585 lines
17 KiB
PHP
585 lines
17 KiB
PHP
<?php
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/**
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* Class for fetching backlink lists, approximate backlink counts and
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* partitions.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @author Tim Starling
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* @copyright © 2009, Tim Starling, Domas Mituzas
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* @copyright © 2010, Max Sem
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* @copyright © 2011, Antoine Musso
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*/
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namespace MediaWiki\Cache;
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use Iterator;
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use LogicException;
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use MediaWiki\Config\ServiceOptions;
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use MediaWiki\HookContainer\HookContainer;
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use MediaWiki\HookContainer\HookRunner;
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use MediaWiki\Linker\LinksMigration;
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use MediaWiki\MainConfigNames;
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use MediaWiki\Page\PageIdentity;
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use MediaWiki\Page\PageIdentityValue;
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use MediaWiki\Page\PageReference;
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use MediaWiki\Title\Title;
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use MediaWiki\Title\TitleValue;
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use Psr\Log\LoggerInterface;
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use RuntimeException;
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use stdClass;
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use Wikimedia\ObjectCache\WANObjectCache;
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use Wikimedia\Rdbms\Database;
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use Wikimedia\Rdbms\IConnectionProvider;
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use Wikimedia\Rdbms\IReadableDatabase;
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use Wikimedia\Rdbms\IResultWrapper;
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use Wikimedia\Rdbms\SelectQueryBuilder;
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/**
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* Class for fetching backlink lists, approximate backlink counts and
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* partitions. This is a shared cache.
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*
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* Instances of this class should typically be fetched with the method
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* ::getBacklinkCache() from the BacklinkCacheFactory service.
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*
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* Ideally you should only get your backlinks from here when you think
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* there is some advantage in caching them. Otherwise, it's just a waste
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* of memory.
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*/
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class BacklinkCache {
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/**
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* @internal Used by ServiceWiring.php
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*/
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public const CONSTRUCTOR_OPTIONS = [
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MainConfigNames::UpdateRowsPerJob,
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];
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/**
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* Multi-dimensional array representing batches. Keys are:
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* > (string) links table name
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* > (int) batch size
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* > 'numRows' : Number of rows for this link table
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* > 'batches' : [ [ $start, $end ] ]
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*
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* @see BacklinkCache::partitionResult()
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* @var array[]
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*/
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private $partitionCache = [];
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/**
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* Contains the whole links from a database result.
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* This is raw data that will be partitioned in $partitionCache
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*
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* Initialized with BacklinkCache::queryLinks()
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*
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* @var IResultWrapper[]
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*/
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private $fullResultCache = [];
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/**
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* Cache for hasLinks()
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*
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* @var bool[]
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*/
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private $hasLinksCache = [];
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/** @var WANObjectCache */
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private $wanCache;
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/** @var HookRunner */
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private $hookRunner;
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/**
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* Local copy of a PageReference object
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* @var PageReference
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*/
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private $page;
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private const CACHE_EXPIRY = 3600;
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private IConnectionProvider $dbProvider;
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private ServiceOptions $options;
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private LinksMigration $linksMigration;
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private LoggerInterface $logger;
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/**
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* Create a new BacklinkCache
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*
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* @param ServiceOptions $options
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* @param LinksMigration $linksMigration
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* @param WANObjectCache $wanCache
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* @param HookContainer $hookContainer
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* @param IConnectionProvider $dbProvider
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* @param LoggerInterface $logger
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* @param PageReference $page Page to create a backlink cache for
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*/
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public function __construct(
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ServiceOptions $options,
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LinksMigration $linksMigration,
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WANObjectCache $wanCache,
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HookContainer $hookContainer,
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IConnectionProvider $dbProvider,
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LoggerInterface $logger,
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PageReference $page
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) {
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$options->assertRequiredOptions( self::CONSTRUCTOR_OPTIONS );
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$this->options = $options;
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$this->linksMigration = $linksMigration;
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$this->wanCache = $wanCache;
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$this->hookRunner = new HookRunner( $hookContainer );
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$this->dbProvider = $dbProvider;
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$this->logger = $logger;
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$this->page = $page;
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}
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/**
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* @since 1.37
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* @return PageReference
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*/
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public function getPage(): PageReference {
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return $this->page;
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}
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/**
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* Get the replica DB connection to the database
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*
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* @return IReadableDatabase
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*/
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private function getDB() {
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return $this->dbProvider->getReplicaDatabase();
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}
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/**
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* Get the backlinks for a given table. Cached in process memory only.
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* @param string $table
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* @param int|bool $startId
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* @param int|bool $endId
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* @param int|float $max Integer, or INF for no max
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* @return Iterator<PageIdentity>
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* @since 1.37
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*/
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public function getLinkPages(
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string $table, $startId = false, $endId = false, $max = INF
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): Iterator {
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$i = 0;
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foreach ( $this->queryLinks( $table, $startId, $endId, $max ) as $row ) {
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yield PageIdentityValue::localIdentity(
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$row->page_id, $row->page_namespace, $row->page_title );
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// queryLinks() may return too many rows
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if ( is_finite( $max ) && ++$i >= $max ) {
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break;
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}
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}
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}
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/**
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* Get the backlinks for a given table. Cached in process memory only.
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*
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* @param string $table
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* @param int|bool $startId
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* @param int|bool $endId
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* @param int|float $max A hint for the maximum number of rows to return.
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* May return more rows if there is a previously cached result set.
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* @param string $select 'all' or 'ids'
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* @return IResultWrapper
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*/
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private function queryLinks( $table, $startId, $endId, $max, $select = 'all' ) {
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if ( !$startId && !$endId && isset( $this->fullResultCache[$table] ) ) {
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$this->logger->debug( __METHOD__ . ': got results from cache' );
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return $this->fullResultCache[$table];
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}
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$this->logger->debug( __METHOD__ . ': got results from DB' );
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$queryBuilder = $this->initQueryBuilderForTable( $table, $select );
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$fromField = $this->getPrefix( $table ) . '_from';
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// Use the from field in the condition rather than the joined page_id,
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// because databases are stupid and don't necessarily propagate indexes.
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if ( $startId ) {
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$queryBuilder->where(
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$this->getDB()->expr( $fromField, '>=', $startId )
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);
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}
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if ( $endId ) {
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$queryBuilder->where(
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$this->getDB()->expr( $fromField, '<=', $endId )
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);
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}
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$queryBuilder->orderBy( $fromField );
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if ( is_finite( $max ) && $max > 0 ) {
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$queryBuilder->limit( $max );
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}
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$res = $queryBuilder->caller( __METHOD__ )->fetchResultSet();
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if ( $select === 'all' && !$startId && !$endId && $res->numRows() < $max ) {
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// The full results fit within the limit, so cache them
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$this->fullResultCache[$table] = $res;
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} else {
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$this->logger->debug( __METHOD__ . ": results from DB were uncacheable" );
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}
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return $res;
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}
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/**
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* Get the field name prefix for a given table
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* @param string $table
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* @return null|string
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*/
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private function getPrefix( $table ) {
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static $prefixes = [
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'pagelinks' => 'pl',
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'imagelinks' => 'il',
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'categorylinks' => 'cl',
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'templatelinks' => 'tl',
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'redirect' => 'rd',
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];
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if ( isset( $prefixes[$table] ) ) {
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return $prefixes[$table];
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} else {
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$prefix = null;
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$this->hookRunner->onBacklinkCacheGetPrefix( $table, $prefix );
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if ( $prefix ) {
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return $prefix;
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} else {
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throw new LogicException( "Invalid table \"$table\" in " . __CLASS__ );
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}
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}
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}
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/**
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* Initialize a new SelectQueryBuilder for selecting backlinks,
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* with a join on the page table if needed.
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*
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* @param string $table
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* @param string $select
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* @return SelectQueryBuilder
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*/
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private function initQueryBuilderForTable( string $table, string $select ): SelectQueryBuilder {
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$prefix = $this->getPrefix( $table );
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$queryBuilder = $this->getDB()->newSelectQueryBuilder();
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$joinPageTable = $select !== 'ids';
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if ( $select === 'ids' ) {
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$queryBuilder->select( [ 'page_id' => $prefix . '_from' ] );
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} else {
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$queryBuilder->select( [ 'page_namespace', 'page_title', 'page_id' ] );
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}
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$queryBuilder->from( $table );
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/*
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* If the table is one of the tables known to this method,
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* we can use a nice join() method later, always joining on page_id={$prefix}_from.
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* If the table is unknown here, and only supported via a hook,
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* the hook only produces a single $conds array,
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* so we have to use a traditional / ANSI-89 JOIN,
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* with the page table just added to the list of tables and the join conds in the WHERE part.
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*/
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$knownTable = true;
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switch ( $table ) {
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case 'pagelinks':
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case 'templatelinks':
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$queryBuilder->where(
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$this->linksMigration->getLinksConditions( $table, TitleValue::newFromPage( $this->page ) )
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);
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break;
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case 'redirect':
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$queryBuilder->where( [
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"{$prefix}_namespace" => $this->page->getNamespace(),
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"{$prefix}_title" => $this->page->getDBkey(),
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"{$prefix}_interwiki" => [ '', null ],
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] );
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break;
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case 'imagelinks':
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case 'categorylinks':
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$queryBuilder->where( [
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"{$prefix}_to" => $this->page->getDBkey(),
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] );
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break;
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default:
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$knownTable = false;
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$conds = null;
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$this->hookRunner->onBacklinkCacheGetConditions( $table,
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Title::newFromPageReference( $this->page ),
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$conds
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);
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if ( !$conds ) {
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throw new LogicException( "Invalid table \"$table\" in " . __CLASS__ );
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}
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if ( $joinPageTable ) {
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$queryBuilder->table( 'page' ); // join condition in $conds
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} else {
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// remove any page_id condition from $conds
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$conds = array_filter( (array)$conds, static function ( $clause ) { // kind of janky
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return !preg_match( '/(\b|=)page_id(\b|=)/', (string)$clause );
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} );
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}
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$queryBuilder->where( $conds );
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break;
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}
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if ( $knownTable && $joinPageTable ) {
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$queryBuilder->join( 'page', null, "page_id={$prefix}_from" );
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}
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if ( $joinPageTable ) {
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$queryBuilder->straightJoinOption();
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}
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return $queryBuilder;
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}
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/**
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* Check if there are any backlinks. Only use the process cache, since the
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* WAN cache is potentially stale (T368006).
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*
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* @param string $table
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* @return bool
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*/
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public function hasLinks( $table ) {
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if ( isset( $this->hasLinksCache[$table] ) ) {
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return $this->hasLinksCache[$table];
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}
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if ( isset( $this->partitionCache[$table] ) ) {
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$entry = reset( $this->partitionCache[$table] );
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return (bool)$entry['numRows'];
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}
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if ( isset( $this->fullResultCache[$table] ) ) {
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return (bool)$this->fullResultCache[$table]->numRows();
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}
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$hasLinks = (bool)$this->queryLinks( $table, false, false, 1 )->numRows();
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$this->hasLinksCache[$table] = $hasLinks;
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return $hasLinks;
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}
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/**
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* Get the approximate number of backlinks
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* @param string $table
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* @return int
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*/
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public function getNumLinks( $table ) {
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if ( isset( $this->partitionCache[$table] ) ) {
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$entry = reset( $this->partitionCache[$table] );
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return $entry['numRows'];
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}
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if ( isset( $this->fullResultCache[$table] ) ) {
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return $this->fullResultCache[$table]->numRows();
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}
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return $this->wanCache->getWithSetCallback(
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$this->wanCache->makeKey(
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'numbacklinks',
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CacheKeyHelper::getKeyForPage( $this->page ),
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$table
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),
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self::CACHE_EXPIRY,
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function ( $oldValue, &$ttl, array &$setOpts ) use ( $table ) {
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$setOpts += Database::getCacheSetOptions( $this->getDB() );
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// Use partition() since it will batch the query and skip the JOIN.
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// Use $wgUpdateRowsPerJob just to encourage cache reuse for jobs.
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$batchSize = $this->options->get( MainConfigNames::UpdateRowsPerJob );
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$this->partition( $table, $batchSize );
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return $this->partitionCache[$table][$batchSize]['numRows'];
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}
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);
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}
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/**
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* Partition the backlinks into batches.
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* Returns an array giving the start and end of each range. The first
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* batch has a start of false, and the last batch has an end of false.
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*
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* @param string $table The links table name
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* @param int $batchSize
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* @return array
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*/
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public function partition( $table, $batchSize ) {
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if ( isset( $this->partitionCache[$table][$batchSize] ) ) {
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$this->logger->debug( __METHOD__ . ": got from partition cache" );
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return $this->partitionCache[$table][$batchSize]['batches'];
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}
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$this->partitionCache[$table][$batchSize] = false;
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$cacheEntry =& $this->partitionCache[$table][$batchSize];
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if ( isset( $this->fullResultCache[$table] ) ) {
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$res = $this->fullResultCache[$table];
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$numRows = $res->numRows();
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$batches = $this->partitionResult( $res, $numRows, $batchSize );
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$this->openBatchEnds( $batches );
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$cacheEntry = [ 'numRows' => $numRows, 'batches' => $batches ];
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$this->logger->debug( __METHOD__ . ": got from full result cache" );
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return $cacheEntry['batches'];
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}
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$cacheEntry = $this->wanCache->getWithSetCallback(
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$this->wanCache->makeKey(
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'backlinks',
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CacheKeyHelper::getKeyForPage( $this->page ),
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$table,
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$batchSize
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),
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self::CACHE_EXPIRY,
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function ( $oldValue, &$ttl, array &$setOpts ) use ( $table, $batchSize ) {
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$setOpts += Database::getCacheSetOptions( $this->getDB() );
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$value = [ 'numRows' => 0, 'batches' => [] ];
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// Do the selects in batches to avoid client-side OOMs (T45452).
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// Use a LIMIT that plays well with $batchSize to keep equal sized partitions.
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$selectSize = max( $batchSize, 200_000 - ( 200_000 % $batchSize ) );
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$start = false;
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do {
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$res = $this->queryLinks( $table, $start, false, $selectSize, 'ids' );
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$numRows = $res->numRows();
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$batches = $this->partitionResult( $res, $numRows, $batchSize );
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// Merge the link count and range partitions for this chunk
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$value['numRows'] += $numRows;
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$value['batches'] = array_merge( $value['batches'], $batches );
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if ( count( $batches ) ) {
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// pick up after this inclusive range
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$start = end( $batches )[1] + 1;
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}
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} while ( $numRows >= $selectSize );
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// Make sure the first range has start=false and the last one has end=false
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$this->openBatchEnds( $value['batches'] );
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return $value;
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}
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);
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return $cacheEntry['batches'];
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}
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/**
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* Modify an array of batches, setting the start of the first batch to
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* false, and the end of the last batch to false, so that the complete
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* set of batches covers the entire ID range from 0 to infinity.
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*
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* @param array &$batches
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*/
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private function openBatchEnds( array &$batches ) {
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if ( !count( $batches ) ) {
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$batches = [ [ false, false ] ];
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} else {
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$batches[0][0] = false;
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$batches[ array_key_last( $batches ) ][1] = false;
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}
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}
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/**
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* Partition a DB result with backlinks in it into batches
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* @param IResultWrapper $res Database result
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* @param int $numRows The number of rows to use from the result set
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* @param int $batchSize
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* @return int[][]
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*/
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private function partitionResult( $res, $numRows, $batchSize ) {
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$numBatches = ceil( $numRows / $batchSize );
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$batches = [];
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for ( $i = 0; $i < $numBatches; $i++ ) {
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$rowNum = $i * $batchSize;
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$res->seek( $rowNum );
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$row = $res->fetchObject();
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$start = (int)$row->page_id;
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$rowNum = min( $numRows - 1, ( $i + 1 ) * $batchSize - 1 );
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$res->seek( $rowNum );
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$row = $res->fetchObject();
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$end = (int)$row->page_id;
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// Check order
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if ( $start && $end && $start > $end ) {
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throw new RuntimeException( __METHOD__ . ': Internal error: query result out of order' );
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}
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$batches[] = [ $start, $end ];
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}
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return $batches;
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|
}
|
|
|
|
/**
|
|
* Get a PageIdentity iterator for cascade-protected template/file use backlinks
|
|
*
|
|
* @return Iterator<PageIdentity>
|
|
* @since 1.37
|
|
*/
|
|
public function getCascadeProtectedLinkPages(): Iterator {
|
|
foreach ( $this->getCascadeProtectedLinksInternal() as $row ) {
|
|
yield PageIdentityValue::localIdentity(
|
|
$row->page_id, $row->page_namespace, $row->page_title );
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Get an array of cascade-protected template/file use backlinks
|
|
*
|
|
* @return stdClass[]
|
|
*/
|
|
private function getCascadeProtectedLinksInternal(): array {
|
|
$dbr = $this->getDB();
|
|
|
|
// @todo: use UNION without breaking tests that use temp tables
|
|
$resSets = [];
|
|
$linkConds = $this->linksMigration->getLinksConditions(
|
|
'templatelinks', TitleValue::newFromPage( $this->page )
|
|
);
|
|
$resSets[] = $dbr->newSelectQueryBuilder()
|
|
->select( [ 'page_namespace', 'page_title', 'page_id' ] )
|
|
->from( 'templatelinks' )
|
|
->join( 'page_restrictions', null, 'tl_from = pr_page' )
|
|
->join( 'page', null, 'page_id = tl_from' )
|
|
->where( $linkConds )
|
|
->andWhere( [ 'pr_cascade' => 1 ] )
|
|
->distinct()
|
|
->caller( __METHOD__ )->fetchResultSet();
|
|
if ( $this->page->getNamespace() === NS_FILE ) {
|
|
$resSets[] = $dbr->newSelectQueryBuilder()
|
|
->select( [ 'page_namespace', 'page_title', 'page_id' ] )
|
|
->from( 'imagelinks' )
|
|
->join( 'page_restrictions', null, 'il_from = pr_page' )
|
|
->join( 'page', null, 'page_id = il_from' )
|
|
->where( [
|
|
'il_to' => $this->page->getDBkey(),
|
|
'pr_cascade' => 1,
|
|
] )
|
|
->distinct()
|
|
->caller( __METHOD__ )->fetchResultSet();
|
|
}
|
|
|
|
// Combine and de-duplicate the results
|
|
$mergedRes = [];
|
|
foreach ( $resSets as $res ) {
|
|
foreach ( $res as $row ) {
|
|
// Index by page_id to remove duplicates
|
|
$mergedRes[$row->page_id] = $row;
|
|
}
|
|
}
|
|
|
|
// Now that we've de-duplicated, throw away the keys
|
|
return array_values( $mergedRes );
|
|
}
|
|
}
|
|
|
|
/** @deprecated class alias since 1.42 */
|
|
class_alias( BacklinkCache::class, 'BacklinkCache' );
|