third_party/sqlite/sqlite-src-3080704/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 _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_ */