RCFilters: Cache ChangesListSpecialPage::buildChangeTagList()

Calling Message::parse() on 2 messages per tag (for 80+ tags)
is fairly expensive. It takes about 400ms in production, but
adding that to requests that normally take 150-400ms is a pretty
big hit.

Bug: T176652
Change-Id: I9114f69de8b18007735de3438809f5695e380738

diff --git a/includes/specialpage/ChangesListSpecialPage.php b/includes/specialpage/ChangesListSpecialPage.php
index d7519d3..dc08dab 100644 (file)
--- a/includes/specialpage/ChangesListSpecialPage.php
+++ b/includes/specialpage/ChangesListSpecialPage.php
@@ -619,7 +619,7 @@ abstract class ChangesListSpecialPage extends SpecialPage {
 
                        $out->addJsConfigVars(
                                'wgRCFiltersChangeTags',
-                               $this->buildChangeTagList()
+                               $this->getChangeTagList()
                        );
                        $out->addJsConfigVars(
                                'StructuredChangeFiltersDisplayConfig',
@@ -661,49 +661,60 @@ abstract class ChangesListSpecialPage extends SpecialPage {
         *
         * @return Array Tag data
         */
-       protected function buildChangeTagList() {
-               $explicitlyDefinedTags = array_fill_keys( ChangeTags::listExplicitlyDefinedTags(), 0 );
-               $softwareActivatedTags = array_fill_keys( ChangeTags::listSoftwareActivatedTags(), 0 );
-
-               // Hit counts disabled for perf reasons, see T169997
-               /*
-               $tagStats = ChangeTags::tagUsageStatistics();
-               $tagHitCounts = array_merge( $explicitlyDefinedTags, $softwareActivatedTags, $tagStats );
-
-               // Sort by hits
-               arsort( $tagHitCounts );
-               */
-               $tagHitCounts = array_merge( $explicitlyDefinedTags, $softwareActivatedTags );
-
-               // Build the list and data
-               $result = [];
-               foreach ( $tagHitCounts as $tagName => $hits ) {
-                       if (
-                               // Only get active tags
-                               isset( $explicitlyDefinedTags[ $tagName ] ) ||
-                               isset( $softwareActivatedTags[ $tagName ] )
-                       ) {
-                               // Parse description
-                               $desc = ChangeTags::tagLongDescriptionMessage( $tagName, $this->getContext() );
-
-                               $result[] = [
-                                       'name' => $tagName,
-                                       'label' => Sanitizer::stripAllTags(
-                                               ChangeTags::tagDescription( $tagName, $this->getContext() )
-                                       ),
-                                       'description' => $desc ? Sanitizer::stripAllTags( $desc->parse() ) : '',
-                                       'cssClass' => Sanitizer::escapeClass( 'mw-tag-' . $tagName ),
-                                       'hits' => $hits,
-                               ];
-                       }
-               }
+       protected function getChangeTagList() {
+               $cache = ObjectCache::getMainWANInstance();
+               $context = $this->getContext();
+               return $cache->getWithSetCallback(
+                       $cache->makeKey( 'changeslistspecialpage-changetags', $context->getLanguage()->getCode() ),
+                       $cache::TTL_MINUTE * 10,
+                       function () use ( $context ) {
+                               $explicitlyDefinedTags = array_fill_keys( ChangeTags::listExplicitlyDefinedTags(), 0 );
+                               $softwareActivatedTags = array_fill_keys( ChangeTags::listSoftwareActivatedTags(), 0 );
+
+                               // Hit counts disabled for perf reasons, see T169997
+                               /*
+                               $tagStats = ChangeTags::tagUsageStatistics();
+                               $tagHitCounts = array_merge( $explicitlyDefinedTags, $softwareActivatedTags, $tagStats );
+
+                               // Sort by hits
+                               arsort( $tagHitCounts );
+                               */
+                               $tagHitCounts = array_merge( $explicitlyDefinedTags, $softwareActivatedTags );
+
+                               // Build the list and data
+                               $result = [];
+                               foreach ( $tagHitCounts as $tagName => $hits ) {
+                                       if (
+                                               // Only get active tags
+                                               isset( $explicitlyDefinedTags[ $tagName ] ) ||
+                                               isset( $softwareActivatedTags[ $tagName ] )
+                                       ) {
+                                               // Parse description
+                                               $desc = ChangeTags::tagLongDescriptionMessage( $tagName, $context );
+
+                                               $result[] = [
+                                                       'name' => $tagName,
+                                                       'label' => Sanitizer::stripAllTags(
+                                                               ChangeTags::tagDescription( $tagName, $context )
+                                                       ),
+                                                       'description' => $desc ? Sanitizer::stripAllTags( $desc->parse() ) : '',
+                                                       'cssClass' => Sanitizer::escapeClass( 'mw-tag-' . $tagName ),
+                                                       'hits' => $hits,
+                                               ];
+                                       }
+                               }
 
-               // Instead of sorting by hit count (disabled, see above), sort by display name
-               usort( $result, function ( $a, $b ) {
-                       return strcasecmp( $a['label'], $b['label'] );
-               } );
+                               // Instead of sorting by hit count (disabled, see above), sort by display name
+                               usort( $result, function ( $a, $b ) {
+                                       return strcasecmp( $a['label'], $b['label'] );
+                               } );
 
-               return $result;
+                               return $result;
+                       },
+                       [
+                               'lockTSE' => 30
+                       ]
+               );
        }
 
        /**