Fix bug in BacklinkCache: the lack of an ORDER BY clause in getLinks(), combined...

The BacklinkCache bug was there since r47317, but was relatively harmless until r54841 introduced the infinite loop issue.

diff --git a/RELEASE-NOTES b/RELEASE-NOTES
index 3683eb0..9fd3ce7 100644 (file)
--- a/RELEASE-NOTES
+++ b/RELEASE-NOTES
@@ -661,6 +661,8 @@ Hopefully we will remove this configuration var soon)
 * (bug 18762) both redirects and links get fixed one after another if 
   redirects-only switch is not present
 * (bug 20159) thumbnails rerendered if older that $wgThumbnailEpoch
+* Fixed a bug which in some situations causes the job queue to grow forever, 
+  due to an infinite loop of job requeues.
 
 == API changes in 1.16 ==
 

diff --git a/includes/BacklinkCache.php b/includes/BacklinkCache.php
index a7bcd85..ff1a1a3 100644 (file)
--- a/includes/BacklinkCache.php
+++ b/includes/BacklinkCache.php
@@ -53,13 +53,13 @@ class BacklinkCache {
        public function getLinks( $table, $startId = false, $endId = false ) {
                wfProfileIn( __METHOD__ );
 
+               $fromField = $this->getPrefix( $table ) . '_from';
                if ( $startId || $endId ) {
                        // Partial range, not cached
                        wfDebug( __METHOD__.": from DB (uncacheable range)\n" );
                        $conds = $this->getConditions( $table );
                        // Use the from field in the condition rather than the joined page_id,
                        // because databases are stupid and don't necessarily propagate indexes.
-                       $fromField = $this->getPrefix( $table ) . '_from';
                        if ( $startId ) {
                                $conds[] = "$fromField >= " . intval( $startId );
                        }
@@ -71,7 +71,10 @@ class BacklinkCache {
                                array( 'page_namespace', 'page_title', 'page_id'),
                                $conds,
                                __METHOD__,
-                               array('STRAIGHT_JOIN') );
+                               array(
+                                       'STRAIGHT_JOIN',
+                                       'ORDER BY' => $fromField
+                               ) );
                        $ta = TitleArray::newFromResult( $res );
                        wfProfileOut( __METHOD__ );
                        return $ta;
@@ -84,7 +87,10 @@ class BacklinkCache {
                                array( 'page_namespace', 'page_title', 'page_id' ),
                                $this->getConditions( $table ),
                                __METHOD__,
-                               array('STRAIGHT_JOIN') );
+                               array(
+                                       'STRAIGHT_JOIN',
+                                       'ORDER BY' => $fromField,
+                               ) );
                        $this->fullResultCache[$table] = $res;
                }
                $ta = TitleArray::newFromResult( $this->fullResultCache[$table] );
@@ -225,6 +231,12 @@ class BacklinkCache {
                                $row = $res->fetchObject();
                                $end = $row->page_id - 1;
                        }
+
+                       # Sanity check order
+                       if ( $start && $end && $start > $end ) {
+                               throw new MWException( __METHOD__.': Internal error: query result out of order' );
+                       }
+
                        $batches[] = array( $start, $end );
                }
                return array( 'numRows' => $numRows, 'batches' => $batches );