RefreshLinksJob.php

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<?php
class RefreshLinksJob extends Job {
    const PARSE_THRESHOLD_SEC = 1.0;
    const CLOCK_FUDGE = 10;

    function __construct( Title $title, array $params ) {
        parent::__construct( 'refreshLinks', $title, $params );
        // Avoid the overhead of de-duplication when it would be pointless
        $this->removeDuplicates = (
            // Master positions won't match
            !isset( $params['masterPos'] ) &&
            // Ranges rarely will line up
            !isset( $params['range'] ) &&
            // Multiple pages per job make matches unlikely
            !( isset( $params['pages'] ) && count( $params['pages'] ) != 1 )
        );
    }

    public static function newPrioritized( Title $title, array $params ) {
        $job = new self( $title, $params );
        $job->command = 'refreshLinksPrioritized';

        return $job;
    }

    public static function newDynamic( Title $title, array $params ) {
        $job = new self( $title, $params );
        $job->command = 'refreshLinksDynamic';

        return $job;
    }

    function run() {
        global $wgUpdateRowsPerJob;

        // Job to update all (or a range of) backlink pages for a page
        if ( !empty( $this->params['recursive'] ) ) {
            // Carry over information for de-duplication
            $extraParams = $this->getRootJobParams();
            // Avoid slave lag when fetching templates.
            // When the outermost job is run, we know that the caller that enqueued it must have
            // committed the relevant changes to the DB by now. At that point, record the master
            // position and pass it along as the job recursively breaks into smaller range jobs.
            // Hopefully, when leaf jobs are popped, the slaves will have reached that position.
            if ( isset( $this->params['masterPos'] ) ) {
                $extraParams['masterPos'] = $this->params['masterPos'];
            } elseif ( wfGetLB()->getServerCount() > 1 ) {
                $extraParams['masterPos'] = wfGetLB()->getMasterPos();
            } else {
                $extraParams['masterPos'] = false;
            }
            $extraParams['triggeredRecursive'] = true;
            // Convert this into no more than $wgUpdateRowsPerJob RefreshLinks per-title
            // jobs and possibly a recursive RefreshLinks job for the rest of the backlinks
            $jobs = BacklinkJobUtils::partitionBacklinkJob(
                $this,
                $wgUpdateRowsPerJob,
                1, // job-per-title
                [ 'params' => $extraParams ]
            );
            JobQueueGroup::singleton()->push( $jobs );
        // Job to update link tables for a set of titles
        } elseif ( isset( $this->params['pages'] ) ) {
            $this->waitForMasterPosition();
            foreach ( $this->params['pages'] as $pageId => $nsAndKey ) {
                list( $ns, $dbKey ) = $nsAndKey;
                $this->runForTitle( Title::makeTitleSafe( $ns, $dbKey ) );
            }
        // Job to update link tables for a given title
        } else {
            $this->waitForMasterPosition();
            $this->runForTitle( $this->title );
        }

        return true;
    }

    protected function waitForMasterPosition() {
        if ( !empty( $this->params['masterPos'] ) && wfGetLB()->getServerCount() > 1 ) {
            // Wait for the current/next slave DB handle to catch up to the master.
            // This way, we get the correct page_latest for templates or files that just
            // changed milliseconds ago, having triggered this job to begin with.
            wfGetLB()->waitFor( $this->params['masterPos'] );
        }
    }

    protected function runForTitle( Title $title ) {
        $page = WikiPage::factory( $title );
        if ( !empty( $this->params['triggeringRevisionId'] ) ) {
            // Fetch the specified revision; lockAndGetLatest() below detects if the page
            // was edited since and aborts in order to avoid corrupting the link tables
            $revision = Revision::newFromId(
                $this->params['triggeringRevisionId'],
                Revision::READ_LATEST
            );
        } else {
            // Fetch current revision; READ_LATEST reduces lockAndGetLatest() check failures
            $revision = Revision::newFromTitle( $title, false, Revision::READ_LATEST );
        }

        if ( !$revision ) {
            $this->setLastError( "Revision not found for {$title->getPrefixedDBkey()}" );
            return false; // just deleted?
        }

        if ( !$revision->isCurrent() ) {
            // If the revision isn't current, there's no point in doing a bunch
            // of work just to fail at the lockAndGetLatest() check later.
            $this->setLastError( "Revision {$revision->getId()} is not current" );
            return false;
        }

        $content = $revision->getContent( Revision::RAW );
        if ( !$content ) {
            // If there is no content, pretend the content is empty
            $content = $revision->getContentHandler()->makeEmptyContent();
        }

        $parserOutput = false;
        $parserOptions = $page->makeParserOptions( 'canonical' );
        // If page_touched changed after this root job, then it is likely that
        // any views of the pages already resulted in re-parses which are now in
        // cache. The cache can be reused to avoid expensive parsing in some cases.
        if ( isset( $this->params['rootJobTimestamp'] ) ) {
            $opportunistic = !empty( $this->params['isOpportunistic'] );

            $skewedTimestamp = $this->params['rootJobTimestamp'];
            if ( $opportunistic ) {
                // Neither clock skew nor DB snapshot/slave lag matter much for such
                // updates; focus on reusing the (often recently updated) cache
            } else {
                // For transclusion updates, the template changes must be reflected
                $skewedTimestamp = wfTimestamp( TS_MW,
                    wfTimestamp( TS_UNIX, $skewedTimestamp ) + self::CLOCK_FUDGE
                );
            }

            if ( $page->getLinksTimestamp() > $skewedTimestamp ) {
                // Something already updated the backlinks since this job was made
                return true;
            }

            if ( $page->getTouched() >= $skewedTimestamp || $opportunistic ) {
                // Something bumped page_touched since this job was made or the cache is
                // otherwise suspected to be up-to-date. As long as the cache rev ID matches
                // and it reflects the job's triggering change, then it is usable.
                $parserOutput = ParserCache::singleton()->getDirty( $page, $parserOptions );
                if ( !$parserOutput
                    || $parserOutput->getCacheRevisionId() != $revision->getId()
                    || $parserOutput->getCacheTime() < $skewedTimestamp
                ) {
                    $parserOutput = false; // too stale
                }
            }
        }

        // Fetch the current revision and parse it if necessary...
        if ( !$parserOutput ) {
            $start = microtime( true );
            // Revision ID must be passed to the parser output to get revision variables correct
            $parserOutput = $content->getParserOutput(
                $title, $revision->getId(), $parserOptions, false );
            $elapsed = microtime( true ) - $start;
            // If it took a long time to render, then save this back to the cache to avoid
            // wasted CPU by other apaches or job runners. We don't want to always save to
            // cache as this can cause high cache I/O and LRU churn when a template changes.
            if ( $elapsed >= self::PARSE_THRESHOLD_SEC
                && $page->shouldCheckParserCache( $parserOptions, $revision->getId() )
                && $parserOutput->isCacheable()
            ) {
                $ctime = wfTimestamp( TS_MW, (int)$start ); // cache time
                ParserCache::singleton()->save(
                    $parserOutput, $page, $parserOptions, $ctime, $revision->getId()
                );
            }
        }

        $updates = $content->getSecondaryDataUpdates(
            $title,
            null,
            !empty( $this->params['useRecursiveLinksUpdate'] ),
            $parserOutput
        );

        foreach ( $updates as $key => $update ) {
            // FIXME: This code probably shouldn't be here?
            // Needed by things like Echo notifications which need
            // to know which user caused the links update
            if ( $update instanceof LinksUpdate ) {
                if ( !empty( $this->params['triggeringUser'] ) ) {
                    $userInfo = $this->params['triggeringUser'];
                    if ( $userInfo['userId'] ) {
                        $user = User::newFromId( $userInfo['userId'] );
                    } else {
                        // Anonymous, use the username
                        $user = User::newFromName( $userInfo['userName'], false );
                    }
                    $update->setTriggeringUser( $user );
                }
            }
        }

        $latestNow = $page->lockAndGetLatest();
        if ( !$latestNow || $revision->getId() != $latestNow ) {
            // Do not clobber over newer updates with older ones. If all jobs where FIFO and
            // serialized, it would be OK to update links based on older revisions since it
            // would eventually get to the latest. Since that is not the case (by design),
            // only update the link tables to a state matching the current revision's output.
            $this->setLastError( "page_latest changed from {$revision->getId()} to $latestNow" );
            return false;
        }

        DataUpdate::runUpdates( $updates );

        InfoAction::invalidateCache( $title );

        return true;
    }

    public function getDeduplicationInfo() {
        $info = parent::getDeduplicationInfo();
        if ( is_array( $info['params'] ) ) {
            // For per-pages jobs, the job title is that of the template that changed
            // (or similar), so remove that since it ruins duplicate detection
            if ( isset( $info['pages'] ) ) {
                unset( $info['namespace'] );
                unset( $info['title'] );
            }
        }

        return $info;
    }

    public function workItemCount() {
        return isset( $this->params['pages'] ) ? count( $this->params['pages'] ) : 1;
    }
}