Merge "Fixed getLagTimes() locking"

includes/db/LoadMonitor.php

@@ -115,10 +115,10 @@ class LoadMonitorMySQL implements LoadMonitor {
 		}
 
 		# Cache key missing or expired
-		if ( $cache->add( "$memcKey:lock", 1, 10 ) ) {
+		if ( $cache->lock( $memcKey, 0, 10 ) ) {
 			# Let this process alone update the cache value
 			$unlocker = new ScopedCallback( function () use ( $cache, $memcKey ) {
-				$cache->delete( $memcKey );
+				$cache->unlock( $memcKey );
 			} );
 		} elseif ( is_array( $times ) ) {
 			# Could not acquire lock but an old cache exists, so use it

includes/libs/objectcache/BagOStuff.php

@@ -205,7 +205,7 @@ abstract class BagOStuff implements LoggerAwareInterface {
 
 	/**
 	 * @param string $key
-	 * @param int $timeout Lock wait timeout [optional]
+	 * @param int $timeout Lock wait timeout; 0 for non-blocking [optional]
 	 * @param int $expiry Lock expiry [optional]
 	 * @return bool Success
 	 */