Tweaked MessageCache locks to handle exceptions better.

Change-Id: I3066d8dbebc97abcc0567d71625f995d62549b4c

diff --git a/includes/cache/MessageCache.php b/includes/cache/MessageCache.php
index 6e9d413..7425978 100644 (file)
--- a/includes/cache/MessageCache.php
+++ b/includes/cache/MessageCache.php
@@ -327,31 +327,39 @@ class MessageCache {
                        $where[] = 'cache is empty';
                        $where[] = 'loading from database';
 
-                       $this->lock( $cacheKey );
+                       if ( $this->lock( $cacheKey ) ) {
+                               $that = $this;
+                               $osc = new ScopedCallback( function() use ( $that, $cacheKey ) {
+                                       $that->unlock( $cacheKey );
+                               } );
+                       }
                        # Limit the concurrency of loadFromDB to a single process
                        # This prevents the site from going down when the cache expires
                        $statusKey = wfMemcKey( 'messages', $code, 'status' );
                        $success = $this->mMemc->add( $statusKey, 'loading', MSG_LOAD_TIMEOUT );
                        if ( $success ) { // acquired lock
+                               $cache = $this->mMemc;
+                               $isc = new ScopedCallback( function() use ( $cache, $statusKey ) {
+                                       $cache->delete( $statusKey );
+                               } );
                                $cache = $this->loadFromDB( $code );
                                $success = $this->setCache( $cache, $code );
                                if ( $success ) { // messages loaded
                                        $success = $this->saveToCaches( $cache, true, $code );
-                                       if ( $success ) {
-                                               $this->mMemc->delete( $statusKey );
-                                       } else {
+                                       $isc = null; // unlock
+                                       if ( !$success ) {
                                                $this->mMemc->set( $statusKey, 'error', 60 * 5 );
                                                wfDebug( __METHOD__ . ": set() error: restart memcached server!\n" );
                                                $exception = new MWException( "Could not save cache for '$code'." );
                                        }
                                } else {
-                                       $this->mMemc->delete( $statusKey );
+                                       $isc = null; // unlock
                                        $exception = new MWException( "Could not load cache from DB for '$code'." );
                                }
                        } else {
                                $exception = new MWException( "Could not acquire '$statusKey' lock." );
                        }
-                       $this->unlock( $cacheKey );
+                       $osc = null; // unlock
                }
 
                if ( !$success ) {