15821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 25821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 2008 August 05 35821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 45821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** The author disclaims copyright to this source code. In place of 55821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** a legal notice, here is a blessing: 65821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 75821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** May you do good and not evil. 85821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** May you find forgiveness for yourself and forgive others. 95821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** May you share freely, never taking more than you give. 105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)************************************************************************* 125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** This header file defines the interface that the sqlite page cache 135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** subsystem. 145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifndef _PCACHE_H_ 175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)typedef struct PgHdr PgHdr; 195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)typedef struct PCache PCache; 205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Every page in the cache is controlled by an instance of the following 235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** structure. 245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct PgHdr { 265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void *pData; /* Content of this page */ 275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void *pExtra; /* Extra content */ 285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr *pDirty; /* Transient list of dirty pages */ 295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) Pgno pgno; /* Page number for this page */ 305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) Pager *pPager; /* The pager this page is part of */ 315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifdef SQLITE_CHECK_PAGES 325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) u32 pageHash; /* Hash of page content */ 335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif 345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) u16 flags; /* PGHDR flags defined below */ 355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /********************************************************************** 375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** Elements above are public. All that follows is private to pcache.c 385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** and should not be accessed by other modules. 395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) */ 405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) i16 nRef; /* Number of users of this page */ 415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache *pCache; /* Cache that owns this page */ 425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr *pDirtyNext; /* Next element in list of dirty pages */ 445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr *pDirtyPrev; /* Previous element in list of dirty pages */ 455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Bit values for PgHdr.flags */ 485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define PGHDR_DIRTY 0x002 /* Page has changed */ 495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define PGHDR_NEED_SYNC 0x004 /* Fsync the rollback journal before 505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** writing this page to the database */ 515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define PGHDR_NEED_READ 0x008 /* Content is unread */ 525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define PGHDR_REUSE_UNLIKELY 0x010 /* A hint that reuse is unlikely */ 535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define PGHDR_DONT_WRITE 0x020 /* Do not write content to disk */ 545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Initialize and shutdown the page cache subsystem */ 565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)int sqlite3PcacheInitialize(void); 575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheShutdown(void); 585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Page cache buffer management: 605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** These routines implement SQLITE_CONFIG_PAGECACHE. 615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PCacheBufferSetup(void *, int sz, int n); 635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Create a new pager cache. 655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Under memory stress, invoke xStress to try to make pages clean. 665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Only clean and unpinned pages can be reclaimed. 675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheOpen( 695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int szPage, /* Size of every page */ 705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int szExtra, /* Extra space associated with each page */ 715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int bPurgeable, /* True if pages are on backing store */ 725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int (*xStress)(void*, PgHdr*), /* Call to try to make pages clean */ 735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void *pStress, /* Argument to xStress */ 745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache *pToInit /* Preallocated space for the PCache */ 755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)); 765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Modify the page-size after the cache has been created. */ 785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheSetPageSize(PCache *, int); 795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Return the size in bytes of a PCache object. Used to preallocate 815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** storage space. 825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)int sqlite3PcacheSize(void); 845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* One release per successful fetch. Page is pinned until released. 865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Reference counted. 875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)int sqlite3PcacheFetch(PCache*, Pgno, int createFlag, PgHdr**); 895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheRelease(PgHdr*); 905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheDrop(PgHdr*); /* Remove page from cache */ 925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheMakeDirty(PgHdr*); /* Make sure page is marked dirty */ 935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheMakeClean(PgHdr*); /* Mark a single page as clean */ 945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheCleanAll(PCache*); /* Mark all dirty list pages as clean */ 955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Change a page number. Used by incr-vacuum. */ 975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheMove(PgHdr*, Pgno); 985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Remove all pages with pgno>x. Reset the cache if x==0 */ 1005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheTruncate(PCache*, Pgno x); 1015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Get a list of all dirty pages in the cache, sorted by page number */ 1035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)PgHdr *sqlite3PcacheDirtyList(PCache*); 1045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Reset and close the cache object */ 1065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheClose(PCache*); 1075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Clear flags from pages of the page cache */ 1095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheClearSyncFlags(PCache *); 1105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Discard the contents of the cache */ 1125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheClear(PCache*); 1135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Return the total number of outstanding page references */ 1155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)int sqlite3PcacheRefCount(PCache*); 1165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Increment the reference count of an existing page */ 1185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheRef(PgHdr*); 1195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)int sqlite3PcachePageRefcount(PgHdr*); 1215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Return the total number of pages stored in the cache */ 1235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)int sqlite3PcachePagecount(PCache*); 1245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG) 1265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Iterate through all dirty pages currently stored in the cache. This 1275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** interface is only available if SQLITE_CHECK_PAGES is defined when the 1285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** library is built. 1295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 1305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *)); 1315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif 1325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Set and get the suggested cache-size for the specified pager-cache. 1345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 1355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** If no global maximum is configured, then the system attempts to limit 1365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** the total number of pages cached by purgeable pager-caches to the sum 1375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** of the suggested cache-sizes. 1385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 1395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheSetCachesize(PCache *, int); 1405d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles)#ifdef SQLITE_TEST 1415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)int sqlite3PcacheGetCachesize(PCache *); 1425d1f7b1de12d16ceb2c938c56701a3e8bfa558f7Torne (Richard Coles)#endif 1435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT 1455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Try to return memory used by the pcache module to the main memory heap */ 1465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)int sqlite3PcacheReleaseMemory(int); 1475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif 1485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifdef SQLITE_TEST 1505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheStats(int*,int*,int*,int*); 1515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif 1525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PCacheSetDefault(void); 1545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif /* _PCACHE_H_ */ 156