QueryPage.php

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<?php
namespace MediaWiki\SpecialPage;
 
use Exception;
use MediaWiki\Config\Config;
use MediaWiki\HookContainer\HookRunner;
use MediaWiki\Html\Html;
use MediaWiki\Http\HttpRequestFactory;
use MediaWiki\Linker\LinkTarget;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use MediaWiki\Output\OutputPage;
use MediaWiki\Page\LinkBatchFactory;
use MediaWiki\Skin\Skin;
use MediaWiki\Specials\SpecialAncientPages;
use MediaWiki\Specials\SpecialBrokenRedirects;
use MediaWiki\Specials\SpecialDeadendPages;
use MediaWiki\Specials\SpecialDoubleRedirects;
use MediaWiki\Specials\SpecialFewestRevisions;
use MediaWiki\Specials\SpecialLinkSearch;
use MediaWiki\Specials\SpecialListDuplicatedFiles;
use MediaWiki\Specials\SpecialListRedirects;
use MediaWiki\Specials\SpecialLonelyPages;
use MediaWiki\Specials\SpecialLongPages;
use MediaWiki\Specials\SpecialMediaStatistics;
use MediaWiki\Specials\SpecialMIMESearch;
use MediaWiki\Specials\SpecialMostCategories;
use MediaWiki\Specials\SpecialMostImages;
use MediaWiki\Specials\SpecialMostInterwikis;
use MediaWiki\Specials\SpecialMostLinked;
use MediaWiki\Specials\SpecialMostLinkedCategories;
use MediaWiki\Specials\SpecialMostLinkedTemplates;
use MediaWiki\Specials\SpecialMostRevisions;
use MediaWiki\Specials\SpecialShortPages;
use MediaWiki\Specials\SpecialUncategorizedCategories;
use MediaWiki\Specials\SpecialUncategorizedImages;
use MediaWiki\Specials\SpecialUncategorizedPages;
use MediaWiki\Specials\SpecialUncategorizedTemplates;
use MediaWiki\Specials\SpecialUnusedCategories;
use MediaWiki\Specials\SpecialUnusedImages;
use MediaWiki\Specials\SpecialUnusedTemplates;
use MediaWiki\Specials\SpecialUnwatchedPages;
use MediaWiki\Specials\SpecialWantedCategories;
use MediaWiki\Specials\SpecialWantedFiles;
use MediaWiki\Specials\SpecialWantedPages;
use MediaWiki\Specials\SpecialWantedTemplates;
use MediaWiki\Specials\SpecialWithoutInterwiki;
use RuntimeException;
use stdClass;
use Wikimedia\Rdbms\DBError;
use Wikimedia\Rdbms\FakeResultWrapper;
use Wikimedia\Rdbms\IConnectionProvider;
use Wikimedia\Rdbms\IDatabase;
use Wikimedia\Rdbms\ILoadBalancer;
use Wikimedia\Rdbms\IReadableDatabase;
use Wikimedia\Rdbms\IResultWrapper;
use Wikimedia\Rdbms\SelectQueryBuilder;
use Wikimedia\Timestamp\TimestampFormat as TS;
 
abstract class QueryPage extends SpecialPage {
    protected $listoutput = false;
 
    protected $offset = 0;
 
    protected $limit = 0;
 
    protected $numRows;
 
    protected $cachedTimestamp = null;
 
    protected $shownavigation = true;
 
    private $loadBalancer = null;
 
    private $databaseProvider = null;
 
    private $linkBatchFactory = null;
 
    private $httpRequestFactory = null;
 
    public static function getPages() {
        static $qp = null;
 
        if ( $qp === null ) {
            $qp = [
                [ SpecialAncientPages::class, 'Ancientpages' ],
                [ SpecialBrokenRedirects::class, 'BrokenRedirects' ],
                [ SpecialDeadendPages::class, 'Deadendpages' ],
                [ SpecialDoubleRedirects::class, 'DoubleRedirects' ],
                [ SpecialListDuplicatedFiles::class, 'ListDuplicatedFiles' ],
                [ SpecialLinkSearch::class, 'LinkSearch' ],
                [ SpecialListRedirects::class, 'Listredirects' ],
                [ SpecialLonelyPages::class, 'Lonelypages' ],
                [ SpecialLongPages::class, 'Longpages' ],
                [ SpecialMediaStatistics::class, 'MediaStatistics', SpecialMediaStatistics::MAX_LIMIT ],
                [ SpecialMIMESearch::class, 'MIMEsearch' ],
                [ SpecialMostCategories::class, 'Mostcategories' ],
                [ SpecialMostImages::class, 'Mostimages' ],
                [ SpecialMostInterwikis::class, 'Mostinterwikis' ],
                [ SpecialMostLinkedCategories::class, 'Mostlinkedcategories' ],
                [ SpecialMostLinkedTemplates::class, 'Mostlinkedtemplates' ],
                [ SpecialMostLinked::class, 'Mostlinked' ],
                [ SpecialMostRevisions::class, 'Mostrevisions' ],
                [ SpecialFewestRevisions::class, 'Fewestrevisions' ],
                [ SpecialShortPages::class, 'Shortpages' ],
                [ SpecialUncategorizedCategories::class, 'Uncategorizedcategories' ],
                [ SpecialUncategorizedPages::class, 'Uncategorizedpages' ],
                [ SpecialUncategorizedImages::class, 'Uncategorizedimages' ],
                [ SpecialUncategorizedTemplates::class, 'Uncategorizedtemplates' ],
                [ SpecialUnusedCategories::class, 'Unusedcategories' ],
                [ SpecialUnusedImages::class, 'Unusedimages' ],
                [ SpecialWantedCategories::class, 'Wantedcategories' ],
                [ SpecialWantedFiles::class, 'Wantedfiles' ],
                [ SpecialWantedPages::class, 'Wantedpages' ],
                [ SpecialWantedTemplates::class, 'Wantedtemplates' ],
                [ SpecialUnwatchedPages::class, 'Unwatchedpages' ],
                [ SpecialUnusedTemplates::class, 'Unusedtemplates' ],
                [ SpecialWithoutInterwiki::class, 'Withoutinterwiki' ],
            ];
            ( new HookRunner( MediaWikiServices::getInstance()->getHookContainer() ) )->onWgQueryPages( $qp );
        }
 
        return $qp;
    }
 
    final protected function setLinkBatchFactory( LinkBatchFactory $linkBatchFactory ) {
        $this->linkBatchFactory = $linkBatchFactory;
    }
 
    final protected function getLinkBatchFactory(): LinkBatchFactory {
        if ( $this->linkBatchFactory === null ) {
            // Fallback if not provided
            // TODO Change to wfWarn in a future release
            $this->linkBatchFactory = MediaWikiServices::getInstance()->getLinkBatchFactory();
        }
        return $this->linkBatchFactory;
    }
 
    private function getHttpRequestFactory(): HttpRequestFactory {
        if ( $this->httpRequestFactory === null ) {
            // Fallback if not provided
            // TODO Do not rely on global state
            $this->httpRequestFactory = MediaWikiServices::getInstance()->getHttpRequestFactory();
        }
        return $this->httpRequestFactory;
    }
 
    public static function getDisabledQueryPages( Config $config ) {
        $disableQueryPageUpdate = $config->get( MainConfigNames::DisableQueryPageUpdate );
 
        if ( !is_array( $disableQueryPageUpdate ) ) {
            return [];
        }
 
        $pages = [];
        foreach ( $disableQueryPageUpdate as $name => $runMode ) {
            if ( is_int( $name ) ) {
                // The run mode may be omitted
                $pages[$runMode] = 'disabled';
            } else {
                $pages[$name] = $runMode;
            }
        }
        return $pages;
    }
 
    protected function setListoutput( $bool ) {
        $this->listoutput = $bool;
    }
 
    abstract public function getQueryInfo();
 
    protected function getOrderFields() {
        return [ 'value' ];
    }
 
    public function usesTimestamps() {
        return false;
    }
 
    protected function sortDescending() {
        return true;
    }
 
    public function isExpensive() {
        return $this->getConfig()->get( MainConfigNames::DisableQueryPages );
    }
 
    public function isCacheable() {
        return true;
    }
 
    public function isCached() {
        return $this->isExpensive() && $this->getConfig()->get( MainConfigNames::MiserMode );
    }
 
    public function isSyndicated() {
        return true;
    }
 
    public function usesExternalSource(): bool {
        $config = $this->getConfig();
        $externalSources = $config->get( MainConfigNames::ExternalQuerySources );
        $pageName = $this->getName();
 
        return !empty( $externalSources[$pageName]['enabled'] ) &&
            !empty( $externalSources[$pageName]['url'] );
    }
 
    abstract protected function formatResult( $skin, $result );
 
    protected function getPageHeader() {
        return '';
    }
 
    protected function showEmptyText() {
        $this->getOutput()->addWikiMsg( 'specialpage-empty' );
    }
 
    protected function linkParameters() {
        return [];
    }
 
    public function recache( $limit, $unused = true ) {
        if ( !$this->isCacheable() ) {
            return 0;
        }
 
        $fname = static::class . '::recache';
        $dbw = $this->getDatabaseProvider()->getPrimaryDatabase();
 
        // Do query
        $res = $this->reallyDoQuery( $limit, false );
        $num = false;
        if ( $res ) {
            $num = $res->numRows();
            // Fetch results
            $vals = [];
            foreach ( $res as $i => $row ) {
                if ( isset( $row->value ) ) {
                    if ( $this->usesTimestamps() ) {
                        $value = (int)wfTimestamp( TS::UNIX, $row->value );
                    } else {
                        $value = intval( $row->value ); // T16414
                    }
                } else {
                    $value = $i;
                }
 
                $vals[] = [
                    'qc_type' => $this->getName(),
                    'qc_namespace' => $row->namespace,
                    'qc_title' => $row->title,
                    'qc_value' => $value
                ];
            }
 
            $dbw->doAtomicSection(
                $fname,
                function ( IDatabase $dbw, $fname ) {
                    // Clear out any old cached data
                    $dbw->newDeleteQueryBuilder()
                        ->deleteFrom( 'querycache' )
                        ->where( [ 'qc_type' => $this->getName() ] )
                        ->caller( $fname )->execute();
                    // Update the querycache_info record for the page
                    $dbw->newInsertQueryBuilder()
                        ->insertInto( 'querycache_info' )
                        ->row( [ 'qci_type' => $this->getName(), 'qci_timestamp' => $dbw->timestamp() ] )
                        ->onDuplicateKeyUpdate()
                        ->uniqueIndexFields( [ 'qci_type' ] )
                        ->set( [ 'qci_timestamp' => $dbw->timestamp() ] )
                        ->caller( $fname )->execute();
                }
            );
            // Save results into the querycache table on the primary DB
            if ( count( $vals ) ) {
                foreach ( array_chunk( $vals, 500 ) as $chunk ) {
                    $dbw->newInsertQueryBuilder()
                        ->insertInto( 'querycache' )
                        ->rows( $chunk )
                        ->caller( $fname )->execute();
                }
            }
        }
 
        return $num;
    }
 
    protected function getRecacheDB() {
        return $this->getDatabaseProvider()->getReplicaDatabase( false, 'vslow' );
    }
 
    public function delete( LinkTarget $title ) {
        if ( $this->isCached() ) {
            $dbw = $this->getDatabaseProvider()->getPrimaryDatabase();
            $dbw->newDeleteQueryBuilder()
                ->deleteFrom( 'querycache' )
                ->where( [
                    'qc_type' => $this->getName(),
                    'qc_namespace' => $title->getNamespace(),
                    'qc_title' => $title->getDBkey(),
                ] )
                ->caller( __METHOD__ )->execute();
        }
    }
 
    public function deleteAllCachedData() {
        $fname = static::class . '::' . __FUNCTION__;
        $dbw = $this->getDatabaseProvider()->getPrimaryDatabase();
        $dbw->newDeleteQueryBuilder()
            ->deleteFrom( 'querycache' )
            ->where( [ 'qc_type' => $this->getName() ] )
            ->caller( $fname )->execute();
        $dbw->newDeleteQueryBuilder()
            ->deleteFrom( 'querycachetwo' )
            ->where( [ 'qcc_type' => $this->getName() ] )
            ->caller( $fname )->execute();
        $dbw->newDeleteQueryBuilder()
            ->deleteFrom( 'querycache_info' )
            ->where( [ 'qci_type' => $this->getName() ] )
            ->caller( $fname )->execute();
    }
 
    public function reallyDoQuery( $limit, $offset = false ) {
        if ( $this->usesExternalSource() ) {
            return $this->reallyDoQueryExternal( $limit, $offset );
        }
 
        return $this->reallyDoQueryInternal( $limit, $offset );
    }
 
    private function reallyDoQueryInternal( $limit, $offset = false ) {
        $fname = static::class . '::reallyDoQueryInternal';
        $dbr = $this->getRecacheDB();
        $query = $this->getQueryInfo();
        $order = $this->getOrderFields();
 
        if ( $this->sortDescending() ) {
            foreach ( $order as &$field ) {
                $field .= ' DESC';
            }
        }
 
        $tables = isset( $query['tables'] ) ? (array)$query['tables'] : [];
        $fields = isset( $query['fields'] ) ? (array)$query['fields'] : [];
        $conds = isset( $query['conds'] ) ? (array)$query['conds'] : [];
        $options = isset( $query['options'] ) ? (array)$query['options'] : [];
        $join_conds = isset( $query['join_conds'] ) ? (array)$query['join_conds'] : [];
 
        $queryBuilder = $dbr->newSelectQueryBuilder()
            ->tables( $tables )
            ->fields( $fields )
            ->conds( $conds )
            ->caller( $fname )
            ->options( $options )
            ->joinConds( $join_conds );
        if ( $order ) {
            $queryBuilder->orderBy( $order );
        }
 
        if ( $limit !== false ) {
            $queryBuilder->limit( intval( $limit ) );
        }
 
        if ( $offset !== false ) {
            $queryBuilder->offset( intval( $offset ) );
        }
 
        return $queryBuilder->fetchResultSet();
    }
 
    private function reallyDoQueryExternal( $limit, $offset = false ) {
        $fname = static::class . '::reallyDoQueryExternal';
        $httpRequestFactory = $this->getHttpRequestFactory();
        $externalSources = $this->getConfig()->get( MainConfigNames::ExternalQuerySources );
        $pageName = $this->getName();
        $config = $externalSources[$pageName];
 
        $options = [];
        if ( isset( $config['timeout'] ) ) {
            $options['timeout'] = (int)$config['timeout'];
        }
 
        $request = $httpRequestFactory->create( $config['url'], $options, $fname );
 
        $status = $request->execute();
        if ( !$status->isOK() ) {
            throw new RuntimeException( "Failed to fetch data from external source '{$pageName}': " .
                $status->getMessage()->text() );
        }
 
        $content = $request->getContent();
        if ( $content === null || $content === '' ) {
            throw new RuntimeException( "Empty response received from external source '{$pageName}'" );
        }
 
        $decoded = json_decode( $content, true );
        if ( $decoded === null ) {
            throw new RuntimeException( "Invalid JSON response from external source '{$pageName}': " .
                json_last_error_msg() );
        }
 
        if ( !is_array( $decoded ) ) {
            throw new RuntimeException( "Expected array data from external source '{$pageName}', got " .
                gettype( $decoded ) );
        }
 
        $result = [];
        foreach ( $decoded as $i => $row ) {
            if ( !is_array( $row ) ) {
                throw new RuntimeException( "Invalid row data at index {$i} from external source '{$pageName}': " .
                    'expected array, got ' . gettype( $row ) );
            }
 
            $requiredFields = [ 'qc_namespace', 'qc_title', 'qc_value' ];
            foreach ( $requiredFields as $field ) {
                if ( !array_key_exists( $field, $row ) ) {
                    throw new RuntimeException(
                        "Missing required field '{$field}' in row {$i} from external source '{$pageName}'" );
                }
            }
 
            $result[] = (object)[
                'namespace' => $row['qc_namespace'],
                'title' => $row['qc_title'],
                'value' => $row['qc_value']
            ];
        }
 
        return new FakeResultWrapper( $result );
    }
 
    public function doQuery( $offset = false, $limit = false ) {
        if ( $this->isCached() && $this->isCacheable() ) {
            return $this->fetchFromCache( $limit, $offset );
        } else {
            return $this->reallyDoQuery( $limit, $offset );
        }
    }
 
    public function fetchFromCache( $limit, $offset = false ) {
        $dbr = $this->getDatabaseProvider()->getReplicaDatabase();
        $queryBuilder = $dbr->newSelectQueryBuilder()
            ->select( [ 'qc_type', 'namespace' => 'qc_namespace', 'title' => 'qc_title', 'value' => 'qc_value' ] )
            ->from( 'querycache' )
            ->where( [ 'qc_type' => $this->getName() ] );
 
        if ( $limit !== false ) {
            $queryBuilder->limit( intval( $limit ) );
        }
 
        if ( $offset !== false ) {
            $queryBuilder->offset( intval( $offset ) );
        }
 
        $order = $this->getCacheOrderFields();
        if ( $this->sortDescending() ) {
            $queryBuilder->orderBy( $order, SelectQueryBuilder::SORT_DESC );
        } else {
            $queryBuilder->orderBy( $order );
        }
 
        return $queryBuilder->caller( __METHOD__ )->fetchResultSet();
    }
 
    protected function getCacheOrderFields() {
        return [ 'value' ];
    }
 
    public function getCachedTimestamp() {
        if ( $this->cachedTimestamp === null ) {
            $dbr = $this->getDatabaseProvider()->getReplicaDatabase();
            $fname = static::class . '::getCachedTimestamp';
            $this->cachedTimestamp = $dbr->newSelectQueryBuilder()
                ->select( 'qci_timestamp' )
                ->from( 'querycache_info' )
                ->where( [ 'qci_type' => $this->getName() ] )
                ->caller( $fname )->fetchField();
        }
        return $this->cachedTimestamp;
    }
 
    protected function getLimitOffset() {
        [ $limit, $offset ] = $this->getRequest()
            ->getLimitOffsetForUser( $this->getUser() );
        if ( $this->getConfig()->get( MainConfigNames::MiserMode ) ) {
            $maxResults = $this->getMaxResults();
            // Can't display more than max results on a page
            $limit = min( $limit, $maxResults );
            // Can't skip over more than the end of $maxResults
            $offset = min( $offset, $maxResults + 1 );
        }
        return [ $limit, $offset ];
    }
 
    protected function getDBLimit( $uiLimit, $uiOffset ) {
        $maxResults = $this->getMaxResults();
        if ( $this->getConfig()->get( MainConfigNames::MiserMode ) ) {
            $limit = min( $uiLimit + 1, $maxResults - $uiOffset );
            return max( $limit, 0 );
        } else {
            return $uiLimit + 1;
        }
    }
 
    protected function getMaxResults() {
        // Max of 10000, unless we store more than 10000 in query cache.
        return max( $this->getConfig()->get( MainConfigNames::QueryCacheLimit ), 10000 );
    }
 
    public function execute( $par ) {
        $this->checkPermissions();
 
        $this->setHeaders();
        $this->outputHeader();
 
        $out = $this->getOutput();
 
        if ( $this->isCached() && !$this->isCacheable() ) {
            $out->addWikiMsg( 'querypage-disabled' );
            return;
        }
 
        $out->setSyndicated( $this->isSyndicated() );
 
        if ( $this->limit == 0 && $this->offset == 0 ) {
            [ $this->limit, $this->offset ] = $this->getLimitOffset();
        }
        $dbLimit = $this->getDBLimit( $this->limit, $this->offset );
        // @todo Use doQuery()
        if ( !$this->isCached() ) {
            // select one extra row for navigation
            $res = $this->reallyDoQuery( $dbLimit, $this->offset );
        } else {
            // Get the cached result, select one extra row for navigation
            $res = $this->fetchFromCache( $dbLimit, $this->offset );
            if ( !$this->listoutput ) {
                // Fetch the timestamp of this update
                $ts = $this->getCachedTimestamp();
                $lang = $this->getLanguage();
                $maxResults = $lang->formatNum( $this->getConfig()->get(
                    MainConfigNames::QueryCacheLimit ) );
 
                if ( $ts ) {
                    $user = $this->getUser();
                    $updated = $lang->userTimeAndDate( $ts, $user );
                    $updateddate = $lang->userDate( $ts, $user );
                    $updatedtime = $lang->userTime( $ts, $user );
                    $out->addMeta( 'Data-Cache-Time', $ts );
                    $out->addJsConfigVars( 'dataCacheTime', $ts );
                    $out->addWikiMsg( 'perfcachedts', $updated, $updateddate, $updatedtime, $maxResults );
                } else {
                    $out->addWikiMsg( 'perfcached', $maxResults );
                }
 
                // If updates on this page have been disabled, let the user know
                // that the data set won't be refreshed for now
                $disabledQueryPages = self::getDisabledQueryPages( $this->getConfig() );
                if ( isset( $disabledQueryPages[$this->getName()] ) ) {
                    $runMode = $disabledQueryPages[$this->getName()];
                    if ( $runMode === 'disabled' ) {
                        $out->wrapWikiMsg(
                            "<div class=\"mw-querypage-no-updates\">\n$1\n</div>",
                            'querypage-no-updates'
                        );
                    } else {
                        // Messages used here: querypage-updates-periodical
                        $out->wrapWikiMsg(
                            "<div class=\"mw-querypage-updates-" . $runMode . "\">\n$1\n</div>",
                            'querypage-updates-' . $runMode
                        );
                    }
                }
            }
        }
 
        $this->numRows = $res->numRows();
 
        $dbr = $this->getRecacheDB();
        $this->preprocessResults( $dbr, $res );
 
        $out->addHTML( Html::openElement( 'div', [ 'class' => 'mw-spcontent' ] ) );
 
        // Top header and navigation
        if ( $this->shownavigation ) {
            $out->addHTML( $this->getPageHeader() );
            if ( $this->numRows > 0 ) {
                $out->addHTML( $this->msg( 'showingresultsinrange' )->numParams(
                    min( $this->numRows, $this->limit ), // do not show the one extra row, if exist
                    $this->offset + 1, ( min( $this->numRows, $this->limit ) + $this->offset ) )->parseAsBlock() );
                // Disable the "next" link when we reach the end
                $miserMaxResults = $this->getConfig()->get( MainConfigNames::MiserMode )
                    && ( $this->offset + $this->limit >= $this->getMaxResults() );
                $atEnd = ( $this->numRows <= $this->limit ) || $miserMaxResults;
                $paging = $this->buildPrevNextNavigation( $this->offset,
                    $this->limit, $this->linkParameters(), $atEnd, $par );
                $out->addHTML( '<p>' . $paging . '</p>' );
            } else {
                // No results to show, so don't bother with "showing X of Y" etc.
                // -- just let the user know and give up now
                $this->showEmptyText();
                $out->addHTML( Html::closeElement( 'div' ) );
                return;
            }
        }
 
        // The actual results; specialist subclasses will want to handle this
        // with more than a straight list, so we hand them the info, plus
        // an OutputPage, and let them get on with it
        $this->outputResults( $out,
            $this->getSkin(),
            $dbr, // Should use IResultWrapper for this
            $res,
            min( $this->numRows, $this->limit ), // do not format the one extra row, if exist
            $this->offset );
 
        // Repeat the paging links at the bottom
        if ( $this->shownavigation ) {
            // @phan-suppress-next-line PhanPossiblyUndeclaredVariable paging is set when used here
            $out->addHTML( '<p>' . $paging . '</p>' );
        }
 
        $out->addHTML( Html::closeElement( 'div' ) );
    }
 
    protected function outputResults( $out, $skin, $dbr, $res, $num, $offset ) {
        if ( $num > 0 ) {
            $html = [];
            if ( !$this->listoutput ) {
                $html[] = $this->openList( $offset );
            }
 
            // $res might contain the whole 1,000 rows, so we read up to
            // $num [should update this to use a Pager]
            // phpcs:ignore Generic.CodeAnalysis.AssignmentInCondition.Found
            for ( $i = 0; $i < $num && $row = $res->fetchObject(); $i++ ) {
                $line = $this->formatResult( $skin, $row );
                if ( $line ) {
                    $html[] = $this->listoutput
                        ? $line
                        : "<li>{$line}</li>\n";
                }
            }
 
            if ( !$this->listoutput ) {
                $html[] = $this->closeList();
            }
 
            $html = $this->listoutput
                ? $this->getContentLanguage()->listToText( $html )
                : implode( '', $html );
 
            $out->addHTML( $html );
        }
    }
 
    protected function openList( $offset ) {
        return "\n<ol start='" . ( $offset + 1 ) . "' class='special'>\n";
    }
 
    protected function closeList() {
        return "</ol>\n";
    }
 
    protected function preprocessResults( $db, $res ) {
    }
 
    protected function executeLBFromResultWrapper( IResultWrapper $res, $ns = null ) {
        if ( !$res->numRows() ) {
            return;
        }
 
        $batch = $this->getLinkBatchFactory()->newLinkBatch()->setCaller( __METHOD__ );
        foreach ( $res as $row ) {
            $batch->add( $ns ?? (int)$row->namespace, $row->title );
        }
        $batch->execute();
 
        $res->seek( 0 );
    }
 
    final protected function setDBLoadBalancer( ILoadBalancer $loadBalancer ) {
        $this->loadBalancer = $loadBalancer;
    }
 
    final protected function getDBLoadBalancer(): ILoadBalancer {
        if ( $this->loadBalancer === null ) {
            // Fallback if not provided
            // TODO Change to wfWarn in a future release
            $this->loadBalancer = MediaWikiServices::getInstance()->getDBLoadBalancer();
        }
        return $this->loadBalancer;
    }
 
    final protected function setDatabaseProvider( IConnectionProvider $databaseProvider ) {
        $this->databaseProvider = $databaseProvider;
    }
 
    final protected function getDatabaseProvider(): IConnectionProvider {
        if ( $this->databaseProvider === null ) {
            $this->databaseProvider = MediaWikiServices::getInstance()->getConnectionProvider();
        }
        return $this->databaseProvider;
    }
}
 
class_alias( QueryPage::class, 'QueryPage' );