RedirectStore.php

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<?php
namespace MediaWiki\Page;
 
use MapCacheLRU;
use MediaWiki\Linker\LinkTarget;
use MediaWiki\Title\Title;
use MediaWiki\Title\TitleParser;
use MediaWiki\Title\TitleValue;
use Psr\Log\LoggerInterface;
use RepoGroup;
use Wikimedia\Rdbms\IConnectionProvider;
 
class RedirectStore implements RedirectLookup {
    private IConnectionProvider $dbProvider;
    private PageLookup $pageLookup;
    private TitleParser $titleParser;
    private RepoGroup $repoGroup;
    private LoggerInterface $logger;
    private MapCacheLRU $procCache;
 
    public function __construct(
        IConnectionProvider $dbProvider,
        PageLookup $pageLookup,
        TitleParser $titleParser,
        RepoGroup $repoGroup,
        LoggerInterface $logger
    ) {
        $this->dbProvider = $dbProvider;
        $this->pageLookup = $pageLookup;
        $this->titleParser = $titleParser;
        $this->repoGroup = $repoGroup;
        $this->logger = $logger;
        $this->procCache = new MapCacheLRU( 16 );
    }
 
    public function getRedirectTarget( PageIdentity $page ): ?LinkTarget {
        $cacheKey = self::makeCacheKey( $page );
        $cachedValue = $this->procCache->get( $cacheKey );
        if ( $cachedValue !== null ) {
            return $cachedValue ?: null;
        }
 
        // Handle redirects for files included from foreign image repositories.
        if ( $page->getNamespace() === NS_FILE ) {
            $file = $this->repoGroup->findFile( $page );
            if ( $file && !$file->isLocal() ) {
                $from = $file->getRedirected();
                $to = $file->getName();
                if ( $from === null || $from === $to ) {
                    $this->procCache->set( $cacheKey, false );
                    return null;
                }
 
                $target = new TitleValue( NS_FILE, $to );
                $this->procCache->set( $cacheKey, $target );
                return $target;
            }
        }
 
        $page = $this->pageLookup->getPageByReference( $page );
        if ( $page === null || !$page->isRedirect() ) {
            $this->procCache->set( $cacheKey, false );
            return null;
        }
 
        $dbr = $this->dbProvider->getReplicaDatabase();
        $row = $dbr->newSelectQueryBuilder()
            ->select( [ 'rd_namespace', 'rd_title', 'rd_fragment', 'rd_interwiki' ] )
            ->from( 'redirect' )
            ->where( [ 'rd_from' => $page->getId() ] )
            ->caller( __METHOD__ )
            ->fetchRow();
 
        if ( !$row ) {
            $this->logger->info(
                'Found inconsistent redirect status; probably the page was deleted after it was loaded'
            );
            $this->procCache->set( $cacheKey, false );
            return null;
        }
 
        $target = $this->createRedirectTarget(
            $row->rd_namespace,
            $row->rd_title,
            $row->rd_fragment,
            $row->rd_interwiki
        );
 
        $this->procCache->set( $cacheKey, $target );
        return $target;
    }
 
    public function updateRedirectTarget(
        PageIdentity $page,
        ?LinkTarget $target,
        ?bool $lastRevWasRedirect = null
    ) {
        // Always update redirects (target link might have changed)
        // Update/Insert if we don't know if the last revision was a redirect or not
        // Delete if changing from redirect to non-redirect
        $isRedirect = $target !== null;
        $cacheKey = self::makeCacheKey( $page );
 
        if ( !$isRedirect && $lastRevWasRedirect === false ) {
            $this->procCache->set( $cacheKey, false );
            return true;
        }
 
        if ( $isRedirect ) {
            $rt = Title::newFromLinkTarget( $target );
            if ( !$rt->isValidRedirectTarget() ) {
                // Don't put a bad redirect into the database (T278367)
                $this->procCache->set( $cacheKey, false );
                return false;
            }
 
            $dbw = $this->dbProvider->getPrimaryDatabase();
            $dbw->startAtomic( __METHOD__ );
 
            $truncatedFragment = self::truncateFragment( $rt->getFragment() );
            $dbw->newInsertQueryBuilder()
                ->insertInto( 'redirect' )
                ->row( [
                    'rd_from' => $page->getId(),
                    'rd_namespace' => $rt->getNamespace(),
                    'rd_title' => $rt->getDBkey(),
                    'rd_fragment' => $truncatedFragment,
                    'rd_interwiki' => $rt->getInterwiki(),
                ] )
                ->onDuplicateKeyUpdate()
                ->uniqueIndexFields( [ 'rd_from' ] )
                ->set( [
                    'rd_namespace' => $rt->getNamespace(),
                    'rd_title' => $rt->getDBkey(),
                    'rd_fragment' => $truncatedFragment,
                    'rd_interwiki' => $rt->getInterwiki(),
                ] )
                ->caller( __METHOD__ )
                ->execute();
 
            $dbw->endAtomic( __METHOD__ );
 
            $this->procCache->set(
                $cacheKey,
                $this->createRedirectTarget(
                    $rt->getNamespace(),
                    $rt->getDBkey(),
                    $truncatedFragment,
                    $rt->getInterwiki()
                )
            );
        } else {
            $dbw = $this->dbProvider->getPrimaryDatabase();
            // This is not a redirect, remove row from redirect table
            $dbw->newDeleteQueryBuilder()
                ->deleteFrom( 'redirect' )
                ->where( [ 'rd_from' => $page->getId() ] )
                ->caller( __METHOD__ )
                ->execute();
 
            $this->procCache->set( $cacheKey, false );
        }
 
        if ( $page->getNamespace() === NS_FILE ) {
            $this->repoGroup->getLocalRepo()->invalidateImageRedirect( $page );
        }
 
        return true;
    }
 
    public function clearCache( $page ) {
        $this->procCache->clear( self::makeCacheKey( $page ) );
    }
 
    private static function makeCacheKey( $page ) {
        return "{$page->getNamespace()}:{$page->getDBkey()}";
    }
 
    private function createRedirectTarget( $namespace, $title, $fragment, $interwiki ): ?LinkTarget {
        // (T203942) We can't redirect to Media namespace because it's virtual.
        // We don't want to modify Title objects farther down the
        // line. So, let's fix this here by changing to File namespace.
        if ( $namespace == NS_MEDIA ) {
            $namespace = NS_FILE;
        }
 
        // mimic behaviour of self::insertRedirectEntry for fragments that didn't
        // come from the redirect table
        $fragment = self::truncateFragment( $fragment );
 
        // T261347: be defensive when fetching data from the redirect table.
        // Use Title::makeTitleSafe(), and if that returns null, ignore the
        // row. In an ideal world, the DB would be cleaned up after a
        // namespace change, but nobody could be bothered to do that.
        $target = $this->titleParser->makeTitleValueSafe( $namespace, $title, $fragment, $interwiki );
        if ( $target !== null && Title::newFromLinkTarget( $target )->isValidRedirectTarget() ) {
            return $target;
        }
 
        return null;
    }
 
    private static function truncateFragment( $fragment ) {
        return mb_strcut( $fragment, 0, 255 );
    }
}