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Rename the sqlite3_log_hook() to sqlite3_wal_hook(). Added comments to

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wal.h.

FossilOrigin-Name: bbc385111b19071e20fe963fab814262c815b3e9
This commit is contained in:
drh
2010-04-28 14:42:19 +00:00
parent 4b64c1e365
commit 833bf968e3
8 changed files with 81 additions and 52 deletions
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30
src/wal.h
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@@ -19,19 +19,30 @@
#include "sqliteInt.h"
/* Connection to a log file. There is one object of this type for each pager. */
/* Connection to a write-ahead log (WAL) file.
** There is one object of this type for each pager.
*/
typedef struct Log Log;
/* Open and close a connection to a log file. */
/* Open and close a connection to a write-ahead log. */
int sqlite3WalOpen(sqlite3_vfs*, const char *zDb, Log **ppLog);
int sqlite3WalClose(Log *pLog, sqlite3_file *pFd, int sync_flags, u8 *zBuf);
/* Used by readers to open (lock) and close (unlock) a snapshot. */
/* 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 sqlite3WalOpenSnapshot(Log *pLog, int *);
void sqlite3WalCloseSnapshot(Log *pLog);
/* Read a page from the log, if it is present. */
/* Read a page from the write-ahead log, if it is present. */
int sqlite3WalRead(Log *pLog, Pgno pgno, int *pInLog, u8 *pOut);
/* Return the size of the database as it existed at the beginning
** of the snapshot */
void sqlite3WalDbsize(Log *pLog, Pgno *pPgno);
/* Obtain or release the WRITER lock. */
@@ -40,7 +51,12 @@ int sqlite3WalWriteLock(Log *pLog, int op);
/* Undo any frames written (but not committed) to the log */
int sqlite3WalUndo(Log *pLog, int (*xUndo)(void *, Pgno), void *pUndoCtx);
/* Return an integer that records the current (uncommitted) write
** position in the WAL */
u32 sqlite3WalSavepoint(Log *pLog);
/* Move the write position of the WAL back to iFrame. Called in
** response to a ROLLBACK TO command. */
int sqlite3WalSavepointUndo(Log *pLog, u32 iFrame);
/* Return true if data has been written but not committed to the log file. */
@@ -59,7 +75,11 @@ int sqlite3WalCheckpoint(
void *pBusyHandlerArg /* Argument to pass to xBusyHandler */
);
/* Return the value to pass to a log callback. Or 0 for no callback. */
/* 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(Log *pLog);
#endif /* _WAL_H_ */