Avoid cache stampedes in ChangeTag class

Change-Id: Ieec931c4211323ae7b838c783e45e1a83a7bb6a1

diff --git a/includes/changetags/ChangeTags.php b/includes/changetags/ChangeTags.php
index 64f89bf..7da25fe 100644 (file)
--- a/includes/changetags/ChangeTags.php
+++ b/includes/changetags/ChangeTags.php
@@ -1064,22 +1064,18 @@ class ChangeTags {
         * @since 1.25
         */
        public static function listExtensionActivatedTags() {
-               $cache = ObjectCache::getMainWANInstance();
-
-               $key = wfMemcKey( 'active-tags' );
-               $tags = $cache->get( $key );
-               if ( $tags ) {
-                       return $tags;
-               }
-
-               // ask extensions which tags they consider active
-               $extensionActive = array();
-               Hooks::run( 'ChangeTagsListActive', array( &$extensionActive ) );
-
-               // Short-term caching.
-               $cache->set( $key, $extensionActive, 300 );
-
-               return $extensionActive;
+               return ObjectCache::getMainWANInstance()->getWithSetCallback(
+                       wfMemcKey( 'active-tags' ),
+                       function() {
+                               // Ask extensions which tags they consider active
+                               $extensionActive = array();
+                               Hooks::run( 'ChangeTagsListActive', array( &$extensionActive ) );
+                               return $extensionActive;
+                       },
+                       300,
+                       array( wfMemcKey( 'active-tags' ) ),
+                       array( 'lockTSE' => INF )
+               );
        }
 
        /**
@@ -1106,29 +1102,21 @@ class ChangeTags {
         * @since 1.25
         */
        public static function listExplicitlyDefinedTags() {
-               $cache = ObjectCache::getMainWANInstance();
-
-               $key = wfMemcKey( 'valid-tags-db' );
-               $tags = $cache->get( $key );
-               if ( $tags ) {
-                       return $tags;
-               }
-
-               $emptyTags = array();
-
-               // Some DB stuff
-               $dbr = wfGetDB( DB_SLAVE );
-               $res = $dbr->select( 'valid_tag', 'vt_tag', array(), __METHOD__ );
-               foreach ( $res as $row ) {
-                       $emptyTags[] = $row->vt_tag;
-               }
-
-               $emptyTags = array_filter( array_unique( $emptyTags ) );
-
-               // Short-term caching.
-               $cache->set( $key, $emptyTags, 300 );
-
-               return $emptyTags;
+               $fname = __METHOD__;
+
+               return ObjectCache::getMainWANInstance()->getWithSetCallback(
+                       wfMemcKey( 'valid-tags-db' ),
+                       function() use ( $fname ) {
+                               $dbr = wfGetDB( DB_SLAVE );
+                               $tags = $dbr->selectFieldValues(
+                                       'valid_tag', 'vt_tag', array(), $fname );
+
+                               return array_filter( array_unique( $tags ) );
+                       },
+                       300,
+                       array( wfMemcKey( 'valid-tags-db' ) ),
+                       array( 'lockTSE' => INF )
+               );
        }
 
        /**
@@ -1141,22 +1129,17 @@ class ChangeTags {
         * @since 1.25
         */
        public static function listExtensionDefinedTags() {
-               $cache = ObjectCache::getMainWANInstance();
-
-               $key = wfMemcKey( 'valid-tags-hook' );
-               $tags = $cache->get( $key );
-               if ( $tags ) {
-                       return $tags;
-               }
-
-               $emptyTags = array();
-               Hooks::run( 'ListDefinedTags', array( &$emptyTags ) );
-               $emptyTags = array_filter( array_unique( $emptyTags ) );
-
-               // Short-term caching.
-               $cache->set( $key, $emptyTags, 300 );
-
-               return $emptyTags;
+               return ObjectCache::getMainWANInstance()->getWithSetCallback(
+                       wfMemcKey( 'valid-tags-hook' ),
+                       function() {
+                               $tags = array();
+                               Hooks::run( 'ListDefinedTags', array( &$tags ) );
+                               return array_filter( array_unique( $tags ) );
+                       },
+                       300,
+                       array( wfMemcKey( 'valid-tags-hook' ) ),
+                       array( 'lockTSE' => INF )
+               );
        }
 
        /**
@@ -1167,9 +1150,9 @@ class ChangeTags {
        public static function purgeTagCacheAll() {
                $cache = ObjectCache::getMainWANInstance();
 
-               $cache->delete( wfMemcKey( 'active-tags' ) );
-               $cache->delete( wfMemcKey( 'valid-tags-db' ) );
-               $cache->delete( wfMemcKey( 'valid-tags-hook' ) );
+               $cache->touchCheckKey( wfMemcKey( 'active-tags' ) );
+               $cache->touchCheckKey( wfMemcKey( 'valid-tags-db' ) );
+               $cache->touchCheckKey( wfMemcKey( 'valid-tags-hook' ) );
 
                self::purgeTagUsageCache();
        }
@@ -1194,38 +1177,38 @@ class ChangeTags {
         * @return array Array of string => int
         */
        public static function tagUsageStatistics() {
-               $cache = ObjectCache::getMainWANInstance();
-
-               $key = wfMemcKey( 'change-tag-statistics' );
-               $stats = $cache->get( $key );
-               if ( $stats ) {
-                       return $stats;
-               }
-
-               $out = array();
+               $fname = __METHOD__;
+
+               return ObjectCache::getMainWANInstance()->getWithSetCallback(
+                       wfMemcKey( 'change-tag-statistics' ),
+                       function() use ( $fname ) {
+                               $out = array();
+
+                               $dbr = wfGetDB( DB_SLAVE, 'vslow' );
+                               $res = $dbr->select(
+                                       'change_tag',
+                                       array( 'ct_tag', 'hitcount' => 'count(*)' ),
+                                       array(),
+                                       $fname,
+                                       array( 'GROUP BY' => 'ct_tag', 'ORDER BY' => 'hitcount DESC' )
+                               );
 
-               $dbr = wfGetDB( DB_SLAVE, 'vslow' );
-               $res = $dbr->select(
-                       'change_tag',
-                       array( 'ct_tag', 'hitcount' => 'count(*)' ),
-                       array(),
-                       __METHOD__,
-                       array( 'GROUP BY' => 'ct_tag', 'ORDER BY' => 'hitcount DESC' )
+                               foreach ( $res as $row ) {
+                                       $out[$row->ct_tag] = $row->hitcount;
+                               }
+
+                               foreach ( ChangeTags::listDefinedTags() as $tag ) {
+                                       if ( !isset( $out[$tag] ) ) {
+                                               $out[$tag] = 0;
+                                       }
+                               }
+
+                               return $out;
+                       },
+                       300,
+                       array( wfMemcKey( 'change-tag-statistics' ) ),
+                       array( 'lockTSE' => INF )
                );
-
-               foreach ( $res as $row ) {
-                       $out[$row->ct_tag] = $row->hitcount;
-               }
-               foreach ( self::listDefinedTags() as $tag ) {
-                       if ( !isset( $out[$tag] ) ) {
-                               $out[$tag] = 0;
-                       }
-               }
-
-               // Cache for a very short time
-               $cache->set( $key, $out, 300 );
-
-               return $out;
        }
 
        /**