Move remaining LoadBalancer classes to Rdbms

[mediawiki.git] / includes / specials / SpecialDoubleRedirects.php

<?php
/**
 * Implements Special:DoubleRedirects
 *
 * 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 SpecialPage
 */

/**
 * A special page listing redirects to redirecting page.
 * The software will automatically not follow double redirects, to prevent loops.
 *
 * @ingroup SpecialPage
 */
class DoubleRedirectsPage extends QueryPage {
        function __construct( $name = 'DoubleRedirects' ) {
                parent::__construct( $name );
        }

        public function isExpensive() {
                return true;
        }

        function isSyndicated() {
                return false;
        }

        function sortDescending() {
                return false;
        }

        function getPageHeader() {
                return $this->msg( 'doubleredirectstext' )->parseAsBlock();
        }

        function reallyGetQueryInfo( $namespace = null, $title = null ) {
                $limitToTitle = !( $namespace === null && $title === null );
                $dbr = wfGetDB( DB_REPLICA );
                $retval = [
                        'tables' => [
                                'ra' => 'redirect',
                                'rb' => 'redirect',
                                'pa' => 'page',
                                'pb' => 'page'
                        ],
                        'fields' => [
                                'namespace' => 'pa.page_namespace',
                                'title' => 'pa.page_title',
                                'value' => 'pa.page_title',

                                'nsb' => 'pb.page_namespace',
                                'tb' => 'pb.page_title',

                                // Select fields from redirect instead of page. Because there may
                                // not actually be a page table row for this target (e.g. for interwiki redirects)
                                'nsc' => 'rb.rd_namespace',
                                'tc' => 'rb.rd_title',
                                'iwc' => 'rb.rd_interwiki',
                        ],
                        'conds' => [
                                'ra.rd_from = pa.page_id',

                                // Filter out redirects where the target goes interwiki (bug 40353).
                                // This isn't an optimization, it is required for correct results,
                                // otherwise a non-double redirect like Bar -> w:Foo will show up
                                // like "Bar -> Foo -> w:Foo".

                                // Need to check both NULL and "" for some reason,
                                // apparently either can be stored for non-iw entries.
                                'ra.rd_interwiki IS NULL OR ra.rd_interwiki = ' . $dbr->addQuotes( '' ),

                                'pb.page_namespace = ra.rd_namespace',
                                'pb.page_title = ra.rd_title',

                                'rb.rd_from = pb.page_id',
                        ]
                ];

                if ( $limitToTitle ) {
                        $retval['conds']['pa.page_namespace'] = $namespace;
                        $retval['conds']['pa.page_title'] = $title;
                }

                return $retval;
        }

        public function getQueryInfo() {
                return $this->reallyGetQueryInfo();
        }

        function getOrderFields() {
                return [ 'ra.rd_namespace', 'ra.rd_title' ];
        }

        /**
         * @param Skin $skin
         * @param object $result Result row
         * @return string
         */
        function formatResult( $skin, $result ) {
                $titleA = Title::makeTitle( $result->namespace, $result->title );

                // If only titleA is in the query, it means this came from
                // querycache (which only saves 3 columns).
                // That does save the bulk of the query cost, but now we need to
                // get a little more detail about each individual entry quickly
                // using the filter of reallyGetQueryInfo.
                if ( $result && !isset( $result->nsb ) ) {
                        $dbr = wfGetDB( DB_REPLICA );
                        $qi = $this->reallyGetQueryInfo(
                                $result->namespace,
                                $result->title
                        );
                        $res = $dbr->select(
                                $qi['tables'],
                                $qi['fields'],
                                $qi['conds'],
                                __METHOD__
                        );

                        if ( $res ) {
                                $result = $dbr->fetchObject( $res );
                        }
                }
                $linkRenderer = $this->getLinkRenderer();
                if ( !$result ) {
                        return '<del>' . $linkRenderer->makeLink( $titleA, null, [], [ 'redirect' => 'no' ] ) . '</del>';
                }

                $titleB = Title::makeTitle( $result->nsb, $result->tb );
                $titleC = Title::makeTitle( $result->nsc, $result->tc, '', $result->iwc );

                $linkA = $linkRenderer->makeKnownLink(
                        $titleA,
                        null,
                        [],
                        [ 'redirect' => 'no' ]
                );

                // if the page is editable, add an edit link
                if (
                        // check user permissions
                        $this->getUser()->isAllowed( 'edit' ) &&
                        // check, if the content model is editable through action=edit
                        ContentHandler::getForTitle( $titleA )->supportsDirectEditing()
                ) {
                        $edit = $linkRenderer->makeKnownLink(
                                $titleA,
                                $this->msg( 'parentheses', $this->msg( 'editlink' )->text() )->text(),
                                [],
                                [ 'action' => 'edit' ]
                        );
                } else {
                        $edit = '';
                }

                $linkB = $linkRenderer->makeKnownLink(
                        $titleB,
                        null,
                        [],
                        [ 'redirect' => 'no' ]
                );

                $linkC = $linkRenderer->makeKnownLink( $titleC );

                $lang = $this->getLanguage();
                $arr = $lang->getArrow() . $lang->getDirMark();

                return ( "{$linkA} {$edit} {$arr} {$linkB} {$arr} {$linkC}" );
        }

        /**
         * Cache page content model and gender distinction for performance
         *
         * @param IDatabase $db
         * @param ResultWrapper $res
         */
        function preprocessResults( $db, $res ) {
                if ( !$res->numRows() ) {
                        return;
                }

                $batch = new LinkBatch;
                foreach ( $res as $row ) {
                        $batch->add( $row->namespace, $row->title );
                        if ( isset( $row->nsb ) ) {
                                // lazy loaded when using cached results
                                $batch->add( $row->nsb, $row->tb );
                        }
                        if ( isset( $row->iwc ) && !$row->iwc ) {
                                // lazy loaded when using cached result, not added when interwiki link
                                $batch->add( $row->nsc, $row->tc );
                        }
                }
                $batch->execute();

                // Back to start for display
                $res->seek( 0 );
        }

        protected function getGroupName() {
                return 'maintenance';
        }
}