Index: Makefile.in ================================================================== --- Makefile.in +++ Makefile.in @@ -165,12 +165,12 @@ hash.lo journal.lo insert.lo legacy.lo loadext.lo \ main.lo malloc.lo mem0.lo mem1.lo mem2.lo mem3.lo mem5.lo \ memjournal.lo \ mutex.lo mutex_noop.lo mutex_os2.lo mutex_unix.lo mutex_w32.lo \ opcodes.lo os.lo os_unix.lo os_win.lo os_os2.lo \ - pager.lo parse.lo pcache.lo pragma.lo prepare.lo printf.lo random.lo \ - resolve.lo select.lo status.lo \ + pager.lo parse.lo pcache.lo pcache1.lo pragma.lo prepare.lo printf.lo \ + random.lo resolve.lo select.lo status.lo \ table.lo tokenize.lo trigger.lo update.lo \ util.lo vacuum.lo \ vdbe.lo vdbeapi.lo vdbeaux.lo vdbeblob.lo vdbefifo.lo vdbemem.lo \ walker.lo where.lo utf.lo vtab.lo @@ -235,10 +235,11 @@ $(TOP)/src/pager.c \ $(TOP)/src/pager.h \ $(TOP)/src/parse.y \ $(TOP)/src/pcache.c \ $(TOP)/src/pcache.h \ + $(TOP)/src/pcache1.c \ $(TOP)/src/pragma.c \ $(TOP)/src/prepare.c \ $(TOP)/src/printf.c \ $(TOP)/src/random.c \ $(TOP)/src/resolve.c \ @@ -333,10 +334,11 @@ $(TOP)/src/os_os2.c \ $(TOP)/src/os_unix.c \ $(TOP)/src/os_win.c \ $(TOP)/src/pager.c \ $(TOP)/src/pcache.c \ + $(TOP)/src/pcache1.c \ $(TOP)/src/pragma.c \ $(TOP)/src/prepare.c \ $(TOP)/src/printf.c \ $(TOP)/src/random.c \ $(TOP)/src/select.c \ @@ -593,10 +595,13 @@ pager.lo: $(TOP)/src/pager.c $(HDR) $(TOP)/src/pager.h $(LTCOMPILE) -c $(TOP)/src/pager.c pcache.lo: $(TOP)/src/pcache.c $(HDR) $(TOP)/src/pcache.h $(LTCOMPILE) -c $(TOP)/src/pcache.c + +pcache1.lo: $(TOP)/src/pcache1.c $(HDR) $(TOP)/src/pcache.h + $(LTCOMPILE) -c $(TOP)/src/pcache1.c opcodes.lo: opcodes.c $(LTCOMPILE) -c opcodes.c opcodes.c: opcodes.h $(TOP)/mkopcodec.awk Index: main.mk ================================================================== --- main.mk +++ main.mk @@ -58,11 +58,11 @@ icu.o insert.o journal.o legacy.o loadext.o \ main.o malloc.o mem0.o mem1.o mem2.o mem3.o mem5.o \ memjournal.o \ mutex.o mutex_noop.o mutex_os2.o mutex_unix.o mutex_w32.o \ opcodes.o os.o os_os2.o os_unix.o os_win.o \ - pager.o parse.o pcache.o pragma.o prepare.o printf.o \ + pager.o parse.o pcache.o pcache1.o pragma.o prepare.o printf.o \ random.o resolve.o rtree.o select.o status.o \ table.o tokenize.o trigger.o \ update.o util.o vacuum.o \ vdbe.o vdbeapi.o vdbeaux.o vdbeblob.o vdbefifo.o vdbemem.o \ walker.o where.o utf.o vtab.o @@ -120,10 +120,11 @@ $(TOP)/src/pager.c \ $(TOP)/src/pager.h \ $(TOP)/src/parse.y \ $(TOP)/src/pcache.c \ $(TOP)/src/pcache.h \ + $(TOP)/src/pcache1.c \ $(TOP)/src/pragma.c \ $(TOP)/src/prepare.c \ $(TOP)/src/printf.c \ $(TOP)/src/random.c \ $(TOP)/src/resolve.c \ @@ -240,11 +241,11 @@ $(TOP)/src/attach.c $(TOP)/src/btree.c $(TOP)/src/build.c $(TOP)/src/date.c \ $(TOP)/src/expr.c $(TOP)/src/func.c $(TOP)/src/insert.c $(TOP)/src/os.c \ $(TOP)/src/os_os2.c $(TOP)/src/os_unix.c $(TOP)/src/os_win.c \ $(TOP)/src/pager.c $(TOP)/src/pragma.c $(TOP)/src/prepare.c \ $(TOP)/src/printf.c $(TOP)/src/random.c $(TOP)/src/pcache.c \ - $(TOP)/src/select.c $(TOP)/src/tokenize.c \ + $(TOP)/src/pcache1.c $(TOP)/src/select.c $(TOP)/src/tokenize.c \ $(TOP)/src/utf.c $(TOP)/src/util.c $(TOP)/src/vdbeapi.c $(TOP)/src/vdbeaux.c \ $(TOP)/src/vdbe.c $(TOP)/src/vdbemem.c $(TOP)/src/where.c parse.c \ $(TOP)/ext/fts3/fts3.c $(TOP)/ext/fts3/fts3_tokenizer.c # Header files used by all library source files. Index: src/btree.c ================================================================== --- src/btree.c +++ src/btree.c @@ -7,11 +7,11 @@ ** May you do good and not evil. ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* -** $Id: btree.c,v 1.534 2008/11/12 18:21:36 danielk1977 Exp $ +** $Id: btree.c,v 1.535 2008/11/13 14:28:29 danielk1977 Exp $ ** ** This file implements a external (disk-based) database using BTrees. ** See the header comment on "btreeInt.h" for additional information. ** Including a description of file format and an overview of operation. */ @@ -2601,13 +2601,18 @@ */ void sqlite3BtreeTripAllCursors(Btree *pBtree, int errCode){ BtCursor *p; sqlite3BtreeEnter(pBtree); for(p=pBtree->pBt->pCursor; p; p=p->pNext){ + int i; sqlite3BtreeClearCursor(p); p->eState = CURSOR_FAULT; p->skip = errCode; + for(i=0; i<=p->iPage; i++){ + releasePage(p->apPage[i]); + p->apPage[i] = 0; + } } sqlite3BtreeLeave(pBtree); } /* @@ -5613,11 +5618,12 @@ hdr = pPage->hdrOffset; cbrk = get2byte(&data[hdr+5]); cdata = pChild->aData; memcpy(cdata, &data[hdr], pPage->cellOffset+2*pPage->nCell-hdr); memcpy(&cdata[cbrk], &data[cbrk], usableSize-cbrk); - + + assert( pChild->isInit==0 ); rc = sqlite3BtreeInitPage(pChild); if( rc==SQLITE_OK ){ int nCopy = pPage->nOverflow*sizeof(pPage->aOvfl[0]); memcpy(pChild->aOvfl, pPage->aOvfl, nCopy); pChild->nOverflow = pPage->nOverflow; Index: src/main.c ================================================================== --- src/main.c +++ src/main.c @@ -12,11 +12,11 @@ ** Main file for the SQLite library. The routines in this file ** implement the programmer interface to the library. Routines in ** other files are for internal use by SQLite and should not be ** accessed by users of the library. ** -** $Id: main.c,v 1.511 2008/11/10 18:05:36 shane Exp $ +** $Id: main.c,v 1.512 2008/11/13 14:28:29 danielk1977 Exp $ */ #include "sqliteInt.h" #include #ifdef SQLITE_ENABLE_FTS3 @@ -306,10 +306,16 @@ sqlite3GlobalConfig.pPage = va_arg(ap, void*); sqlite3GlobalConfig.szPage = va_arg(ap, int); sqlite3GlobalConfig.nPage = va_arg(ap, int); break; } + + case SQLITE_CONFIG_PCACHE: { + /* Specify an alternative malloc implementation */ + sqlite3GlobalConfig.pcache = *va_arg(ap, sqlite3_pcache_methods*); + break; + } #if defined(SQLITE_ENABLE_MEMSYS3) || defined(SQLITE_ENABLE_MEMSYS5) case SQLITE_CONFIG_HEAP: { /* Designate a buffer for heap memory space */ sqlite3GlobalConfig.pHeap = va_arg(ap, void*); Index: src/pager.c ================================================================== --- src/pager.c +++ src/pager.c @@ -16,11 +16,11 @@ ** is separate from the database file. The pager also implements file ** locking to prevent two processes from writing the same database ** file simultaneously, or one process from reading the database while ** another is writing. ** -** @(#) $Id: pager.c,v 1.502 2008/11/07 00:24:54 drh Exp $ +** @(#) $Id: pager.c,v 1.503 2008/11/13 14:28:29 danielk1977 Exp $ */ #ifndef SQLITE_OMIT_DISKIO #include "sqliteInt.h" /* @@ -309,10 +309,14 @@ */ static int pageInStatement(PgHdr *pPg){ Pager *pPager = pPg->pPager; return sqlite3BitvecTest(pPager->pInStmt, pPg->pgno); } + +static int pageInJournal(PgHdr *pPg){ + return sqlite3BitvecTest(pPg->pPager->pInJournal, pPg->pgno); +} /* ** Read a 32-bit integer from the given file descriptor. Store the integer ** that is read in *pRes. Return SQLITE_OK if everything worked, or an ** error code is something goes wrong. @@ -452,11 +456,11 @@ return hash; } static u32 pager_pagehash(PgHdr *pPage){ return pager_datahash(pPage->pPager->pageSize, (unsigned char *)pPage->pData); } -static u32 pager_set_pagehash(PgHdr *pPage){ +static void pager_set_pagehash(PgHdr *pPage){ pPage->pageHash = pager_pagehash(pPage); } /* ** The CHECK_PAGE macro takes a PgHdr* as an argument. If SQLITE_CHECK_PAGES @@ -995,17 +999,14 @@ } sqlite3BitvecDestroy(pPager->pInJournal); pPager->pInJournal = 0; sqlite3BitvecDestroy(pPager->pAlwaysRollback); pPager->pAlwaysRollback = 0; - sqlite3PcacheCleanAll(pPager->pPCache); #ifdef SQLITE_CHECK_PAGES - sqlite3PcacheIterate(pPager->pPCache, pager_set_pagehash); + sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash); #endif - sqlite3PcacheClearFlags(pPager->pPCache, - PGHDR_IN_JOURNAL | PGHDR_NEED_SYNC - ); + sqlite3PcacheCleanAll(pPager->pPCache); pPager->dirtyCache = 0; pPager->nRec = 0; }else{ assert( pPager->pInJournal==0 ); } @@ -2337,23 +2338,13 @@ } pPager->needSync = 0; /* Erase the needSync flag from every page. */ - sqlite3PcacheClearFlags(pPager->pPCache, PGHDR_NEED_SYNC); + sqlite3PcacheClearSyncFlags(pPager->pPCache); } -#ifndef NDEBUG - /* If the Pager.needSync flag is clear then the PgHdr.needSync - ** flag must also be clear for all pages. Verify that this - ** invariant is true. - */ - else{ - sqlite3PcacheAssertFlags(pPager->pPCache, 0, PGHDR_NEED_SYNC); - } -#endif - return rc; } /* ** Given a list of pages (connected by the PgHdr.pDirty pointer) write @@ -2850,13 +2841,10 @@ ** be initialized. */ int nMax; PAGER_INCR(pPager->nMiss); pPg->pPager = pPager; - if( sqlite3BitvecTest(pPager->pInJournal, pgno) ){ - pPg->flags |= PGHDR_IN_JOURNAL; - } memset(pPg->pExtra, 0, pPager->nExtra); rc = sqlite3PagerPagecount(pPager, &nMax); if( rc!=SQLITE_OK ){ sqlite3PagerUnref(pPg); @@ -3056,11 +3044,10 @@ assert( pPg->nRef>0 ); assert( pPager->state!=PAGER_UNLOCK ); if( pPager->state==PAGER_SHARED ){ assert( pPager->pInJournal==0 ); assert( !MEMDB ); - sqlite3PcacheAssertFlags(pPager->pPCache, 0, PGHDR_IN_JOURNAL); rc = sqlite3OsLock(pPager->fd, RESERVED_LOCK); if( rc==SQLITE_OK ){ pPager->state = PAGER_RESERVED; if( exFlag ){ rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK); @@ -3165,13 +3152,11 @@ /* Mark the page as dirty. If the page has already been written ** to the journal then we can return right away. */ makeDirty(pPg); - if( (pPg->flags&PGHDR_IN_JOURNAL) - && (pageInStatement(pPg) || pPager->stmtInUse==0) - ){ + if( pageInJournal(pPg) && (pageInStatement(pPg) || pPager->stmtInUse==0) ){ pPager->dirtyCache = 1; pPager->dbModified = 1; }else{ /* If we get this far, it means that the page needs to be @@ -3197,11 +3182,11 @@ /* The transaction journal now exists and we have a RESERVED or an ** EXCLUSIVE lock on the main database file. Write the current page to ** the transaction journal if it is not there already. */ - if( !(pPg->flags&PGHDR_IN_JOURNAL) && pPager->journalOpen ){ + if( !pageInJournal(pPg) && pPager->journalOpen ){ if( (int)pPg->pgno <= pPager->origDbSize ){ u32 cksum; char *pData2; /* We should never write to the journal file the page that @@ -3252,11 +3237,10 @@ ((pPg->flags&PGHDR_NEED_SYNC)?1:0)); } if( pPg->flags&PGHDR_NEED_SYNC ){ pPager->needSync = 1; } - pPg->flags |= PGHDR_IN_JOURNAL; } /* If the statement journal is open and the page is not in it, ** then write the current page to the statement journal. Note that ** the statement journal format differs from the standard journal format @@ -3266,12 +3250,11 @@ && !pageInStatement(pPg) && (int)pPg->pgno<=pPager->stmtSize ){ i64 offset = pPager->stmtNRec*(4+pPager->pageSize); char *pData2 = CODEC2(pPager, pData, pPg->pgno, 7); - assert( (pPg->flags&PGHDR_IN_JOURNAL) - || (int)pPg->pgno>pPager->origDbSize ); + assert( pageInJournal(pPg) || (int)pPg->pgno>pPager->origDbSize ); rc = write32bits(pPager->stfd, offset, pPg->pgno); if( rc==SQLITE_OK ){ rc = sqlite3OsWrite(pPager->stfd, pData2, pPager->pageSize, offset+4); } PAGERTRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno); @@ -3513,11 +3496,10 @@ */ /* assert( !pPg->inJournal && (int)pPg->pgno <= pPager->origDbSize ); */ assert( pPager->pInJournal!=0 ); sqlite3BitvecSet(pPager->pInJournal, pPg->pgno); - pPg->flags |= PGHDR_IN_JOURNAL; pPg->flags &= ~PGHDR_NEED_READ; if( pPager->stmtInUse ){ assert( pPager->stmtSize >= pPager->origDbSize ); sqlite3BitvecSet(pPager->pInStmt, pPg->pgno); } @@ -4075,34 +4057,30 @@ ** the journal needs to be sync()ed before database page pPg->pgno ** can be written to. The caller has already promised not to write to it. */ if( (pPg->flags&PGHDR_NEED_SYNC) && !isCommit ){ needSyncPgno = pPg->pgno; - assert( (pPg->flags&PGHDR_IN_JOURNAL) || (int)pgno>pPager->origDbSize ); + assert( pageInJournal(pPg) || (int)pgno>pPager->origDbSize ); assert( pPg->flags&PGHDR_DIRTY ); assert( pPager->needSync ); } /* If the cache contains a page with page-number pgno, remove it ** from its hash chain. Also, if the PgHdr.needSync was set for ** page pgno before the 'move' operation, it needs to be retained ** for the page moved there. */ - pPg->flags &= ~(PGHDR_NEED_SYNC|PGHDR_IN_JOURNAL); + pPg->flags &= ~PGHDR_NEED_SYNC; pPgOld = pager_lookup(pPager, pgno); assert( !pPgOld || pPgOld->nRef==1 ); if( pPgOld ){ pPg->flags |= (pPgOld->flags&PGHDR_NEED_SYNC); } - if( sqlite3BitvecTest(pPager->pInJournal, pgno) ){ - pPg->flags |= PGHDR_IN_JOURNAL; - } sqlite3PcacheMove(pPg, pgno); if( pPgOld ){ - sqlite3PcacheMove(pPgOld, 0); - sqlite3PcacheRelease(pPgOld); + sqlite3PcacheDrop(pPgOld); } makeDirty(pPg); pPager->dirtyCache = 1; pPager->dbModified = 1; @@ -4136,11 +4114,10 @@ return rc; } pPager->needSync = 1; assert( pPager->noSync==0 && !MEMDB ); pPgHdr->flags |= PGHDR_NEED_SYNC; - pPgHdr->flags |= PGHDR_IN_JOURNAL; makeDirty(pPgHdr); sqlite3PagerUnref(pPgHdr); } return SQLITE_OK; Index: src/pcache.c ================================================================== --- src/pcache.c +++ src/pcache.c @@ -9,108 +9,32 @@ ** May you share freely, never taking more than you give. ** ************************************************************************* ** This file implements that page cache. ** -** @(#) $Id: pcache.c,v 1.36 2008/11/11 18:43:00 danielk1977 Exp $ +** @(#) $Id: pcache.c,v 1.37 2008/11/13 14:28:29 danielk1977 Exp $ */ #include "sqliteInt.h" /* ** A complete page cache is an instance of this structure. -** -** A cache may only be deleted by its owner and while holding the -** SQLITE_MUTEX_STATUS_LRU mutex. */ struct PCache { - /********************************************************************* - ** The first group of elements may be read or written at any time by - ** the cache owner without holding the mutex. No thread other than the - ** cache owner is permitted to access these elements at any time. - */ PgHdr *pDirty, *pDirtyTail; /* List of dirty pages in LRU order */ PgHdr *pSynced; /* Last synced page in dirty page list */ - int nRef; /* Number of pinned pages */ - int nPinned; /* Number of pinned and/or dirty pages */ + int nRef; /* Number of referenced pages */ int nMax; /* Configured cache size */ int nMin; /* Configured minimum cache size */ - /********************************************************************** - ** The next group of elements are fixed when the cache is created and - ** may not be changed afterwards. These elements can read at any time by - ** the cache owner or by any thread holding the the mutex. Non-owner - ** threads must hold the mutex when reading these elements to prevent - ** the entire PCache object from being deleted during the read. - */ int szPage; /* Size of every page in this cache */ int szExtra; /* Size of extra space for each page */ int bPurgeable; /* True if pages are on backing store */ int (*xStress)(void*,PgHdr*); /* Call to try make a page clean */ void *pStress; /* Argument to xStress */ - /********************************************************************** - ** The final group of elements can only be accessed while holding the - ** mutex. Both the cache owner and any other thread must hold the mutex - ** to read or write any of these elements. - */ - int nPage; /* Total number of pages in apHash */ - int nHash; /* Number of slots in apHash[] */ - PgHdr **apHash; /* Hash table for fast lookup by pgno */ - PgHdr *pClean; /* List of clean pages in use */ + sqlite3_pcache *pCache; /* Pluggable cache module */ + PgHdr *pPage1; }; -/* -** Free slots in the page block allocator -*/ -typedef struct PgFreeslot PgFreeslot; -struct PgFreeslot { - PgFreeslot *pNext; /* Next free slot */ -}; - -/* -** Global data for the page cache. -*/ -static SQLITE_WSD struct PCacheGlobal { - int isInit; /* True when initialized */ - sqlite3_mutex *mutex; /* static mutex MUTEX_STATIC_LRU */ - - int nMaxPage; /* Sum of nMaxPage for purgeable caches */ - int nMinPage; /* Sum of nMinPage for purgeable caches */ - int nCurrentPage; /* Number of purgeable pages allocated */ - PgHdr *pLruHead, *pLruTail; /* LRU list of unused clean pgs */ - - /* Variables related to SQLITE_CONFIG_PAGECACHE settings. */ - int szSlot; /* Size of each free slot */ - void *pStart, *pEnd; /* Bounds of pagecache malloc range */ - PgFreeslot *pFree; /* Free page blocks */ -} pcache = {0}; - -/* -** All code in this file should access the global pcache structure via the -** alias "pcache_g". This ensures that the WSD emulation is used when -** compiling for systems that do not support real WSD. -*/ -#define pcache_g (GLOBAL(struct PCacheGlobal, pcache)) - -/* -** All global variables used by this module (all of which are grouped -** together in global structure "pcache" above) are protected by the static -** SQLITE_MUTEX_STATIC_LRU mutex. A pointer to this mutex is stored in -** variable "pcache.mutex". -** -** Some elements of the PCache and PgHdr structures are protected by the -** SQLITE_MUTEX_STATUS_LRU mutex and other are not. The protected -** elements are grouped at the end of the structures and are clearly -** marked. -** -** Use the following macros must surround all access (read or write) -** of protected elements. The mutex is not recursive and may not be -** entered more than once. The pcacheMutexHeld() macro should only be -** used within an assert() to verify that the mutex is being held. -*/ -#define pcacheEnterMutex() sqlite3_mutex_enter(pcache_g.mutex) -#define pcacheExitMutex() sqlite3_mutex_leave(pcache_g.mutex) -#define pcacheMutexHeld() sqlite3_mutex_held(pcache_g.mutex) - /* ** Some of the assert() macros in this code are too expensive to run ** even during normal debugging. Use them only rarely on long-running ** tests. Enable the expensive asserts using the ** -DSQLITE_ENABLE_EXPENSIVE_ASSERT=1 compile-time option. @@ -120,52 +44,10 @@ #else # define expensive_assert(X) #endif /********************************** Linked List Management ********************/ - -#if !defined(NDEBUG) && defined(SQLITE_ENABLE_EXPENSIVE_ASSERT) -/* -** This routine verifies that the number of entries in the hash table -** is pCache->nPage. This routine is used within assert() statements -** only and is therefore disabled during production builds. -*/ -static int pcacheCheckHashCount(PCache *pCache){ - int i; - int nPage = 0; - for(i=0; inHash; i++){ - PgHdr *p; - for(p=pCache->apHash[i]; p; p=p->pNextHash){ - nPage++; - } - } - assert( nPage==pCache->nPage ); - return 1; -} -#endif /* !NDEBUG && SQLITE_ENABLE_EXPENSIVE_ASSERT */ - - -#if !defined(NDEBUG) && defined(SQLITE_ENABLE_EXPENSIVE_ASSERT) -/* -** Based on the current value of PCache.nRef and the contents of the -** PCache.pDirty list, return the expected value of the PCache.nPinned -** counter. This is only used in debugging builds, as follows: -** -** expensive_assert( pCache->nPinned==pcachePinnedCount(pCache) ); -*/ -static int pcachePinnedCount(PCache *pCache){ - PgHdr *p; - int nPinned = pCache->nRef; - for(p=pCache->pDirty; p; p=p->pNext){ - if( p->nRef==0 ){ - nPinned++; - } - } - return nPinned; -} -#endif /* !NDEBUG && SQLITE_ENABLE_EXPENSIVE_ASSERT */ - #if !defined(NDEBUG) && defined(SQLITE_ENABLE_EXPENSIVE_ASSERT) /* ** Check that the pCache->pSynced variable is set correctly. If it ** is not, either fail an assert or return zero. Otherwise, return @@ -172,503 +54,148 @@ ** non-zero. This is only used in debugging builds, as follows: ** ** expensive_assert( pcacheCheckSynced(pCache) ); */ static int pcacheCheckSynced(PCache *pCache){ - PgHdr *p = pCache->pDirtyTail; - for(p=pCache->pDirtyTail; p!=pCache->pSynced; p=p->pPrev){ + PgHdr *p; + for(p=pCache->pDirtyTail; p!=pCache->pSynced; p=p->pDirtyPrev){ assert( p->nRef || (p->flags&PGHDR_NEED_SYNC) ); } return (p==0 || p->nRef || (p->flags&PGHDR_NEED_SYNC)==0); } #endif /* !NDEBUG && SQLITE_ENABLE_EXPENSIVE_ASSERT */ +/* +** Remove page pPage from the list of dirty pages. +*/ +static void pcacheRemoveFromDirtyList(PgHdr *pPage){ + PCache *p = pPage->pCache; + assert( pPage->pDirtyNext || pPage==p->pDirtyTail ); + assert( pPage->pDirtyPrev || pPage==p->pDirty ); -/* -** Remove a page from its hash table (PCache.apHash[]). -*/ -static void pcacheRemoveFromHash(PgHdr *pPage){ - assert( pcacheMutexHeld() ); - if( pPage->pPrevHash ){ - pPage->pPrevHash->pNextHash = pPage->pNextHash; + /* Update the PCache1.pSynced variable if necessary. */ + if( p->pSynced==pPage ){ + PgHdr *pSynced = pPage->pDirtyPrev; + while( pSynced && (pSynced->flags&PGHDR_NEED_SYNC) ){ + pSynced = pSynced->pDirtyPrev; + } + p->pSynced = pSynced; + } + + if( pPage->pDirtyNext ){ + pPage->pDirtyNext->pDirtyPrev = pPage->pDirtyPrev; }else{ - PCache *pCache = pPage->pCache; - u32 h = pPage->pgno % pCache->nHash; - assert( pCache->apHash[h]==pPage ); - pCache->apHash[h] = pPage->pNextHash; + assert( pPage==p->pDirtyTail ); + p->pDirtyTail = pPage->pDirtyPrev; } - if( pPage->pNextHash ){ - pPage->pNextHash->pPrevHash = pPage->pPrevHash; - } - pPage->pCache->nPage--; - expensive_assert( pcacheCheckHashCount(pPage->pCache) ); -} - -/* -** Insert a page into the hash table -** -** The mutex must be held by the caller. -*/ -static void pcacheAddToHash(PgHdr *pPage){ - PCache *pCache = pPage->pCache; - u32 h = pPage->pgno % pCache->nHash; - assert( pcacheMutexHeld() ); - pPage->pNextHash = pCache->apHash[h]; - pPage->pPrevHash = 0; - if( pCache->apHash[h] ){ - pCache->apHash[h]->pPrevHash = pPage; - } - pCache->apHash[h] = pPage; - pCache->nPage++; - expensive_assert( pcacheCheckHashCount(pCache) ); -} - -/* -** Attempt to increase the size the hash table to contain -** at least nHash buckets. -*/ -static int pcacheResizeHash(PCache *pCache, int nHash){ - PgHdr *p; - PgHdr **pNew; - assert( pcacheMutexHeld() ); -#ifdef SQLITE_MALLOC_SOFT_LIMIT - if( nHash*sizeof(PgHdr*)>SQLITE_MALLOC_SOFT_LIMIT ){ - nHash = SQLITE_MALLOC_SOFT_LIMIT/sizeof(PgHdr *); - } -#endif - pcacheExitMutex(); - pNew = (PgHdr **)sqlite3Malloc(sizeof(PgHdr*)*nHash); - pcacheEnterMutex(); - if( !pNew ){ - return SQLITE_NOMEM; - } - memset(pNew, 0, sizeof(PgHdr *)*nHash); - sqlite3_free(pCache->apHash); - pCache->apHash = pNew; - pCache->nHash = nHash; - pCache->nPage = 0; - - for(p=pCache->pClean; p; p=p->pNext){ - pcacheAddToHash(p); - } - for(p=pCache->pDirty; p; p=p->pNext){ - pcacheAddToHash(p); - } - return SQLITE_OK; -} - -/* -** Remove a page from a linked list that is headed by *ppHead. -** *ppHead is either PCache.pClean or PCache.pDirty. -*/ -static void pcacheRemoveFromList(PgHdr **ppHead, PgHdr *pPage){ - int isDirtyList = (ppHead==&pPage->pCache->pDirty); - assert( ppHead==&pPage->pCache->pClean || ppHead==&pPage->pCache->pDirty ); - assert( pcacheMutexHeld() || ppHead!=&pPage->pCache->pClean ); - - if( pPage->pPrev ){ - pPage->pPrev->pNext = pPage->pNext; + if( pPage->pDirtyPrev ){ + pPage->pDirtyPrev->pDirtyNext = pPage->pDirtyNext; }else{ - assert( *ppHead==pPage ); - *ppHead = pPage->pNext; - } - if( pPage->pNext ){ - pPage->pNext->pPrev = pPage->pPrev; - } - - if( isDirtyList ){ - PCache *pCache = pPage->pCache; - assert( pPage->pNext || pCache->pDirtyTail==pPage ); - if( !pPage->pNext ){ - pCache->pDirtyTail = pPage->pPrev; - } - if( pCache->pSynced==pPage ){ - PgHdr *pSynced = pPage->pPrev; - while( pSynced && (pSynced->flags&PGHDR_NEED_SYNC) ){ - pSynced = pSynced->pPrev; - } - pCache->pSynced = pSynced; - } - } -} - -/* -** Add a page from a linked list that is headed by *ppHead. -** *ppHead is either PCache.pClean or PCache.pDirty. -*/ -static void pcacheAddToList(PgHdr **ppHead, PgHdr *pPage){ - int isDirtyList = (ppHead==&pPage->pCache->pDirty); - assert( ppHead==&pPage->pCache->pClean || ppHead==&pPage->pCache->pDirty ); - - if( (*ppHead) ){ - (*ppHead)->pPrev = pPage; - } - pPage->pNext = *ppHead; - pPage->pPrev = 0; - *ppHead = pPage; - - if( isDirtyList ){ - PCache *pCache = pPage->pCache; - if( !pCache->pDirtyTail ){ - assert( pPage->pNext==0 ); - pCache->pDirtyTail = pPage; - } - if( !pCache->pSynced && 0==(pPage->flags&PGHDR_NEED_SYNC) ){ - pCache->pSynced = pPage; - } - } -} - -/* -** Remove a page from the global LRU list -*/ -static void pcacheRemoveFromLruList(PgHdr *pPage){ - assert( sqlite3_mutex_held(pcache_g.mutex) ); - assert( (pPage->flags&PGHDR_DIRTY)==0 ); - if( pPage->pCache->bPurgeable==0 ) return; - if( pPage->pNextLru ){ - assert( pcache_g.pLruTail!=pPage ); - pPage->pNextLru->pPrevLru = pPage->pPrevLru; - }else{ - assert( pcache_g.pLruTail==pPage ); - pcache_g.pLruTail = pPage->pPrevLru; - } - if( pPage->pPrevLru ){ - assert( pcache_g.pLruHead!=pPage ); - pPage->pPrevLru->pNextLru = pPage->pNextLru; - }else{ - assert( pcache_g.pLruHead==pPage ); - pcache_g.pLruHead = pPage->pNextLru; - } -} - -/* -** Add a page to the global LRU list. The page is normally added -** to the front of the list so that it will be the last page recycled. -** However, if the PGHDR_REUSE_UNLIKELY bit is set, the page is added -** to the end of the LRU list so that it will be the next to be recycled. -*/ -static void pcacheAddToLruList(PgHdr *pPage){ - assert( sqlite3_mutex_held(pcache_g.mutex) ); - assert( (pPage->flags&PGHDR_DIRTY)==0 ); - if( pPage->pCache->bPurgeable==0 ) return; - if( pcache_g.pLruTail && (pPage->flags & PGHDR_REUSE_UNLIKELY)!=0 ){ - /* If reuse is unlikely. Put the page at the end of the LRU list - ** where it will be recycled sooner rather than later. - */ - assert( pcache_g.pLruHead ); - pPage->pNextLru = 0; - pPage->pPrevLru = pcache_g.pLruTail; - pcache_g.pLruTail->pNextLru = pPage; - pcache_g.pLruTail = pPage; - pPage->flags &= ~PGHDR_REUSE_UNLIKELY; - }else{ - /* If reuse is possible. the page goes at the beginning of the LRU - ** list so that it will be the last to be recycled. - */ - if( pcache_g.pLruHead ){ - pcache_g.pLruHead->pPrevLru = pPage; - } - pPage->pNextLru = pcache_g.pLruHead; - pcache_g.pLruHead = pPage; - pPage->pPrevLru = 0; - if( pcache_g.pLruTail==0 ){ - pcache_g.pLruTail = pPage; - } - } -} - -/*********************************************** Memory Allocation *********** -** -** Initialize the page cache memory pool. -** -** This must be called at start-time when no page cache lines are -** checked out. This function is not threadsafe. -*/ -void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){ - PgFreeslot *p; - sz &= ~7; - pcache_g.szSlot = sz; - pcache_g.pStart = pBuf; - pcache_g.pFree = 0; - while( n-- ){ - p = (PgFreeslot*)pBuf; - p->pNext = pcache_g.pFree; - pcache_g.pFree = p; - pBuf = (void*)&((char*)pBuf)[sz]; - } - pcache_g.pEnd = pBuf; -} - -/* -** Allocate a page cache line. Look in the page cache memory pool first -** and use an element from it first if available. If nothing is available -** in the page cache memory pool, go to the general purpose memory allocator. -*/ -static void *pcacheMalloc(int sz, PCache *pCache){ - assert( sqlite3_mutex_held(pcache_g.mutex) ); - if( sz<=pcache_g.szSlot && pcache_g.pFree ){ - PgFreeslot *p = pcache_g.pFree; - pcache_g.pFree = p->pNext; - sqlite3StatusSet(SQLITE_STATUS_PAGECACHE_SIZE, sz); - sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, 1); - return (void*)p; - }else{ - void *p; - - /* Allocate a new buffer using sqlite3Malloc. Before doing so, exit the - ** global pcache mutex and unlock the pager-cache object pCache. This is - ** so that if the attempt to allocate a new buffer causes the the - ** configured soft-heap-limit to be breached, it will be possible to - ** reclaim memory from this pager-cache. - */ - pcacheExitMutex(); - p = sqlite3Malloc(sz); - pcacheEnterMutex(); - - if( p ){ - sz = sqlite3MallocSize(p); - sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz); - } - return p; - } -} -void *sqlite3PageMalloc(int sz){ - void *p; - pcacheEnterMutex(); - p = pcacheMalloc(sz, 0); - pcacheExitMutex(); - return p; -} - -/* -** Release a pager memory allocation -*/ -static void pcacheFree(void *p){ - assert( sqlite3_mutex_held(pcache_g.mutex) ); - if( p==0 ) return; - if( p>=pcache_g.pStart && ppNext = pcache_g.pFree; - pcache_g.pFree = pSlot; - }else{ - int iSize = sqlite3MallocSize(p); - sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, -iSize); - sqlite3_free(p); - } -} -void sqlite3PageFree(void *p){ - pcacheEnterMutex(); - pcacheFree(p); - pcacheExitMutex(); -} - -/* -** Allocate a new page. -*/ -static PgHdr *pcachePageAlloc(PCache *pCache){ - PgHdr *p; - int sz = sizeof(*p) + pCache->szPage + pCache->szExtra; - assert( sqlite3_mutex_held(pcache_g.mutex) ); - p = pcacheMalloc(sz, pCache); - if( p==0 ) return 0; - memset(p, 0, sizeof(PgHdr)); - p->pData = (void*)&p[1]; - p->pExtra = (void*)&((char*)p->pData)[pCache->szPage]; + assert( pPage==p->pDirty ); + p->pDirty = pPage->pDirtyNext; + } + pPage->pDirtyNext = 0; + pPage->pDirtyPrev = 0; + + expensive_assert( pcacheCheckSynced(p) ); +} + +/* +** Add page pPage to the head of the dirty list (PCache1.pDirty is set to +** pPage). +*/ +static void pcacheAddToDirtyList(PgHdr *pPage){ + PCache *p = pPage->pCache; + + assert( pPage->pDirtyNext==0 && pPage->pDirtyPrev==0 && p->pDirty!=pPage ); + + pPage->pDirtyNext = p->pDirty; + if( pPage->pDirtyNext ){ + assert( pPage->pDirtyNext->pDirtyPrev==0 ); + pPage->pDirtyNext->pDirtyPrev = pPage; + } + p->pDirty = pPage; + if( !p->pDirtyTail ){ + p->pDirtyTail = pPage; + } + if( !p->pSynced && 0==(pPage->flags&PGHDR_NEED_SYNC) ){ + p->pSynced = pPage; + } + expensive_assert( pcacheCheckSynced(p) ); +} + +/* +** Wrapper around the pluggable caches xUnpin method. If the cache is +** being used for an in-memory database, this function is a no-op. +*/ +static void pcacheUnpin(PgHdr *p){ + PCache *pCache = p->pCache; if( pCache->bPurgeable ){ - pcache_g.nCurrentPage++; - } - return p; -} - -/* -** Deallocate a page -*/ -static void pcachePageFree(PgHdr *p){ - assert( sqlite3_mutex_held(pcache_g.mutex) ); - if( p->pCache->bPurgeable ){ - pcache_g.nCurrentPage--; - } - pcacheFree(p); -} - -#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT -/* -** Return the number of bytes that will be returned to the heap when -** the argument is passed to pcachePageFree(). -*/ -static int pcachePageSize(PgHdr *p){ - assert( sqlite3_mutex_held(pcache_g.mutex) ); - assert( !pcache_g.pStart ); - assert( p && p->pCache ); - return sqlite3MallocSize(p); -} -#endif - -/* -** Attempt to 'recycle' a page from the global LRU list. Only clean, -** unreferenced pages from purgeable caches are eligible for recycling. -** -** This function removes page pcache.pLruTail from the global LRU list, -** and from the hash-table and PCache.pClean list of the owner pcache. -** There should be no other references to the page. -** -** A pointer to the recycled page is returned, or NULL if no page is -** eligible for recycling. -*/ -static PgHdr *pcacheRecyclePage(void){ - PgHdr *p = 0; - assert( sqlite3_mutex_held(pcache_g.mutex) ); - - if( (p=pcache_g.pLruTail)!=0 ){ - assert( (p->flags&PGHDR_DIRTY)==0 ); - pcacheRemoveFromLruList(p); - pcacheRemoveFromHash(p); - pcacheRemoveFromList(&p->pCache->pClean, p); - } - - return p; -} - -/* -** Obtain space for a page. Try to recycle an old page if the limit on the -** number of pages has been reached. If the limit has not been reached or -** there are no pages eligible for recycling, allocate a new page. -** -** Return a pointer to the new page, or NULL if an OOM condition occurs. -*/ -static int pcacheRecycleOrAlloc(PCache *pCache, PgHdr **ppPage){ - PgHdr *p = 0; - - int szPage = pCache->szPage; - int szExtra = pCache->szExtra; - - assert( pcache_g.isInit ); - assert( sqlite3_mutex_held(pcache_g.mutex) ); - - *ppPage = 0; - - /* If we have reached either the global or the local limit for - ** pinned+dirty pages, and there is at least one dirty page, - ** invoke the xStress callback to cause a page to become clean. - */ - expensive_assert( pCache->nPinned==pcachePinnedCount(pCache) ); - expensive_assert( pcacheCheckSynced(pCache) ); - if( pCache->xStress - && pCache->pDirty - && (pCache->nPinned>=(pcache_g.nMaxPage+pCache->nMin-pcache_g.nMinPage) - || pCache->nPinned>=pCache->nMax) - ){ - PgHdr *pPg; - assert(pCache->pDirtyTail); - - for(pPg=pCache->pSynced; - pPg && (pPg->nRef || (pPg->flags&PGHDR_NEED_SYNC)); - pPg=pPg->pPrev - ); - if( !pPg ){ - for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pPrev); - } - if( pPg ){ - int rc; - pcacheExitMutex(); - rc = pCache->xStress(pCache->pStress, pPg); - pcacheEnterMutex(); - if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){ - return rc; - } - } - } - - /* If either the local or the global page limit has been reached, - ** try to recycle a page. - */ - if( pCache->bPurgeable && (pCache->nPage>=pCache->nMax-1 || - pcache_g.nCurrentPage>=pcache_g.nMaxPage) ){ - p = pcacheRecyclePage(); - } - - /* If a page has been recycled but it is the wrong size, free it. */ - if( p && (p->pCache->szPage!=szPage || p->pCache->szPage!=szExtra) ){ - pcachePageFree(p); - p = 0; - } - - if( !p ){ - p = pcachePageAlloc(pCache); - } - - *ppPage = p; - return (p?SQLITE_OK:SQLITE_NOMEM); + if( p->pgno==1 ){ + pCache->pPage1 = 0; + } + sqlite3GlobalConfig.pcache.xUnpin(pCache->pCache, p, 0); + } } /*************************************************** General Interfaces ****** ** ** Initialize and shutdown the page cache subsystem. Neither of these ** functions are threadsafe. */ int sqlite3PcacheInitialize(void){ - assert( pcache_g.isInit==0 ); - memset(&pcache_g, 0, sizeof(pcache)); - if( sqlite3GlobalConfig.bCoreMutex ){ - /* No need to check the return value of sqlite3_mutex_alloc(). - ** Allocating a static mutex cannot fail. - */ - pcache_g.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU); + if( sqlite3GlobalConfig.pcache.xInit==0 ){ + sqlite3PCacheSetDefault(); } - pcache_g.isInit = 1; - return SQLITE_OK; + return sqlite3GlobalConfig.pcache.xInit(sqlite3GlobalConfig.pcache.pArg); } void sqlite3PcacheShutdown(void){ - memset(&pcache_g, 0, sizeof(pcache)); + if( sqlite3GlobalConfig.pcache.xShutdown ){ + sqlite3GlobalConfig.pcache.xShutdown(sqlite3GlobalConfig.pcache.pArg); + } } /* ** Return the size in bytes of a PCache object. */ int sqlite3PcacheSize(void){ return sizeof(PCache); } /* -** Create a new PCache object. Storage space to hold the object -** has already been allocated and is passed in as the p pointer. +** Create a new PCache object. Storage space to hold the object +** has already been allocated and is passed in as the p pointer. +** The caller discovers how much space needs to be allocated by +** calling sqlite3PcacheSize(). */ void sqlite3PcacheOpen( int szPage, /* Size of every page */ int szExtra, /* Extra space associated with each page */ int bPurgeable, /* True if pages are on backing store */ int (*xStress)(void*,PgHdr*),/* Call to try to make pages clean */ void *pStress, /* Argument to xStress */ PCache *p /* Preallocated space for the PCache */ ){ - assert( pcache_g.isInit ); memset(p, 0, sizeof(PCache)); p->szPage = szPage; p->szExtra = szExtra; p->bPurgeable = bPurgeable; p->xStress = xStress; p->pStress = pStress; p->nMax = 100; p->nMin = 10; - - pcacheEnterMutex(); - if( bPurgeable ){ - pcache_g.nMaxPage += p->nMax; - pcache_g.nMinPage += p->nMin; - } - - pcacheExitMutex(); } /* -** Change the page size for PCache object. This can only happen -** when the cache is empty. +** Change the page size for PCache object. The caller must ensure that there +** are no outstanding page references when this function is called. */ void sqlite3PcacheSetPageSize(PCache *pCache, int szPage){ - assert(pCache->nPage==0); + assert( pCache->nRef==0 && pCache->pDirty==0 ); + if( pCache->pCache ){ + sqlite3GlobalConfig.pcache.xDestroy(pCache->pCache); + pCache->pCache = 0; + } pCache->szPage = szPage; } /* ** Try to obtain a page from the cache. @@ -677,96 +204,106 @@ PCache *pCache, /* Obtain the page from this cache */ Pgno pgno, /* Page number to obtain */ int createFlag, /* If true, create page if it does not exist already */ PgHdr **ppPage /* Write the page here */ ){ - int rc = SQLITE_OK; PgHdr *pPage = 0; + int eCreate; - assert( pcache_g.isInit ); assert( pCache!=0 ); assert( pgno>0 ); - expensive_assert( pCache->nPinned==pcachePinnedCount(pCache) ); - - pcacheEnterMutex(); - - /* Search the hash table for the requested page. Exit early if it is found. */ - if( pCache->apHash ){ - u32 h = pgno % pCache->nHash; - for(pPage=pCache->apHash[h]; pPage; pPage=pPage->pNextHash){ - if( pPage->pgno==pgno ){ - if( pPage->nRef==0 ){ - if( 0==(pPage->flags&PGHDR_DIRTY) ){ - pcacheRemoveFromLruList(pPage); - pCache->nPinned++; - } - pCache->nRef++; - } - pPage->nRef++; - break; + + /* If the pluggable cache (sqlite3_pcache*) has not been allocated, + ** allocate it now. + */ + if( !pCache->pCache && createFlag ){ + sqlite3_pcache *p; + int nByte; + nByte = pCache->szPage + pCache->szExtra + sizeof(PgHdr); + p = sqlite3GlobalConfig.pcache.xCreate(nByte, pCache->bPurgeable); + if( !p ){ + return SQLITE_NOMEM; + } + sqlite3GlobalConfig.pcache.xCachesize(p, pCache->nMax); + pCache->pCache = p; + } + + eCreate = createFlag ? 1 : 0; + if( eCreate && (!pCache->bPurgeable || !pCache->pDirty) ){ + eCreate = 2; + } + if( pCache->pCache ){ + pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, eCreate); + } + + if( !pPage && eCreate==1 ){ + PgHdr *pPg; + + /* Find a dirty page to write-out and recycle. First try to find a + ** page that does not require a journal-sync (one with PGHDR_NEED_SYNC + ** cleared), but if that is not possible settle for any other + ** unreferenced dirty page. + */ + expensive_assert( pcacheCheckSynced(pCache) ); + for(pPg=pCache->pSynced; + pPg && (pPg->nRef || (pPg->flags&PGHDR_NEED_SYNC)); + pPg=pPg->pDirtyPrev + ); + if( !pPg ){ + for(pPg=pCache->pDirtyTail; pPg && pPg->nRef; pPg=pPg->pDirtyPrev); + } + if( pPg ){ + int rc; + rc = pCache->xStress(pCache->pStress, pPg); + if( rc!=SQLITE_OK && rc!=SQLITE_BUSY ){ + return rc; } } + + pPage = sqlite3GlobalConfig.pcache.xFetch(pCache->pCache, pgno, 2); } - if( !pPage && createFlag ){ - if( pCache->nHash<=pCache->nPage ){ - rc = pcacheResizeHash(pCache, pCache->nHash<256 ? 256 : pCache->nHash*2); - } - if( rc==SQLITE_OK ){ - rc = pcacheRecycleOrAlloc(pCache, &pPage); + if( pPage ){ + if( 0==pPage->nRef ){ + pCache->nRef++; } - if( rc==SQLITE_OK ){ - pPage->pPager = 0; - pPage->flags = 0; - pPage->pDirty = 0; - pPage->pgno = pgno; - pPage->pCache = pCache; - pPage->nRef = 1; - pCache->nRef++; - pCache->nPinned++; - pcacheAddToList(&pCache->pClean, pPage); - pcacheAddToHash(pPage); + pPage->nRef++; + pPage->pData = (void*)&pPage[1]; + pPage->pExtra = (void*)&((char*)pPage->pData)[pCache->szPage]; + pPage->pCache = pCache; + pPage->pgno = pgno; + if( pgno==1 ){ + pCache->pPage1 = pPage; } } - - pcacheExitMutex(); - *ppPage = pPage; - expensive_assert( pCache->nPinned==pcachePinnedCount(pCache) ); - assert( pPage || !createFlag || rc!=SQLITE_OK ); - return rc; + return (pPage==0 && eCreate) ? SQLITE_NOMEM : SQLITE_OK; } /* -** Dereference a page. When the reference count reaches zero, -** move the page to the LRU list if it is clean. +** Decrement the reference count on a page. If the page is clean and the +** reference count drops to 0, then it is made elible for recycling. */ void sqlite3PcacheRelease(PgHdr *p){ assert( p->nRef>0 ); p->nRef--; if( p->nRef==0 ){ PCache *pCache = p->pCache; pCache->nRef--; if( (p->flags&PGHDR_DIRTY)==0 ){ - pCache->nPinned--; - pcacheEnterMutex(); - if( pcache_g.nCurrentPage>pcache_g.nMaxPage ){ - pcacheRemoveFromList(&pCache->pClean, p); - pcacheRemoveFromHash(p); - pcachePageFree(p); - }else{ - pcacheAddToLruList(p); - } - pcacheExitMutex(); + pcacheUnpin(p); }else{ - /* Move the page to the head of the caches dirty list. */ - pcacheRemoveFromList(&pCache->pDirty, p); - pcacheAddToList(&pCache->pDirty, p); + /* Move the page to the head of the dirty list. */ + pcacheRemoveFromDirtyList(p); + pcacheAddToDirtyList(p); } } } +/* +** Increase the reference count of a supplied page by 1. +*/ void sqlite3PcacheRef(PgHdr *p){ assert(p->nRef>0); p->nRef++; } @@ -776,225 +313,134 @@ ** page pointed to by p is invalid. */ void sqlite3PcacheDrop(PgHdr *p){ PCache *pCache; assert( p->nRef==1 ); - assert( 0==(p->flags&PGHDR_DIRTY) ); + if( p->flags&PGHDR_DIRTY ){ + pcacheRemoveFromDirtyList(p); + } pCache = p->pCache; pCache->nRef--; - pCache->nPinned--; - pcacheEnterMutex(); - pcacheRemoveFromList(&pCache->pClean, p); - pcacheRemoveFromHash(p); - pcachePageFree(p); - pcacheExitMutex(); + if( p->pgno==1 ){ + pCache->pPage1 = 0; + } + sqlite3GlobalConfig.pcache.xUnpin(pCache->pCache, p, 1); } /* -** Make sure the page is marked as dirty. If it isn't dirty already, +** Make sure the page is marked as dirty. If it isn't dirty already, ** make it so. */ void sqlite3PcacheMakeDirty(PgHdr *p){ PCache *pCache; p->flags &= ~PGHDR_DONT_WRITE; - if( p->flags & PGHDR_DIRTY ) return; - assert( (p->flags & PGHDR_DIRTY)==0 ); assert( p->nRef>0 ); - pCache = p->pCache; - pcacheEnterMutex(); - pcacheRemoveFromList(&pCache->pClean, p); - pcacheAddToList(&pCache->pDirty, p); - pcacheExitMutex(); - p->flags |= PGHDR_DIRTY; -} - -static void pcacheMakeClean(PgHdr *p){ - PCache *pCache = p->pCache; - assert( p->flags & PGHDR_DIRTY ); - pcacheRemoveFromList(&pCache->pDirty, p); - pcacheAddToList(&pCache->pClean, p); - p->flags &= ~PGHDR_DIRTY; - if( p->nRef==0 ){ - pcacheAddToLruList(p); - pCache->nPinned--; + if( 0==(p->flags & PGHDR_DIRTY) ){ + pCache = p->pCache; + p->flags |= PGHDR_DIRTY; + pcacheAddToDirtyList( p); } - expensive_assert( pCache->nPinned==pcachePinnedCount(pCache) ); } /* -** Make sure the page is marked as clean. If it isn't clean already, +** Make sure the page is marked as clean. If it isn't clean already, ** make it so. */ void sqlite3PcacheMakeClean(PgHdr *p){ if( (p->flags & PGHDR_DIRTY) ){ - pcacheEnterMutex(); - pcacheMakeClean(p); - pcacheExitMutex(); + pcacheRemoveFromDirtyList(p); + p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC); + if( p->nRef==0 ){ + pcacheUnpin(p); + } } } /* ** Make every page in the cache clean. */ void sqlite3PcacheCleanAll(PCache *pCache){ PgHdr *p; - pcacheEnterMutex(); while( (p = pCache->pDirty)!=0 ){ - pcacheRemoveFromList(&pCache->pDirty, p); - p->flags &= ~PGHDR_DIRTY; - pcacheAddToList(&pCache->pClean, p); - if( p->nRef==0 ){ - pcacheAddToLruList(p); - pCache->nPinned--; - } + sqlite3PcacheMakeClean(p); + } +} + +/* +** Clear the PGHDR_NEED_SYNC flag from all dirty pages. +*/ +void sqlite3PcacheClearSyncFlags(PCache *pCache){ + PgHdr *p; + for(p=pCache->pDirty; p; p=p->pDirtyNext){ + p->flags &= ~PGHDR_NEED_SYNC; } - sqlite3PcacheAssertFlags(pCache, 0, PGHDR_DIRTY); - expensive_assert( pCache->nPinned==pcachePinnedCount(pCache) ); - pcacheExitMutex(); + pCache->pSynced = pCache->pDirtyTail; } /* -** Change the page number of page p to newPgno. If newPgno is 0, then the -** page object is added to the clean-list and the PGHDR_REUSE_UNLIKELY -** flag set. +** Change the page number of page p to newPgno. */ void sqlite3PcacheMove(PgHdr *p, Pgno newPgno){ + PCache *pCache = p->pCache; assert( p->nRef>0 ); - pcacheEnterMutex(); - pcacheRemoveFromHash(p); + assert( newPgno>0 ); + sqlite3GlobalConfig.pcache.xRekey(pCache->pCache, p, p->pgno, newPgno); p->pgno = newPgno; - if( newPgno==0 ){ - if( (p->flags & PGHDR_DIRTY) ){ - pcacheMakeClean(p); - } - p->flags = PGHDR_REUSE_UNLIKELY; + if( (p->flags&PGHDR_DIRTY) && (p->flags&PGHDR_NEED_SYNC) ){ + pcacheRemoveFromDirtyList(p); + pcacheAddToDirtyList(p); } - pcacheAddToHash(p); - pcacheExitMutex(); } /* -** Remove all content from a page cache -*/ -static void pcacheClear(PCache *pCache){ - PgHdr *p, *pNext; - assert( sqlite3_mutex_held(pcache_g.mutex) ); - for(p=pCache->pClean; p; p=pNext){ - pNext = p->pNext; - pcacheRemoveFromLruList(p); - pcachePageFree(p); - } - for(p=pCache->pDirty; p; p=pNext){ - pNext = p->pNext; - pcachePageFree(p); - } - pCache->pClean = 0; - pCache->pDirty = 0; - pCache->pDirtyTail = 0; - pCache->nPage = 0; - pCache->nPinned = 0; - memset(pCache->apHash, 0, pCache->nHash*sizeof(pCache->apHash[0])); -} - - -/* -** Drop every cache entry whose page number is greater than "pgno". +** Drop every cache entry whose page number is greater than "pgno". The +** caller must ensure that there are no outstanding references to any pages +** other than page 1 with a page number greater than pgno. +** +** If there is a reference to page 1 and the pgno parameter passed to this +** function is 0, then the data area associated with page 1 is zeroed, but +** the page object is not dropped. */ void sqlite3PcacheTruncate(PCache *pCache, Pgno pgno){ - PgHdr *p, *pNext; - PgHdr *pDirty = pCache->pDirty; - pcacheEnterMutex(); - for(p=pCache->pClean; p||pDirty; p=pNext){ - if( !p ){ - p = pDirty; - pDirty = 0; - } - pNext = p->pNext; - if( p->pgno>pgno ){ - if( p->nRef==0 ){ - pcacheRemoveFromHash(p); - if( p->flags&PGHDR_DIRTY ){ - pcacheRemoveFromList(&pCache->pDirty, p); - pCache->nPinned--; - }else{ - pcacheRemoveFromList(&pCache->pClean, p); - pcacheRemoveFromLruList(p); - } - pcachePageFree(p); - }else{ - /* If there are references to the page, it cannot be freed. In this - ** case, zero the page content instead. - */ - memset(p->pData, 0, pCache->szPage); + if( pCache->pCache ){ + PgHdr *p; + PgHdr *pNext; + for(p=pCache->pDirty; p; p=pNext){ + pNext = p->pDirtyNext; + if( p->pgno>pgno ){ + assert( p->flags&PGHDR_DIRTY ); + sqlite3PcacheMakeClean(p); } } - } - pcacheExitMutex(); -} - -/* -** If there are currently more than pcache.nMaxPage pages allocated, try -** to recycle pages to reduce the number allocated to pcache.nMaxPage. -*/ -static void pcacheEnforceMaxPage(void){ - PgHdr *p; - assert( sqlite3_mutex_held(pcache_g.mutex) ); - while( pcache_g.nCurrentPage>pcache_g.nMaxPage - && (p = pcacheRecyclePage())!=0 ){ - pcachePageFree(p); + if( pgno==0 && pCache->pPage1 ){ + memset(pCache->pPage1->pData, 0, pCache->szPage); + pgno = 1; + } + sqlite3GlobalConfig.pcache.xTruncate(pCache->pCache, pgno+1); } } /* ** Close a cache. */ void sqlite3PcacheClose(PCache *pCache){ - pcacheEnterMutex(); - - /* Free all the pages used by this pager and remove them from the LRU list. */ - pcacheClear(pCache); - if( pCache->bPurgeable ){ - pcache_g.nMaxPage -= pCache->nMax; - pcache_g.nMinPage -= pCache->nMin; - pcacheEnforceMaxPage(); - } - sqlite3_free(pCache->apHash); - pcacheExitMutex(); -} - - -#ifndef NDEBUG -/* -** Assert flags settings on all pages. Debugging only. -*/ -void sqlite3PcacheAssertFlags(PCache *pCache, int trueMask, int falseMask){ - PgHdr *p; - for(p=pCache->pDirty; p; p=p->pNext){ - assert( (p->flags&trueMask)==trueMask ); - assert( (p->flags&falseMask)==0 ); - } - for(p=pCache->pClean; p; p=p->pNext){ - assert( (p->flags&trueMask)==trueMask ); - assert( (p->flags&falseMask)==0 ); + if( pCache->pCache ){ + sqlite3GlobalConfig.pcache.xDestroy(pCache->pCache); } } -#endif /* ** Discard the contents of the cache. */ int sqlite3PcacheClear(PCache *pCache){ - assert(pCache->nRef==0); - pcacheEnterMutex(); - pcacheClear(pCache); - pcacheExitMutex(); + sqlite3PcacheTruncate(pCache, 0); return SQLITE_OK; } /* ** Merge two lists of pages connected by pDirty and in pgno order. -** Do not both fixing the pPrevDirty pointers. +** Do not both fixing the pDirtyPrev pointers. */ static PgHdr *pcacheMergeDirtyList(PgHdr *pA, PgHdr *pB){ PgHdr result, *pTail; pTail = &result; while( pA && pB ){ @@ -1018,11 +464,11 @@ return result.pDirty; } /* ** Sort the list of pages in accending order by pgno. Pages are -** connected by pDirty pointers. The pPrevDirty pointers are +** connected by pDirty pointers. The pDirtyPrev pointers are ** corrupted by this sort. */ #define N_SORT_BUCKET_ALLOC 25 #define N_SORT_BUCKET 25 #ifdef SQLITE_TEST @@ -1067,142 +513,67 @@ /* ** Return a list of all dirty pages in the cache, sorted by page number. */ PgHdr *sqlite3PcacheDirtyList(PCache *pCache){ PgHdr *p; - for(p=pCache->pDirty; p; p=p->pNext){ - p->pDirty = p->pNext; + for(p=pCache->pDirty; p; p=p->pDirtyNext){ + p->pDirty = p->pDirtyNext; } return pcacheSortDirtyList(pCache->pDirty); } /* -** Return the total number of outstanding page references. +** Return the total number of referenced pages held by the cache. */ int sqlite3PcacheRefCount(PCache *pCache){ return pCache->nRef; } +/* +** Return the number of references to the page supplied as an argument. +*/ int sqlite3PcachePageRefcount(PgHdr *p){ return p->nRef; } /* ** Return the total number of pages in the cache. */ int sqlite3PcachePagecount(PCache *pCache){ - assert( pCache->nPage>=0 ); - return pCache->nPage; -} - -#ifdef SQLITE_CHECK_PAGES -/* -** This function is used by the pager.c module to iterate through all -** pages in the cache. At present, this is only required if the -** SQLITE_CHECK_PAGES macro (used for debugging) is specified. -*/ -void sqlite3PcacheIterate(PCache *pCache, void (*xIter)(PgHdr *)){ - PgHdr *p; - for(p=pCache->pClean; p; p=p->pNext){ - xIter(p); + int nPage = 0; + if( pCache->pCache ){ + nPage = sqlite3GlobalConfig.pcache.xPagecount(pCache->pCache); } - for(p=pCache->pDirty; p; p=p->pNext){ - xIter(p); - } -} -#endif - -/* -** Set flags on all pages in the page cache -*/ -void sqlite3PcacheClearFlags(PCache *pCache, int mask){ - PgHdr *p; - - /* Obtain the global mutex before modifying any PgHdr.flags variables - ** or traversing the LRU list. - */ - pcacheEnterMutex(); - - mask = ~mask; - for(p=pCache->pDirty; p; p=p->pNext){ - p->flags &= mask; - } - for(p=pCache->pClean; p; p=p->pNext){ - p->flags &= mask; - } - - if( 0==(mask&PGHDR_NEED_SYNC) ){ - pCache->pSynced = pCache->pDirtyTail; - assert( !pCache->pSynced || (pCache->pSynced->flags&PGHDR_NEED_SYNC)==0 ); - } - - pcacheExitMutex(); + return nPage; } /* -** Set the suggested cache-size value. +** Get the suggested cache-size value. */ int sqlite3PcacheGetCachesize(PCache *pCache){ return pCache->nMax; } /* ** Set the suggested cache-size value. */ void sqlite3PcacheSetCachesize(PCache *pCache, int mxPage){ - if( mxPage<10 ){ - mxPage = 10; - } - if( pCache->bPurgeable ){ - pcacheEnterMutex(); - pcache_g.nMaxPage -= pCache->nMax; - pcache_g.nMaxPage += mxPage; - pcacheEnforceMaxPage(); - pcacheExitMutex(); - } pCache->nMax = mxPage; + if( pCache->pCache ){ + sqlite3GlobalConfig.pcache.xCachesize(pCache->pCache, mxPage); + } } -#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT +#ifdef SQLITE_CHECK_PAGES /* -** This function is called to free superfluous dynamically allocated memory -** held by the pager system. Memory in use by any SQLite pager allocated -** by the current thread may be sqlite3_free()ed. -** -** nReq is the number of bytes of memory required. Once this much has -** been released, the function returns. The return value is the total number -** of bytes of memory released. +** For all dirty pages currently in the cache, invoke the specified +** callback. This is only used if the SQLITE_CHECK_PAGES macro is +** defined. */ -int sqlite3PcacheReleaseMemory(int nReq){ - int nFree = 0; - if( pcache_g.pStart==0 ){ - PgHdr *p; - pcacheEnterMutex(); - while( (nReq<0 || nFreepDirty; pDirty; pDirty=pDirty->pDirtyNext){ + xIter(pDirty); } - return nFree; -} -#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */ - -#ifdef SQLITE_TEST -void sqlite3PcacheStats( - int *pnCurrent, - int *pnMax, - int *pnMin, - int *pnRecyclable -){ - PgHdr *p; - int nRecyclable = 0; - for(p=pcache_g.pLruHead; p; p=p->pNextLru){ - nRecyclable++; - } - - *pnCurrent = pcache_g.nCurrentPage; - *pnMax = pcache_g.nMaxPage; - *pnMin = pcache_g.nMinPage; - *pnRecyclable = nRecyclable; } #endif + Index: src/pcache.h ================================================================== --- src/pcache.h +++ src/pcache.h @@ -10,11 +10,11 @@ ** ************************************************************************* ** This header file defines the interface that the sqlite page cache ** subsystem. ** -** @(#) $Id: pcache.h,v 1.14 2008/10/17 18:51:53 danielk1977 Exp $ +** @(#) $Id: pcache.h,v 1.15 2008/11/13 14:28:29 danielk1977 Exp $ */ #ifndef _PCACHE_H_ typedef struct PgHdr PgHdr; @@ -32,29 +32,23 @@ Pager *pPager; /* The pager this page is part of */ #ifdef SQLITE_CHECK_PAGES u32 pageHash; /* Hash of page content */ #endif u16 flags; /* PGHDR flags defined below */ + /********************************************************************** ** Elements above are public. All that follows is private to pcache.c ** and should not be accessed by other modules. */ i16 nRef; /* Number of users of this page */ PCache *pCache; /* Cache that owns this page */ - /********************************************************************** - ** Elements above are accessible at any time by the owner of the cache - ** without the need for a mutex. The elements that follow can only be - ** accessed while holding the SQLITE_MUTEX_STATIC_LRU mutex. - */ - PgHdr *pNextHash, *pPrevHash; /* Hash collision chain for PgHdr.pgno */ - PgHdr *pNext, *pPrev; /* List of clean or dirty pages */ - PgHdr *pNextLru, *pPrevLru; /* Part of global LRU list */ + PgHdr *pDirtyNext; /* Next element in list of dirty pages */ + PgHdr *pDirtyPrev; /* Previous element in list of dirty pages */ }; /* Bit values for PgHdr.flags */ -#define PGHDR_IN_JOURNAL 0x001 /* Page is in rollback journal */ #define PGHDR_DIRTY 0x002 /* Page has changed */ #define PGHDR_NEED_SYNC 0x004 /* Fsync the rollback journal before ** writing this page to the database */ #define PGHDR_NEED_READ 0x008 /* Content is unread */ #define PGHDR_REUSE_UNLIKELY 0x010 /* A hint that reuse is unlikely */ @@ -114,18 +108,11 @@ /* Reset and close the cache object */ void sqlite3PcacheClose(PCache*); /* Clear flags from pages of the page cache */ -void sqlite3PcacheClearFlags(PCache*, int mask); - -/* Assert flags settings on all pages. Debugging only */ -#ifndef NDEBUG - void sqlite3PcacheAssertFlags(PCache*, int trueMask, int falseMask); -#else -# define sqlite3PcacheAssertFlags(A,B,C) -#endif +void sqlite3PcacheClearSyncFlags(PCache *); /* Return true if the number of dirty pages is 0 or 1 */ int sqlite3PcacheZeroOrOneDirtyPages(PCache*); /* Discard the contents of the cache */ @@ -141,15 +128,15 @@ /* Return the total number of pages stored in the cache */ int sqlite3PcachePagecount(PCache*); #ifdef SQLITE_CHECK_PAGES -/* Iterate through all pages currently stored in the cache. This interface -** is only available if SQLITE_CHECK_PAGES is defined when the library is -** built. +/* Iterate through all dirty pages currently stored in the cache. This +** interface is only available if SQLITE_CHECK_PAGES is defined when the +** library is built. */ -void sqlite3PcacheIterate(PCache *pCache, void (*xIter)(PgHdr *)); +void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *)); #endif /* Set and get the suggested cache-size for the specified pager-cache. ** ** If no global maximum is configured, then the system attempts to limit @@ -165,7 +152,9 @@ #endif #ifdef SQLITE_TEST void sqlite3PcacheStats(int*,int*,int*,int*); #endif + +void sqlite3PCacheSetDefault(void); #endif /* _PCACHE_H_ */ ADDED src/pcache1.c Index: src/pcache1.c ================================================================== --- src/pcache1.c +++ src/pcache1.c @@ -0,0 +1,735 @@ +/* +** 2008 November 05 +** +** The author disclaims copyright to this source code. In place of +** a legal notice, here is a blessing: +** +** May you do good and not evil. +** May you find forgiveness for yourself and forgive others. +** May you share freely, never taking more than you give. +** +************************************************************************* +** +** This file implements the default page cache implementation (the +** sqlite3_pcache interface). It also contains part of the implementation +** of the SQLITE_CONFIG_PAGECACHE and sqlite3_release_memory() features. +** If the default page cache implementation is overriden, then neither of +** these two features are available. +** +** @(#) $Id: pcache1.c,v 1.1 2008/11/13 14:28:29 danielk1977 Exp $ +*/ + +#include "sqliteInt.h" + +typedef struct PCache1 PCache1; +typedef struct PgHdr1 PgHdr1; +typedef struct PgFreeslot PgFreeslot; + +/* Pointers to structures of this type are cast and returned as +** opaque sqlite3_pcache* handles +*/ +struct PCache1 { + /* Cache configuration parameters. Page size (szPage) and the purgeable + ** flag (bPurgeable) are set when the cache is created. nMax may be + ** modified at any time by a call to the pcache1CacheSize() method. + ** The global mutex must be held when accessing nMax. + */ + int szPage; /* Size of allocated pages in bytes */ + int bPurgeable; /* True if cache is purgeable */ + int nMin; /* Minimum number of pages reserved */ + int nMax; /* Configured "cache_size" value */ + + /* Hash table of all pages. The following variables may only be accessed + ** when the accessor is holding the global mutex (see pcache1EnterMutex() + ** and pcache1LeaveMutex()). + */ + int nRecyclable; /* Number of pages in the LRU list */ + int nPage; /* Total number of pages in apHash */ + int nHash; /* Number of slots in apHash[] */ + PgHdr1 **apHash; /* Hash table for fast lookup by key */ +}; + +/* +** Each cache entry is represented by an instance of the following +** structure. A buffer of PgHdr1.pCache->szPage bytes is allocated +** directly after the structure in memory (see the PGHDR1_TO_PAGE() +** macro below). +*/ +struct PgHdr1 { + unsigned int iKey; /* Key value (page number) */ + PgHdr1 *pNext; /* Next in hash table chain */ + PCache1 *pCache; /* Cache that currently owns this page */ + PgHdr1 *pLruNext; /* Next in LRU list of unpinned pages */ + PgHdr1 *pLruPrev; /* Previous in LRU list of unpinned pages */ +}; + +/* +** Free slots in the allocator used to divide up the buffer provided using +** the SQLITE_CONFIG_PAGECACHE mechanism. +*/ +struct PgFreeslot { + PgFreeslot *pNext; /* Next free slot */ +}; + +/* +** Global data used by this cache. +*/ +static SQLITE_WSD struct PCacheGlobal { + sqlite3_mutex *mutex; /* static mutex MUTEX_STATIC_LRU */ + + int nMaxPage; /* Sum of nMaxPage for purgeable caches */ + int nMinPage; /* Sum of nMinPage for purgeable caches */ + int nCurrentPage; /* Number of purgeable pages allocated */ + PgHdr1 *pLruHead, *pLruTail; /* LRU list of unpinned pages */ + + /* Variables related to SQLITE_CONFIG_PAGECACHE settings. */ + int szSlot; /* Size of each free slot */ + void *pStart, *pEnd; /* Bounds of pagecache malloc range */ + PgFreeslot *pFree; /* Free page blocks */ +} pcache1_g = {0}; + +/* +** All code in this file should access the global structure above via the +** alias "pcache1". This ensures that the WSD emulation is used when +** compiling for systems that do not support real WSD. +*/ +#define pcache1 (GLOBAL(struct PCacheGlobal, pcache1_g)) + +/* +** When a PgHdr1 structure is allocated, the associated PCache1.szPage +** bytes of data are located directly after it in memory (i.e. the total +** size of the allocation is sizeof(PgHdr1)+PCache1.szPage byte). The +** PGHDR1_TO_PAGE() macro takes a pointer to a PgHdr1 structure as +** an argument and returns a pointer to the associated block of szPage +** bytes. The PAGE_TO_PGHDR1() macro does the opposite: its argument is +** a pointer to a block of szPage bytes of data and the return value is +** a pointer to the associated PgHdr1 structure. +** +** assert( PGHDR1_TO_PAGE(PAGE_TO_PGHDR1(X))==X ); +*/ +#define PGHDR1_TO_PAGE(p) (void *)(&((unsigned char *)p)[sizeof(PgHdr1)]) +#define PAGE_TO_PGHDR1(p) (PgHdr1 *)(&((unsigned char *)p)[-1*sizeof(PgHdr1)]) + +/* +** Macros to enter and leave the global LRU mutex. +*/ +#define pcache1EnterMutex() sqlite3_mutex_enter(pcache1.mutex) +#define pcache1LeaveMutex() sqlite3_mutex_leave(pcache1.mutex) + +/******************************************************************************/ +/******** Page Allocation/SQLITE_CONFIG_PCACHE Related Functions **************/ + +/* +** This function is called during initialization if a static buffer is +** supplied to use for the page-cache by passing the SQLITE_CONFIG_PAGECACHE +** verb to sqlite3_config(). Parameter pBuf points to an allocation large +** enough to contain 'n' buffers of 'sz' bytes each. +*/ +void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){ + PgFreeslot *p; + sz &= ~7; + pcache1.szSlot = sz; + pcache1.pStart = pBuf; + pcache1.pFree = 0; + while( n-- ){ + p = (PgFreeslot*)pBuf; + p->pNext = pcache1.pFree; + pcache1.pFree = p; + pBuf = (void*)&((char*)pBuf)[sz]; + } + pcache1.pEnd = pBuf; +} + +/* +** Malloc function used within this file to allocate space from the buffer +** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no +** such buffer exists or there is no space left in it, this function falls +** back to sqlite3Malloc(). +*/ +static void *pcache1Alloc(int nByte){ + void *p; + assert( sqlite3_mutex_held(pcache1.mutex) ); + if( nByte<=pcache1.szSlot && pcache1.pFree ){ + p = (PgHdr1 *)pcache1.pFree; + pcache1.pFree = pcache1.pFree->pNext; + sqlite3StatusSet(SQLITE_STATUS_PAGECACHE_SIZE, nByte); + sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, 1); + }else{ + + /* Allocate a new buffer using sqlite3Malloc. Before doing so, exit the + ** global pcache mutex and unlock the pager-cache object pCache. This is + ** so that if the attempt to allocate a new buffer causes the the + ** configured soft-heap-limit to be breached, it will be possible to + ** reclaim memory from this pager-cache. + */ + pcache1LeaveMutex(); + p = sqlite3Malloc(nByte); + pcache1EnterMutex(); + if( p ){ + int sz = sqlite3MallocSize(p); + sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz); + } + } + return p; +} + +/* +** Free an allocated buffer obtained from pcache1Alloc(). +*/ +static void pcache1Free(void *p){ + assert( sqlite3_mutex_held(pcache1.mutex) ); + if( p==0 ) return; + if( p>=pcache1.pStart && ppNext = pcache1.pFree; + pcache1.pFree = pSlot; + }else{ + int iSize = sqlite3MallocSize(p); + sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, -iSize); + sqlite3_free(p); + } +} + +/* +** Allocate a new page object initially associated with cache pCache. +*/ +static PgHdr1 *pcache1AllocPage(PCache1 *pCache){ + int nByte = sizeof(PgHdr1) + pCache->szPage; + PgHdr1 *p = (PgHdr1 *)pcache1Alloc(nByte); + if( p ){ + memset(p, 0, nByte); + if( pCache->bPurgeable ){ + pcache1.nCurrentPage++; + } + } + return p; +} + +/* +** Free a page object allocated by pcache1AllocPage(). +*/ +static void pcache1FreePage(PgHdr1 *p){ + if( p ){ + if( p->pCache->bPurgeable ){ + pcache1.nCurrentPage--; + } + pcache1Free(p); + } +} + +/* +** Malloc function used by SQLite to obtain space from the buffer configured +** using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no such buffer +** exists, this function falls back to sqlite3Malloc(). +*/ +void *sqlite3PageMalloc(int sz){ + void *p; + pcache1EnterMutex(); + p = pcache1Alloc(sz); + pcache1LeaveMutex(); + return p; +} + +/* +** Free an allocated buffer obtained from sqlite3PageMalloc(). +*/ +void sqlite3PageFree(void *p){ + pcache1EnterMutex(); + pcache1Free(p); + pcache1LeaveMutex(); +} + +/******************************************************************************/ +/******** General Implementation Functions ************************************/ + +/* +** This function is used to resize the hash table used by the cache passed +** as the first argument. +** +** The global mutex must be held when this function is called. +*/ +static int pcache1ResizeHash(PCache1 *p){ + PgHdr1 **apNew; + int nNew; + unsigned int i; + + assert( sqlite3_mutex_held(pcache1.mutex) ); + + nNew = p->nHash*2; + if( nNew<256 ){ + nNew = 256; + } + + pcache1LeaveMutex(); + apNew = (PgHdr1 **)sqlite3_malloc(sizeof(PgHdr1 *)*nNew); + pcache1EnterMutex(); + if( apNew ){ + memset(apNew, 0, sizeof(PgHdr1 *)*nNew); + for(i=0; inHash; i++){ + PgHdr1 *pPage; + PgHdr1 *pNext = p->apHash[i]; + while( (pPage = pNext) ){ + unsigned int h = pPage->iKey % nNew; + pNext = pPage->pNext; + pPage->pNext = apNew[h]; + apNew[h] = pPage; + } + } + sqlite3_free(p->apHash); + p->apHash = apNew; + p->nHash = nNew; + } + + return (p->apHash ? SQLITE_OK : SQLITE_NOMEM); +} + +/* +** This function is used internally to remove the page pPage from the +** global LRU list, if is part of it. If pPage is not part of the global +** LRU list, then this function is a no-op. +** +** The global mutex must be held when this function is called. +*/ +static void pcache1PinPage(PgHdr1 *pPage){ + assert( sqlite3_mutex_held(pcache1.mutex) ); + if( pPage && (pPage->pLruNext || pPage==pcache1.pLruTail) ){ + if( pPage->pLruPrev ){ + pPage->pLruPrev->pLruNext = pPage->pLruNext; + } + if( pPage->pLruNext ){ + pPage->pLruNext->pLruPrev = pPage->pLruPrev; + } + if( pcache1.pLruHead==pPage ){ + pcache1.pLruHead = pPage->pLruNext; + } + if( pcache1.pLruTail==pPage ){ + pcache1.pLruTail = pPage->pLruPrev; + } + pPage->pLruNext = 0; + pPage->pLruPrev = 0; + pPage->pCache->nRecyclable--; + } +} + + +/* +** Remove the page supplied as an argument from the hash table +** (PCache1.apHash structure) that it is currently stored in. +** +** The global mutex must be held when this function is called. +*/ +static void pcache1RemoveFromHash(PgHdr1 *pPage){ + unsigned int h; + PCache1 *pCache = pPage->pCache; + PgHdr1 **pp; + + h = pPage->iKey % pCache->nHash; + for(pp=&pCache->apHash[h]; (*pp)!=pPage; pp=&(*pp)->pNext); + *pp = (*pp)->pNext; + + pCache->nPage--; +} + +/* +** If there are currently more than pcache.nMaxPage pages allocated, try +** to recycle pages to reduce the number allocated to pcache.nMaxPage. +*/ +static void pcache1EnforceMaxPage(void){ + assert( sqlite3_mutex_held(pcache1.mutex) ); + while( pcache1.nCurrentPage>pcache1.nMaxPage && pcache1.pLruTail ){ + PgHdr1 *p = pcache1.pLruTail; + pcache1PinPage(p); + pcache1RemoveFromHash(p); + pcache1FreePage(p); + } +} + +/* +** Discard all pages from cache pCache with a page number (key value) +** greater than or equal to iLimit. Any pinned pages that meet this +** criteria are unpinned before they are discarded. +** +** The global mutex must be held when this function is called. +*/ +static void pcache1TruncateUnsafe( + PCache1 *pCache, + unsigned int iLimit +){ + unsigned int h; + assert( sqlite3_mutex_held(pcache1.mutex) ); + for(h=0; hnHash; h++){ + PgHdr1 **pp = &pCache->apHash[h]; + PgHdr1 *pPage; + while( (pPage = *pp) ){ + if( pPage->iKey>=iLimit ){ + pcache1PinPage(pPage); + *pp = pPage->pNext; + pcache1FreePage(pPage); + }else{ + pp = &pPage->pNext; + } + } + } +} + +/******************************************************************************/ +/******** sqlite3_pcache Methods **********************************************/ + +/* +** Implementation of the sqlite3_pcache.xInit method. +*/ +static int pcache1Init(void *pUnused){ + memset(&pcache1, 0, sizeof(pcache1)); + if( sqlite3GlobalConfig.bCoreMutex ){ + pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU); + } + return SQLITE_OK; +} + +/* +** Implementation of the sqlite3_pcache.xShutdown method. +*/ +static void pcache1Shutdown(void *pUnused){ + /* no-op */ +} + +/* +** Implementation of the sqlite3_pcache.xCreate method. +** +** Allocate a new cache. +*/ +static sqlite3_pcache *pcache1Create(int szPage, int bPurgeable){ + PCache1 *pCache; + + pCache = (PCache1 *)sqlite3_malloc(sizeof(PCache1)); + if( pCache ){ + memset(pCache, 0, sizeof(PCache1)); + pCache->szPage = szPage; + pCache->bPurgeable = (bPurgeable ? 1 : 0); + if( bPurgeable ){ + pCache->nMin = 10; + pcache1EnterMutex(); + pcache1.nMinPage += pCache->nMin; + pcache1LeaveMutex(); + } + } + return (sqlite3_pcache *)pCache; +} + +/* +** Implementation of the sqlite3_pcache.xCachesize method. +** +** Configure the cache_size limit for a cache. +*/ +static void pcache1Cachesize(sqlite3_pcache *p, int nMax){ + PCache1 *pCache = (PCache1 *)p; + if( pCache->bPurgeable ){ + pcache1EnterMutex(); + pcache1.nMaxPage += (nMax - pCache->nMax); + pCache->nMax = nMax; + pcache1EnforceMaxPage(); + pcache1LeaveMutex(); + } +} + +/* +** Implementation of the sqlite3_pcache.xPagecount method. +*/ +static int pcache1Pagecount(sqlite3_pcache *p){ + int n; + pcache1EnterMutex(); + n = ((PCache1 *)p)->nPage; + pcache1LeaveMutex(); + return n; +} + +/* +** Implementation of the sqlite3_pcache.xFetch method. +** +** Fetch a page by key value. +** +** Whether or not a new page may be allocated by this function depends on +** the value of the createFlag argument. +** +** There are three different approaches to obtaining space for a page, +** depending on the value of parameter createFlag (which may be 0, 1 or 2). +** +** 1. Regardless of the value of createFlag, the cache is searched for a +** copy of the requested page. If one is found, it is returned. +** +** 2. If createFlag==0 and the page is not already in the cache, NULL is +** returned. +** +** 3. If createFlag is 1, the cache is marked as purgeable and the page is +** not already in the cache, and if either of the following are true, +** return NULL: +** +** (a) the number of pages pinned by the cache is greater than +** PCache1.nMax, or +** (b) the number of pages pinned by the cache is greater than +** the sum of nMax for all purgeable caches, less the sum of +** nMin for all other purgeable caches. +** +** 4. If none of the first three conditions apply and the cache is marked +** as purgeable, and if one of the following is true: +** +** (a) The number of pages allocated for the cache is already +** PCache1.nMax, or +** +** (b) The number of pages allocated for all purgeable caches is +** already equal to or greater than the sum of nMax for all +** purgeable caches, +** +** then attempt to recycle a page from the LRU list. If it is the right +** size, return the recycled buffer. Otherwise, free the buffer and +** proceed to step 5. +** +** 5. Otherwise, allocate and return a new page buffer. +*/ +static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){ + int nPinned; + PCache1 *pCache = (PCache1 *)p; + PgHdr1 *pPage = 0; + + pcache1EnterMutex(); + if( createFlag==1 ) sqlite3BeginBenignMalloc(); + + /* Search the hash table for an existing entry. */ + if( pCache->nHash>0 ){ + unsigned int h = iKey % pCache->nHash; + for(pPage=pCache->apHash[h]; pPage&&pPage->iKey!=iKey; pPage=pPage->pNext); + } + + if( pPage || createFlag==0 ){ + pcache1PinPage(pPage); + goto fetch_out; + } + + /* Step 3 of header comment. */ + nPinned = pCache->nPage - pCache->nRecyclable; + if( createFlag==1 && pCache->bPurgeable && ( + nPinned>=(pcache1.nMaxPage+pCache->nMin-pcache1.nMinPage) + || nPinned>=(pCache->nMax) + )){ + goto fetch_out; + } + + if( pCache->nPage>=pCache->nHash && pcache1ResizeHash(pCache) ){ + goto fetch_out; + } + + /* Step 4. Try to recycle a page buffer if appropriate. */ + if( pCache->bPurgeable && pcache1.pLruTail && ( + pCache->nPage>=pCache->nMax-1 || pcache1.nCurrentPage>=pcache1.nMaxPage + )){ + pPage = pcache1.pLruTail; + pcache1RemoveFromHash(pPage); + pcache1PinPage(pPage); + if( pPage->pCache->szPage!=pCache->szPage ){ + pcache1FreePage(pPage); + pPage = 0; + }else{ + pcache1.nCurrentPage -= (pPage->pCache->bPurgeable - pCache->bPurgeable); + } + } + + /* Step 5. If a usable page buffer has still not been found, + ** attempt to allocate a new one. + */ + if( !pPage ){ + pPage = pcache1AllocPage(pCache); + } + + if( pPage ){ + unsigned int h = iKey % pCache->nHash; + memset(pPage, 0, pCache->szPage + sizeof(PgHdr1)); + pCache->nPage++; + pPage->iKey = iKey; + pPage->pNext = pCache->apHash[h]; + pPage->pCache = pCache; + pCache->apHash[h] = pPage; + } + +fetch_out: + if( createFlag==1 ) sqlite3EndBenignMalloc(); + pcache1LeaveMutex(); + return (pPage ? PGHDR1_TO_PAGE(pPage) : 0); +} + + +/* +** Implementation of the sqlite3_pcache.xUnpin method. +** +** Mark a page as unpinned (eligible for asynchronous recycling). +*/ +static void pcache1Unpin(sqlite3_pcache *p, void *pPg, int reuseUnlikely){ + PCache1 *pCache = (PCache1 *)p; + PgHdr1 *pPage = PAGE_TO_PGHDR1(pPg); + + pcache1EnterMutex(); + + /* It is an error to call this function if the page is already + ** part of the global LRU list. + */ + assert( pPage->pLruPrev==0 && pPage->pLruNext==0 ); + assert( pcache1.pLruHead!=pPage && pcache1.pLruTail!=pPage ); + + if( reuseUnlikely || pcache1.nCurrentPage>pcache1.nMaxPage ){ + pcache1RemoveFromHash(pPage); + pcache1FreePage(pPage); + }else{ + /* Add the page to the global LRU list. Normally, the page is added to + ** the head of the list (last page to be recycled). However, if the + ** reuseUnlikely flag passed to this function is true, the page is added + ** to the tail of the list (first page to be recycled). + */ + if( pcache1.pLruHead ){ + pcache1.pLruHead->pLruPrev = pPage; + pPage->pLruNext = pcache1.pLruHead; + pcache1.pLruHead = pPage; + }else{ + pcache1.pLruTail = pPage; + pcache1.pLruHead = pPage; + } + pCache->nRecyclable++; + } + + pcache1LeaveMutex(); +} + +/* +** Implementation of the sqlite3_pcache.xRekey method. +*/ +static void pcache1Rekey( + sqlite3_pcache *p, + void *pPg, + unsigned int iOld, + unsigned int iNew +){ + PCache1 *pCache = (PCache1 *)p; + PgHdr1 *pPage = PAGE_TO_PGHDR1(pPg); + PgHdr1 **pp; + unsigned int h; + assert( pPage->iKey==iOld ); + + pcache1EnterMutex(); + + h = iOld%pCache->nHash; + pp = &pCache->apHash[h]; + while( (*pp)!=pPage ){ + pp = &(*pp)->pNext; + } + *pp = pPage->pNext; + + h = iNew%pCache->nHash; + pPage->iKey = iNew; + pPage->pNext = pCache->apHash[h]; + pCache->apHash[h] = pPage; + + pcache1LeaveMutex(); +} + +/* +** Implementation of the sqlite3_pcache.xTruncate method. +** +** Discard all unpinned pages in the cache with a page number equal to +** or greater than parameter iLimit. Any pinned pages with a page number +** equal to or greater than iLimit are implicitly unpinned. +*/ +static void pcache1Truncate(sqlite3_pcache *p, unsigned int iLimit){ + PCache1 *pCache = (PCache1 *)p; + pcache1EnterMutex(); + pcache1TruncateUnsafe(pCache, iLimit); + pcache1LeaveMutex(); +} + +/* +** Implementation of the sqlite3_pcache.xDestroy method. +** +** Destroy a cache allocated using pcache1Create(). +*/ +static void pcache1Destroy(sqlite3_pcache *p){ + PCache1 *pCache = (PCache1 *)p; + pcache1EnterMutex(); + pcache1TruncateUnsafe(pCache, 0); + pcache1.nMaxPage -= pCache->nMax; + pcache1.nMinPage -= pCache->nMin; + pcache1EnforceMaxPage(); + pcache1LeaveMutex(); + sqlite3_free(pCache->apHash); + sqlite3_free(pCache); +} + +/* +** This function is called during initialization (sqlite3_initialize()) to +** install the default pluggable cache module, assuming the user has not +** already provided an alternative. +*/ +void sqlite3PCacheSetDefault(void){ + static sqlite3_pcache_methods defaultMethods = { + 0, /* pArg */ + pcache1Init, /* xInit */ + pcache1Shutdown, /* xShutdown */ + pcache1Create, /* xCreate */ + pcache1Cachesize, /* xCachesize */ + pcache1Pagecount, /* xPagecount */ + pcache1Fetch, /* xFetch */ + pcache1Unpin, /* xUnpin */ + pcache1Rekey, /* xRekey */ + pcache1Truncate, /* xTruncate */ + pcache1Destroy /* xDestroy */ + }; + sqlite3_config(SQLITE_CONFIG_PCACHE, &defaultMethods); +} + +#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT +/* +** This function is called to free superfluous dynamically allocated memory +** held by the pager system. Memory in use by any SQLite pager allocated +** by the current thread may be sqlite3_free()ed. +** +** nReq is the number of bytes of memory required. Once this much has +** been released, the function returns. The return value is the total number +** of bytes of memory released. +*/ +int sqlite3PcacheReleaseMemory(int nReq){ + int nFree = 0; + if( pcache1.pStart==0 ){ + PgHdr1 *p; + pcache1EnterMutex(); + while( (nReq<0 || nFreepLruNext){ + nRecyclable++; + } + *pnCurrent = pcache1.nCurrentPage; + *pnMax = pcache1.nMaxPage; + *pnMin = pcache1.nMinPage; + *pnRecyclable = nRecyclable; +} +#endif Index: src/sqlite.h.in ================================================================== --- src/sqlite.h.in +++ src/sqlite.h.in @@ -28,11 +28,11 @@ ** The name of this file under configuration management is "sqlite.h.in". ** The makefile makes some minor changes to this file (such as inserting ** the version number) and changes its name to "sqlite3.h" as ** part of the build process. ** -** @(#) $Id: sqlite.h.in,v 1.412 2008/11/10 23:54:06 drh Exp $ +** @(#) $Id: sqlite.h.in,v 1.413 2008/11/13 14:28:29 danielk1977 Exp $ */ #ifndef _SQLITE3_H_ #define _SQLITE3_H_ #include /* Needed for the definition of va_list */ @@ -1332,10 +1332,12 @@ #define SQLITE_CONFIG_MEMSTATUS 9 /* boolean */ #define SQLITE_CONFIG_MUTEX 10 /* sqlite3_mutex_methods* */ #define SQLITE_CONFIG_GETMUTEX 11 /* sqlite3_mutex_methods* */ /* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ #define SQLITE_CONFIG_LOOKASIDE 13 /* int int */ +#define SQLITE_CONFIG_PCACHE 14 /* sqlite3_pcache_methods* */ +#define SQLITE_CONFIG_GETPCACHE 15 /* sqlite3_pcache_methods* */ /* ** CAPI3REF: Configuration Options {H10170} ** EXPERIMENTAL ** @@ -6552,10 +6554,147 @@ ** ** */ #define SQLITE_STMTSTATUS_FULLSCAN_STEP 1 #define SQLITE_STMTSTATUS_SORT 2 + +/* +** The sqlite3_pcache type is opaque. It is implemented by +** the pluggable module. The SQLite core has no knowledge of +** its size or internal structure and never deals with the +** sqlite3_pcache object except by holding and passing pointers +** to the object. +*/ +typedef struct sqlite3_pcache sqlite3_pcache; + +/* +** CAPI3REF: Custom Page Cache API. +** EXPERIMENTAL +** +** The sqlite3_config(SQLITE_CONFIG_SET_PCACHE, ...) interface can +** register an alternative page cache implementation by passing in an +** instance of the sqlite3_pcache_methods structure. The majority of the +** heap memory used by sqlite is used by the page cache to cache data read +** from, or ready to be written to, the database file. By implementing a +** custom page cache using this API, an application can control more +** precisely the amount of memory consumed by sqlite, the way in which +** said memory is allocated and released, and the policies used to +** determine exactly which parts of a database file are cached and for +** how long. +** +** The contents of the structure are copied to an internal buffer by sqlite +** within the call to [sqlite3_config]. +** +** The xInit() method is called once for each call to sqlite3_initialize() +** (usually only once during the lifetime of the process). It is passed +** a copy of the sqlite3_pcache_methods.pArg value. It can be used to set +** up global structures and mutexes required by the custom page cache +** implementation. The xShutdown() method is called from within +** sqlite3_shutdown(), if the application invokes this API. It can be used +** to clean up any outstanding resources before process shutdown, if required. +** +** The xCreate() method is used to construct a new cache instance. The +** first parameter, szPage, is the size in bytes of the pages that must +** be allocated by the cache. szPage will not be a power of two. The +** second argument, bPurgeable, is true if the cache being created will +** be used to cache database pages read from a file stored on disk, or +** false if it is used for an in-memory database. The cache implementation +** does not have to do anything special based on the value of bPurgeable, +** it is purely advisory. +** +** The xCachesize() method may be called at any time by SQLite to set the +** suggested maximum cache-size (number of pages stored by) the cache +** instance passed as the first argument. This is the value configured using +** the SQLite "PRAGMA cache_size" command. As with the bPurgeable parameter, +** the implementation is not required to do anything special with this +** value, it is advisory only. +** +** The xPagecount() method should return the number of pages currently +** stored in the cache supplied as an argument. +** +** The xFetch() method is used to fetch a page and return a pointer to it. +** A 'page', in this context, is a buffer of szPage bytes aligned at an +** 8-byte boundary. The page to be fetched is determined by the key. The +** mimimum key value is 1. After it has been retrieved using xFetch, the page +** is considered to be pinned. +** +** If the requested page is already in the page cache, then a pointer to +** the cached buffer should be returned with its contents intact. If the +** page is not already in the cache, then the expected behaviour of the +** cache is determined by the value of the createFlag parameter passed +** to xFetch, according to the following table: +** +** +**
createFlagExpected Behaviour +**
0NULL should be returned. No new cache entry is created. +**
1If createFlag is set to 1, this indicates that +** SQLite is holding pinned pages that can be unpinned +** by writing their contents to the database file (a +** relatively expensive operation). In this situation the +** cache implementation has two choices: it can return NULL, +** in which case SQLite will attempt to unpin one or more +** pages before re-requesting the same page, or it can +** allocate a new page and return a pointer to it. If a new +** page is allocated, then it must be completely zeroed before +** it is returned. +**
2If createFlag is set to 2, then SQLite is not holding any +** pinned pages associated with the specific cache passed +** as the first argument to xFetch() that can be unpinned. The +** cache implementation should attempt to allocate a new +** cache entry and return a pointer to it. Again, the new +** page should be zeroed before it is returned. If the xFetch() +** method returns NULL when createFlag==2, SQLite assumes that +** a memory allocation failed and returns SQLITE_NOMEM to the +** user. +**
+** +** xUnpin() is called by SQLite with a pointer to a currently pinned page +** as its second argument. If the third parameter, discard, is non-zero, +** then the page should be evicted from the cache. In this case SQLite +** assumes that the next time the page is retrieved from the cache using +** the xFetch() method, it will be zeroed. If the discard parameter is +** zero, then the page is considered to be unpinned. The cache implementation +** may choose to reclaim (free or recycle) unpinned pages at any time. +** SQLite assumes that next time the page is retrieved from the cache +** it will either be zeroed, or contain the same data that it did when it +** was unpinned. +** +** The cache is not required to perform any reference counting. A single +** call to xUnpin() unpins the page regardless of the number of prior calls +** to xFetch(). +** +** The xRekey() method is used to change the key value associated with the +** page passed as the second argument from oldKey to newKey. If the cache +** contains an entry associated with oldKey, it should be discarded. Any +** cache entry associated with oldKey is guaranteed not to be pinned. +** +** When SQLite calls the xTruncate() method, the cache must discard all +** existing cache entries with page numbers (keys) greater than or equal +** to the value of the iLimit parameter passed to xTruncate(). If any +** of these pages are pinned, they are implicitly unpinned, meaning that +** they can be safely discarded. +** +** The xDestroy() method is used to delete a cache allocated by xCreate(). +** All resources associated with the specified cache should be freed. After +** calling the xDestroy() method, SQLite considers the sqlite3_pcache* +** handle invalid, and will not use it with any other sqlite3_pcache_methods +** functions. +*/ +typedef struct sqlite3_pcache_methods sqlite3_pcache_methods; +struct sqlite3_pcache_methods { + void *pArg; + int (*xInit)(void*); + void (*xShutdown)(void*); + sqlite3_pcache *(*xCreate)(int szPage, int bPurgeable); + void (*xCachesize)(sqlite3_pcache*, int nCachesize); + int (*xPagecount)(sqlite3_pcache*); + void *(*xFetch)(sqlite3_pcache*, unsigned key, int createFlag); + void (*xUnpin)(sqlite3_pcache*, void*, int discard); + void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey); + void (*xTruncate)(sqlite3_pcache*, unsigned iLimit); + void (*xDestroy)(sqlite3_pcache*); +}; /* ** Undo the hack that converts floating point types to integer for ** builds on processors without floating point support. */ Index: src/sqliteInt.h ================================================================== --- src/sqliteInt.h +++ src/sqliteInt.h @@ -9,11 +9,11 @@ ** May you share freely, never taking more than you give. ** ************************************************************************* ** Internal interface definitions for SQLite. ** -** @(#) $Id: sqliteInt.h,v 1.790 2008/11/11 18:29:00 drh Exp $ +** @(#) $Id: sqliteInt.h,v 1.791 2008/11/13 14:28:30 danielk1977 Exp $ */ #ifndef _SQLITEINT_H_ #define _SQLITEINT_H_ /* @@ -1956,10 +1956,11 @@ int mxStrlen; /* Maximum string length */ int szLookaside; /* Default lookaside buffer size */ int nLookaside; /* Default lookaside buffer count */ sqlite3_mem_methods m; /* Low-level memory allocation interface */ sqlite3_mutex_methods mutex; /* Low-level mutex interface */ + sqlite3_pcache_methods pcache; /* Low-level page-cache interface */ void *pHeap; /* Heap storage space */ int nHeap; /* Size of pHeap[] */ int mnReq, mxReq; /* Min and max heap requests sizes */ void *pScratch; /* Scratch memory */ int szScratch; /* Size of each scratch buffer */