db::ObjectLock

lock lock try_lock try_lock unlock

int db::ObjectLock::try_lock ( const ObjectId &  _object_id, ObjectLockMode  _mode, ObjectLockDuration  _duration = DB_COMMIT_LOCK   ) [inline] Lock a database table or row. If a different table or row was locked previously, that lock will be released only after the new lock is granted. If a lock cannot be granted, try_lock immediately returns DB_ELOCKED. Parameters: _object_id  Table or row identifier. _mode  DB_LOCK_SHARED Obtain a shared lock. When applied to a table or row, a shared object allows other transactions to read, but not modify, the locked object. When applied to a transaction, a shared lock allows other transactions to access the database concurrently. DB_LOCK_EXCLUSIVE Obtain an exclusive lock. When applied to a table or row, an exclusive lock prevents other transactions from reading or writing the locked object. When applied to a transaction, an exclusive lock prevents other transactions from starting until the current transaction is finished. _duration  DB_COMMIT_LOCK Release the lock automatically when the current transaction is committed. DB_MANUAL_LOCK Release the lock manually, by explicitly calling ObjectLock::unlock or destroying the ObjectLock object. Returns: DB_NOERROR if the lock has been granted. DB_ELOCKED if the lock has not been granted. See also: TableId, RowId