1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
|
/*
** 2010 February 1
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface to the write-ahead logging
** system. Refer to the comments below and the header comment attached to
** the implementation of each function in log.c for further details.
*/
#ifndef _WAL_H_
#define _WAL_H_
#include "sqliteInt.h"
/* Additional values that can be added to the sync_flags argument of
** sqlite3WalFrames():
*/
#define WAL_SYNC_TRANSACTIONS 0x20 /* Sync at the end of each transaction */
#define SQLITE_SYNC_MASK 0x13 /* Mask off the SQLITE_SYNC_* values */
#ifdef SQLITE_OMIT_WAL
# define sqlite3WalOpen(x,y,z) 0
# define sqlite3WalLimit(x,y)
# define sqlite3WalClose(w,x,y,z) 0
# define sqlite3WalBeginReadTransaction(y,z) 0
# define sqlite3WalEndReadTransaction(z)
# define sqlite3WalDbsize(y) 0
# define sqlite3WalBeginWriteTransaction(y) 0
# define sqlite3WalEndWriteTransaction(x) 0
# define sqlite3WalUndo(x,y,z) 0
# define sqlite3WalSavepoint(y,z)
# define sqlite3WalSavepointUndo(y,z) 0
# define sqlite3WalFrames(u,v,w,x,y,z) 0
# define sqlite3WalCheckpoint(r,s,t,u,v,w,x,y,z) 0
# define sqlite3WalCallback(z) 0
# define sqlite3WalExclusiveMode(y,z) 0
# define sqlite3WalHeapMemory(z) 0
# define sqlite3WalFramesize(z) 0
# define sqlite3WalFindFrame(x,y,z) 0
#else
#define WAL_SAVEPOINT_NDATA 4
/* Connection to a write-ahead log (WAL) file.
** There is one object of this type for each pager.
*/
typedef struct Wal Wal;
/* Open and close a connection to a write-ahead log. */
int sqlite3WalOpen(sqlite3_vfs*, sqlite3_file*, const char *, int, i64, Wal**);
int sqlite3WalClose(Wal *pWal, int sync_flags, int, u8 *);
/* Set the limiting size of a WAL file. */
void sqlite3WalLimit(Wal*, i64);
/* Used by readers to open (lock) and close (unlock) a snapshot. A
** snapshot is like a read-transaction. It is the state of the database
** at an instant in time. sqlite3WalOpenSnapshot gets a read lock and
** preserves the current state even if the other threads or processes
** write to or checkpoint the WAL. sqlite3WalCloseSnapshot() closes the
** transaction and releases the lock.
*/
int sqlite3WalBeginReadTransaction(Wal *pWal, int *);
void sqlite3WalEndReadTransaction(Wal *pWal);
/* Read a page from the write-ahead log, if it is present. */
int sqlite3WalFindFrame(Wal *, Pgno, u32 *);
int sqlite3WalReadFrame(Wal *, u32, int, u8 *);
/* If the WAL is not empty, return the size of the database. */
Pgno sqlite3WalDbsize(Wal *pWal);
/* Obtain or release the WRITER lock. */
int sqlite3WalBeginWriteTransaction(Wal *pWal);
int sqlite3WalEndWriteTransaction(Wal *pWal);
/* Undo any frames written (but not committed) to the log */
int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx);
/* Return an integer that records the current (uncommitted) write
** position in the WAL */
void sqlite3WalSavepoint(Wal *pWal, u32 *aWalData);
/* Move the write position of the WAL back to iFrame. Called in
** response to a ROLLBACK TO command. */
int sqlite3WalSavepointUndo(Wal *pWal, u32 *aWalData);
/* Write a frame or frames to the log. */
int sqlite3WalFrames(Wal *pWal, int, PgHdr *, Pgno, int, int);
/* Copy pages from the log to the database file */
int sqlite3WalCheckpoint(
Wal *pWal, /* Write-ahead log connection */
int eMode, /* One of PASSIVE, FULL and RESTART */
int (*xBusy)(void*), /* Function to call when busy */
void *pBusyArg, /* Context argument for xBusyHandler */
int sync_flags, /* Flags to sync db file with (or 0) */
int nBuf, /* Size of buffer nBuf */
u8 *zBuf, /* Temporary buffer to use */
int *pnLog, /* OUT: Number of frames in WAL */
int *pnCkpt /* OUT: Number of backfilled frames in WAL */
);
/* Return the value to pass to a sqlite3_wal_hook callback, the
** number of frames in the WAL at the point of the last commit since
** sqlite3WalCallback() was called. If no commits have occurred since
** the last call, then return 0.
*/
int sqlite3WalCallback(Wal *pWal);
/* Tell the wal layer that an EXCLUSIVE lock has been obtained (or released)
** by the pager layer on the database file.
*/
int sqlite3WalExclusiveMode(Wal *pWal, int op);
/* Return true if the argument is non-NULL and the WAL module is using
** heap-memory for the wal-index. Otherwise, if the argument is NULL or the
** WAL module is using shared-memory, return false.
*/
int sqlite3WalHeapMemory(Wal *pWal);
#ifdef SQLITE_ENABLE_ZIPVFS
/* If the WAL file is not empty, return the number of bytes of content
** stored in each frame (i.e. the db page-size when the WAL was created).
*/
int sqlite3WalFramesize(Wal *pWal);
#endif
#endif /* ifndef SQLITE_OMIT_WAL */
#endif /* _WAL_H_ */
|
