Merge "Set namespaces for dtp"

[mediawiki.git] / includes / cache / LinkCache.php

<?php
/**
 * Page existence cache.
 *
 * 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 Cache
 */

namespace MediaWiki\Cache;

use InvalidArgumentException;
use MapCacheLRU;
use MediaWiki\Linker\LinkTarget;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use MediaWiki\Page\PageIdentity;
use MediaWiki\Page\PageReference;
use MediaWiki\Page\PageStoreRecord;
use MediaWiki\Title\NamespaceInfo;
use MediaWiki\Title\TitleFormatter;
use MediaWiki\Title\TitleValue;
use Psr\Log\LoggerAwareInterface;
use Psr\Log\LoggerInterface;
use Psr\Log\NullLogger;
use stdClass;
use Wikimedia\ObjectCache\WANObjectCache;
use Wikimedia\Rdbms\Database;
use Wikimedia\Rdbms\IDBAccessObject;
use Wikimedia\Rdbms\ILoadBalancer;
use Wikimedia\Rdbms\IReadableDatabase;

/**
 * Cache for article titles (prefixed DB keys) and ids linked from one source
 *
 * @ingroup Cache
 */
class LinkCache implements LoggerAwareInterface {
        /** @var MapCacheLRU */
        private $entries;
        /** @var WANObjectCache */
        private $wanCache;
        /** @var TitleFormatter */
        private $titleFormatter;
        /** @var NamespaceInfo */
        private $nsInfo;
        /** @var ILoadBalancer|null */
        private $loadBalancer;
        /** @var LoggerInterface */
        private $logger;

        /** How many Titles to store */
        private const MAX_SIZE = 10000;

        /** Key to page row object or null */
        private const ROW = 0;
        /** Key to query READ_* flags */
        private const FLAGS = 1;

        /**
         * @param TitleFormatter $titleFormatter
         * @param WANObjectCache $cache
         * @param NamespaceInfo $nsInfo
         * @param ILoadBalancer|null $loadBalancer Use null when no database is set up, for example on installation
         */
        public function __construct(
                TitleFormatter $titleFormatter,
                WANObjectCache $cache,
                NamespaceInfo $nsInfo,
                ?ILoadBalancer $loadBalancer = null
        ) {
                $this->entries = new MapCacheLRU( self::MAX_SIZE );
                $this->wanCache = $cache;
                $this->titleFormatter = $titleFormatter;
                $this->nsInfo = $nsInfo;
                $this->loadBalancer = $loadBalancer;
                $this->logger = new NullLogger();
        }

        /**
         * @param LoggerInterface $logger
         */
        public function setLogger( LoggerInterface $logger ) {
                $this->logger = $logger;
        }

        /**
         * @param LinkTarget|PageReference|array|string $page
         * @param bool $passThrough Return $page if $page is a string
         * @return ?string the cache key
         */
        private function getCacheKey( $page, $passThrough = false ) {
                if ( is_string( $page ) ) {
                        if ( $passThrough ) {
                                return $page;
                        } else {
                                throw new InvalidArgumentException( 'They key may not be given as a string here' );
                        }
                }

                if ( is_array( $page ) ) {
                        $namespace = $page['page_namespace'];
                        $dbkey = $page['page_title'];
                        return strtr( $this->titleFormatter->formatTitle( $namespace, $dbkey ), ' ', '_' );
                }

                if ( $page instanceof PageReference && $page->getWikiId() !== PageReference::LOCAL ) {
                        // No cross-wiki support yet. Perhaps LinkCache can become wiki-aware in the future.
                        $this->logger->info(
                                'cross-wiki page reference',
                                [
                                        'page-wiki' => $page->getWikiId(),
                                        'page-reference' => $this->titleFormatter->getFullText( $page )
                                ]
                        );
                        return null;
                }

                if ( $page instanceof PageIdentity && !$page->canExist() ) {
                        // Non-proper page, perhaps a special page or interwiki link or relative section link.
                        $this->logger->warning(
                                'non-proper page reference: {page-reference}',
                                [ 'page-reference' => $this->titleFormatter->getFullText( $page ) ]
                        );
                        return null;
                }

                if ( $page instanceof LinkTarget
                        && ( $page->isExternal() || $page->getText() === '' || $page->getNamespace() < 0 )
                ) {
                        // Interwiki link or relative section link. These do not have a page ID, so they
                        // can neither be "good" nor "bad" in the sense of this class.
                        $this->logger->warning(
                                'link to non-proper page: {page-link}',
                                [ 'page-link' => $this->titleFormatter->getFullText( $page ) ]
                        );
                        return null;
                }

                return $this->titleFormatter->getPrefixedDBkey( $page );
        }

        /**
         * Get the ID of a page known to the process cache
         *
         * @param LinkTarget|PageReference|array|string $page The page to get the ID for,
         *        as an object, an array containing the page_namespace and page_title fields,
         *        or a prefixed DB key. In MediaWiki 1.36 and earlier, only a string was accepted.
         * @return int Page ID, or zero if the page was not cached or does not exist or is not a
         *         proper page (e.g. a special page or an interwiki link).
         */
        public function getGoodLinkID( $page ) {
                $key = $this->getCacheKey( $page, true );
                if ( $key === null ) {
                        return 0;
                }

                $entry = $this->entries->get( $key );
                if ( !$entry ) {
                        return 0;
                }

                $row = $entry[self::ROW];

                return $row ? (int)$row->page_id : 0;
        }

        /**
         * Get the field of a page known to the process cache
         *
         * If this link is not a cached good title, it will return NULL.
         * @param LinkTarget|PageReference|array $page The page to get cached info for.
         *        Can be given as an object or an associative array containing the
         *        page_namespace and page_title fields.
         *        In MediaWiki 1.36 and earlier, only LinkTarget was accepted.
         * @param string $field ( 'id', 'length', 'redirect', 'revision', 'model', 'lang' )
         * @return string|int|null The field value, or null if the page was not cached or does not exist
         *         or is not a proper page (e.g. a special page or interwiki link).
         */
        public function getGoodLinkFieldObj( $page, string $field ) {
                $key = $this->getCacheKey( $page );
                if ( $key === null ) {
                        return null;
                }

                $entry = $this->entries->get( $key );
                if ( !$entry ) {
                        return null;
                }

                $row = $entry[self::ROW];
                if ( !$row ) {
                        return null;
                }

                switch ( $field ) {
                        case 'id':
                                return (int)$row->page_id;
                        case 'length':
                                return (int)$row->page_len;
                        case 'redirect':
                                return (int)$row->page_is_redirect;
                        case 'revision':
                                return (int)$row->page_latest;
                        case 'model':
                                return !empty( $row->page_content_model )
                                        ? (string)$row->page_content_model
                                        : null;
                        case 'lang':
                                return !empty( $row->page_lang )
                                        ? (string)$row->page_lang
                                        : null;
                        default:
                                throw new InvalidArgumentException( "Unknown field: $field" );
                }
        }

        /**
         * Check if a page is known to be missing based on the process cache
         *
         * @param LinkTarget|PageReference|array|string $page The page to get cached info for,
         *        as an object, an array containing the page_namespace and page_title fields,
         *        or a prefixed DB key. In MediaWiki 1.36 and earlier, only a string was accepted.
         *        In MediaWiki 1.36 and earlier, only a string was accepted.
         * @return bool Whether the page is known to be missing based on the process cache
         */
        public function isBadLink( $page ) {
                $key = $this->getCacheKey( $page, true );
                if ( $key === null ) {
                        return false;
                }

                $entry = $this->entries->get( $key );

                return ( $entry && !$entry[self::ROW] );
        }

        /**
         * Add information about an existing page to the process cache
         *
         * Callers must set the READ_LATEST flag if the row came from a DB_PRIMARY source.
         * However, the use of such data is highly discouraged; most callers rely on seeing
         * consistent DB_REPLICA data (e.g. REPEATABLE-READ point-in-time snapshots) and the
         * accidental use of DB_PRIMARY data via LinkCache is prone to causing anomalies.
         *
         * @param LinkTarget|PageReference|array $page The page to set cached info for.
         *        Can be given as an object or an associative array containing the
         *        page_namespace and page_title fields.
         *        In MediaWiki 1.36 and earlier, only LinkTarget was accepted.
         * @param stdClass $row Object which has all fields returned by getSelectFields().
         * @param int $queryFlags The query flags used to retrieve the row, IDBAccessObject::READ_*
         * @since 1.19
         */
        public function addGoodLinkObjFromRow(
                $page,
                stdClass $row,
                int $queryFlags = IDBAccessObject::READ_NORMAL
        ) {
                $key = $this->getCacheKey( $page );
                if ( $key === null ) {
                        return;
                }

                foreach ( self::getSelectFields() as $field ) {
                        if ( !property_exists( $row, $field ) ) {
                                throw new InvalidArgumentException( "Missing field: $field" );
                        }
                }

                $this->entries->set( $key, [ self::ROW => $row, self::FLAGS => $queryFlags ] );
        }

        /**
         * Add information about a missing page to the process cache
         *
         * Callers must set the READ_LATEST flag if the row came from a DB_PRIMARY source.
         * However, the use of such data is highly discouraged; most callers rely on seeing
         * consistent DB_REPLICA data (e.g. REPEATABLE-READ point-in-time snapshots) and the
         * accidental use of DB_PRIMARY data via LinkCache is prone to causing anomalies.
         *
         * @param LinkTarget|PageReference|array $page The page to set cached info for.
         *        Can be given as an object or an associative array containing the
         *        page_namespace and page_title fields.
         *        In MediaWiki 1.36 and earlier, only LinkTarget was accepted.
         * @param int $queryFlags The query flags used to retrieve the row, IDBAccessObject::READ_*
         */
        public function addBadLinkObj( $page, int $queryFlags = IDBAccessObject::READ_NORMAL ) {
                $key = $this->getCacheKey( $page );
                if ( $key === null ) {
                        return;
                }

                $this->entries->set( $key, [ self::ROW => null, self::FLAGS => $queryFlags ] );
        }

        /**
         * Clear information about a page being missing from the process cache
         *
         * @param LinkTarget|PageReference|array|string $page The page to clear cached info for,
         *        as an object, an array containing the page_namespace and page_title fields,
         *        or a prefixed DB key. In MediaWiki 1.36 and earlier, only a string was accepted.
         *        In MediaWiki 1.36 and earlier, only a string was accepted.
         */
        public function clearBadLink( $page ) {
                $key = $this->getCacheKey( $page, true );
                if ( $key === null ) {
                        return;
                }

                $entry = $this->entries->get( $key );
                if ( $entry && !$entry[self::ROW] ) {
                        $this->entries->clear( $key );
                }
        }

        /**
         * Clear information about a page from the process cache
         *
         * @param LinkTarget|PageReference|array $page The page to clear cached info for.
         *        Can be given as an object or an associative array containing the
         *        page_namespace and page_title fields.
         *        In MediaWiki 1.36 and earlier, only LinkTarget was accepted.
         */
        public function clearLink( $page ) {
                $key = $this->getCacheKey( $page );
                if ( $key !== null ) {
                        $this->entries->clear( $key );
                }
        }

        /**
         * Fields that LinkCache needs to select
         *
         * @since 1.28
         * @return array
         */
        public static function getSelectFields() {
                $pageLanguageUseDB = MediaWikiServices::getInstance()->getMainConfig()
                        ->get( MainConfigNames::PageLanguageUseDB );

                $fields = array_merge(
                        PageStoreRecord::REQUIRED_FIELDS,
                        [
                                'page_len',
                                'page_content_model',
                        ]
                );

                if ( $pageLanguageUseDB ) {
                        $fields[] = 'page_lang';
                }

                return $fields;
        }

        /**
         * Add a title to the link cache, return the page_id or zero if non-existent.
         * This causes the link to be looked up in the database if it is not yet cached.
         *
         * @deprecated since 1.37, use PageStore::getPageForLink() instead.
         *
         * @param LinkTarget|PageReference|array $page The page to load.
         *        Can be given as an object or an associative array containing the
         *        page_namespace and page_title fields.
         *        In MediaWiki 1.36 and earlier, only LinkTarget was accepted.
         * @param int $queryFlags IDBAccessObject::READ_XXX
         *
         * @return int Page ID or zero
         */
        public function addLinkObj( $page, int $queryFlags = IDBAccessObject::READ_NORMAL ) {
                $row = $this->getGoodLinkRow(
                        $page->getNamespace(),
                        $page->getDBkey(),
                        [ $this, 'fetchPageRow' ],
                        $queryFlags
                );

                return $row ? (int)$row->page_id : 0;
        }

        /**
         * @param TitleValue $link
         * @param callable|null $fetchCallback
         * @param int $queryFlags
         * @return array [ $shouldAddGoodLink, $row ], $shouldAddGoodLink is a bool indicating
         * whether addGoodLinkObjFromRow should be called, and $row is the row the caller was looking
         * for (or null, when it was not found).
         */
        private function getGoodLinkRowInternal(
                TitleValue $link,
                ?callable $fetchCallback = null,
                int $queryFlags = IDBAccessObject::READ_NORMAL
        ): array {
                $callerShouldAddGoodLink = false;

                $key = $this->getCacheKey( $link );
                if ( $key === null ) {
                        return [ $callerShouldAddGoodLink, null ];
                }

                $ns = $link->getNamespace();
                $dbkey = $link->getDBkey();

                $entry = $this->entries->get( $key );
                if ( $entry && $entry[self::FLAGS] >= $queryFlags ) {
                        return [ $callerShouldAddGoodLink, $entry[self::ROW] ?: null ];
                }

                if ( !$fetchCallback ) {
                        return [ $callerShouldAddGoodLink, null ];
                }

                $callerShouldAddGoodLink = true;

                $wanCacheKey = $this->getPersistentCacheKey( $link );
                if ( $wanCacheKey !== null && !( $queryFlags & IDBAccessObject::READ_LATEST ) ) {
                        // Some pages are often transcluded heavily, so use persistent caching
                        $row = $this->wanCache->getWithSetCallback(
                                $wanCacheKey,
                                WANObjectCache::TTL_DAY,
                                function ( $curValue, &$ttl, array &$setOpts ) use ( $fetchCallback, $ns, $dbkey ) {
                                        $dbr = $this->loadBalancer->getConnection( ILoadBalancer::DB_REPLICA );
                                        $setOpts += Database::getCacheSetOptions( $dbr );

                                        $row = $fetchCallback( $dbr, $ns, $dbkey, [] );
                                        $mtime = $row ? (int)wfTimestamp( TS_UNIX, $row->page_touched ) : false;
                                        $ttl = $this->wanCache->adaptiveTTL( $mtime, $ttl );

                                        return $row;
                                }
                        );
                } else {
                        // No persistent caching needed, but we can still use the callback.
                        if ( ( $queryFlags & IDBAccessObject::READ_LATEST ) == IDBAccessObject::READ_LATEST ) {
                                $dbr = $this->loadBalancer->getConnection( DB_PRIMARY );
                        } else {
                                $dbr = $this->loadBalancer->getConnection( DB_REPLICA );
                        }
                        $options = [];
                        if ( ( $queryFlags & IDBAccessObject::READ_EXCLUSIVE ) == IDBAccessObject::READ_EXCLUSIVE ) {
                                $options[] = 'FOR UPDATE';
                        } elseif ( ( $queryFlags & IDBAccessObject::READ_LOCKING ) == IDBAccessObject::READ_LOCKING ) {
                                $options[] = 'LOCK IN SHARE MODE';
                        }
                        $row = $fetchCallback( $dbr, $ns, $dbkey, $options );
                }

                return [ $callerShouldAddGoodLink, $row ?: null ];
        }

        /**
         * Returns the row for the page if the page exists (subject to race conditions).
         * The row will be returned from local cache or WAN cache if possible, or it
         * will be looked up using the callback provided.
         *
         * @param int $ns
         * @param string $dbkey
         * @param callable|null $fetchCallback A callback that will retrieve the link row with the
         *        signature ( IReadableDatabase $db, int $ns, string $dbkey, array $queryOptions ): ?stdObj.
         * @param int $queryFlags IDBAccessObject::READ_XXX
         *
         * @return stdClass|null
         * @internal for use by PageStore. Other code should use a PageLookup instead.
         */
        public function getGoodLinkRow(
                int $ns,
                string $dbkey,
                ?callable $fetchCallback = null,
                int $queryFlags = IDBAccessObject::READ_NORMAL
        ): ?stdClass {
                $link = TitleValue::tryNew( $ns, $dbkey );
                if ( $link === null ) {
                        return null;
                }

                [ $shouldAddGoodLink, $row ] = $this->getGoodLinkRowInternal(
                        $link,
                        $fetchCallback,
                        $queryFlags
                );

                if ( $row ) {
                        if ( $shouldAddGoodLink ) {
                                try {
                                        $this->addGoodLinkObjFromRow( $link, $row, $queryFlags );
                                } catch ( InvalidArgumentException $e ) {
                                        // a field is missing from $row; maybe we used a cache?; invalidate it and try again
                                        $this->invalidateTitle( $link );
                                        [ , $row ] = $this->getGoodLinkRowInternal(
                                                $link,
                                                $fetchCallback,
                                                $queryFlags
                                        );
                                        $this->addGoodLinkObjFromRow( $link, $row, $queryFlags );
                                }
                        }
                } else {
                        $this->addBadLinkObj( $link );
                }

                return $row ?: null;
        }

        /**
         * @param LinkTarget|PageReference|TitleValue $page
         * @return string|null
         */
        private function getPersistentCacheKey( $page ) {
                // if no key can be derived, the page isn't cacheable
                if ( $this->getCacheKey( $page ) === null || !$this->usePersistentCache( $page ) ) {
                        return null;
                }

                return $this->wanCache->makeKey(
                        'page',
                        $page->getNamespace(),
                        sha1( $page->getDBkey()
                ) );
        }

        /**
         * @param LinkTarget|PageReference|int $pageOrNamespace
         * @return bool
         */
        private function usePersistentCache( $pageOrNamespace ) {
                $ns = is_int( $pageOrNamespace ) ? $pageOrNamespace : $pageOrNamespace->getNamespace();
                if ( in_array( $ns, [ NS_TEMPLATE, NS_FILE, NS_CATEGORY, NS_MEDIAWIKI ] ) ) {
                        return true;
                }
                // Focus on transcluded pages more than the main content
                if ( $this->nsInfo->isContent( $ns ) ) {
                        return false;
                }
                // Non-talk extension namespaces (e.g. NS_MODULE)
                return ( $ns >= 100 && $this->nsInfo->isSubject( $ns ) );
        }

        /**
         * @param IReadableDatabase $db
         * @param int $ns
         * @param string $dbkey
         * @param array $options Query options, see IDatabase::select() for details.
         * @return stdClass|false
         */
        private function fetchPageRow( IReadableDatabase $db, int $ns, string $dbkey, $options = [] ) {
                $queryBuilder = $db->newSelectQueryBuilder()
                        ->select( self::getSelectFields() )
                        ->from( 'page' )
                        ->where( [ 'page_namespace' => $ns, 'page_title' => $dbkey ] )
                        ->options( $options );

                return $queryBuilder->caller( __METHOD__ )->fetchRow();
        }

        /**
         * Purge the persistent link cache for a title
         *
         * @param LinkTarget|PageReference $page
         *        In MediaWiki 1.36 and earlier, only LinkTarget was accepted.
         * @since 1.28
         */
        public function invalidateTitle( $page ) {
                $wanCacheKey = $this->getPersistentCacheKey( $page );
                if ( $wanCacheKey !== null ) {
                        $this->wanCache->delete( $wanCacheKey );
                }

                $this->clearLink( $page );
        }

        /**
         * Clears cache
         */
        public function clear() {
                $this->entries->clear();
        }
}

/** @deprecated class alias since 1.42 */
class_alias( LinkCache::class, 'LinkCache' );