wfMsgForContentNoTrans() was removed

[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
 */

/**
 * Cache for article titles (prefixed DB keys) and ids linked from one source
 *
 * @ingroup Cache
 */
class LinkCache {
        /**
         * @var HashBagOStuff
         */
        private $mGoodLinks;
        /**
         * @var HashBagOStuff
         */
        private $mBadLinks;
        private $mForUpdate = false;

        /**
         * How many Titles to store. There are two caches, so the amount actually
         * stored in memory can be up to twice this.
         */
        const MAX_SIZE = 10000;

        /**
         * @var LinkCache
         */
        protected static $instance;

        public function __construct() {
                $this->mGoodLinks = new HashBagOStuff( array( 'maxKeys' => self::MAX_SIZE ) );
                $this->mBadLinks = new HashBagOStuff( array( 'maxKeys' => self::MAX_SIZE ) );
        }

        /**
         * Get an instance of this class.
         *
         * @return LinkCache
         */
        public static function &singleton() {
                if ( !self::$instance ) {
                        self::$instance = new LinkCache;
                }

                return self::$instance;
        }

        /**
         * Destroy the singleton instance
         *
         * A new one will be created next time singleton() is called.
         *
         * @since 1.22
         */
        public static function destroySingleton() {
                self::$instance = null;
        }

        /**
         * Set the singleton instance to a given object.
         *
         * Since we do not have an interface for LinkCache, you have to be sure the
         * given object implements all the LinkCache public methods.
         *
         * @param LinkCache $instance
         * @since 1.22
         */
        public static function setSingleton( LinkCache $instance ) {
                self::$instance = $instance;
        }

        /**
         * General accessor to get/set whether the master DB should be used
         *
         * This used to also set the FOR UPDATE option (locking the rows read
         * in order to avoid link table inconsistency), which was later removed
         * for performance on wikis with a high edit rate.
         *
         * @param bool $update
         * @return bool
         */
        public function forUpdate( $update = null ) {
                return wfSetVar( $this->mForUpdate, $update );
        }

        /**
         * @param string $title
         * @return int Page ID or zero
         */
        public function getGoodLinkID( $title ) {
                $info = $this->mGoodLinks->get( $title );
                if ( !$info ) {
                        return 0;
                }
                return $info['id'];
        }

        /**
         * Get a field of a title object from cache.
         * If this link is not a cached good title, it will return NULL.
         * @param Title $title
         * @param string $field ('length','redirect','revision','model')
         * @return string|int|null
         */
        public function getGoodLinkFieldObj( $title, $field ) {
                $dbkey = $title->getPrefixedDBkey();
                $info = $this->mGoodLinks->get( $dbkey );
                if ( !$info ) {
                        return null;
                }
                return $info[$field];
        }

        /**
         * @param string $title
         * @return bool
         */
        public function isBadLink( $title ) {
                // Use get() to ensure it records as used for LRU.
                return $this->mBadLinks->get( $title ) !== false;
        }

        /**
         * Add a link for the title to the link cache
         *
         * @param int $id Page's ID
         * @param Title $title
         * @param int $len Text's length
         * @param int $redir Whether the page is a redirect
         * @param int $revision Latest revision's ID
         * @param string|null $model Latest revision's content model ID
         */
        public function addGoodLinkObj( $id, Title $title, $len = -1, $redir = null,
                $revision = 0, $model = null
        ) {
                $dbkey = $title->getPrefixedDBkey();
                $this->mGoodLinks->set( $dbkey, array(
                        'id' => (int)$id,
                        'length' => (int)$len,
                        'redirect' => (int)$redir,
                        'revision' => (int)$revision,
                        'model' => $model ? (string)$model : null,
                ) );
        }

        /**
         * Same as above with better interface.
         * @since 1.19
         * @param Title $title
         * @param stdClass $row Object which has the fields page_id, page_is_redirect,
         *  page_latest and page_content_model
         */
        public function addGoodLinkObjFromRow( Title $title, $row ) {
                $dbkey = $title->getPrefixedDBkey();
                $this->mGoodLinks->set( $dbkey, array(
                        'id' => intval( $row->page_id ),
                        'length' => intval( $row->page_len ),
                        'redirect' => intval( $row->page_is_redirect ),
                        'revision' => intval( $row->page_latest ),
                        'model' => !empty( $row->page_content_model ) ? strval( $row->page_content_model ) : null,
                ) );
        }

        /**
         * @param Title $title
         */
        public function addBadLinkObj( Title $title ) {
                $dbkey = $title->getPrefixedDBkey();
                if ( !$this->isBadLink( $dbkey ) ) {
                        $this->mBadLinks->set( $dbkey, 1 );
                }
        }

        public function clearBadLink( $title ) {
                $this->mBadLinks->clear( array( $title ) );
        }

        /**
         * @param Title $title
         */
        public function clearLink( $title ) {
                $dbkey = $title->getPrefixedDBkey();
                $this->mBadLinks->delete( $dbkey );
                $this->mGoodLinks->delete( $dbkey );
        }

        /**
         * Add a title to the link cache, return the page_id or zero if non-existent
         *
         * @param string $title Title to add
         * @return int Page ID or zero
         */
        public function addLink( $title ) {
                $nt = Title::newFromDBkey( $title );
                if ( !$nt ) {
                        return 0;
                }
                return $this->addLinkObj( $nt );
        }

        /**
         * Add a title to the link cache, return the page_id or zero if non-existent
         *
         * @param Title $nt Title object to add
         * @return int Page ID or zero
         */
        public function addLinkObj( Title $nt ) {
                global $wgContentHandlerUseDB;

                $key = $nt->getPrefixedDBkey();
                if ( $this->isBadLink( $key ) || $nt->isExternal() ) {
                        return 0;
                }
                $id = $this->getGoodLinkID( $key );
                if ( $id != 0 ) {
                        return $id;
                }

                if ( $key === '' ) {
                        return 0;
                }

                // Some fields heavily used for linking...
                $db = $this->mForUpdate ? wfGetDB( DB_MASTER ) : wfGetDB( DB_SLAVE );

                $fields = array( 'page_id', 'page_len', 'page_is_redirect', 'page_latest' );
                if ( $wgContentHandlerUseDB ) {
                        $fields[] = 'page_content_model';
                }

                $row = $db->selectRow( 'page', $fields,
                        array( 'page_namespace' => $nt->getNamespace(), 'page_title' => $nt->getDBkey() ),
                        __METHOD__
                );

                if ( $row !== false ) {
                        $this->addGoodLinkObjFromRow( $nt, $row );
                        $id = intval( $row->page_id );
                } else {
                        $this->addBadLinkObj( $nt );
                        $id = 0;
                }

                return $id;
        }

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