src/pager.h

   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 SQLITE_PAGER_H
  18 #define SQLITE_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 ** The numeric values encoded here (other than PAGER_JOURNALMODE_QUERY)
  74 ** are exposed in the API via the "PRAGMA journal_mode" command and
  75 ** therefore cannot be changed without a compatibility break.
  76 */
  77 #define PAGER_JOURNALMODE_QUERY     (-1)  /* Query the value of journalmode */
  78 #define PAGER_JOURNALMODE_DELETE      0   /* Commit by deleting journal file */
  79 #define PAGER_JOURNALMODE_PERSIST     1   /* Commit by zeroing journal header */
  80 #define PAGER_JOURNALMODE_OFF         2   /* Journal omitted.  */
  81 #define PAGER_JOURNALMODE_TRUNCATE    3   /* Commit by truncating journal */
  82 #define PAGER_JOURNALMODE_MEMORY      4   /* In-memory journal file */
  83 #define PAGER_JOURNALMODE_WAL         5   /* Use write-ahead logging */
  84
  85 /*
  86 ** Flags that make up the mask passed to sqlite3PagerGet().
  87 */
  88 #define PAGER_GET_NOCONTENT     0x01  /* Do not load data from disk */
  89 #define PAGER_GET_READONLY      0x02  /* Read-only page is acceptable */
  90
  91 /*
  92 ** Flags for sqlite3PagerSetFlags()
  93 **
  94 ** Value constraints (enforced via assert()):
  95 **    PAGER_FULLFSYNC      == SQLITE_FullFSync
  96 **    PAGER_CKPT_FULLFSYNC == SQLITE_CkptFullFSync
  97 **    PAGER_CACHE_SPILL    == SQLITE_CacheSpill
  98 */
  99 #define PAGER_SYNCHRONOUS_OFF       0x01  /* PRAGMA synchronous=OFF */
 100 #define PAGER_SYNCHRONOUS_NORMAL    0x02  /* PRAGMA synchronous=NORMAL */
 101 #define PAGER_SYNCHRONOUS_FULL      0x03  /* PRAGMA synchronous=FULL */
 102 #define PAGER_SYNCHRONOUS_EXTRA     0x04  /* PRAGMA synchronous=EXTRA */
 103 #define PAGER_SYNCHRONOUS_MASK      0x07  /* Mask for four values above */
 104 #define PAGER_FULLFSYNC             0x08  /* PRAGMA fullfsync=ON */
 105 #define PAGER_CKPT_FULLFSYNC        0x10  /* PRAGMA checkpoint_fullfsync=ON */
 106 #define PAGER_CACHESPILL            0x20  /* PRAGMA cache_spill=ON */
 107 #define PAGER_FLAGS_MASK            0x38  /* All above except SYNCHRONOUS */
 108
 109 /*
 110 ** The remainder of this file contains the declarations of the functions
 111 ** that make up the Pager sub-system API. See source code comments for
 112 ** a detailed description of each routine.
 113 */
 114
 115 /* Open and close a Pager connection. */
 116 int sqlite3PagerOpen(
 117   sqlite3_vfs*,
 118   Pager **ppPager,
 119   const char*,
 120   int,
 121   int,
 122   int,
 123   void(*)(DbPage*)
 124 );
 125 int sqlite3PagerClose(Pager *pPager);
 126 int sqlite3PagerReadFileheader(Pager*, int, unsigned char*);
 127
 128 /* Functions used to configure a Pager object. */
 129 void sqlite3PagerSetBusyhandler(Pager*, int(*)(void *), void *);
 130 int sqlite3PagerSetPagesize(Pager*, u32*, int);
 131 #ifdef SQLITE_HAS_CODEC
 132 void sqlite3PagerAlignReserve(Pager*,Pager*);
 133 #endif
 134 int sqlite3PagerMaxPageCount(Pager*, int);
 135 void sqlite3PagerSetCachesize(Pager*, int);
 136 int sqlite3PagerSetSpillsize(Pager*, int);
 137 void sqlite3PagerSetMmapLimit(Pager *, sqlite3_int64);
 138 void sqlite3PagerShrink(Pager*);
 139 void sqlite3PagerSetFlags(Pager*,unsigned);
 140 int sqlite3PagerLockingMode(Pager *, int);
 141 int sqlite3PagerSetJournalMode(Pager *, int);
 142 int sqlite3PagerGetJournalMode(Pager*);
 143 int sqlite3PagerOkToChangeJournalMode(Pager*);
 144 i64 sqlite3PagerJournalSizeLimit(Pager *, i64);
 145 sqlite3_backup **sqlite3PagerBackupPtr(Pager*);
 146 int sqlite3PagerFlush(Pager*);
 147
 148 /* Functions used to obtain and release page references. */
 149 int sqlite3PagerGet(Pager *pPager, Pgno pgno, DbPage **ppPage, int clrFlag);
 150 DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno);
 151 void sqlite3PagerRef(DbPage*);
 152 void sqlite3PagerUnref(DbPage*);
 153 void sqlite3PagerUnrefNotNull(DbPage*);
 154
 155 /* Operations on page references. */
 156 int sqlite3PagerWrite(DbPage*);
 157 void sqlite3PagerDontWrite(DbPage*);
 158 int sqlite3PagerMovepage(Pager*,DbPage*,Pgno,int);
 159 int sqlite3PagerPageRefcount(DbPage*);
 160 void *sqlite3PagerGetData(DbPage *);
 161 void *sqlite3PagerGetExtra(DbPage *);
 162
 163 /* Functions used to manage pager transactions and savepoints. */
 164 void sqlite3PagerPagecount(Pager*, int*);
 165 int sqlite3PagerBegin(Pager*, int exFlag, int);
 166 int sqlite3PagerCommitPhaseOne(Pager*,const char *zMaster, int);
 167 int sqlite3PagerExclusiveLock(Pager*);
 168 int sqlite3PagerSync(Pager *pPager, const char *zMaster);
 169 int sqlite3PagerCommitPhaseTwo(Pager*);
 170 int sqlite3PagerRollback(Pager*);
 171 int sqlite3PagerOpenSavepoint(Pager *pPager, int n);
 172 int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint);
 173 int sqlite3PagerSharedLock(Pager *pPager);
 174
 175 #ifndef SQLITE_OMIT_WAL
 176   int sqlite3PagerCheckpoint(Pager *pPager, int, int*, int*);
 177   int sqlite3PagerWalSupported(Pager *pPager);
 178   int sqlite3PagerWalCallback(Pager *pPager);
 179   int sqlite3PagerOpenWal(Pager *pPager, int *pisOpen);
 180   int sqlite3PagerCloseWal(Pager *pPager);
 181   int sqlite3PagerUseWal(Pager *pPager);
 182 # ifdef SQLITE_ENABLE_SNAPSHOT
 183   int sqlite3PagerSnapshotGet(Pager *pPager, sqlite3_snapshot **ppSnapshot);
 184   int sqlite3PagerSnapshotOpen(Pager *pPager, sqlite3_snapshot *pSnapshot);
 185 # endif
 186 #else
 187 # define sqlite3PagerUseWal(x) 0
 188 #endif
 189
 190 #ifdef SQLITE_ENABLE_ZIPVFS
 191   int sqlite3PagerWalFramesize(Pager *pPager);
 192 #endif
 193
 194 /* Functions used to query pager state and configuration. */
 195 u8 sqlite3PagerIsreadonly(Pager*);
 196 u32 sqlite3PagerDataVersion(Pager*);
 197 #ifdef SQLITE_DEBUG
 198   int sqlite3PagerRefcount(Pager*);
 199 #endif
 200 int sqlite3PagerMemUsed(Pager*);
 201 const char *sqlite3PagerFilename(Pager*, int);
 202 sqlite3_vfs *sqlite3PagerVfs(Pager*);
 203 sqlite3_file *sqlite3PagerFile(Pager*);
 204 sqlite3_file *sqlite3PagerJrnlFile(Pager*);
 205 const char *sqlite3PagerJournalname(Pager*);
 206 void *sqlite3PagerTempSpace(Pager*);
 207 int sqlite3PagerIsMemdb(Pager*);
 208 void sqlite3PagerCacheStat(Pager *, int, int, int *);
 209 void sqlite3PagerClearCache(Pager*);
 210 int sqlite3SectorSize(sqlite3_file *);
 211
 212 /* Functions used to truncate the database file. */
 213 void sqlite3PagerTruncateImage(Pager*,Pgno);
 214
 215 void sqlite3PagerRekey(DbPage*, Pgno, u16);
 216
 217 #if defined(SQLITE_HAS_CODEC) && !defined(SQLITE_OMIT_WAL)
 218 void *sqlite3PagerCodec(DbPage *);
 219 #endif
 220
 221 /* Functions to support testing and debugging. */
 222 #if !defined(NDEBUG) || defined(SQLITE_TEST)
 223   Pgno sqlite3PagerPagenumber(DbPage*);
 224   int sqlite3PagerIswriteable(DbPage*);
 225 #endif
 226 #ifdef SQLITE_TEST
 227   int *sqlite3PagerStats(Pager*);
 228   void sqlite3PagerRefdump(Pager*);
 229   void disable_simulated_io_errors(void);
 230   void enable_simulated_io_errors(void);
 231 #else
 232 # define disable_simulated_io_errors()
 233 # define enable_simulated_io_errors()
 234 #endif
 235
 236 #endif /* SQLITE_PAGER_H */