ParserOutput::addLanguageLink needs a string

[lhc/web/wiklou.git] / includes / job / JobQueue.php

diff --git a/includes/job/JobQueue.php b/includes/job/JobQueue.php
index aa3d6e2..e88441d 100644 (file)
--- a/includes/job/JobQueue.php
+++ b/includes/job/JobQueue.php
@@ -183,6 +183,53 @@ abstract class JobQueue {
         */
        abstract protected function doAck( Job $job );
 
+       /**
+        * Register the "root job" of a given job into the queue for de-duplication.
+        * This should only be called right *after* all the new jobs have been inserted.
+        * This is used to turn older, duplicate, job entries into no-ops. The root job
+        * information will remain in the registry until it simply falls out of cache.
+        *
+        * This requires that $job has two special fields in the "params" array:
+        *   - rootJobSignature : hash (e.g. SHA1) that identifies the task
+        *   - rootJobTimestamp : TS_MW timestamp of this instance of the task
+        *
+        * A "root job" is a conceptual job that consist of potentially many smaller jobs
+        * that are actually inserted into the queue. For example, "refreshLinks" jobs are
+        * spawned when a template is edited. One can think of the task as "update links
+        * of pages that use template X" and an instance of that task as a "root job".
+        * However, what actually goes into the queue are potentially many refreshLinks2 jobs.
+        * Since these jobs include things like page ID ranges and DB master positions, and morph
+        * into smaller refreshLinks2 jobs recursively, simple duplicate detection (like job_sha1)
+        * for individual jobs being identical is not useful.
+        *
+        * In the case of "refreshLinks", if these jobs are still in the queue when the template
+        * is edited again, we want all of these old refreshLinks jobs for that template to become
+        * no-ops. This can greatly reduce server load, since refreshLinks jobs involves parsing.
+        * Essentially, the new batch of jobs belong to a new "root job" and the older ones to a
+        * previous "root job" for the same task of "update links of pages that use template X".
+        *
+        * @param $job Job
+        * @return bool
+        */
+       final public function deduplicateRootJob( Job $job ) {
+               if ( $job->getType() !== $this->type ) {
+                       throw new MWException( "Got '{$job->getType()}' job; expected '{$this->type}'." );
+               }
+               wfProfileIn( __METHOD__ );
+               $ok = $this->doDeduplicateRootJob( $job );
+               wfProfileOut( __METHOD__ );
+               return $ok;
+       }
+
+       /**
+        * @see JobQueue::deduplicateRootJob()
+        * @param $job Job
+        * @return bool
+        */
+       protected function doDeduplicateRootJob( Job $job ) {
+               return true;
+       }
+
        /**
         * Wait for any slaves or backup servers to catch up
         *