Allow description text caching for ForeignDBFile

A large amount of real time is spent in fetching Commons
descriptions pages from wikipedias, according to xenon
flame graphs.

Change-Id: I3935bf8bf23da58b734f897d7a1979e9b2f7e5c8

diff --git a/includes/filerepo/file/ForeignDBFile.php b/includes/filerepo/file/ForeignDBFile.php
index f38248b..cf0045e 100644 (file)
--- a/includes/filerepo/file/ForeignDBFile.php
+++ b/includes/filerepo/file/ForeignDBFile.php
@@ -124,8 +124,51 @@ class ForeignDBFile extends LocalFile {
         * @return string
         */
        function getDescriptionText( $lang = false ) {
-               // Restore remote behavior
-               return File::getDescriptionText( $lang );
+               global $wgLang;
+
+               if ( !$this->repo->fetchDescription ) {
+                       return false;
+               }
+
+               $lang = $lang ?: $wgLang;
+               $renderUrl = $this->repo->getDescriptionRenderUrl( $this->getName(), $lang->getCode() );
+               if ( !$renderUrl ) {
+                       return false;
+               }
+
+               $touched = $this->repo->getSlaveDB()->selectField(
+                       'page',
+                       'page_touched',
+                       [
+                               'page_namespace' => NS_FILE,
+                               'page_title' => $this->title->getDBkey()
+                       ]
+               );
+               if ( $touched === false ) {
+                       return false; // no description page
+               }
+
+               $cache = ObjectCache::getMainWANInstance();
+
+               return $cache->getWithSetCallback(
+                       $this->repo->getLocalCacheKey(
+                               'RemoteFileDescription',
+                               'url',
+                               $lang->getCode(),
+                               $this->getName(),
+                               $touched
+                       ),
+                       $this->repo->descriptionCacheExpiry ?: $cache::TTL_UNCACHEABLE,
+                       function ( $oldValue, &$ttl, array &$setOpts ) use ( $renderUrl ) {
+                               wfDebug( "Fetching shared description from $renderUrl\n" );
+                               $res = Http::get( $renderUrl, [], __METHOD__ );
+                               if ( !$res ) {
+                                       $ttl = WANObjectCache::TTL_UNCACHEABLE;
+                               }
+
+                               return $res;
+                       }
+               );
        }
 
        /**
@@ -137,10 +180,14 @@ class ForeignDBFile extends LocalFile {
         */
        public function getDescriptionShortUrl() {
                $dbr = $this->repo->getSlaveDB();
-               $pageId = $dbr->selectField( 'page', 'page_id', [
-                       'page_namespace' => NS_FILE,
-                       'page_title' => $this->title->getDBkey()
-               ] );
+               $pageId = $dbr->selectField(
+                       'page',
+                       'page_id',
+                       [
+                               'page_namespace' => NS_FILE,
+                               'page_title' => $this->title->getDBkey()
+                       ]
+               );
 
                if ( $pageId !== false ) {
                        $url = $this->repo->makeUrl( [ 'curid' => $pageId ] );