User::isSafeToLoad() should return false if MW_NO_SESSION

[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
 */

/**
 * 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;

        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 )
                );
        }

        /**
         * @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'] ) ) {
                        // 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'] );
                }
        }

        /**
         * @param Title $title
         * @return bool
         */
        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?
                }

                $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
                                $parserOutput = ParserCache::singleton()->getDirty( $page, $parserOptions );
                                if ( $parserOutput && $parserOutput->getCacheTime() < $skewedTimestamp ) {
                                        $parserOutput = false; // too stale
                                }
                        }
                }

                // Fetch the current revision and parse it if necessary...
                if ( $parserOutput == false ) {
                        $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;
        }
}