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| 1 /* | |
| 2 ** 2008 August 05 | |
| 3 ** | |
| 4 ** The author disclaims copyright to this source code. In place of | |
| 5 ** a legal notice, here is a blessing: | |
| 6 ** | |
| 7 ** May you do good and not evil. | |
| 8 ** May you find forgiveness for yourself and forgive others. | |
| 9 ** May you share freely, never taking more than you give. | |
| 10 ** | |
| 11 ************************************************************************* | |
| 12 ** This header file defines the interface that the sqlite page cache | |
| 13 ** subsystem. | |
| 14 ** | |
| 15 ** @(#) $Id: pcache.h,v 1.20 2009/07/25 11:46:49 danielk1977 Exp $ | |
| 16 */ | |
| 17 | |
| 18 #ifndef _PCACHE_H_ | |
| 19 | |
| 20 typedef struct PgHdr PgHdr; | |
| 21 typedef struct PCache PCache; | |
| 22 | |
| 23 /* | |
| 24 ** Every page in the cache is controlled by an instance of the following | |
| 25 ** structure. | |
| 26 */ | |
| 27 struct PgHdr { | |
| 28 void *pData; /* Content of this page */ | |
| 29 void *pExtra; /* Extra content */ | |
| 30 PgHdr *pDirty; /* Transient list of dirty pages */ | |
| 31 Pgno pgno; /* Page number for this page */ | |
| 32 Pager *pPager; /* The pager this page is part of */ | |
| 33 #ifdef SQLITE_CHECK_PAGES | |
| 34 u32 pageHash; /* Hash of page content */ | |
| 35 #endif | |
| 36 u16 flags; /* PGHDR flags defined below */ | |
| 37 | |
| 38 /********************************************************************** | |
| 39 ** Elements above are public. All that follows is private to pcache.c | |
| 40 ** and should not be accessed by other modules. | |
| 41 */ | |
| 42 i16 nRef; /* Number of users of this page */ | |
| 43 PCache *pCache; /* Cache that owns this page */ | |
| 44 | |
| 45 PgHdr *pDirtyNext; /* Next element in list of dirty pages */ | |
| 46 PgHdr *pDirtyPrev; /* Previous element in list of dirty pages */ | |
| 47 }; | |
| 48 | |
| 49 /* Bit values for PgHdr.flags */ | |
| 50 #define PGHDR_DIRTY 0x002 /* Page has changed */ | |
| 51 #define PGHDR_NEED_SYNC 0x004 /* Fsync the rollback journal before | |
| 52 ** writing this page to the database */ | |
| 53 #define PGHDR_NEED_READ 0x008 /* Content is unread */ | |
| 54 #define PGHDR_REUSE_UNLIKELY 0x010 /* A hint that reuse is unlikely */ | |
| 55 #define PGHDR_DONT_WRITE 0x020 /* Do not write content to disk */ | |
| 56 | |
| 57 /* Initialize and shutdown the page cache subsystem */ | |
| 58 int sqlite3PcacheInitialize(void); | |
| 59 void sqlite3PcacheShutdown(void); | |
| 60 | |
| 61 /* Page cache buffer management: | |
| 62 ** These routines implement SQLITE_CONFIG_PAGECACHE. | |
| 63 */ | |
| 64 void sqlite3PCacheBufferSetup(void *, int sz, int n); | |
| 65 | |
| 66 /* Create a new pager cache. | |
| 67 ** Under memory stress, invoke xStress to try to make pages clean. | |
| 68 ** Only clean and unpinned pages can be reclaimed. | |
| 69 */ | |
| 70 void sqlite3PcacheOpen( | |
| 71 int szPage, /* Size of every page */ | |
| 72 int szExtra, /* Extra space associated with each page */ | |
| 73 int bPurgeable, /* True if pages are on backing store */ | |
| 74 int (*xStress)(void*, PgHdr*), /* Call to try to make pages clean */ | |
| 75 void *pStress, /* Argument to xStress */ | |
| 76 PCache *pToInit /* Preallocated space for the PCache */ | |
| 77 ); | |
| 78 | |
| 79 /* Modify the page-size after the cache has been created. */ | |
| 80 void sqlite3PcacheSetPageSize(PCache *, int); | |
| 81 | |
| 82 /* Return the size in bytes of a PCache object. Used to preallocate | |
| 83 ** storage space. | |
| 84 */ | |
| 85 int sqlite3PcacheSize(void); | |
| 86 | |
| 87 /* One release per successful fetch. Page is pinned until released. | |
| 88 ** Reference counted. | |
| 89 */ | |
| 90 int sqlite3PcacheFetch(PCache*, Pgno, int createFlag, PgHdr**); | |
| 91 void sqlite3PcacheRelease(PgHdr*); | |
| 92 | |
| 93 void sqlite3PcacheDrop(PgHdr*); /* Remove page from cache */ | |
| 94 void sqlite3PcacheMakeDirty(PgHdr*); /* Make sure page is marked dirty */ | |
| 95 void sqlite3PcacheMakeClean(PgHdr*); /* Mark a single page as clean */ | |
| 96 void sqlite3PcacheCleanAll(PCache*); /* Mark all dirty list pages as clean */ | |
| 97 | |
| 98 /* Change a page number. Used by incr-vacuum. */ | |
| 99 void sqlite3PcacheMove(PgHdr*, Pgno); | |
| 100 | |
| 101 /* Remove all pages with pgno>x. Reset the cache if x==0 */ | |
| 102 void sqlite3PcacheTruncate(PCache*, Pgno x); | |
| 103 | |
| 104 /* Get a list of all dirty pages in the cache, sorted by page number */ | |
| 105 PgHdr *sqlite3PcacheDirtyList(PCache*); | |
| 106 | |
| 107 /* Reset and close the cache object */ | |
| 108 void sqlite3PcacheClose(PCache*); | |
| 109 | |
| 110 /* Clear flags from pages of the page cache */ | |
| 111 void sqlite3PcacheClearSyncFlags(PCache *); | |
| 112 | |
| 113 /* Discard the contents of the cache */ | |
| 114 void sqlite3PcacheClear(PCache*); | |
| 115 | |
| 116 /* Return the total number of outstanding page references */ | |
| 117 int sqlite3PcacheRefCount(PCache*); | |
| 118 | |
| 119 /* Increment the reference count of an existing page */ | |
| 120 void sqlite3PcacheRef(PgHdr*); | |
| 121 | |
| 122 int sqlite3PcachePageRefcount(PgHdr*); | |
| 123 | |
| 124 /* Return the total number of pages stored in the cache */ | |
| 125 int sqlite3PcachePagecount(PCache*); | |
| 126 | |
| 127 #if defined(SQLITE_CHECK_PAGES) || defined(SQLITE_DEBUG) | |
| 128 /* Iterate through all dirty pages currently stored in the cache. This | |
| 129 ** interface is only available if SQLITE_CHECK_PAGES is defined when the | |
| 130 ** library is built. | |
| 131 */ | |
| 132 void sqlite3PcacheIterateDirty(PCache *pCache, void (*xIter)(PgHdr *)); | |
| 133 #endif | |
| 134 | |
| 135 /* Set and get the suggested cache-size for the specified pager-cache. | |
| 136 ** | |
| 137 ** If no global maximum is configured, then the system attempts to limit | |
| 138 ** the total number of pages cached by purgeable pager-caches to the sum | |
| 139 ** of the suggested cache-sizes. | |
| 140 */ | |
| 141 void sqlite3PcacheSetCachesize(PCache *, int); | |
| 142 int sqlite3PcacheGetCachesize(PCache *); | |
| 143 | |
| 144 #ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT | |
| 145 /* Try to return memory used by the pcache module to the main memory heap */ | |
| 146 int sqlite3PcacheReleaseMemory(int); | |
| 147 #endif | |
| 148 | |
| 149 #ifdef SQLITE_TEST | |
| 150 void sqlite3PcacheStats(int*,int*,int*,int*); | |
| 151 #endif | |
| 152 | |
| 153 void sqlite3PCacheSetDefault(void); | |
| 154 | |
| 155 #endif /* _PCACHE_H_ */ | |
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Chromium Code Reviews
Issue 3108030:
Move bundled copy of sqlite one level deeper to better separate it... (Closed)
Base URL: svn://svn.chromium.org/chrome/trunk/src/