Merge "Update docs/hooks.txt for ShowSearchHitTitle"

[mediawiki.git] / maintenance / refreshLinks.php

<?php
/**
 * Refresh link tables.
 *
 * 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 Maintenance
 */

require_once __DIR__ . '/Maintenance.php';

/**
 * Maintenance script to refresh link tables.
 *
 * @ingroup Maintenance
 */
class RefreshLinks extends Maintenance {
        /** @var int|bool */
        protected $namespace = false;

        public function __construct() {
                parent::__construct();
                $this->addDescription( 'Refresh link tables' );
                $this->addOption( 'dfn-only', 'Delete links from nonexistent articles only' );
                $this->addOption( 'new-only', 'Only affect articles with just a single edit' );
                $this->addOption( 'redirects-only', 'Only fix redirects, not all links' );
                $this->addOption( 'old-redirects-only', 'Only fix redirects with no redirect table entry' );
                $this->addOption( 'e', 'Last page id to refresh', false, true );
                $this->addOption( 'dfn-chunk-size', 'Maximum number of existent IDs to check per ' .
                        'query, default 100000', false, true );
                $this->addOption( 'namespace', 'Only fix pages in this namespace', false, true );
                $this->addArg( 'start', 'Page_id to start from, default 1', false );
                $this->setBatchSize( 100 );
        }

        public function execute() {
                // Note that there is a difference between not specifying the start
                // and end IDs and using the minimum and maximum values from the page
                // table. In the latter case, deleteLinksFromNonexistent() will not
                // delete entries for nonexistent IDs that fall outside the range.
                $start = (int)$this->getArg( 0 ) ?: null;
                $end = (int)$this->getOption( 'e' ) ?: null;
                $dfnChunkSize = (int)$this->getOption( 'dfn-chunk-size', 100000 );
                $ns = $this->getOption( 'namespace' );
                if ( $ns === null ) {
                        $this->namespace = false;
                } else {
                        $this->namespace = (int)$ns;
                }
                if ( !$this->hasOption( 'dfn-only' ) ) {
                        $new = $this->getOption( 'new-only', false );
                        $redir = $this->getOption( 'redirects-only', false );
                        $oldRedir = $this->getOption( 'old-redirects-only', false );
                        $this->doRefreshLinks( $start, $new, $end, $redir, $oldRedir );
                        $this->deleteLinksFromNonexistent( null, null, $this->mBatchSize, $dfnChunkSize );
                } else {
                        $this->deleteLinksFromNonexistent( $start, $end, $this->mBatchSize, $dfnChunkSize );
                }
        }

        private function namespaceCond() {
                return $this->namespace !== false
                        ? [ 'page_namespace' => $this->namespace ]
                        : [];
        }

        /**
         * Do the actual link refreshing.
         * @param int|null $start Page_id to start from
         * @param bool $newOnly Only do pages with 1 edit
         * @param int|null $end Page_id to stop at
         * @param bool $redirectsOnly Only fix redirects
         * @param bool $oldRedirectsOnly Only fix redirects without redirect entries
         */
        private function doRefreshLinks( $start, $newOnly = false,
                $end = null, $redirectsOnly = false, $oldRedirectsOnly = false
        ) {
                $reportingInterval = 100;
                $dbr = $this->getDB( DB_REPLICA, [ 'vslow' ] );

                if ( $start === null ) {
                        $start = 1;
                }

                // Give extensions a chance to optimize settings
                Hooks::run( 'MaintenanceRefreshLinksInit', [ $this ] );

                $what = $redirectsOnly ? "redirects" : "links";

                if ( $oldRedirectsOnly ) {
                        # This entire code path is cut-and-pasted from below.  Hurrah.

                        $conds = [
                                "page_is_redirect=1",
                                "rd_from IS NULL",
                                self::intervalCond( $dbr, 'page_id', $start, $end ),
                        ] + $this->namespaceCond();

                        $res = $dbr->select(
                                [ 'page', 'redirect' ],
                                'page_id',
                                $conds,
                                __METHOD__,
                                [],
                                [ 'redirect' => [ "LEFT JOIN", "page_id=rd_from" ] ]
                        );
                        $num = $res->numRows();
                        $this->output( "Refreshing $num old redirects from $start...\n" );

                        $i = 0;

                        foreach ( $res as $row ) {
                                if ( !( ++$i % $reportingInterval ) ) {
                                        $this->output( "$i\n" );
                                        wfWaitForSlaves();
                                }
                                $this->fixRedirect( $row->page_id );
                        }
                } elseif ( $newOnly ) {
                        $this->output( "Refreshing $what from " );
                        $res = $dbr->select( 'page',
                                [ 'page_id' ],
                                [
                                        'page_is_new' => 1,
                                        self::intervalCond( $dbr, 'page_id', $start, $end ),
                                ] + $this->namespaceCond(),
                                __METHOD__
                        );
                        $num = $res->numRows();
                        $this->output( "$num new articles...\n" );

                        $i = 0;
                        foreach ( $res as $row ) {
                                if ( !( ++$i % $reportingInterval ) ) {
                                        $this->output( "$i\n" );
                                        wfWaitForSlaves();
                                }
                                if ( $redirectsOnly ) {
                                        $this->fixRedirect( $row->page_id );
                                } else {
                                        self::fixLinksFromArticle( $row->page_id, $this->namespace );
                                }
                        }
                } else {
                        if ( !$end ) {
                                $maxPage = $dbr->selectField( 'page', 'max(page_id)', false );
                                $maxRD = $dbr->selectField( 'redirect', 'max(rd_from)', false );
                                $end = max( $maxPage, $maxRD );
                        }
                        $this->output( "Refreshing redirects table.\n" );
                        $this->output( "Starting from page_id $start of $end.\n" );

                        for ( $id = $start; $id <= $end; $id++ ) {

                                if ( !( $id % $reportingInterval ) ) {
                                        $this->output( "$id\n" );
                                        wfWaitForSlaves();
                                }
                                $this->fixRedirect( $id );
                        }

                        if ( !$redirectsOnly ) {
                                $this->output( "Refreshing links tables.\n" );
                                $this->output( "Starting from page_id $start of $end.\n" );

                                for ( $id = $start; $id <= $end; $id++ ) {

                                        if ( !( $id % $reportingInterval ) ) {
                                                $this->output( "$id\n" );
                                                wfWaitForSlaves();
                                        }
                                        self::fixLinksFromArticle( $id, $this->namespace );
                                }
                        }
                }
        }

        /**
         * Update the redirect entry for a given page.
         *
         * This methods bypasses the "redirect" table to get the redirect target,
         * and parses the page's content to fetch it. This allows to be sure that
         * the redirect target is up to date and valid.
         * This is particularly useful when modifying namespaces to be sure the
         * entry in the "redirect" table points to the correct page and not to an
         * invalid one.
         *
         * @param int $id The page ID to check
         */
        private function fixRedirect( $id ) {
                $page = WikiPage::newFromID( $id );
                $dbw = $this->getDB( DB_MASTER );

                if ( $page === null ) {
                        // This page doesn't exist (any more)
                        // Delete any redirect table entry for it
                        $dbw->delete( 'redirect', [ 'rd_from' => $id ],
                                __METHOD__ );

                        return;
                } elseif ( $this->namespace !== false
                        && !$page->getTitle()->inNamespace( $this->namespace )
                ) {
                        return;
                }

                $rt = null;
                $content = $page->getContent( Revision::RAW );
                if ( $content !== null ) {
                        $rt = $content->getUltimateRedirectTarget();
                }

                if ( $rt === null ) {
                        // The page is not a redirect
                        // Delete any redirect table entry for it
                        $dbw->delete( 'redirect', [ 'rd_from' => $id ], __METHOD__ );
                        $fieldValue = 0;
                } else {
                        $page->insertRedirectEntry( $rt );
                        $fieldValue = 1;
                }

                // Update the page table to be sure it is an a consistent state
                $dbw->update( 'page', [ 'page_is_redirect' => $fieldValue ],
                        [ 'page_id' => $id ], __METHOD__ );
        }

        /**
         * Run LinksUpdate for all links on a given page_id
         * @param int $id The page_id
         * @param int|bool $ns Only fix links if it is in this namespace
         */
        public static function fixLinksFromArticle( $id, $ns = false ) {
                $page = WikiPage::newFromID( $id );

                LinkCache::singleton()->clear();

                if ( $page === null ) {
                        return;
                } elseif ( $ns !== false
                        && !$page->getTitle()->inNamespace( $ns ) ) {
                        return;
                }

                $content = $page->getContent( Revision::RAW );
                if ( $content === null ) {
                        return;
                }

                foreach ( $content->getSecondaryDataUpdates( $page->getTitle() ) as $update ) {
                        DeferredUpdates::addUpdate( $update );
                }
        }

        /**
         * Removes non-existing links from pages from pagelinks, imagelinks,
         * categorylinks, templatelinks, externallinks, interwikilinks, langlinks and redirect tables.
         *
         * @param int|null $start Page_id to start from
         * @param int|null $end Page_id to stop at
         * @param int $batchSize The size of deletion batches
         * @param int $chunkSize Maximum number of existent IDs to check per query
         *
         * @author Merlijn van Deen <valhallasw@arctus.nl>
         */
        private function deleteLinksFromNonexistent( $start = null, $end = null, $batchSize = 100,
                $chunkSize = 100000
        ) {
                wfWaitForSlaves();
                $this->output( "Deleting illegal entries from the links tables...\n" );
                $dbr = $this->getDB( DB_REPLICA, [ 'vslow' ] );
                do {
                        // Find the start of the next chunk. This is based only
                        // on existent page_ids.
                        $nextStart = $dbr->selectField(
                                'page',
                                'page_id',
                                [ self::intervalCond( $dbr, 'page_id', $start, $end ) ]
                                + $this->namespaceCond(),
                                __METHOD__,
                                [ 'ORDER BY' => 'page_id', 'OFFSET' => $chunkSize ]
                        );

                        if ( $nextStart !== false ) {
                                // To find the end of the current chunk, subtract one.
                                // This will serve to limit the number of rows scanned in
                                // dfnCheckInterval(), per query, to at most the sum of
                                // the chunk size and deletion batch size.
                                $chunkEnd = $nextStart - 1;
                        } else {
                                // This is the last chunk. Check all page_ids up to $end.
                                $chunkEnd = $end;
                        }

                        $fmtStart = $start !== null ? "[$start" : '(-INF';
                        $fmtChunkEnd = $chunkEnd !== null ? "$chunkEnd]" : 'INF)';
                        $this->output( "  Checking interval $fmtStart, $fmtChunkEnd\n" );
                        $this->dfnCheckInterval( $start, $chunkEnd, $batchSize );

                        $start = $nextStart;

                } while ( $nextStart !== false );
        }

        /**
         * @see RefreshLinks::deleteLinksFromNonexistent()
         * @param int|null $start Page_id to start from
         * @param int|null $end Page_id to stop at
         * @param int $batchSize The size of deletion batches
         */
        private function dfnCheckInterval( $start = null, $end = null, $batchSize = 100 ) {
                $dbw = $this->getDB( DB_MASTER );
                $dbr = $this->getDB( DB_REPLICA, [ 'vslow' ] );

                $linksTables = [ // table name => page_id field
                        'pagelinks' => 'pl_from',
                        'imagelinks' => 'il_from',
                        'categorylinks' => 'cl_from',
                        'templatelinks' => 'tl_from',
                        'externallinks' => 'el_from',
                        'iwlinks' => 'iwl_from',
                        'langlinks' => 'll_from',
                        'redirect' => 'rd_from',
                        'page_props' => 'pp_page',
                ];

                foreach ( $linksTables as $table => $field ) {
                        $this->output( "    $table: 0" );
                        $tableStart = $start;
                        $counter = 0;
                        do {
                                $ids = $dbr->selectFieldValues(
                                        $table,
                                        $field,
                                        [
                                                self::intervalCond( $dbr, $field, $tableStart, $end ),
                                                "$field NOT IN ({$dbr->selectSQLText( 'page', 'page_id' )})",
                                        ],
                                        __METHOD__,
                                        [ 'DISTINCT', 'ORDER BY' => $field, 'LIMIT' => $batchSize ]
                                );

                                $numIds = count( $ids );
                                if ( $numIds ) {
                                        $counter += $numIds;
                                        $dbw->delete( $table, [ $field => $ids ], __METHOD__ );
                                        $this->output( ", $counter" );
                                        $tableStart = $ids[$numIds - 1] + 1;
                                        wfWaitForSlaves();
                                }

                        } while ( $numIds >= $batchSize && ( $end === null || $tableStart <= $end ) );

                        $this->output( " deleted.\n" );
                }
        }

        /**
         * Build a SQL expression for a closed interval (i.e. BETWEEN).
         *
         * By specifying a null $start or $end, it is also possible to create
         * half-bounded or unbounded intervals using this function.
         *
         * @param IDatabase $db Database connection
         * @param string $var Field name
         * @param mixed $start First value to include or null
         * @param mixed $end Last value to include or null
         */
        private static function intervalCond( IDatabase $db, $var, $start, $end ) {
                if ( $start === null && $end === null ) {
                        return "$var IS NOT NULL";
                } elseif ( $end === null ) {
                        return "$var >= {$db->addQuotes( $start )}";
                } elseif ( $start === null ) {
                        return "$var <= {$db->addQuotes( $end )}";
                } else {
                        return "$var BETWEEN {$db->addQuotes( $start )} AND {$db->addQuotes( $end )}";
                }
        }
}

$maintClass = 'RefreshLinks';
require_once RUN_MAINTENANCE_IF_MAIN;