1 /* 2 ** 2001 September 15 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. The page cache subsystem reads and writes a file a page 14 ** at a time and provides a journal for rollback. 15 */ 16 17 #ifndef _PAGER_H_ 18 #define _PAGER_H_ 19 20 /* 21 ** Default maximum size for persistent journal files. A negative 22 ** value means no limit. This value may be overridden using the 23 ** sqlite3PagerJournalSizeLimit() API. See also "PRAGMA journal_size_limit". 24 */ 25 #ifndef SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT 26 #define SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT -1 27 #endif 28 29 /* 30 ** The type used to represent a page number. The first page in a file 31 ** is called page 1. 0 is used to represent "not a page". 32 */ 33 typedef u32 Pgno; 34 35 /* 36 ** Each open file is managed by a separate instance of the "Pager" structure. 37 */ 38 typedef struct Pager Pager; 39 40 /* 41 ** Handle type for pages. 42 */ 43 typedef struct PgHdr DbPage; 44 45 /* 46 ** Page number PAGER_MJ_PGNO is never used in an SQLite database (it is 47 ** reserved for working around a windows/posix incompatibility). It is 48 ** used in the journal to signify that the remainder of the journal file 49 ** is devoted to storing a master journal name - there are no more pages to 50 ** roll back. See comments for function writeMasterJournal() in pager.c 51 ** for details. 52 */ 53 #define PAGER_MJ_PGNO(x) ((Pgno)((PENDING_BYTE/((x)->pageSize))+1)) 54 55 /* 56 ** Allowed values for the flags parameter to sqlite3PagerOpen(). 57 ** 58 ** NOTE: These values must match the corresponding BTREE_ values in btree.h. 59 */ 60 #define PAGER_OMIT_JOURNAL 0x0001 /* Do not use a rollback journal */ 61 #define PAGER_MEMORY 0x0002 /* In-memory database */ 62 63 /* 64 ** Valid values for the second argument to sqlite3PagerLockingMode(). 65 */ 66 #define PAGER_LOCKINGMODE_QUERY -1 67 #define PAGER_LOCKINGMODE_NORMAL 0 68 #define PAGER_LOCKINGMODE_EXCLUSIVE 1 69 70 /* 71 ** Numeric constants that encode the journalmode. 72 */ 73 #define PAGER_JOURNALMODE_QUERY (-1) /* Query the value of journalmode */ 74 #define PAGER_JOURNALMODE_DELETE 0 /* Commit by deleting journal file */ 75 #define PAGER_JOURNALMODE_PERSIST 1 /* Commit by zeroing journal header */ 76 #define PAGER_JOURNALMODE_OFF 2 /* Journal omitted. */ 77 #define PAGER_JOURNALMODE_TRUNCATE 3 /* Commit by truncating journal */ 78 #define PAGER_JOURNALMODE_MEMORY 4 /* In-memory journal file */ 79 #define PAGER_JOURNALMODE_WAL 5 /* Use write-ahead logging */ 80 81 /* 82 ** Flags that make up the mask passed to sqlite3PagerAcquire(). 83 */ 84 #define PAGER_GET_NOCONTENT 0x01 /* Do not load data from disk */ 85 #define PAGER_GET_READONLY 0x02 /* Read-only page is acceptable */ 86 87 /* 88 ** Flags for sqlite3PagerSetFlags() 89 */ 90 #define PAGER_SYNCHRONOUS_OFF 0x01 /* PRAGMA synchronous=OFF */ 91 #define PAGER_SYNCHRONOUS_NORMAL 0x02 /* PRAGMA synchronous=NORMAL */ 92 #define PAGER_SYNCHRONOUS_FULL 0x03 /* PRAGMA synchronous=FULL */ 93 #define PAGER_SYNCHRONOUS_MASK 0x03 /* Mask for three values above */ 94 #define PAGER_FULLFSYNC 0x04 /* PRAGMA fullfsync=ON */ 95 #define PAGER_CKPT_FULLFSYNC 0x08 /* PRAGMA checkpoint_fullfsync=ON */ 96 #define PAGER_CACHESPILL 0x10 /* PRAGMA cache_spill=ON */ 97 #define PAGER_FLAGS_MASK 0x1c /* All above except SYNCHRONOUS */ 98 99 /* 100 ** The remainder of this file contains the declarations of the functions 101 ** that make up the Pager sub-system API. See source code comments for 102 ** a detailed description of each routine. 103 */ 104 105 /* Open and close a Pager connection. */ 106 int sqlite3PagerOpen( 107 sqlite3_vfs*, 108 Pager **ppPager, 109 const char*, 110 int, 111 int, 112 int, 113 void(*)(DbPage*) 114 ); 115 int sqlite3PagerClose(Pager *pPager); 116 int sqlite3PagerReadFileheader(Pager*, int, unsigned char*); 117 118 /* Functions used to configure a Pager object. */ 119 void sqlite3PagerSetBusyhandler(Pager*, int(*)(void *), void *); 120 int sqlite3PagerSetPagesize(Pager*, u32*, int); 121 int sqlite3PagerMaxPageCount(Pager*, int); 122 void sqlite3PagerSetCachesize(Pager*, int); 123 void sqlite3PagerSetMmapLimit(Pager *, sqlite3_int64); 124 void sqlite3PagerShrink(Pager*); 125 void sqlite3PagerSetFlags(Pager*,unsigned); 126 int sqlite3PagerLockingMode(Pager *, int); 127 int sqlite3PagerSetJournalMode(Pager *, int); 128 int sqlite3PagerGetJournalMode(Pager*); 129 int sqlite3PagerOkToChangeJournalMode(Pager*); 130 i64 sqlite3PagerJournalSizeLimit(Pager *, i64); 131 sqlite3_backup **sqlite3PagerBackupPtr(Pager*); 132 133 /* Functions used to obtain and release page references. */ 134 int sqlite3PagerAcquire(Pager *pPager, Pgno pgno, DbPage **ppPage, int clrFlag); 135 #define sqlite3PagerGet(A,B,C) sqlite3PagerAcquire(A,B,C,0) 136 DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno); 137 void sqlite3PagerRef(DbPage*); 138 void sqlite3PagerUnref(DbPage*); 139 void sqlite3PagerUnrefNotNull(DbPage*); 140 141 /* Operations on page references. */ 142 int sqlite3PagerWrite(DbPage*); 143 void sqlite3PagerDontWrite(DbPage*); 144 int sqlite3PagerMovepage(Pager*,DbPage*,Pgno,int); 145 int sqlite3PagerPageRefcount(DbPage*); 146 void *sqlite3PagerGetData(DbPage *); 147 void *sqlite3PagerGetExtra(DbPage *); 148 149 /* Functions used to manage pager transactions and savepoints. */ 150 void sqlite3PagerPagecount(Pager*, int*); 151 int sqlite3PagerBegin(Pager*, int exFlag, int); 152 int sqlite3PagerCommitPhaseOne(Pager*,const char *zMaster, int); 153 int sqlite3PagerExclusiveLock(Pager*); 154 int sqlite3PagerSync(Pager *pPager, const char *zMaster); 155 int sqlite3PagerCommitPhaseTwo(Pager*); 156 int sqlite3PagerRollback(Pager*); 157 int sqlite3PagerOpenSavepoint(Pager *pPager, int n); 158 int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint); 159 int sqlite3PagerSharedLock(Pager *pPager); 160 161 #ifndef SQLITE_OMIT_WAL 162 int sqlite3PagerCheckpoint(Pager *pPager, int, int*, int*); 163 int sqlite3PagerWalSupported(Pager *pPager); 164 int sqlite3PagerWalCallback(Pager *pPager); 165 int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen); 166 int sqlite3PagerCloseWal(Pager *pPager); 167 #endif 168 169 #ifdef SQLITE_ENABLE_ZIPVFS 170 int sqlite3PagerWalFramesize(Pager *pPager); 171 #endif 172 173 /* Functions used to query pager state and configuration. */ 174 u8 sqlite3PagerIsreadonly(Pager*); 175 int sqlite3PagerRefcount(Pager*); 176 int sqlite3PagerMemUsed(Pager*); 177 const char *sqlite3PagerFilename(Pager*, int); 178 const sqlite3_vfs *sqlite3PagerVfs(Pager*); 179 sqlite3_file *sqlite3PagerFile(Pager*); 180 const char *sqlite3PagerJournalname(Pager*); 181 int sqlite3PagerNosync(Pager*); 182 void *sqlite3PagerTempSpace(Pager*); 183 int sqlite3PagerIsMemdb(Pager*); 184 void sqlite3PagerCacheStat(Pager *, int, int, int *); 185 void sqlite3PagerClearCache(Pager *); 186 int sqlite3SectorSize(sqlite3_file *); 187 188 /* Functions used to truncate the database file. */ 189 void sqlite3PagerTruncateImage(Pager*,Pgno); 190 191 #if defined(SQLITE_HAS_CODEC) && !defined(SQLITE_OMIT_WAL) 192 void *sqlite3PagerCodec(DbPage *); 193 #endif 194 195 /* Functions to support testing and debugging. */ 196 #if !defined(NDEBUG) || defined(SQLITE_TEST) 197 Pgno sqlite3PagerPagenumber(DbPage*); 198 int sqlite3PagerIswriteable(DbPage*); 199 #endif 200 #ifdef SQLITE_TEST 201 int *sqlite3PagerStats(Pager*); 202 void sqlite3PagerRefdump(Pager*); 203 void disable_simulated_io_errors(void); 204 void enable_simulated_io_errors(void); 205 #else 206 # define disable_simulated_io_errors() 207 # define enable_simulated_io_errors() 208 #endif 209 210 #endif /* _PAGER_H_ */ 211