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Add evidence marks and assert()s used as evidence for checkpoint requirements.

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FossilOrigin-Name: b2da8afc7657266fbe8e683c6e50fe18216cbcf3
This commit is contained in:
drh
2014-12-03 19:25:41 +00:00
parent 86e166a778
commit dd90d7ee81
4 changed files with 40 additions and 24 deletions
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45
src/wal.c
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@@ -1689,7 +1689,7 @@ static void walRestartHdr(Wal *pWal, u32 salt1){
static int walCheckpoint(
Wal *pWal, /* Wal connection */
int eMode, /* One of PASSIVE, FULL or RESTART */
int (*xBusyCall)(void*), /* Function to call when busy */
int (*xBusy)(void*), /* Function to call when busy */
void *pBusyArg, /* Context argument for xBusyHandler */
int sync_flags, /* Flags for OsSync() (or 0) */
u8 *zBuf /* Temporary buffer to use */
@@ -1703,7 +1703,6 @@ static int walCheckpoint(
u32 mxPage; /* Max database page to write */
int i; /* Loop counter */
volatile WalCkptInfo *pInfo; /* The checkpoint status information */
int (*xBusy)(void*) = 0; /* Function to call when waiting for locks */
szPage = walPagesize(pWal);
testcase( szPage<=32768 );
@@ -1718,7 +1717,9 @@ static int walCheckpoint(
}
assert( pIter );
if( eMode!=SQLITE_CHECKPOINT_PASSIVE ) xBusy = xBusyCall;
/* EVIDENCE-OF: R-62920-47450 The busy-handler callback is never invoked
** in the SQLITE_CHECKPOINT_PASSIVE mode. */
assert( eMode!=SQLITE_CHECKPOINT_PASSIVE || xBusy==0 );
/* Compute in mxSafeFrame the index of the last frame of the WAL that is
** safe to write into the database. Frames beyond mxSafeFrame might
@@ -2943,7 +2944,7 @@ int sqlite3WalFrames(
*/
int sqlite3WalCheckpoint(
Wal *pWal, /* Wal connection */
int eMode, /* PASSIVE, FULL or RESTART */
int eMode, /* PASSIVE, FULL, RESTART, or TRUNCATE */
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) */
@@ -2955,29 +2956,42 @@ int sqlite3WalCheckpoint(
int rc; /* Return code */
int isChanged = 0; /* True if a new wal-index header is loaded */
int eMode2 = eMode; /* Mode to pass to walCheckpoint() */
int (*xBusy2)(void*) = xBusy; /* Busy handler for eMode2 */
assert( pWal->ckptLock==0 );
assert( pWal->writeLock==0 );
/* EVIDENCE-OF: R-62920-47450 The busy-handler callback is never invoked
** in the SQLITE_CHECKPOINT_PASSIVE mode. */
assert( eMode!=SQLITE_CHECKPOINT_PASSIVE || xBusy==0 );
if( pWal->readOnly ) return SQLITE_READONLY;
WALTRACE(("WAL%p: checkpoint begins\n", pWal));
/* IMPLEMENTATION-OF: R-62028-47212 All calls obtain an exclusive
** "checkpoint" lock on the database file. */
rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
if( rc ){
/* Usually this is SQLITE_BUSY meaning that another thread or process
** is already running a checkpoint, or maybe a recovery. But it might
** also be SQLITE_IOERR. */
/* EVIDENCE-OF: R-10421-19736 If any other process is running a
** checkpoint operation at the same time, the lock cannot be obtained and
** SQLITE_BUSY is returned.
** EVIDENCE-OF: R-53820-33897 Even if there is a busy-handler configured,
** it will not be invoked in this case.
*/
testcase( rc==SQLITE_BUSY );
testcase( xBusy!=0 );
return rc;
}
pWal->ckptLock = 1;
/* If this is a blocking-checkpoint, then obtain the write-lock as well
** to prevent any writers from running while the checkpoint is underway.
** This has to be done before the call to walIndexReadHdr() below.
/* IMPLEMENTATION-OF: R-59782-36818 The SQLITE_CHECKPOINT_FULL, RESTART and
** TRUNCATE modes also obtain the exclusive "writer" lock on the database
** file.
**
** If the writer lock cannot be obtained, then a passive checkpoint is
** run instead. Since the checkpointer is not holding the writer lock,
** there is no point in blocking waiting for any readers. Assuming no
** other error occurs, this function will return SQLITE_BUSY to the caller.
** EVIDENCE-OF: R-60642-04082 If the writer lock cannot be obtained
** immediately, and a busy-handler is configured, it is invoked and the
** writer lock retried until either the busy-handler returns 0 or the
** lock is successfully obtained.
*/
if( eMode!=SQLITE_CHECKPOINT_PASSIVE ){
rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_WRITE_LOCK, 1);
@@ -2985,6 +2999,7 @@ int sqlite3WalCheckpoint(
pWal->writeLock = 1;
}else if( rc==SQLITE_BUSY ){
eMode2 = SQLITE_CHECKPOINT_PASSIVE;
xBusy2 = 0;
rc = SQLITE_OK;
}
}
@@ -3002,7 +3017,7 @@ int sqlite3WalCheckpoint(
if( pWal->hdr.mxFrame && walPagesize(pWal)!=nBuf ){
rc = SQLITE_CORRUPT_BKPT;
}else{
rc = walCheckpoint(pWal, eMode2, xBusy, pBusyArg, sync_flags, zBuf);
rc = walCheckpoint(pWal, eMode2, xBusy2, pBusyArg, sync_flags, zBuf);
}
/* If no error occurred, set the output variables. */