ApiQueryTags: Use cached statistics instead of querying hit counts ourselves

The hit count query was quite slow. Unfortunately, it seems that we do need
tagUsageStatistics() even when hitcounts are not requested, because it
might list additional tags that aren't listed by the list*Tags() functions.
I don't know if this can happen in practice, but all the code around tags
seems to operate as if it might.

Bug: T164552
Change-Id: Ifccf7f5ac7a1220ff67a68589398cbf30aefd3ad

diff --git a/includes/api/ApiQueryTags.php b/includes/api/ApiQueryTags.php
index be67dd2..1b154fa 100644 (file)
--- a/includes/api/ApiQueryTags.php
+++ b/includes/api/ApiQueryTags.php
@@ -53,37 +53,24 @@ class ApiQueryTags extends ApiQueryBase {
                $softwareDefinedTags = array_fill_keys( ChangeTags::listSoftwareDefinedTags(), 0 );
                $explicitlyDefinedTags = array_fill_keys( ChangeTags::listExplicitlyDefinedTags(), 0 );
                $softwareActivatedTags = array_fill_keys( ChangeTags::listSoftwareActivatedTags(), 0 );
+               $tagStats = ChangeTags::tagUsageStatistics();
 
-               $definedTags = array_merge( $softwareDefinedTags, $explicitlyDefinedTags );
+               $tagHitcounts = array_merge( $softwareDefinedTags, $explicitlyDefinedTags, $tagStats );
+               $tags = array_keys( $tagHitcounts );
 
                # Fetch defined tags that aren't past the continuation
                if ( $params['continue'] !== null ) {
                        $cont = $params['continue'];
-                       $tags = array_filter( array_keys( $definedTags ), function ( $v ) use ( $cont ) {
+                       $tags = array_filter( $tags, function ( $v ) use ( $cont ) {
                                return $v >= $cont;
                        } );
-                       $tags = array_fill_keys( $tags, 0 );
-               } else {
-                       $tags = $definedTags;
-               }
-
-               # Merge in all used tags
-               $this->addTables( 'change_tag' );
-               $this->addFields( 'ct_tag' );
-               $this->addFields( [ 'hitcount' => $fld_hitcount ? 'COUNT(*)' : '0' ] );
-               $this->addOption( 'LIMIT', $limit + 1 );
-               $this->addOption( 'GROUP BY', 'ct_tag' );
-               $this->addWhereRange( 'ct_tag', 'newer', $params['continue'], null );
-               $res = $this->select( __METHOD__ );
-               foreach ( $res as $row ) {
-                       $tags[$row->ct_tag] = (int)$row->hitcount;
                }
 
                # Now make sure the array is sorted for proper continuation
-               ksort( $tags );
+               sort( $tags );
 
                $count = 0;
-               foreach ( $tags as $tagName => $hitcount ) {
+               foreach ( $tags as $tagName ) {
                        if ( ++$count > $limit ) {
                                $this->setContinueEnumParameter( 'continue', $tagName );
                                break;
@@ -102,7 +89,7 @@ class ApiQueryTags extends ApiQueryBase {
                        }
 
                        if ( $fld_hitcount ) {
-                               $tag['hitcount'] = $hitcount;
+                               $tag['hitcount'] = intval( $tagHitcounts[$tagName] );
                        }
 
                        $isSoftware = isset( $softwareDefinedTags[$tagName] );