diff options
Diffstat (limited to 'includes/dao/IDBAccessObject.php')
| -rw-r--r-- | includes/dao/IDBAccessObject.php | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/includes/dao/IDBAccessObject.php b/includes/dao/IDBAccessObject.php index 4eb6ff3e..3690735e 100644 --- a/includes/dao/IDBAccessObject.php +++ b/includes/dao/IDBAccessObject.php @@ -28,10 +28,12 @@ * functions. In general, objects should assume READ_NORMAL if no flags are explicitly given, * though certain objects may assume READ_LATEST for common use case or legacy reasons. * - * There are three types of reads: - * - READ_NORMAL : Potentially cached read of data (e.g. from a slave or stale replica) - * - READ_LATEST : Up-to-date read as of transaction start (e.g. from master or a quorum read) - * - READ_LOCKING : Up-to-date read as of now, that locks the records for the transaction + * There are four types of reads: + * - READ_NORMAL : Potentially cached read of data (e.g. from a slave or stale replica) + * - READ_LATEST : Up-to-date read as of transaction start (e.g. from master or a quorum read) + * - READ_LOCKING : Up-to-date read as of now, that locks (shared) the records + * - READ_EXCLUSIVE : Up-to-date read as of now, that locks (exclusive) the records + * All record locks persist for the duration of the transaction. * * Callers should use READ_NORMAL (or pass in no flags) unless the read determines a write. * In theory, such cases may require READ_LOCKING, though to avoid contention, READ_LATEST is @@ -47,7 +49,8 @@ interface IDBAccessObject { // Constants for object loading bitfield flags (higher => higher QoS) const READ_LATEST = 1; // read from the master - const READ_LOCKING = 3; // READ_LATEST and "FOR UPDATE" + const READ_LOCKING = 3; // READ_LATEST (1) and "LOCK IN SHARE MODE" (2) + const READ_EXCLUSIVE = 7; // READ_LOCKING (3) and "FOR UPDATE" (4) // Convenience constant for callers to explicitly request slave data const READ_NORMAL = 0; // read from the slave |