diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/os_unix.c | 37 | ||||
| -rw-r--r-- | src/os_win.c | 3 |
2 files changed, 25 insertions, 15 deletions
diff --git a/src/os_unix.c b/src/os_unix.c index d62cfdd08..37a04f38b 100644 --- a/src/os_unix.c +++ b/src/os_unix.c @@ -733,7 +733,6 @@ int sqlite3OsLock(OsFile *id, int locktype){ */ if( (id->locktype!=pLock->locktype && (pLock->locktype>=PENDING_LOCK || locktype>SHARED_LOCK)) - || (locktype==EXCLUSIVE_LOCK && pLock->cnt>1) ){ rc = SQLITE_BUSY; goto end_lock; @@ -757,16 +756,13 @@ int sqlite3OsLock(OsFile *id, int locktype){ lock.l_len = 1L; lock.l_whence = SEEK_SET; - /* If control gets to this point, then actually go ahead and make - ** operating system calls for the specified lock. + /* A PENDING lock is needed before acquiring a SHARED lock and before + ** acquiring an EXCLUSIVE lock. For the SHARED lock, the PENDING will + ** be released. */ - if( locktype==SHARED_LOCK ){ - assert( pLock->cnt==0 ); - assert( pLock->locktype==0 ); - - /* Temporarily grab a PENDING lock. This prevents new SHARED locks from - ** being formed if a PENDING lock is already held. - */ + if( locktype==SHARED_LOCK + || (locktype==EXCLUSIVE_LOCK && id->locktype<PENDING_LOCK) + ){ lock.l_type = F_RDLCK; lock.l_start = PENDING_BYTE; s = fcntl(id->h, F_SETLK, &lock); @@ -774,6 +770,15 @@ int sqlite3OsLock(OsFile *id, int locktype){ rc = (errno==EINVAL) ? SQLITE_NOLFS : SQLITE_BUSY; goto end_lock; } + } + + + /* If control gets to this point, then actually go ahead and make + ** operating system calls for the specified lock. + */ + if( locktype==SHARED_LOCK ){ + assert( pLock->cnt==0 ); + assert( pLock->locktype==0 ); /* Now get the read-lock */ lock.l_start = SHARED_FIRST; @@ -792,8 +797,12 @@ int sqlite3OsLock(OsFile *id, int locktype){ id->pOpen->nLock++; pLock->cnt = 1; } + }else if( locktype==EXCLUSIVE_LOCK && pLock->cnt>1 ){ + /* We are trying for an exclusive lock but another thread in this + ** same process is still holding a shared lock. */ + rc = SQLITE_BUSY; }else{ - /* The request was for a RESERVED, PENDING or EXCLUSIVE lock. It is + /* The request was for a RESERVED or EXCLUSIVE lock. It is ** assumed that there is a SHARED or greater lock on the file ** already. */ @@ -803,9 +812,6 @@ int sqlite3OsLock(OsFile *id, int locktype){ case RESERVED_LOCK: lock.l_start = RESERVED_BYTE; break; - case PENDING_LOCK: - lock.l_start = PENDING_BYTE; - break; case EXCLUSIVE_LOCK: lock.l_start = SHARED_FIRST; lock.l_len = SHARED_SIZE; @@ -822,6 +828,9 @@ int sqlite3OsLock(OsFile *id, int locktype){ if( rc==SQLITE_OK ){ id->locktype = locktype; pLock->locktype = locktype; + }else if( locktype==EXCLUSIVE_LOCK ){ + id->locktype = PENDING_LOCK; + pLock->locktype = PENDING_LOCK; } end_lock: diff --git a/src/os_win.c b/src/os_win.c index 217a61cbb..b729c0f68 100644 --- a/src/os_win.c +++ b/src/os_win.c @@ -420,6 +420,7 @@ int sqlite3OsLock(OsFile *id, int locktype){ ** a SHARED lock. If we are acquiring a SHARED lock, the acquisition of ** the PENDING_LOCK byte is temporary. */ + newLocktype = id->locktype; if( id->locktype==NO_LOCK || (locktype==EXCLUSIVE_LOCK && id->locktype==RESERVED_LOCK) ){ @@ -536,7 +537,7 @@ int sqlite3OsCheckReservedLock(OsFile *id){ int sqlite3OsUnlock(OsFile *id, int locktype){ int rc, type; assert( locktype<=SHARED_LOCK ); - TRACE4("UNLOCK %d to %d was %d(%d)\n", id->h, locktype, + TRACE5("UNLOCK %d to %d was %d(%d)\n", id->h, locktype, id->locktype, id->sharedLockByte); type = id->locktype; if( type>=EXCLUSIVE_LOCK ){ |