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Add error code SQLITE_BUSY_TIMEOUT, used internally by the OS layer to indicate that a call to xShmLock() has failed due to timeout of a blocking lock.

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FossilOrigin-Name: f3ef9c7c2b4ba3de1057ad569f068b241d5f23e6629d8e0dacf85e57fd13b8aa
This commit is contained in:
dan
2020-05-06 20:27:18 +00:00
parent fc87ab8c4a
commit 7bb8b8a4f7
7 changed files with 233 additions and 108 deletions
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182
src/wal.c
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@@ -843,7 +843,7 @@ static int walLockShared(Wal *pWal, int lockIdx){
SQLITE_SHM_LOCK | SQLITE_SHM_SHARED);
WALTRACE(("WAL%p: acquire SHARED-%s %s\n", pWal,
walLockName(lockIdx), rc ? "failed" : "ok"));
VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && rc!=SQLITE_BUSY); )
VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && (rc&0xFF)!=SQLITE_BUSY); )
return rc;
}
static void walUnlockShared(Wal *pWal, int lockIdx){
@@ -859,7 +859,7 @@ static int walLockExclusive(Wal *pWal, int lockIdx, int n){
SQLITE_SHM_LOCK | SQLITE_SHM_EXCLUSIVE);
WALTRACE(("WAL%p: acquire EXCLUSIVE-%s cnt=%d %s\n", pWal,
walLockName(lockIdx), n, rc ? "failed" : "ok"));
VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && rc!=SQLITE_BUSY); )
VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && (rc&0xFF)!=SQLITE_BUSY); )
return rc;
}
static void walUnlockExclusive(Wal *pWal, int lockIdx, int n){
@@ -1679,6 +1679,89 @@ static int walIteratorInit(Wal *pWal, u32 nBackfill, WalIterator **pp){
return rc;
}
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
/*
** Attempt to enable blocking locks. Blocking locks are enabled only if (a)
** they are supported by the VFS, and (b) the database handle is configured
** with a busy-timeout. Return 1 if blocking locks are successfully enabled,
** or 0 otherwise.
*/
static int walEnableBlocking(Wal *pWal){
int res = 0;
if( pWal->db ){
int tmout = pWal->db->busyTimeout;
if( tmout ){
int rc;
rc = sqlite3OsFileControl(
pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&tmout
);
res = (rc==SQLITE_OK);
}
}
return res;
}
/*
** Disable blocking locks.
*/
static void walDisableBlocking(Wal *pWal){
int tmout = 0;
sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&tmout);
}
/*
** If parameter bLock is true, attempt to enable blocking locks, take
** the WRITER lock, and then disable blocking locks. If blocking locks
** cannot be enabled, no attempt to obtain the WRITER lock is made. Return
** an SQLite error code if an error occurs, or SQLITE_OK otherwise. It is not
** an error if blocking locks can not be enabled.
**
** If the bLock parameter is false and the WRITER lock is held, release it.
*/
int sqlite3WalWriteLock(Wal *pWal, int bLock){
int rc = SQLITE_OK;
assert( pWal->readLock<0 || bLock==0 );
if( bLock ){
assert( pWal->db );
if( walEnableBlocking(pWal) ){
rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
if( rc==SQLITE_OK ){
pWal->writeLock = 1;
}
walDisableBlocking(pWal);
}
}else if( pWal->writeLock ){
walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
pWal->writeLock = 0;
}
return rc;
}
/*
** Set the database handle used to determine if blocking locks are required.
*/
void sqlite3WalDb(Wal *pWal, sqlite3 *db){
pWal->db = db;
}
/*
** Take an exclusive WRITE lock. Blocking if so configured.
*/
static int walLockWriter(Wal *pWal){
int rc;
walEnableBlocking(pWal);
rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
walDisableBlocking(pWal);
return rc;
}
#else
# define walEnableBlocking(x) 0
# define walDisableBlocking(x)
# define walLockWriter(pWal) walLockExclusive((pWal), WAL_WRITE_LOCK, 1)
# define sqlite3WalDb(pWal, db)
#endif /* ifdef SQLITE_ENABLE_SETLK_TIMEOUT */
/*
** Attempt to obtain the exclusive WAL lock defined by parameters lockIdx and
** n. If the attempt fails and parameter xBusy is not NULL, then it is a
@@ -1696,6 +1779,12 @@ static int walBusyLock(
do {
rc = walLockExclusive(pWal, lockIdx, n);
}while( xBusy && rc==SQLITE_BUSY && xBusy(pBusyArg) );
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
if( rc==SQLITE_BUSY_TIMEOUT ){
walDisableBlocking(pWal);
rc = SQLITE_BUSY;
}
#endif
return rc;
}
@@ -2118,88 +2207,6 @@ static int walIndexTryHdr(Wal *pWal, int *pChanged){
*/
#define WAL_RETRY (-1)
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
/*
** Attempt to enable blocking locks. Blocking locks are enabled only if (a)
** they are supported by the VFS, and (b) the database handle is configured
** with a busy-timeout. Return 1 if blocking locks are successfully enabled,
** or 0 otherwise.
*/
static int walEnableBlocking(Wal *pWal){
int res = 0;
if( pWal->db ){
int tmout = pWal->db->busyTimeout;
if( tmout ){
int rc;
rc = sqlite3OsFileControl(
pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&tmout
);
res = (rc==SQLITE_OK);
}
}
return res;
}
/*
** Disable blocking locks.
*/
static void walDisableBlocking(Wal *pWal){
int tmout = 0;
sqlite3OsFileControl(pWal->pDbFd, SQLITE_FCNTL_LOCK_TIMEOUT, (void*)&tmout);
}
/*
** If parameter bLock is true, attempt to enable blocking locks, take
** the WRITER lock, and then disable blocking locks. If blocking locks
** cannot be enabled, no attempt to obtain the WRITER lock is made. Return
** an SQLite error code if an error occurs, or SQLITE_OK otherwise. It is not
** an error if blocking locks can not be enabled.
**
** If the bLock parameter is false and the WRITER lock is held, release it.
*/
int sqlite3WalWriteLock(Wal *pWal, int bLock){
int rc = SQLITE_OK;
assert( pWal->readLock<0 || bLock==0 );
if( bLock ){
assert( pWal->db );
if( walEnableBlocking(pWal) ){
rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
if( rc==SQLITE_OK ){
pWal->writeLock = 1;
}
walDisableBlocking(pWal);
}
}else if( pWal->writeLock ){
walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
pWal->writeLock = 0;
}
return rc;
}
/*
** Set the database handle used to determine if blocking locks are required.
*/
void sqlite3WalDb(Wal *pWal, sqlite3 *db){
pWal->db = db;
}
/*
** Take an exclusive WRITE lock. Blocking if so configured.
*/
static int walLockWriter(Wal *pWal){
int rc;
walEnableBlocking(pWal);
rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1);
walDisableBlocking(pWal);
return rc;
}
#else
# define walEnableBlocking(x) 0
# define walDisableBlocking(x)
# define walLockWriter(pWal) walLockExclusive((pWal), WAL_WRITE_LOCK, 1)
# define sqlite3WalDb(pWal, db)
#endif /* ifdef SQLITE_ENABLE_SETLK_TIMEOUT */
/*
** Read the wal-index header from the wal-index and into pWal->hdr.
** If the wal-header appears to be corrupt, try to reconstruct the
@@ -3688,9 +3695,7 @@ int sqlite3WalCheckpoint(
/* Enable blocking locks, if possible. If blocking locks are successfully
** enabled, set xBusy2=0 so that the busy-handler is never invoked. */
sqlite3WalDb(pWal, db);
if( walEnableBlocking(pWal) ){
xBusy2 = 0;
}
walEnableBlocking(pWal);
/* IMPLEMENTATION-OF: R-62028-47212 All calls obtain an exclusive
** "checkpoint" lock on the database file.
@@ -3774,6 +3779,9 @@ int sqlite3WalCheckpoint(
pWal->ckptLock = 0;
}
WALTRACE(("WAL%p: checkpoint %s\n", pWal, rc ? "failed" : "ok"));
#ifdef SQLITE_ENABLE_SETLK_TIMEOUT
if( rc==SQLITE_BUSY_TIMEOUT ) rc = SQLITE_BUSY;
#endif
return (rc==SQLITE_OK && eMode!=eMode2 ? SQLITE_BUSY : rc);
}