Current File : /www/varak.net/wiki.varak.net/includes/jobqueue/jobs/CategoryMembershipChangeJob.php
<?php
/**
* Updater for link tracking tables after a page edit.
*
* 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
*/
use MediaWiki\MediaWikiServices;
use Wikimedia\Rdbms\LBFactory;
/**
* Job to add recent change entries mentioning category membership changes
*
* This allows users to easily scan categories for recent page membership changes
*
* Parameters include:
* - pageId : page ID
* - revTimestamp : timestamp of the triggering revision
*
* Category changes will be mentioned for revisions at/after the timestamp for this page
*
* @since 1.27
*/
class CategoryMembershipChangeJob extends Job {
/** @var int|null */
private $ticket;
const ENQUEUE_FUDGE_SEC = 60;
public function __construct( Title $title, array $params ) {
parent::__construct( 'categoryMembershipChange', $title, $params );
// Only need one job per page. Note that ENQUEUE_FUDGE_SEC handles races where an
// older revision job gets inserted while the newer revision job is de-duplicated.
$this->removeDuplicates = true;
}
public function run() {
$lbFactory = MediaWikiServices::getInstance()->getDBLoadBalancerFactory();
$lb = $lbFactory->getMainLB();
$dbw = $lb->getConnection( DB_MASTER );
$this->ticket = $lbFactory->getEmptyTransactionTicket( __METHOD__ );
$page = WikiPage::newFromID( $this->params['pageId'], WikiPage::READ_LATEST );
if ( !$page ) {
$this->setLastError( "Could not find page #{$this->params['pageId']}" );
return false; // deleted?
}
// Cut down on the time spent in safeWaitForMasterPos() in the critical section
$dbr = $lb->getConnection( DB_REPLICA, [ 'recentchanges' ] );
if ( !$lb->safeWaitForMasterPos( $dbr ) ) {
$this->setLastError( "Timed out while pre-waiting for replica DB to catch up" );
return false;
}
// Use a named lock so that jobs for this page see each others' changes
$lockKey = "CategoryMembershipUpdates:{$page->getId()}";
$scopedLock = $dbw->getScopedLockAndFlush( $lockKey, __METHOD__, 3 );
if ( !$scopedLock ) {
$this->setLastError( "Could not acquire lock '$lockKey'" );
return false;
}
// Wait till replica DB is caught up so that jobs for this page see each others' changes
if ( !$lb->safeWaitForMasterPos( $dbr ) ) {
$this->setLastError( "Timed out while waiting for replica DB to catch up" );
return false;
}
// Clear any stale REPEATABLE-READ snapshot
$dbr->flushSnapshot( __METHOD__ );
$cutoffUnix = wfTimestamp( TS_UNIX, $this->params['revTimestamp'] );
// Using ENQUEUE_FUDGE_SEC handles jobs inserted out of revision order due to the delay
// between COMMIT and actual enqueueing of the CategoryMembershipChangeJob job.
$cutoffUnix -= self::ENQUEUE_FUDGE_SEC;
// Get the newest page revision that has a SRC_CATEGORIZE row.
// Assume that category changes before it were already handled.
$row = $dbr->selectRow(
'revision',
[ 'rev_timestamp', 'rev_id' ],
[
'rev_page' => $page->getId(),
'rev_timestamp >= ' . $dbr->addQuotes( $dbr->timestamp( $cutoffUnix ) ),
'EXISTS (' . $dbr->selectSQLText(
'recentchanges',
'1',
[
'rc_this_oldid = rev_id',
'rc_source' => RecentChange::SRC_CATEGORIZE,
// Allow rc_cur_id or rc_timestamp index usage
'rc_cur_id = rev_page',
'rc_timestamp = rev_timestamp'
]
) . ')'
],
__METHOD__,
[ 'ORDER BY' => 'rev_timestamp DESC, rev_id DESC' ]
);
// Only consider revisions newer than any such revision
if ( $row ) {
$cutoffUnix = wfTimestamp( TS_UNIX, $row->rev_timestamp );
$lastRevId = (int)$row->rev_id;
} else {
$lastRevId = 0;
}
// Find revisions to this page made around and after this revision which lack category
// notifications in recent changes. This lets jobs pick up were the last one left off.
$encCutoff = $dbr->addQuotes( $dbr->timestamp( $cutoffUnix ) );
$revQuery = Revision::getQueryInfo();
$res = $dbr->select(
$revQuery['tables'],
$revQuery['fields'],
[
'rev_page' => $page->getId(),
"rev_timestamp > $encCutoff" .
" OR (rev_timestamp = $encCutoff AND rev_id > $lastRevId)"
],
__METHOD__,
[ 'ORDER BY' => 'rev_timestamp ASC, rev_id ASC' ],
$revQuery['joins']
);
// Apply all category updates in revision timestamp order
foreach ( $res as $row ) {
$this->notifyUpdatesForRevision( $lbFactory, $page, Revision::newFromRow( $row ) );
}
return true;
}
/**
* @param LBFactory $lbFactory
* @param WikiPage $page
* @param Revision $newRev
* @throws MWException
*/
protected function notifyUpdatesForRevision(
LBFactory $lbFactory, WikiPage $page, Revision $newRev
) {
$config = RequestContext::getMain()->getConfig();
$title = $page->getTitle();
// Get the new revision
if ( !$newRev->getContent() ) {
return; // deleted?
}
// Get the prior revision (the same for null edits)
if ( $newRev->getParentId() ) {
$oldRev = Revision::newFromId( $newRev->getParentId(), Revision::READ_LATEST );
if ( !$oldRev->getContent() ) {
return; // deleted?
}
} else {
$oldRev = null;
}
// Parse the new revision and get the categories
$categoryChanges = $this->getExplicitCategoriesChanges( $page, $newRev, $oldRev );
list( $categoryInserts, $categoryDeletes ) = $categoryChanges;
if ( !$categoryInserts && !$categoryDeletes ) {
return; // nothing to do
}
$catMembChange = new CategoryMembershipChange( $title, $newRev );
$catMembChange->checkTemplateLinks();
$batchSize = $config->get( 'UpdateRowsPerQuery' );
$insertCount = 0;
foreach ( $categoryInserts as $categoryName ) {
$categoryTitle = Title::makeTitle( NS_CATEGORY, $categoryName );
$catMembChange->triggerCategoryAddedNotification( $categoryTitle );
if ( $insertCount++ && ( $insertCount % $batchSize ) == 0 ) {
$lbFactory->commitAndWaitForReplication( __METHOD__, $this->ticket );
}
}
foreach ( $categoryDeletes as $categoryName ) {
$categoryTitle = Title::makeTitle( NS_CATEGORY, $categoryName );
$catMembChange->triggerCategoryRemovedNotification( $categoryTitle );
if ( $insertCount++ && ( $insertCount++ % $batchSize ) == 0 ) {
$lbFactory->commitAndWaitForReplication( __METHOD__, $this->ticket );
}
}
}
private function getExplicitCategoriesChanges(
WikiPage $page, Revision $newRev, Revision $oldRev = null
) {
// Inject the same timestamp for both revision parses to avoid seeing category changes
// due to time-based parser functions. Inject the same page title for the parses too.
// Note that REPEATABLE-READ makes template/file pages appear unchanged between parses.
$parseTimestamp = $newRev->getTimestamp();
// Parse the old rev and get the categories. Do not use link tables as that
// assumes these updates are perfectly FIFO and that link tables are always
// up to date, neither of which are true.
$oldCategories = $oldRev
? $this->getCategoriesAtRev( $page, $oldRev, $parseTimestamp )
: [];
// Parse the new revision and get the categories
$newCategories = $this->getCategoriesAtRev( $page, $newRev, $parseTimestamp );
$categoryInserts = array_values( array_diff( $newCategories, $oldCategories ) );
$categoryDeletes = array_values( array_diff( $oldCategories, $newCategories ) );
return [ $categoryInserts, $categoryDeletes ];
}
/**
* @param WikiPage $page
* @param Revision $rev
* @param string $parseTimestamp TS_MW
*
* @return string[] category names
*/
private function getCategoriesAtRev( WikiPage $page, Revision $rev, $parseTimestamp ) {
$renderer = MediaWikiServices::getInstance()->getRevisionRenderer();
$options = $page->makeParserOptions( 'canonical' );
$options->setTimestamp( $parseTimestamp );
// This could possibly use the parser cache if it checked the revision ID,
// but that's more complicated than it's worth.
$output = $renderer->getRenderedRevision( $rev->getRevisionRecord(), $options )
->getRevisionParserOutput();
// array keys will cast numeric category names to ints
// so we need to cast them back to strings to avoid breaking things!
return array_map( 'strval', array_keys( $output->getCategories() ) );
}
public function getDeduplicationInfo() {
$info = parent::getDeduplicationInfo();
unset( $info['params']['revTimestamp'] ); // first job wins
return $info;
}
}
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