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<?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;
}
}