax, (mgr->poolmask + 8) / 8); +#else + mgr->pool = GlobalAlloc (GMEM_FIXED|GMEM_ZEROINIT, poolmax * sizeof(BtPool)); + mgr->hash = 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 + // segment area (other pages are zeroed by O/S) + + if( mgr->poolmask ) { + memset(alloc, 0, mgr->page_size); + last = mgr->poolmask; + + while( last < MIN_lvl + 1 ) + last += mgr->poolmask + 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); + + memset (bt->zero, 0, 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 + +int sys_futex(void *addr1, int op, int val1, struct timespec *timeout, void *addr2, int val3) +{ + return syscall(SYS_futex, addr1, op, val1, timeout, addr2, val3); +} + +// wait until write lock mode is clear +// and add 1 to the share count + +void bt_readlock(BtLatch *latch, int private) +{ +uint prev; + + if( private ) + private = FUTEX_PRIVATE_FLAG; + + while( 1 ) { + // obtain latch mutex + if( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex ) { + sched_yield(); + continue; + } + + // wait for writers to clear + // increment read waiters and wait + + if( latch->write || latch->writewait ) { + __sync_fetch_and_add ((uint *)latch, PendRd); + prev = __sync_fetch_and_and ((uint *)latch, ~Mutex) & ~Mutex; + sys_futex( (uint *)latch, FUTEX_WAIT_BITSET | private, prev, NULL, NULL, QueRd ); + __sync_fetch_and_sub ((uint *)latch, PendRd); + continue; + } + + // increment reader lock count + // and release latch mutex + + __sync_fetch_and_add ((uint *)latch, Share); + __sync_fetch_and_and ((uint *)latch, ~Mutex); + return; + } +} + +// wait for other read and write latches to relinquish + +void bt_writelock(BtLatch *latch, int private) +{ +uint prev; + + if( private ) + private = FUTEX_PRIVATE_FLAG; + + while( 1 ) { + // obtain latch mutex + if( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex ) { + sched_yield(); + continue; + } + + // wait for write and reader count to clear + + if( latch->write || latch->share ) { + __sync_fetch_and_add ((uint *)latch, PendWr); + prev = __sync_fetch_and_and ((uint *)latch, ~Mutex) & ~Mutex; + sys_futex( (uint *)latch, FUTEX_WAIT_BITSET | private, prev, NULL, NULL, QueWr ); + __sync_fetch_and_sub ((uint *)latch, PendWr); + continue; + } + + // take write mutex + // release latch mutex + + __sync_fetch_and_or ((uint *)latch, Write); + __sync_fetch_and_and ((uint *)latch, ~Mutex); + return; + } +} + +// try to obtain write lock + +// return 1 if obtained, +// 0 otherwise + +int bt_writetry(BtLatch *latch) +{ +int ans; + + // try for mutex, + // abandon request if not taken + + if( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex ) + return 0; + + // see if write mode is available + + if( !latch->write && !latch->share ) { + __sync_fetch_and_or ((uint *)latch, Write); + ans = 1; + } else + ans = 0; + + // release latch mutex + + __sync_fetch_and_and ((uint *)latch, ~Mutex); + return ans; +} + +// clear write lock + +void bt_releasewrite(BtLatch *latch, int private) +{ + if( private ) + private = FUTEX_PRIVATE_FLAG; + + // obtain latch mutex + + while( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex ) + sched_yield(); + + __sync_fetch_and_and ((uint *)latch, ~Write); + + // favor writers + + if( latch->writewait ) + if( sys_futex( (uint *)latch, FUTEX_WAKE_BITSET | private, 1, NULL, NULL, QueWr ) ) + goto wakexit; + + if( latch->readwait ) + sys_futex( (uint *)latch, FUTEX_WAKE_BITSET | private, INT_MAX, NULL, NULL, QueRd ); + + // release latch mutex + +wakexit: + __sync_fetch_and_and ((uint *)latch, ~Mutex); +} + +// decrement reader count + +void bt_releaseread(BtLatch *latch, int private) +{ + if( private ) + private = FUTEX_PRIVATE_FLAG; + + // obtain latch mutex + + while( __sync_fetch_and_or((uint *)latch, Mutex) & Mutex ) + sched_yield(); + + __sync_fetch_and_sub ((uint *)latch, Share); + + // wake waiting writers + + if( !latch->share && latch->writewait ) + sys_futex( (uint *)latch, FUTEX_WAKE_BITSET | private, 1, NULL, NULL, QueWr ); + + // release latch mutex + + __sync_fetch_and_and ((uint *)latch, ~Mutex); +} + +// Buffer Pool mgr + +// find segment in pool +// must be called with hashslot idx locked +// return NULL if not there +// otherwise return node + +BtPool *bt_findpool(BtDb *bt, uid page_no, uint idx) +{ +BtPool *pool; +uint slot; + + // compute start of hash chain in pool + + if( slot = bt->mgr->hash[idx] ) + pool = bt->mgr->pool + slot; + else + return NULL; + + page_no &= ~bt->mgr->poolmask; + + while( pool->basepage != page_no ) + if( pool = pool->hashnext ) + continue; + else + return NULL; + + return pool; +} + +// add segment to hash table + +void bt_linkhash(BtDb *bt, BtPool *pool, uid page_no, int idx) +{ +BtPool *node; +uint slot; + + pool->hashprev = pool->hashnext = NULL; + pool->basepage = page_no & ~bt->mgr->poolmask; + pool->lru = 1; + + if( slot = bt->mgr->hash[idx] ) { + node = bt->mgr->pool + slot; + pool->hashnext = node; + node->hashprev = pool; + } + + bt->mgr->hash[idx] = pool->slot; +} + +// find best segment to evict from buffer pool + +BtPool *bt_findlru (BtDb *bt, uint hashslot) +{ +unsigned long long int target = ~0LL; +BtPool *pool = NULL, *node; + + if( !hashslot ) + return NULL; + + node = bt->mgr->pool + hashslot; + + // scan pool entries under hash table slot + + do { + if( node->pin ) + continue; + if( node->lru > target ) + continue; + target = node->lru; + pool = node; + } while( node = node->hashnext ); + + return pool; +} + +// map new buffer pool segment to virtual memory + +BTERR bt_mapsegment(BtDb *bt, BtPool *pool, uid page_no) +{ +off64_t off = (page_no & ~bt->mgr->poolmask) << bt->mgr->page_bits; +off64_t limit = off + ((bt->mgr->poolmask+1) << bt->mgr->page_bits); +int flag; + +#ifdef unix + flag = PROT_READ | ( bt->mgr->mode == BT_ro ? 0 : PROT_WRITE ); + pool->map = mmap (0, (bt->mgr->poolmask+1) << bt->mgr->page_bits, flag, MAP_SHARED, bt->mgr->idx, off); + if( pool->map == MAP_FAILED ) + return bt->err = BTERR_map; + + // clear out madvise issued bits + memset (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8) / 8), 0, (bt->mgr->poolmask + 8)/8); +#else + flag = ( bt->mgr->mode == BT_ro ? PAGE_READONLY : PAGE_READWRITE ); + pool->hmap = CreateFileMapping(bt->mgr->idx, NULL, flag, (DWORD)(limit >> 32), (DWORD)limit, NULL); + if( !pool->hmap ) + return bt->err = BTERR_map; + + flag = ( bt->mgr->mode == BT_ro ? FILE_MAP_READ : FILE_MAP_WRITE ); + pool->map = MapViewOfFile(pool->hmap, flag, (DWORD)(off >> 32), (DWORD)off, (bt->mgr->poolmask+1) << bt->mgr->page_bits); + if( !pool->map ) + return bt->err = BTERR_map; +#endif + return bt->err = 0; +} + +// find or place requested page in segment-pool +// return pool table entry, incrementing pin + +BtPool *bt_pinpage(BtDb *bt, uid page_no) +{ +BtPool *pool, *node, *next; +uint slot, idx, victim; + + // lock hash table chain + + idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize; + bt_readlock (&bt->mgr->latch[idx], 1); + + // look up in hash table + + if( pool = bt_findpool(bt, page_no, idx) ) { +#ifdef unix + __sync_fetch_and_add(&pool->pin, 1); +#else + _InterlockedIncrement (&pool->pin); +#endif + bt_releaseread (&bt->mgr->latch[idx], 1); + pool->lru++; + return pool; + } + + // upgrade to write lock + + bt_releaseread (&bt->mgr->latch[idx], 1); + bt_writelock (&bt->mgr->latch[idx], 1); + + // try to find page in pool with write lock + + if( pool = bt_findpool(bt, page_no, idx) ) { +#ifdef unix + __sync_fetch_and_add(&pool->pin, 1); +#else + _InterlockedIncrement (&pool->pin); +#endif + bt_releasewrite (&bt->mgr->latch[idx], 1); + pool->lru++; + return pool; + } + + // allocate a new pool node + // and add to hash table + +#ifdef unix + slot = __sync_fetch_and_add(&bt->mgr->poolcnt, 1); +#else + slot = _InterlockedIncrement (&bt->mgr->poolcnt) - 1; +#endif + + if( ++slot < bt->mgr->poolmax ) { + pool = bt->mgr->pool + slot; + pool->slot = slot; + + if( bt_mapsegment(bt, pool, page_no) ) + return NULL; + + bt_linkhash(bt, pool, page_no, idx); +#ifdef unix + __sync_fetch_and_add(&pool->pin, 1); +#else + _InterlockedIncrement (&pool->pin); +#endif + bt_releasewrite (&bt->mgr->latch[idx], 1); + return pool; + } + + // pool table is full + // find best pool entry to evict + +#ifdef unix + __sync_fetch_and_add(&bt->mgr->poolcnt, -1); +#else + _InterlockedDecrement (&bt->mgr->poolcnt); +#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 pool entry is empty + // or any pages are pinned + // skip this entry + + if( !(pool = bt_findlru(bt, bt->mgr->hash[victim])) ) { + bt_releasewrite (&bt->mgr->latch[victim], 1); + continue; + } + + // unlink victim pool node from hash table + + if( node = pool->hashprev ) + node->hashnext = pool->hashnext; + else if( node = pool->hashnext ) + bt->mgr->hash[victim] = node->slot; + else + bt->mgr->hash[victim] = 0; + + if( node = pool->hashnext ) + node->hashprev = pool->hashprev; + + bt_releasewrite (&bt->mgr->latch[victim], 1); + + // remove old file mapping +#ifdef unix + munmap (pool->map, (bt->mgr->poolmask+1) << bt->mgr->page_bits); +#else + FlushViewOfFile(pool->map, 0); + UnmapViewOfFile(pool->map); + CloseHandle(pool->hmap); +#endif + pool->map = NULL; + + // create new pool mapping + // and link into hash table + + if( bt_mapsegment(bt, pool, page_no) ) + return NULL; + + bt_linkhash(bt, pool, page_no, idx); +#ifdef unix + __sync_fetch_and_add(&pool->pin, 1); +#else + _InterlockedIncrement (&pool->pin); +#endif + bt_releasewrite (&bt->mgr->latch[idx], 1); + return pool; + } +} + +// place write, read, or parent lock on requested page_no. +// pin to buffer pool and return page pointer + +BTERR bt_lockpage(BtDb *bt, uid page_no, BtLock mode, BtPage *pageptr) +{ +uint subpage; +BtPool *pool; +BtPage page; + + // find/create maping in pool table + // and pin our pool slot + + if( pool = bt_pinpage(bt, page_no) ) + subpage = (uint)(page_no & bt->mgr->poolmask); // page within mapping + else + return bt->err; + + page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits)); +#ifdef unix + { + uint idx = subpage / 8; + uint bit = subpage % 8; + + if( ~((bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] >> bit) & 1 ) { + madvise (page, bt->mgr->page_size, MADV_WILLNEED); + (bt->mgr->pooladvise + pool->slot * ((bt->mgr->poolmask + 8)/8))[idx] |= 1 << bit; + } + } +#endif + + switch( mode ) { + case BtLockRead: + bt_readlock (page->latch->readwr, 0); + break; + case BtLockWrite: + bt_writelock (page->latch->readwr, 0); + break; + case BtLockAccess: + bt_readlock (page->latch->access, 0); + break; + case BtLockDelete: + bt_writelock (page->latch->access, 0); + break; + case BtLockParent: + bt_writelock (page->latch->parent, 0); + break; + default: + return bt->err = BTERR_lock; + } + + if( pageptr ) + *pageptr = page; + return bt->err = 0; +} + +// remove write, read, or parent lock on requested page + +BTERR bt_unlockpage(BtDb *bt, uid page_no, BtLock mode) +{ +uint subpage, idx; +BtPool *pool; +BtPage page; + + // since page is pinned + // it should still be in the buffer pool + // and is in no danger of being a victim for reuse + + idx = (uint)(page_no >> bt->mgr->seg_bits) % bt->mgr->hashsize; + bt_readlock (&bt->mgr->latch[idx], 1); + + if( pool = bt_findpool(bt, page_no, idx) ) + subpage = (uint)(page_no & bt->mgr->poolmask); + else + return bt->err = BTERR_hash; + + bt_releaseread (&bt->mgr->latch[idx], 1); + page = (BtPage)(pool->map + (subpage << bt->mgr->page_bits)); + + switch( mode ) { + case BtLockRead: + bt_releaseread (page->latch->readwr, 0); + break; + case BtLockWrite: + bt_releasewrite (page->latch->readwr, 0); + break; + case BtLockAccess: + bt_releaseread (page->latch->access, 0); + break; + case BtLockDelete: + bt_releasewrite (page->latch->access, 0); + break; + case BtLockParent: + bt_releasewrite (page->latch->parent, 0); + break; + default: + return bt->err = BTERR_lock; + } + +#ifdef unix + __sync_fetch_and_add(&pool->pin, -1); +#else + _InterlockedDecrement (&pool->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 subpage; +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 writing first page of pool block + // expand file thru last page in the block + + if( !reuse && (new_page & bt->mgr->poolmask) == 0 ) + if( pwrite(bt->mgr->idx, bt->zero, bt->mgr->page_size, (new_page | bt->mgr->poolmask) << bt->mgr->page_bits) < bt->mgr->page_size ) + return bt->err = BTERR_wrt, 0; +#endif + // unlock page allocation page + + if( bt_unlockpage(bt, ALLOC_page, BtLockWrite) ) + return 0; + + // bring new page into pool and copy page. + // on Windows, this will extend the file into the new page. + + if( bt_lockpage(bt, new_page, BtLockWrite, &pmap) ) + return 0; + + // copy source page but leave latch area intact + + memcpy((char *)pmap + sizeof(BtLatchSet), (char *)page + sizeof(BtLatchSet), bt->mgr->page_size - sizeof(BtLatchSet)); + + if( bt_unlockpage (bt, new_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]; +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; + if( slot < bt->page->cnt ) + bt->page->dirty = 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; + + // keep 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((char *)bt->page + sizeof(BtLatchSet), (char *)bt->temp + sizeof(BtLatchSet), bt->mgr->page_size - sizeof(BtLatchSet)); + + // keep 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; +} + +// check page for space available, +// clean if necessary and return +// 0 - page needs splitting +// 1 - go ahead + +uint bt_cleanpage(BtDb *bt, uint amt) +{ +uint nxt = bt->mgr->page_size; +BtPage page = bt->page; +uint cnt = 0, idx = 0; +uint max = page->cnt; +BtKey key; + + if( page->min >= (page->cnt+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 ) + return 1; + + // skip cleanup if nothing to reclaim + + if( !page->dirty ) + return 0; + + 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->dirty = 0; + page->act = 0; + + 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; + + if( page->min >= (page->cnt+1) * sizeof(BtSlot) + sizeof(*page) + amt + 1 ) + return 1; + + return 0; +} + +// split the root and raise the height of the btree + +BTERR bt_splitroot(BtDb *bt, unsigned char *newkey, unsigned char *oldkey, uid page_no2) +{ +uint nxt = bt->mgr->page_size; +BtPage root = bt->page; +uid new_page; + + // Obtain an empty page to use, and copy the current + // root contents into it which is the lower half of + // the old root. + + 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 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; + + // 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( bt_cleanpage (bt, len) ) + 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; + + 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 type, idx; + char *infile; + BtMgr *mgr; + int num; +} 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, cnt = 0; +uid next, page_no = LEAF_page; // start on first page of leaves +unsigned char key[256]; +ThreadArg *args = arg; +int ch, len = 0, slot; +time_t tod[1]; +BtPage page; +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' ) + { + line++; + + if( args->num == 1 ) + sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9; + else if( args->num ) + sprintf((char *)key+len, "%.9d", line+args->idx * args->num), 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 < 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( args->num == 1 ) + sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9; + else if( args->num ) + sprintf((char *)key+len, "%.9d", line+args->idx * args->num), len += 9; + + 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( args->num == 1 ) + sprintf((char *)key+len, "%.9d", 1000000000 - line), len += 9; + else if( args->num ) + sprintf((char *)key+len, "%.9d", line+args->idx * args->num), len += 9; + + 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); + } + + break; + + case 'c': + fprintf(stderr, "started reading\n"); + + do { + bt_lockpage (bt, page_no, BtLockRead, &page); + cnt += page->act; + next = bt_getid (page->right); + bt_unlockpage (bt, page_no, BtLockRead); + } while( page_no = next ); + + cnt--; // remove stopper key + fprintf(stderr, " Total keys read %d\n", cnt); + break; + } + + 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 poolsize = 0; +int num = 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 line_numbers 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, " line_numbers set to 1 to append line numbers to input lines\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 ) + poolsize = atoi(argv[4]); + + if( !poolsize ) + fprintf (stderr, "Warning: mapped_pool has no segments\n"); + + if( poolsize > 65535 ) + fprintf (stderr, "Warning: mapped_pool > 65535 segments\n"); + + if( argc > 5 ) + segsize = atoi(argv[5]); + else + segsize = 4; // 16 pages per mmap segment + + if( argc > 6 ) + num = atoi(argv[6]); + + cnt = argc - 7; +#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, poolsize, segsize, poolsize / 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 + 7]; + args[idx].type = argv[2][0]; + args[idx].mgr = mgr; + args[idx].num = num; + args[idx].idx = idx; +#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); + bt_mgrclose (mgr); +} + +#endif //STANDALONE