RefreshLinksJob.php

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<?php
use MediaWiki\MediaWikiServices;
use MediaWiki\Revision\RevisionRecord;

class RefreshLinksJob extends Job {
    const PARSE_THRESHOLD_SEC = 1.0;
    const CLOCK_FUDGE = 10;
    const LAG_WAIT_TIMEOUT = 15;

    function __construct( Title $title, array $params ) {
        parent::__construct( 'refreshLinks', $title, $params );
        // Avoid the overhead of de-duplication when it would be pointless
        $this->removeDuplicates = (
            // Ranges rarely will line up
            !isset( $params['range'] ) &&
            // Multiple pages per job make matches unlikely
            !( isset( $params['pages'] ) && count( $params['pages'] ) != 1 )
        );
        $this->params += [ 'causeAction' => 'unknown', 'causeAgent' => 'unknown' ];
        // This will control transaction rounds in order to run DataUpdates
        $this->executionFlags |= self::JOB_NO_EXPLICIT_TRX_ROUND;
    }

    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;

        $ok = true;
        // Job to update all (or a range of) backlink pages for a page
        if ( !empty( $this->params['recursive'] ) ) {
            // When the base job branches, wait for the replica DBs to catch up to the master.
            // From then on, we know that any template changes at the time the base job was
            // enqueued will be reflected in backlink page parses when the leaf jobs run.
            if ( !isset( $this->params['range'] ) ) {
                $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
                if ( !$lbFactory->waitForReplication( [
                        'domain'  => $lbFactory->getLocalDomainID(),
                        'timeout' => self::LAG_WAIT_TIMEOUT
                ] ) ) { // only try so hard
                    $stats = MediaWikiServices::getInstance()->getStatsdDataFactory();
                    $stats->increment( 'refreshlinks.lag_wait_failed' );
                }
            }
            // Carry over information for de-duplication
            $extraParams = $this->getRootJobParams();
            $extraParams['triggeredRecursive'] = true;
            // Carry over cause information for logging
            $extraParams['causeAction'] = $this->params['causeAction'];
            $extraParams['causeAgent'] = $this->params['causeAgent'];
            // 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'] ) ) {
            foreach ( $this->params['pages'] as list( $ns, $dbKey ) ) {
                $title = Title::makeTitleSafe( $ns, $dbKey );
                if ( $title ) {
                    $this->runForTitle( $title );
                } else {
                    $ok = false;
                    $this->setLastError( "Invalid title ($ns,$dbKey)." );
                }
            }
        // Job to update link tables for a given title
        } else {
            $this->runForTitle( $this->title );
        }

        return $ok;
    }

    protected function runForTitle( Title $title ) {
        $services = MediaWikiServices::getInstance();
        $stats = $services->getStatsdDataFactory();
        $lbFactory = $services->getDBLoadBalancerFactory();
        $revisionStore = $services->getRevisionStore();
        $renderer = $services->getRevisionRenderer();
        $ticket = $lbFactory->getEmptyTransactionTicket( __METHOD__ );

        $lbFactory->beginMasterChanges( __METHOD__ );

        $page = WikiPage::factory( $title );
        $page->loadPageData( WikiPage::READ_LATEST );

        // Serialize links updates by page ID so they see each others' changes
        $dbw = $lbFactory->getMainLB()->getConnection( DB_MASTER );
        $scopedLock = LinksUpdate::acquirePageLock( $dbw, $page->getId(), 'job' );
        if ( $scopedLock === null ) {
            $lbFactory->commitMasterChanges( __METHOD__ );
            // Another job is already updating the page, likely for an older revision (T170596).
            $this->setLastError( 'LinksUpdate already running for this page, try again later.' );
            return false;
        }
        // Get the latest ID *after* acquirePageLock() flushed the transaction.
        // This is used to detect edits/moves after loadPageData() but before the scope lock.
        // The works around the chicken/egg problem of determining the scope lock key.
        $latest = $title->getLatestRevID( Title::GAID_FOR_UPDATE );

        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 = $revisionStore->getRevisionById(
                (int)$this->params['triggeringRevisionId'],
                Revision::READ_LATEST
            );
        } else {
            // Fetch current revision; READ_LATEST reduces lockAndGetLatest() check failures
            $revision = $revisionStore->getRevisionByTitle( $title, 0, Revision::READ_LATEST );
        }

        if ( !$revision ) {
            $lbFactory->commitMasterChanges( __METHOD__ );
            $stats->increment( 'refreshlinks.rev_not_found' );
            $this->setLastError( "Revision not found for {$title->getPrefixedDBkey()}" );
            return false; // just deleted?
        } elseif ( $revision->getId() != $latest || $revision->getPageId() !== $page->getId() ) {
            $lbFactory->commitMasterChanges( __METHOD__ );
            // 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.
            $stats->increment( 'refreshlinks.rev_not_current' );
            $this->setLastError( "Revision {$revision->getId()} is not current" );
            return false;
        }

        $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/replica DB 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 ) {
                $lbFactory->commitMasterChanges( __METHOD__ );
                // Something already updated the backlinks since this job was made
                $stats->increment( 'refreshlinks.update_skipped' );
                return true;
            }

            if ( $page->getTouched() >= $this->params['rootJobTimestamp'] || $opportunistic ) {
                // Cache is 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 = $services->getParserCache()->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 ) {
            $stats->increment( 'refreshlinks.parser_cached' );
        } else {
            $start = microtime( true );

            $checkCache = $page->shouldCheckParserCache( $parserOptions, $revision->getId() );

            // Revision ID must be passed to the parser output to get revision variables correct
            $renderedRevision = $renderer->getRenderedRevision(
                $revision,
                $parserOptions,
                null,
                [
                    // use master, for consistency with the getRevisionByTitle call above.
                    'use-master' => true,
                    // bypass audience checks, since we know that this is the current revision.
                    'audience' => RevisionRecord::RAW
                ]
            );
            $parserOutput = $renderedRevision->getRevisionParserOutput(
                // HTML is only needed if the output is to be placed in the parser cache
                [ 'generate-html' => $checkCache ]
            );

            // 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.
            $elapsed = microtime( true ) - $start;

            $parseThreshold = $this->params['parseThreshold'] ?? self::PARSE_THRESHOLD_SEC;

            if ( $checkCache && $elapsed >= $parseThreshold && $parserOutput->isCacheable() ) {
                $ctime = wfTimestamp( TS_MW, (int)$start ); // cache time
                $services->getParserCache()->save(
                    $parserOutput, $page, $parserOptions, $ctime, $revision->getId()
                );
            }
            $stats->increment( 'refreshlinks.parser_uncached' );
        }

        $options = [
            'recursive' => !empty( $this->params['useRecursiveLinksUpdate'] ),
            // Carry over cause so the update can do extra logging
            'causeAction' => $this->params['causeAction'],
            'causeAgent' => $this->params['causeAgent'],
            'defer' => false,
            'transactionTicket' => $ticket,
        ];
        if ( !empty( $this->params['triggeringUser'] ) ) {
            $userInfo = $this->params['triggeringUser'];
            if ( $userInfo['userId'] ) {
                $options['triggeringUser'] = User::newFromId( $userInfo['userId'] );
            } else {
                // Anonymous, use the username
                $options['triggeringUser'] = User::newFromName( $userInfo['userName'], false );
            }
        }

        $lbFactory->commitMasterChanges( __METHOD__ );

        $page->doSecondaryDataUpdates( $options );

        InfoAction::invalidateCache( $title );

        // Commit any writes here in case this method is called in a loop.
        // In that case, the scoped lock will fail to be acquired.
        $lbFactory->commitAndWaitForReplication( __METHOD__, $ticket );

        return true;
    }

    public function getDeduplicationInfo() {
        $info = parent::getDeduplicationInfo();
        unset( $info['causeAction'] );
        unset( $info['causeAgent'] );
        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['params']['pages'] ) ) {
                unset( $info['namespace'] );
                unset( $info['title'] );
            }
        }

        return $info;
    }

    public function workItemCount() {
        if ( !empty( $this->params['recursive'] ) ) {
            return 0; // nothing actually refreshed
        } elseif ( isset( $this->params['pages'] ) ) {
            return count( $this->params['pages'] );
        }

        return 1; // one title
    }
}