Merge "Update docs/hooks.txt for ShowSearchHitTitle"

[mediawiki.git] / includes / jobqueue / jobs / RefreshLinksJob.php

<?php
/**
 * Job to update link tables for pages
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup JobQueue
 */
use MediaWiki\MediaWikiServices;

/**
 * Job to update link tables for pages
 *
 * This job comes in a few variants:
 *   - a) Recursive jobs to update links for backlink pages for a given title.
 *        These jobs have (recursive:true,table:<table>) set.
 *   - b) Jobs to update links for a set of pages (the job title is ignored).
 *            These jobs have (pages:(<page ID>:(<namespace>,<title>),...) set.
 *   - c) Jobs to update links for a single page (the job title)
 *        These jobs need no extra fields set.
 *
 * @ingroup JobQueue
 */
class RefreshLinksJob extends Job {
        /** @var float Cache parser output when it takes this long to render */
        const PARSE_THRESHOLD_SEC = 1.0;
        /** @var integer Lag safety margin when comparing root job times to last-refresh times */
        const CLOCK_FUDGE = 10;
        /** @var integer How many seconds to wait for replica DBs to catch up */
        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 )
                );
        }

        /**
         * @param Title $title
         * @param array $params
         * @return RefreshLinksJob
         */
        public static function newPrioritized( Title $title, array $params ) {
                $job = new self( $title, $params );
                $job->command = 'refreshLinksPrioritized';

                return $job;
        }

        /**
         * @param Title $title
         * @param array $params
         * @return RefreshLinksJob
         */
        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'] ) ) {
                        // 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( $params['range'] ) ) {
                                try {
                                        $lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
                                        $lbFactory->waitForReplication( [
                                                'wiki'    => wfWikiID(),
                                                'timeout' => self::LAG_WAIT_TIMEOUT
                                        ] );
                                } catch ( DBReplicationWaitError $e ) { // 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;
                        // 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 $pageId => $nsAndKey ) {
                                list( $ns, $dbKey ) = $nsAndKey;
                                $this->runForTitle( Title::makeTitleSafe( $ns, $dbKey ) );
                        }
                // Job to update link tables for a given title
                } else {
                        $this->runForTitle( $this->title );
                }

                return true;
        }

        /**
         * @param Title $title
         * @return bool
         */
        protected function runForTitle( Title $title ) {
                $services = MediaWikiServices::getInstance();
                $stats = $services->getStatsdDataFactory();
                $lbFactory = $services->getDBLoadBalancerFactory();
                $ticket = $lbFactory->getEmptyTransactionTicket( __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 );
                /** @noinspection PhpUnusedLocalVariableInspection */
                $scopedLock = LinksUpdate::acquirePageLock( $dbw, $page->getId(), 'job' );
                // 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 = 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 ) {
                        $stats->increment( 'refreshlinks.rev_not_found' );
                        $this->setLastError( "Revision not found for {$title->getPrefixedDBkey()}" );
                        return false; // just deleted?
                } elseif ( $revision->getId() != $latest || $revision->getPage() !== $page->getId() ) {
                        // 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;
                }

                $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/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 ) {
                                // 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 = 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 ) {
                        $stats->increment( 'refreshlinks.parser_cached' );
                } else {
                        $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()
                                );
                        }
                        $stats->increment( 'refreshlinks.parser_uncached' );
                }

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

                // For legacy hook handlers doing updates via LinksUpdateConstructed, make sure
                // any pending writes they made get flushed before the doUpdate() calls below.
                // This avoids snapshot-clearing errors in LinksUpdate::acquirePageLock().
                $lbFactory->commitAndWaitForReplication( __METHOD__, $ticket );

                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 ) {
                                $update->setRevision( $revision );
                                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 );
                                }
                        }
                }

                foreach ( $updates as $update ) {
                        $update->setTransactionTicket( $ticket );
                        $update->doUpdate();
                }

                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;
        }
}