15821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 25821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 2008 November 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)** 135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** This file implements the default page cache implementation (the 145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** sqlite3_pcache interface). It also contains part of the implementation 155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** of the SQLITE_CONFIG_PAGECACHE and sqlite3_release_memory() features. 165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** If the default page cache implementation is overriden, then neither of 175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** these two features are available. 185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#include "sqliteInt.h" 215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)typedef struct PCache1 PCache1; 235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)typedef struct PgHdr1 PgHdr1; 245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)typedef struct PgFreeslot PgFreeslot; 255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)typedef struct PGroup PGroup; 265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Each page cache (or PCache) belongs to a PGroup. A PGroup is a set 285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** of one or more PCaches that are able to recycle each others unpinned 295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** pages when they are under memory pressure. A PGroup is an instance of 305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** the following object. 315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** This page cache implementation works in one of two modes: 335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** (1) Every PCache is the sole member of its own PGroup. There is 355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** one PGroup per PCache. 365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** (2) There is a single global PGroup that all PCaches are a member 385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** of. 395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Mode 1 uses more memory (since PCache instances are not able to rob 415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** unused pages from other PCaches) but it also operates without a mutex, 425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** and is therefore often faster. Mode 2 requires a mutex in order to be 435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** threadsafe, but is able recycle pages more efficient. 445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** For mode (1), PGroup.mutex is NULL. For mode (2) there is only a single 465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** PGroup which is the pcache1.grp global variable and its mutex is 475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** SQLITE_MUTEX_STATIC_LRU. 485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct PGroup { 505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_mutex *mutex; /* MUTEX_STATIC_LRU or NULL */ 515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int nMaxPage; /* Sum of nMax for purgeable caches */ 525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int nMinPage; /* Sum of nMin for purgeable caches */ 535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int mxPinned; /* nMaxpage + 10 - nMinPage */ 545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int nCurrentPage; /* Number of purgeable pages allocated */ 555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *pLruHead, *pLruTail; /* LRU list of unpinned pages */ 565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* Each page cache is an instance of the following object. Every 595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** open database file (including each in-memory database and each 605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** temporary or transient database) has a single page cache which 615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** is an instance of this object. 625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Pointers to structures of this type are cast and returned as 645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** opaque sqlite3_pcache* handles. 655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct PCache1 { 675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Cache configuration parameters. Page size (szPage) and the purgeable 685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** flag (bPurgeable) are set when the cache is created. nMax may be 695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** modified at any time by a call to the pcache1CacheSize() method. 705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** The PGroup mutex must be held when accessing nMax. 715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) */ 725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PGroup *pGroup; /* PGroup this cache belongs to */ 735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int szPage; /* Size of allocated pages in bytes */ 745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int bPurgeable; /* True if cache is purgeable */ 755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int nMin; /* Minimum number of pages reserved */ 765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int nMax; /* Configured "cache_size" value */ 775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int n90pct; /* nMax*9/10 */ 785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Hash table of all pages. The following variables may only be accessed 805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** when the accessor is holding the PGroup mutex. 815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) */ 825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int nRecyclable; /* Number of pages in the LRU list */ 835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int nPage; /* Total number of pages in apHash */ 845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int nHash; /* Number of slots in apHash[] */ 855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 **apHash; /* Hash table for fast lookup by key */ 865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int iMaxKey; /* Largest key seen since xTruncate() */ 885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Each cache entry is represented by an instance of the following 925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** structure. A buffer of PgHdr1.pCache->szPage bytes is allocated 935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** directly before this structure in memory (see the PGHDR1_TO_PAGE() 945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** macro below). 955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct PgHdr1 { 975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int iKey; /* Key value (page number) */ 985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *pNext; /* Next in hash table chain */ 995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache; /* Cache that currently owns this page */ 1005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *pLruNext; /* Next in LRU list of unpinned pages */ 1015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *pLruPrev; /* Previous in LRU list of unpinned pages */ 1025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 1035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 1055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Free slots in the allocator used to divide up the buffer provided using 1065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** the SQLITE_CONFIG_PAGECACHE mechanism. 1075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 1085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)struct PgFreeslot { 1095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgFreeslot *pNext; /* Next free slot */ 1105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)}; 1115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 1135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Global data used by this cache. 1145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 1155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static SQLITE_WSD struct PCacheGlobal { 1165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PGroup grp; /* The global PGroup for mode (2) */ 1175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Variables related to SQLITE_CONFIG_PAGECACHE settings. The 1195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** szSlot, nSlot, pStart, pEnd, nReserve, and isInit values are all 1205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** fixed at sqlite3_initialize() time and do not require mutex protection. 1215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** The nFreeSlot and pFree values do require mutex protection. 1225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) */ 1235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int isInit; /* True if initialized */ 1245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int szSlot; /* Size of each free slot */ 1255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int nSlot; /* The number of pcache slots */ 1265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int nReserve; /* Try to keep nFreeSlot above this */ 1275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void *pStart, *pEnd; /* Bounds of pagecache malloc range */ 1285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Above requires no mutex. Use mutex below for variable that follow. */ 1295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_mutex *mutex; /* Mutex for accessing the following: */ 1305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int nFreeSlot; /* Number of unused pcache slots */ 1315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgFreeslot *pFree; /* Free page blocks */ 1325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* The following value requires a mutex to change. We skip the mutex on 1335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** reading because (1) most platforms read a 32-bit integer atomically and 1345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** (2) even if an incorrect value is read, no great harm is done since this 1355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** is really just an optimization. */ 1365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int bUnderPressure; /* True if low on PAGECACHE memory */ 1375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} pcache1_g; 1385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 1405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** All code in this file should access the global structure above via the 1415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** alias "pcache1". This ensures that the WSD emulation is used when 1425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** compiling for systems that do not support real WSD. 1435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 1445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define pcache1 (GLOBAL(struct PCacheGlobal, pcache1_g)) 1455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 1475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** When a PgHdr1 structure is allocated, the associated PCache1.szPage 1485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** bytes of data are located directly before it in memory (i.e. the total 1495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** size of the allocation is sizeof(PgHdr1)+PCache1.szPage byte). The 1505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** PGHDR1_TO_PAGE() macro takes a pointer to a PgHdr1 structure as 1515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** an argument and returns a pointer to the associated block of szPage 1525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** bytes. The PAGE_TO_PGHDR1() macro does the opposite: its argument is 1535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** a pointer to a block of szPage bytes of data and the return value is 1545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** a pointer to the associated PgHdr1 structure. 1555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 1565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** assert( PGHDR1_TO_PAGE(PAGE_TO_PGHDR1(pCache, X))==X ); 1575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 1585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define PGHDR1_TO_PAGE(p) (void*)(((char*)p) - p->pCache->szPage) 1595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define PAGE_TO_PGHDR1(c, p) (PgHdr1*)(((char*)p) + c->szPage) 1605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 1625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Macros to enter and leave the PCache LRU mutex. 1635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 1645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define pcache1EnterMutex(X) sqlite3_mutex_enter((X)->mutex) 1655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#define pcache1LeaveMutex(X) sqlite3_mutex_leave((X)->mutex) 1665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/******************************************************************************/ 1685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/******** Page Allocation/SQLITE_CONFIG_PCACHE Related Functions **************/ 1695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 1715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** This function is called during initialization if a static buffer is 1725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** supplied to use for the page-cache by passing the SQLITE_CONFIG_PAGECACHE 1735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** verb to sqlite3_config(). Parameter pBuf points to an allocation large 1745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** enough to contain 'n' buffers of 'sz' bytes each. 1755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 1765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** This routine is called from sqlite3_initialize() and so it is guaranteed 1775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** to be serialized already. There is no need for further mutexing. 1785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 1795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PCacheBufferSetup(void *pBuf, int sz, int n){ 1805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pcache1.isInit ){ 1815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgFreeslot *p; 1825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sz = ROUNDDOWN8(sz); 1835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.szSlot = sz; 1845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.nSlot = pcache1.nFreeSlot = n; 1855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.nReserve = n>90 ? 10 : (n/10 + 1); 1865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.pStart = pBuf; 1875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.pFree = 0; 1885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.bUnderPressure = 0; 1895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) while( n-- ){ 1905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) p = (PgFreeslot*)pBuf; 1915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) p->pNext = pcache1.pFree; 1925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.pFree = p; 1935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pBuf = (void*)&((char*)pBuf)[sz]; 1945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.pEnd = pBuf; 1965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 1975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 1985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 1995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 2005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Malloc function used within this file to allocate space from the buffer 2015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** configured using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no 2025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** such buffer exists or there is no space left in it, this function falls 2035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** back to sqlite3Malloc(). 2045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 2055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Multiple threads can run this routine at the same time. Global variables 2065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** in pcache1 need to be protected via mutex. 2075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 2085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void *pcache1Alloc(int nByte){ 2095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void *p = 0; 2105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( sqlite3_mutex_notheld(pcache1.grp.mutex) ); 2115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3StatusSet(SQLITE_STATUS_PAGECACHE_SIZE, nByte); 2125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( nByte<=pcache1.szSlot ){ 2135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_mutex_enter(pcache1.mutex); 2145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) p = (PgHdr1 *)pcache1.pFree; 2155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( p ){ 2165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.pFree = pcache1.pFree->pNext; 2175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.nFreeSlot--; 2185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.bUnderPressure = pcache1.nFreeSlot<pcache1.nReserve; 2195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pcache1.nFreeSlot>=0 ); 2205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, 1); 2215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 2225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_mutex_leave(pcache1.mutex); 2235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 2245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( p==0 ){ 2255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Memory is not available in the SQLITE_CONFIG_PAGECACHE pool. Get 2265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** it from sqlite3Malloc instead. 2275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) */ 2285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) p = sqlite3Malloc(nByte); 2295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( p ){ 2305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int sz = sqlite3MallocSize(p); 2315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_mutex_enter(pcache1.mutex); 2325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz); 2335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_mutex_leave(pcache1.mutex); 2345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 2355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3MemdebugSetType(p, MEMTYPE_PCACHE); 2365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 2375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return p; 2385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 2395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 2415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Free an allocated buffer obtained from pcache1Alloc(). 2425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 2435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void pcache1Free(void *p){ 2445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( p==0 ) return; 2455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( p>=pcache1.pStart && p<pcache1.pEnd ){ 2465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgFreeslot *pSlot; 2475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_mutex_enter(pcache1.mutex); 2485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, -1); 2495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pSlot = (PgFreeslot*)p; 2505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pSlot->pNext = pcache1.pFree; 2515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.pFree = pSlot; 2525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.nFreeSlot++; 2535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.bUnderPressure = pcache1.nFreeSlot<pcache1.nReserve; 2545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pcache1.nFreeSlot<=pcache1.nSlot ); 2555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_mutex_leave(pcache1.mutex); 2565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }else{ 2575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int iSize; 2585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) ); 2595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3MemdebugSetType(p, MEMTYPE_HEAP); 2605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) iSize = sqlite3MallocSize(p); 2615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_mutex_enter(pcache1.mutex); 2625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, -iSize); 2635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_mutex_leave(pcache1.mutex); 2645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_free(p); 2655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 2665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 2675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT 2695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 2705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Return the size of a pcache allocation 2715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 2725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static int pcache1MemSize(void *p){ 2735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( p>=pcache1.pStart && p<pcache1.pEnd ){ 2745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return pcache1.szSlot; 2755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }else{ 2765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int iSize; 2775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) ); 2785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3MemdebugSetType(p, MEMTYPE_HEAP); 2795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) iSize = sqlite3MallocSize(p); 2805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3MemdebugSetType(p, MEMTYPE_PCACHE); 2815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return iSize; 2825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 2835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 2845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */ 2855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 2865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 2875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Allocate a new page object initially associated with cache pCache. 2885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 2895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static PgHdr1 *pcache1AllocPage(PCache1 *pCache){ 2905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int nByte = sizeof(PgHdr1) + pCache->szPage; 2915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void *pPg = pcache1Alloc(nByte); 2925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *p; 2935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pPg ){ 2945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) p = PAGE_TO_PGHDR1(pCache, pPg); 2955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pCache->bPurgeable ){ 2965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->pGroup->nCurrentPage++; 2975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 2985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }else{ 2995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) p = 0; 3005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 3015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return p; 3025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 3035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 3055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Free a page object allocated by pcache1AllocPage(). 3065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 3075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** The pointer is allowed to be NULL, which is prudent. But it turns out 3085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** that the current implementation happens to never call this routine 3095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** with a NULL pointer, so we mark the NULL test with ALWAYS(). 3105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 3115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void pcache1FreePage(PgHdr1 *p){ 3125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( ALWAYS(p) ){ 3135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache = p->pCache; 3145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pCache->bPurgeable ){ 3155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->pGroup->nCurrentPage--; 3165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 3175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1Free(PGHDR1_TO_PAGE(p)); 3185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 3195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 3205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 3225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Malloc function used by SQLite to obtain space from the buffer configured 3235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** using sqlite3_config(SQLITE_CONFIG_PAGECACHE) option. If no such buffer 3245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** exists, this function falls back to sqlite3Malloc(). 3255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 3265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void *sqlite3PageMalloc(int sz){ 3275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return pcache1Alloc(sz); 3285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 3295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 3315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Free an allocated buffer obtained from sqlite3PageMalloc(). 3325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 3335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PageFree(void *p){ 3345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1Free(p); 3355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 3365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 3395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Return true if it desirable to avoid allocating a new page cache 3405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** entry. 3415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 3425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** If memory was allocated specifically to the page cache using 3435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** SQLITE_CONFIG_PAGECACHE but that memory has all been used, then 3445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** it is desirable to avoid allocating a new page cache entry because 3455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** presumably SQLITE_CONFIG_PAGECACHE was suppose to be sufficient 3465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** for all page cache needs and we should not need to spill the 3475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** allocation onto the heap. 3485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 3495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Or, the heap is used for all page cache memory put the heap is 3505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** under memory pressure, then again it is desirable to avoid 3515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** allocating a new page cache entry in order to avoid stressing 3525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** the heap even further. 3535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 3545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static int pcache1UnderMemoryPressure(PCache1 *pCache){ 3555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pcache1.nSlot && pCache->szPage<=pcache1.szSlot ){ 3565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return pcache1.bUnderPressure; 3575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }else{ 3585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return sqlite3HeapNearlyFull(); 3595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 3605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 3615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/******************************************************************************/ 3635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/******** General Implementation Functions ************************************/ 3645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 3665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** This function is used to resize the hash table used by the cache passed 3675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** as the first argument. 3685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 3695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** The PCache mutex must be held when this function is called. 3705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 3715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static int pcache1ResizeHash(PCache1 *p){ 3725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 **apNew; 3735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int nNew; 3745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int i; 3755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( sqlite3_mutex_held(p->pGroup->mutex) ); 3775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) nNew = p->nHash*2; 3795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( nNew<256 ){ 3805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) nNew = 256; 3815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 3825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 3835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1LeaveMutex(p->pGroup); 3845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( p->nHash ){ sqlite3BeginBenignMalloc(); } 3855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) apNew = (PgHdr1 **)sqlite3_malloc(sizeof(PgHdr1 *)*nNew); 3865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( p->nHash ){ sqlite3EndBenignMalloc(); } 3875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnterMutex(p->pGroup); 3885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( apNew ){ 3895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) memset(apNew, 0, sizeof(PgHdr1 *)*nNew); 3905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) for(i=0; i<p->nHash; i++){ 3915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *pPage; 3925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *pNext = p->apHash[i]; 3935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) while( (pPage = pNext)!=0 ){ 3945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int h = pPage->iKey % nNew; 3955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pNext = pPage->pNext; 3965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->pNext = apNew[h]; 3975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) apNew[h] = pPage; 3985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 3995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 4005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_free(p->apHash); 4015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) p->apHash = apNew; 4025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) p->nHash = nNew; 4035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 4045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return (p->apHash ? SQLITE_OK : SQLITE_NOMEM); 4065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 4075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 4095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** This function is used internally to remove the page pPage from the 4105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** PGroup LRU list, if is part of it. If pPage is not part of the PGroup 4115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** LRU list, then this function is a no-op. 4125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 4135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** The PGroup mutex must be held when this function is called. 4145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 4155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** If pPage is NULL then this routine is a no-op. 4165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 4175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void pcache1PinPage(PgHdr1 *pPage){ 4185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache; 4195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PGroup *pGroup; 4205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pPage==0 ) return; 4225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache = pPage->pCache; 4235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup = pCache->pGroup; 4245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( sqlite3_mutex_held(pGroup->mutex) ); 4255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pPage->pLruNext || pPage==pGroup->pLruTail ){ 4265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pPage->pLruPrev ){ 4275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->pLruPrev->pLruNext = pPage->pLruNext; 4285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 4295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pPage->pLruNext ){ 4305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->pLruNext->pLruPrev = pPage->pLruPrev; 4315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 4325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pGroup->pLruHead==pPage ){ 4335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->pLruHead = pPage->pLruNext; 4345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 4355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pGroup->pLruTail==pPage ){ 4365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->pLruTail = pPage->pLruPrev; 4375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 4385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->pLruNext = 0; 4395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->pLruPrev = 0; 4405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->pCache->nRecyclable--; 4415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 4425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 4435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 4465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Remove the page supplied as an argument from the hash table 4475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** (PCache1.apHash structure) that it is currently stored in. 4485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 4495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** The PGroup mutex must be held when this function is called. 4505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 4515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void pcache1RemoveFromHash(PgHdr1 *pPage){ 4525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int h; 4535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache = pPage->pCache; 4545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 **pp; 4555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( sqlite3_mutex_held(pCache->pGroup->mutex) ); 4575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) h = pPage->iKey % pCache->nHash; 4585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) for(pp=&pCache->apHash[h]; (*pp)!=pPage; pp=&(*pp)->pNext); 4595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) *pp = (*pp)->pNext; 4605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->nPage--; 4625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 4635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 4655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** If there are currently more than nMaxPage pages allocated, try 4665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** to recycle pages to reduce the number allocated to nMaxPage. 4675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 4685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void pcache1EnforceMaxPage(PGroup *pGroup){ 4695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( sqlite3_mutex_held(pGroup->mutex) ); 4705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) while( pGroup->nCurrentPage>pGroup->nMaxPage && pGroup->pLruTail ){ 4715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *p = pGroup->pLruTail; 4725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( p->pCache->pGroup==pGroup ); 4735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1PinPage(p); 4745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1RemoveFromHash(p); 4755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1FreePage(p); 4765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 4775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 4785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 4795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 4805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Discard all pages from cache pCache with a page number (key value) 4815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** greater than or equal to iLimit. Any pinned pages that meet this 4825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** criteria are unpinned before they are discarded. 4835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 4845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** The PCache mutex must be held when this function is called. 4855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 4865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void pcache1TruncateUnsafe( 4875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache, /* The cache to truncate */ 4885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int iLimit /* Drop pages with this pgno or larger */ 4895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)){ 4905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) TESTONLY( unsigned int nPage = 0; ) /* To assert pCache->nPage is correct */ 4915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int h; 4925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( sqlite3_mutex_held(pCache->pGroup->mutex) ); 4935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) for(h=0; h<pCache->nHash; h++){ 4945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 **pp = &pCache->apHash[h]; 4955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *pPage; 4965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) while( (pPage = *pp)!=0 ){ 4975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pPage->iKey>=iLimit ){ 4985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->nPage--; 4995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) *pp = pPage->pNext; 5005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1PinPage(pPage); 5015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1FreePage(pPage); 5025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }else{ 5035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pp = &pPage->pNext; 5045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) TESTONLY( nPage++; ) 5055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 5065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 5075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 5085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pCache->nPage==nPage ); 5095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 5105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/******************************************************************************/ 5125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/******** sqlite3_pcache Methods **********************************************/ 5135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 5155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Implementation of the sqlite3_pcache.xInit method. 5165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 5175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static int pcache1Init(void *NotUsed){ 5185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) UNUSED_PARAMETER(NotUsed); 5195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pcache1.isInit==0 ); 5205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) memset(&pcache1, 0, sizeof(pcache1)); 5215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( sqlite3GlobalConfig.bCoreMutex ){ 5225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.grp.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_LRU); 5235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_PMEM); 5245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 5255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.grp.mxPinned = 10; 5265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1.isInit = 1; 5275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return SQLITE_OK; 5285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 5295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 5315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Implementation of the sqlite3_pcache.xShutdown method. 5325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Note that the static mutex allocated in xInit does 5335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** not need to be freed. 5345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 5355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void pcache1Shutdown(void *NotUsed){ 5365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) UNUSED_PARAMETER(NotUsed); 5375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pcache1.isInit!=0 ); 5385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) memset(&pcache1, 0, sizeof(pcache1)); 5395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 5405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 5425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Implementation of the sqlite3_pcache.xCreate method. 5435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 5445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Allocate a new cache. 5455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 5465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static sqlite3_pcache *pcache1Create(int szPage, int bPurgeable){ 5475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache; /* The newly created page cache */ 5485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PGroup *pGroup; /* The group the new page cache will belong to */ 5495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int sz; /* Bytes of memory required to allocate the new cache */ 5505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* 552eb525c5499e34cc9c4b825d6d9e75bb07cc06aceBen Murdoch ** The separateCache variable is true if each PCache has its own private 5535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** PGroup. In other words, separateCache is true for mode (1) where no 5545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** mutexing is required. 5555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** 556eb525c5499e34cc9c4b825d6d9e75bb07cc06aceBen Murdoch ** * Always use separate caches (mode-1) if SQLITE_SEPARATE_CACHE_POOLS 557eb525c5499e34cc9c4b825d6d9e75bb07cc06aceBen Murdoch ** 5585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** * Always use a unified cache (mode-2) if ENABLE_MEMORY_MANAGEMENT 5595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** 5605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** * Always use a unified cache in single-threaded applications 5615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** 5625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** * Otherwise (if multi-threaded and ENABLE_MEMORY_MANAGEMENT is off) 5635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** use separate caches (mode-1) 5645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) */ 565eb525c5499e34cc9c4b825d6d9e75bb07cc06aceBen Murdoch#ifdef SQLITE_SEPARATE_CACHE_POOLS 566eb525c5499e34cc9c4b825d6d9e75bb07cc06aceBen Murdoch const int separateCache = 1; 567eb525c5499e34cc9c4b825d6d9e75bb07cc06aceBen Murdoch#elif defined(SQLITE_ENABLE_MEMORY_MANAGEMENT) || SQLITE_THREADSAFE==0 5685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) const int separateCache = 0; 5695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#else 5705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int separateCache = sqlite3GlobalConfig.bCoreMutex>0; 5715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif 5725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sz = sizeof(PCache1) + sizeof(PGroup)*separateCache; 5745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache = (PCache1 *)sqlite3_malloc(sz); 5755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pCache ){ 5765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) memset(pCache, 0, sz); 5775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( separateCache ){ 5785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup = (PGroup*)&pCache[1]; 5795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->mxPinned = 10; 5805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }else{ 5815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup = &pcache1_g.grp; 5825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 5835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->pGroup = pGroup; 5845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->szPage = szPage; 5855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->bPurgeable = (bPurgeable ? 1 : 0); 5865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( bPurgeable ){ 5875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->nMin = 10; 5885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnterMutex(pGroup); 5895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->nMinPage += pCache->nMin; 5905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage; 5915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1LeaveMutex(pGroup); 5925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 5935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 5945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return (sqlite3_pcache *)pCache; 5955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 5965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 5975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 5985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Implementation of the sqlite3_pcache.xCachesize method. 5995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Configure the cache_size limit for a cache. 6015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 6025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void pcache1Cachesize(sqlite3_pcache *p, int nMax){ 6035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache = (PCache1 *)p; 6045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pCache->bPurgeable ){ 6055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PGroup *pGroup = pCache->pGroup; 6065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnterMutex(pGroup); 6075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->nMaxPage += (nMax - pCache->nMax); 6085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage; 6095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->nMax = nMax; 6105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->n90pct = pCache->nMax*9/10; 6115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnforceMaxPage(pGroup); 6125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1LeaveMutex(pGroup); 6135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 6145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 6155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 6165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 6175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Implementation of the sqlite3_pcache.xPagecount method. 6185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 6195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static int pcache1Pagecount(sqlite3_pcache *p){ 6205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int n; 6215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache = (PCache1*)p; 6225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnterMutex(pCache->pGroup); 6235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) n = pCache->nPage; 6245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1LeaveMutex(pCache->pGroup); 6255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return n; 6265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 6275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 6285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 6295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Implementation of the sqlite3_pcache.xFetch method. 6305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Fetch a page by key value. 6325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Whether or not a new page may be allocated by this function depends on 6345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** the value of the createFlag argument. 0 means do not allocate a new 6355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** page. 1 means allocate a new page if space is easily available. 2 6365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** means to try really hard to allocate a new page. 6375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** For a non-purgeable cache (a cache used as the storage for an in-memory 6395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** database) there is really no difference between createFlag 1 and 2. So 6405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** the calling function (pcache.c) will never have a createFlag of 1 on 6415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** a non-purgable cache. 6425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** There are three different approaches to obtaining space for a page, 6445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** depending on the value of parameter createFlag (which may be 0, 1 or 2). 6455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 1. Regardless of the value of createFlag, the cache is searched for a 6475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** copy of the requested page. If one is found, it is returned. 6485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 2. If createFlag==0 and the page is not already in the cache, NULL is 6505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** returned. 6515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 3. If createFlag is 1, and the page is not already in the cache, then 6535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** return NULL (do not allocate a new page) if any of the following 6545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** conditions are true: 6555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** (a) the number of pages pinned by the cache is greater than 6575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** PCache1.nMax, or 6585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** (b) the number of pages pinned by the cache is greater than 6605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** the sum of nMax for all purgeable caches, less the sum of 6615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** nMin for all other purgeable caches, or 6625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 4. If none of the first three conditions apply and the cache is marked 6645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** as purgeable, and if one of the following is true: 6655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** (a) The number of pages allocated for the cache is already 6675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** PCache1.nMax, or 6685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** (b) The number of pages allocated for all purgeable caches is 6705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** already equal to or greater than the sum of nMax for all 6715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** purgeable caches, 6725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** (c) The system is under memory pressure and wants to avoid 6745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** unnecessary pages cache entry allocations 6755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** then attempt to recycle a page from the LRU list. If it is the right 6775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** size, return the recycled buffer. Otherwise, free the buffer and 6785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** proceed to step 5. 6795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 6805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 5. Otherwise, allocate and return a new page buffer. 6815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 6825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void *pcache1Fetch(sqlite3_pcache *p, unsigned int iKey, int createFlag){ 6835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int nPinned; 6845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache = (PCache1 *)p; 6855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PGroup *pGroup; 6865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *pPage = 0; 6875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 6885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pCache->bPurgeable || createFlag!=1 ); 6895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pCache->bPurgeable || pCache->nMin==0 ); 6905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pCache->bPurgeable==0 || pCache->nMin==10 ); 6915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pCache->nMin==0 || pCache->bPurgeable ); 6925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnterMutex(pGroup = pCache->pGroup); 6935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 6945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Step 1: Search the hash table for an existing entry. */ 6955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pCache->nHash>0 ){ 6965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int h = iKey % pCache->nHash; 6975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) for(pPage=pCache->apHash[h]; pPage&&pPage->iKey!=iKey; pPage=pPage->pNext); 6985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 6995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Step 2: Abort if no existing page is found and createFlag is 0 */ 7015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pPage || createFlag==0 ){ 7025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1PinPage(pPage); 7035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) goto fetch_out; 7045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 7055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* The pGroup local variable will normally be initialized by the 7075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** pcache1EnterMutex() macro above. But if SQLITE_MUTEX_OMIT is defined, 7085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** then pcache1EnterMutex() is a no-op, so we have to initialize the 7095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** local variable here. Delaying the initialization of pGroup is an 7105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** optimization: The common case is to exit the module before reaching 7115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** this point. 7125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) */ 7135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifdef SQLITE_MUTEX_OMIT 7145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup = pCache->pGroup; 7155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif 7165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Step 3: Abort if createFlag is 1 but the cache is nearly full */ 7195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) nPinned = pCache->nPage - pCache->nRecyclable; 7205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( nPinned>=0 ); 7215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pGroup->mxPinned == pGroup->nMaxPage + 10 - pGroup->nMinPage ); 7225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pCache->n90pct == pCache->nMax*9/10 ); 7235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( createFlag==1 && ( 7245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) nPinned>=pGroup->mxPinned 7255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) || nPinned>=(int)pCache->n90pct 7265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) || pcache1UnderMemoryPressure(pCache) 7275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) )){ 7285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) goto fetch_out; 7295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 7305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pCache->nPage>=pCache->nHash && pcache1ResizeHash(pCache) ){ 7325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) goto fetch_out; 7335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 7345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Step 4. Try to recycle a page. */ 7365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pCache->bPurgeable && pGroup->pLruTail && ( 7375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) (pCache->nPage+1>=pCache->nMax) 7385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) || pGroup->nCurrentPage>=pGroup->nMaxPage 7395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) || pcache1UnderMemoryPressure(pCache) 7405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) )){ 7415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pOtherCache; 7425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage = pGroup->pLruTail; 7435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1RemoveFromHash(pPage); 7445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1PinPage(pPage); 7455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( (pOtherCache = pPage->pCache)->szPage!=pCache->szPage ){ 7465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1FreePage(pPage); 7475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage = 0; 7485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }else{ 7495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->nCurrentPage -= 7505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) (pOtherCache->bPurgeable - pCache->bPurgeable); 7515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 7525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 7535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Step 5. If a usable page buffer has still not been found, 7555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** attempt to allocate a new one. 7565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) */ 7575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( !pPage ){ 7585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( createFlag==1 ) sqlite3BeginBenignMalloc(); 7595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1LeaveMutex(pGroup); 7605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage = pcache1AllocPage(pCache); 7615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnterMutex(pGroup); 7625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( createFlag==1 ) sqlite3EndBenignMalloc(); 7635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 7645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pPage ){ 7665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int h = iKey % pCache->nHash; 7675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->nPage++; 7685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->iKey = iKey; 7695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->pNext = pCache->apHash[h]; 7705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->pCache = pCache; 7715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->pLruPrev = 0; 7725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->pLruNext = 0; 7735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) *(void **)(PGHDR1_TO_PAGE(pPage)) = 0; 7745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->apHash[h] = pPage; 7755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 7765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)fetch_out: 7785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pPage && iKey>pCache->iMaxKey ){ 7795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->iMaxKey = iKey; 7805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 7815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1LeaveMutex(pGroup); 7825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return (pPage ? PGHDR1_TO_PAGE(pPage) : 0); 7835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 7845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 7875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Implementation of the sqlite3_pcache.xUnpin method. 7885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 7895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Mark a page as unpinned (eligible for asynchronous recycling). 7905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 7915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void pcache1Unpin(sqlite3_pcache *p, void *pPg, int reuseUnlikely){ 7925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache = (PCache1 *)p; 7935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *pPage = PAGE_TO_PGHDR1(pCache, pPg); 7945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PGroup *pGroup = pCache->pGroup; 7955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pPage->pCache==pCache ); 7975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnterMutex(pGroup); 7985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 7995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* It is an error to call this function if the page is already 8005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) ** part of the PGroup LRU list. 8015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) */ 8025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pPage->pLruPrev==0 && pPage->pLruNext==0 ); 8035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pGroup->pLruHead!=pPage && pGroup->pLruTail!=pPage ); 8045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 8055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( reuseUnlikely || pGroup->nCurrentPage>pGroup->nMaxPage ){ 8065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1RemoveFromHash(pPage); 8075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1FreePage(pPage); 8085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }else{ 8095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) /* Add the page to the PGroup LRU list. */ 8105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pGroup->pLruHead ){ 8115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->pLruHead->pLruPrev = pPage; 8125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->pLruNext = pGroup->pLruHead; 8135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->pLruHead = pPage; 8145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }else{ 8155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->pLruTail = pPage; 8165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->pLruHead = pPage; 8175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 8185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->nRecyclable++; 8195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 8205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 8215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1LeaveMutex(pCache->pGroup); 8225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 8235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 8245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 8255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Implementation of the sqlite3_pcache.xRekey method. 8265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 8275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void pcache1Rekey( 8285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_pcache *p, 8295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) void *pPg, 8305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int iOld, 8315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int iNew 8325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)){ 8335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache = (PCache1 *)p; 8345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *pPage = PAGE_TO_PGHDR1(pCache, pPg); 8355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 **pp; 8365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) unsigned int h; 8375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pPage->iKey==iOld ); 8385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pPage->pCache==pCache ); 8395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 8405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnterMutex(pCache->pGroup); 8415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 8425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) h = iOld%pCache->nHash; 8435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pp = &pCache->apHash[h]; 8445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) while( (*pp)!=pPage ){ 8455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pp = &(*pp)->pNext; 8465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 8475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) *pp = pPage->pNext; 8485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 8495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) h = iNew%pCache->nHash; 8505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->iKey = iNew; 8515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pPage->pNext = pCache->apHash[h]; 8525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->apHash[h] = pPage; 8535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( iNew>pCache->iMaxKey ){ 8545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->iMaxKey = iNew; 8555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 8565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 8575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1LeaveMutex(pCache->pGroup); 8585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 8595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 8605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 8615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Implementation of the sqlite3_pcache.xTruncate method. 8625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 8635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Discard all unpinned pages in the cache with a page number equal to 8645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** or greater than parameter iLimit. Any pinned pages with a page number 8655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** equal to or greater than iLimit are implicitly unpinned. 8665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 8675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void pcache1Truncate(sqlite3_pcache *p, unsigned int iLimit){ 8685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache = (PCache1 *)p; 8695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnterMutex(pCache->pGroup); 8705821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( iLimit<=pCache->iMaxKey ){ 8715821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1TruncateUnsafe(pCache, iLimit); 8725821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pCache->iMaxKey = iLimit-1; 8735821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 8745821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1LeaveMutex(pCache->pGroup); 8755821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 8765821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 8775821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 8785821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Implementation of the sqlite3_pcache.xDestroy method. 8795821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 8805821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** Destroy a cache allocated using pcache1Create(). 8815821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 8825821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)static void pcache1Destroy(sqlite3_pcache *p){ 8835821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PCache1 *pCache = (PCache1 *)p; 8845821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PGroup *pGroup = pCache->pGroup; 8855821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( pCache->bPurgeable || (pCache->nMax==0 && pCache->nMin==0) ); 8865821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnterMutex(pGroup); 8875821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1TruncateUnsafe(pCache, 0); 8885821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->nMaxPage -= pCache->nMax; 8895821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->nMinPage -= pCache->nMin; 8905821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pGroup->mxPinned = pGroup->nMaxPage + 10 - pGroup->nMinPage; 8915821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnforceMaxPage(pGroup); 8925821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1LeaveMutex(pGroup); 8935821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_free(pCache->apHash); 8945821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_free(pCache); 8955821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 8965821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 8975821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 8985821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** This function is called during initialization (sqlite3_initialize()) to 8995821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** install the default pluggable cache module, assuming the user has not 9005821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** already provided an alternative. 9015821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 9025821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PCacheSetDefault(void){ 9035821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) static const sqlite3_pcache_methods defaultMethods = { 9045821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 0, /* pArg */ 9055821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1Init, /* xInit */ 9065821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1Shutdown, /* xShutdown */ 9075821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1Create, /* xCreate */ 9085821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1Cachesize, /* xCachesize */ 9095821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1Pagecount, /* xPagecount */ 9105821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1Fetch, /* xFetch */ 9115821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1Unpin, /* xUnpin */ 9125821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1Rekey, /* xRekey */ 9135821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1Truncate, /* xTruncate */ 9145821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1Destroy /* xDestroy */ 9155821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) }; 9165821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) sqlite3_config(SQLITE_CONFIG_PCACHE, &defaultMethods); 9175821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 9185821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 9195821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT 9205821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 9215821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** This function is called to free superfluous dynamically allocated memory 9225821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** held by the pager system. Memory in use by any SQLite pager allocated 9235821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** by the current thread may be sqlite3_free()ed. 9245821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** 9255821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** nReq is the number of bytes of memory required. Once this much has 9265821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** been released, the function returns. The return value is the total number 9275821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** of bytes of memory released. 9285821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 9295821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)int sqlite3PcacheReleaseMemory(int nReq){ 9305821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int nFree = 0; 9315821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( sqlite3_mutex_notheld(pcache1.grp.mutex) ); 9325821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) assert( sqlite3_mutex_notheld(pcache1.mutex) ); 9335821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) if( pcache1.pStart==0 ){ 9345821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *p; 9355821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1EnterMutex(&pcache1.grp); 9365821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) while( (nReq<0 || nFree<nReq) && ((p=pcache1.grp.pLruTail)!=0) ){ 9375821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) nFree += pcache1MemSize(PGHDR1_TO_PAGE(p)); 9385821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1PinPage(p); 9395821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1RemoveFromHash(p); 9405821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1FreePage(p); 9415821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 9425821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) pcache1LeaveMutex(&pcache1.grp); 9435821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 9445821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) return nFree; 9455821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 9465821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */ 9475821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) 9485821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#ifdef SQLITE_TEST 9495821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)/* 9505821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** This function is used by test procedures to inspect the internal state 9515821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)** of the global cache. 9525821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)*/ 9535821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)void sqlite3PcacheStats( 9545821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int *pnCurrent, /* OUT: Total number of pages cached */ 9555821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int *pnMax, /* OUT: Global maximum cache size */ 9565821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int *pnMin, /* OUT: Sum of PCache1.nMin for purgeable caches */ 9575821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int *pnRecyclable /* OUT: Total number of pages available for recycling */ 9585821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)){ 9595821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) PgHdr1 *p; 9605821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) int nRecyclable = 0; 9615821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) for(p=pcache1.grp.pLruHead; p; p=p->pLruNext){ 9625821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) nRecyclable++; 9635821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) } 9645821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) *pnCurrent = pcache1.grp.nCurrentPage; 9655821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) *pnMax = pcache1.grp.nMaxPage; 9665821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) *pnMin = pcache1.grp.nMinPage; 9675821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles) *pnRecyclable = nRecyclable; 9685821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)} 9695821806d5e7f356e8fa4b058a389a808ea183019Torne (Richard Coles)#endif 970