AryaWu/sqlite
0
1/*2** 2010 February 13**4** The author disclaims copyright to this source code. In place of5** 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 to the write-ahead logging 13** system. Refer to the comments below and the header comment attached to 14** the implementation of each function in log.c for further details.15*/16 17#ifndef SQLITE_WAL_H18#define SQLITE_WAL_H19 20#include "sqliteInt.h"21 22/* Macros for extracting appropriate sync flags for either transaction23** commits (WAL_SYNC_FLAGS(X)) or for checkpoint ops (CKPT_SYNC_FLAGS(X)):24*/25#define WAL_SYNC_FLAGS(X) ((X)&0x03)26#define CKPT_SYNC_FLAGS(X) (((X)>>2)&0x03)27 28#ifdef SQLITE_OMIT_WAL29# define sqlite3WalOpen(x,y,z) 030# define sqlite3WalLimit(x,y)31# define sqlite3WalClose(v,w,x,y,z) 032# define sqlite3WalBeginReadTransaction(y,z) 033# define sqlite3WalEndReadTransaction(z)34# define sqlite3WalDbsize(y) 035# define sqlite3WalBeginWriteTransaction(y) 036# define sqlite3WalEndWriteTransaction(x) 037# define sqlite3WalUndo(x,y,z) 038# define sqlite3WalSavepoint(y,z)39# define sqlite3WalSavepointUndo(y,z) 040# define sqlite3WalFrames(u,v,w,x,y,z) 041# define sqlite3WalCheckpoint(q,r,s,t,u,v,w,x,y,z) 042# define sqlite3WalCallback(z) 043# define sqlite3WalExclusiveMode(y,z) 044# define sqlite3WalHeapMemory(z) 045# define sqlite3WalFramesize(z) 046# define sqlite3WalFindFrame(x,y,z) 047# define sqlite3WalFile(x) 048# undef SQLITE_USE_SEH49#else50 51#define WAL_SAVEPOINT_NDATA 452 53/* Connection to a write-ahead log (WAL) file. 54** There is one object of this type for each pager. 55*/56typedef struct Wal Wal;57 58/* Open and close a connection to a write-ahead log. */59int sqlite3WalOpen(sqlite3_vfs*, sqlite3_file*, const char *, int, i64, Wal**);60int sqlite3WalClose(Wal *pWal, sqlite3*, int sync_flags, int, u8 *);61 62/* Set the limiting size of a WAL file. */63void sqlite3WalLimit(Wal*, i64);64 65/* Used by readers to open (lock) and close (unlock) a snapshot. A 66** snapshot is like a read-transaction. It is the state of the database67** at an instant in time. sqlite3WalOpenSnapshot gets a read lock and68** preserves the current state even if the other threads or processes69** write to or checkpoint the WAL. sqlite3WalCloseSnapshot() closes the70** transaction and releases the lock.71*/72int sqlite3WalBeginReadTransaction(Wal *pWal, int *);73void sqlite3WalEndReadTransaction(Wal *pWal);74 75/* Read a page from the write-ahead log, if it is present. */76int sqlite3WalFindFrame(Wal *, Pgno, u32 *);77int sqlite3WalReadFrame(Wal *, u32, int, u8 *);78 79/* If the WAL is not empty, return the size of the database. */80Pgno sqlite3WalDbsize(Wal *pWal);81 82/* Obtain or release the WRITER lock. */83int sqlite3WalBeginWriteTransaction(Wal *pWal);84int sqlite3WalEndWriteTransaction(Wal *pWal);85 86/* Undo any frames written (but not committed) to the log */87int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx);88 89/* Return an integer that records the current (uncommitted) write90** position in the WAL */91void sqlite3WalSavepoint(Wal *pWal, u32 *aWalData);92 93/* Move the write position of the WAL back to iFrame. Called in94** response to a ROLLBACK TO command. */95int sqlite3WalSavepointUndo(Wal *pWal, u32 *aWalData);96 97/* Write a frame or frames to the log. */98int sqlite3WalFrames(Wal *pWal, int, PgHdr *, Pgno, int, int);99 100/* Copy pages from the log to the database file */ 101int sqlite3WalCheckpoint(102 Wal *pWal, /* Write-ahead log connection */103 sqlite3 *db, /* Check this handle's interrupt flag */104 int eMode, /* One of PASSIVE, FULL and RESTART */105 int (*xBusy)(void*), /* Function to call when busy */106 void *pBusyArg, /* Context argument for xBusyHandler */107 int sync_flags, /* Flags to sync db file with (or 0) */108 int nBuf, /* Size of buffer nBuf */109 u8 *zBuf, /* Temporary buffer to use */110 int *pnLog, /* OUT: Number of frames in WAL */111 int *pnCkpt /* OUT: Number of backfilled frames in WAL */112);113 114/* Return the value to pass to a sqlite3_wal_hook callback, the115** number of frames in the WAL at the point of the last commit since116** sqlite3WalCallback() was called. If no commits have occurred since117** the last call, then return 0.118*/119int sqlite3WalCallback(Wal *pWal);120 121/* Tell the wal layer that an EXCLUSIVE lock has been obtained (or released)122** by the pager layer on the database file.123*/124int sqlite3WalExclusiveMode(Wal *pWal, int op);125 126/* Return true if the argument is non-NULL and the WAL module is using127** heap-memory for the wal-index. Otherwise, if the argument is NULL or the128** WAL module is using shared-memory, return false. 129*/130int sqlite3WalHeapMemory(Wal *pWal);131 132#ifdef SQLITE_ENABLE_SNAPSHOT133int sqlite3WalSnapshotGet(Wal *pWal, sqlite3_snapshot **ppSnapshot);134void sqlite3WalSnapshotOpen(Wal *pWal, sqlite3_snapshot *pSnapshot);135int sqlite3WalSnapshotRecover(Wal *pWal);136int sqlite3WalSnapshotCheck(Wal *pWal, sqlite3_snapshot *pSnapshot);137void sqlite3WalSnapshotUnlock(Wal *pWal);138#endif139 140#ifdef SQLITE_ENABLE_ZIPVFS141/* If the WAL file is not empty, return the number of bytes of content142** stored in each frame (i.e. the db page-size when the WAL was created).143*/144int sqlite3WalFramesize(Wal *pWal);145#endif146 147/* Return the sqlite3_file object for the WAL file */148sqlite3_file *sqlite3WalFile(Wal *pWal);149 150#ifdef SQLITE_ENABLE_SETLK_TIMEOUT151int sqlite3WalWriteLock(Wal *pWal, int bLock);152void sqlite3WalDb(Wal *pWal, sqlite3 *db);153#endif154 155#ifdef SQLITE_USE_SEH156int sqlite3WalSystemErrno(Wal*);157#endif158 159#endif /* ifndef SQLITE_OMIT_WAL */160#endif /* SQLITE_WAL_H */161