Merge "doc: SpanInterface: more dev-friendly comments"

[mediawiki.git] / maintenance / refreshLinks.php

<?php
/**
 * 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
 */

use MediaWiki\Deferred\DeferredUpdates;
use MediaWiki\Linker\LinkTarget;
use MediaWiki\Maintenance\Maintenance;
use MediaWiki\MediaWikiServices;
use MediaWiki\Revision\RevisionRecord;
use MediaWiki\Title\Title;
use Wikimedia\Rdbms\IExpression;
use Wikimedia\Rdbms\IReadableDatabase;
use Wikimedia\Rdbms\SelectQueryBuilder;

// @codeCoverageIgnoreStart
require_once __DIR__ . '/Maintenance.php';
// @codeCoverageIgnoreEnd

/**
 * Refresh link tables.
 *
 * @ingroup Maintenance
 */
class RefreshLinks extends Maintenance {
        private const REPORTING_INTERVAL = 100;

        public function __construct() {
                parent::__construct();
                $this->addDescription( 'Refresh link tables' );
                $this->addOption( 'verbose', 'Output information about link refresh progress', false, false, 'v' );
                $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( 'touched-only', 'Only fix pages that have been touched after last update' );
                $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 100,000', false, true );
                $this->addOption( 'namespace', 'Only fix pages in this namespace', false, true );
                $this->addOption( 'category', 'Only fix pages in this category', false, true );
                $this->addOption( 'tracking-category', 'Only fix pages in this tracking category', false, true );
                $this->addOption( 'before-timestamp', 'Only fix pages that were last updated before this timestamp',
                        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', 100_000 );

                if ( $this->hasOption( 'dfn-only' ) ) {
                        $this->deleteLinksFromNonexistent( $start, $end, $this->getBatchSize(), $dfnChunkSize );
                        return;
                }

                $dbr = $this->getDB( DB_REPLICA, [ 'vslow' ] );
                $builder = $dbr->newSelectQueryBuilder()
                        ->from( 'page' )
                        ->where( self::intervalCond( $dbr, 'page_id', $start, $end ) )
                        ->limit( $this->getBatchSize() );

                if ( $this->hasOption( 'namespace' ) ) {
                        $builder->andWhere( [ 'page_namespace' => (int)$this->getOption( 'namespace' ) ] );
                }

                if ( $this->hasOption( 'before-timestamp' ) ) {
                        $builder->andWhere(
                                $dbr->expr( 'page_links_updated', '<', $this->getOption( 'before-timestamp' ) )
                                        ->or( 'page_links_updated', '=', null )
                        );
                }

                if ( $this->hasOption( 'category' ) ) {
                        $category = $this->getOption( 'category' );
                        $title = Title::makeTitleSafe( NS_CATEGORY, $category );
                        if ( !$title ) {
                                $this->fatalError( "'$category' is an invalid category name!\n" );
                        }
                        $this->refreshCategory( $builder, $title );
                } elseif ( $this->hasOption( 'tracking-category' ) ) {
                        // See TrackingCategories::CORE_TRACKING_CATEGORIES for tracking category keys defined by core
                        $this->refreshTrackingCategory( $builder, $this->getOption( 'tracking-category' ) );
                } else {
                        $new = $this->hasOption( 'new-only' );
                        $redir = $this->hasOption( 'redirects-only' );
                        $touched = $this->hasOption( 'touched-only' );
                        $what = $redir ? 'redirects' : 'links';
                        if ( $new ) {
                                $builder->andWhere( [ 'page_is_new' => 1 ] );
                                $this->output( "Refreshing $what from new pages...\n" );
                        } else {
                                if ( $touched ) {
                                        $builder->andWhere( [
                                                $dbr->expr( 'page_touched', '>', 'page_links_updated' )
                                                        ->or( 'page_links_updated', '=', null ),
                                        ] );
                                }
                                $this->output( "Refreshing $what from pages...\n" );
                        }
                        $this->doRefreshLinks( $builder, $redir );
                        if ( !$this->hasOption( 'namespace' ) ) {
                                $this->deleteLinksFromNonexistent( $start, $end, $this->getBatchSize(), $dfnChunkSize );
                        }
                }
        }

        /**
         * Do the actual link refreshing.
         * @param SelectQueryBuilder $builder
         * @param bool $redirectsOnly Only fix redirects
         * @param array $indexFields
         */
        private function doRefreshLinks(
                SelectQueryBuilder $builder,
                bool $redirectsOnly = false,
                array $indexFields = [ 'page_id' ]
        ) {
                // Give extensions a chance to optimize settings
                $this->getHookRunner()->onMaintenanceRefreshLinksInit( $this );

                $estimateCount = $builder->caller( __METHOD__ )->estimateRowCount();
                $this->output( "Estimated page count: $estimateCount\n" );

                $i = 0;
                $lastIndexes = array_fill_keys( $indexFields, 0 );
                $selectFields = in_array( 'page_id', $indexFields )
                        ? $indexFields : [ 'page_id', ...$indexFields ];
                $verbose = $this->hasOption( 'verbose' );
                $dbr = $this->getDB( DB_REPLICA, [ 'vslow' ] );
                do {
                        $batchCond = $dbr->buildComparison( '>', $lastIndexes );
                        $res = ( clone $builder )->select( $selectFields )
                                ->andWhere( [ $batchCond ] )
                                ->orderBy( $indexFields )
                                ->caller( __METHOD__ )->fetchResultSet();

                        if ( $verbose ) {
                                $this->output( "Refreshing links for {$res->numRows()} pages\n" );
                        }

                        foreach ( $res as $row ) {
                                if ( !( ++$i % self::REPORTING_INTERVAL ) ) {
                                        $this->output( "$i\n" );
                                        $this->waitForReplication();
                                }
                                if ( $verbose ) {
                                        $this->output( "Refreshing links for page ID {$row->page_id}\n" );
                                }
                                self::fixRedirect( $this, $row->page_id );
                                if ( !$redirectsOnly ) {
                                        self::fixLinksFromArticle( $row->page_id );
                                }
                        }
                        if ( $res->numRows() ) {
                                $res->seek( $res->numRows() - 1 );
                                foreach ( $indexFields as $field ) {
                                        $lastIndexes[$field] = $res->current()->$field;
                                }
                        }

                } while ( $res->numRows() == $this->getBatchSize() );
        }

        /**
         * 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.
         *
         * @internal
         * @param Maintenance $maint
         * @param int $id The page ID to check
         */
        public static function fixRedirect( Maintenance $maint, $id ) {
                $page = $maint->getServiceContainer()->getWikiPageFactory()->newFromID( $id );

                // In case the page just got deleted.
                if ( $page === null ) {
                        return;
                }

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

                $dbw = $maint->getDB( DB_PRIMARY );
                if ( $rt === null ) {
                        // The page is not a redirect
                        // Delete any redirect table entry for it
                        $dbw->newDeleteQueryBuilder()
                                ->deleteFrom( 'redirect' )
                                ->where( [ 'rd_from' => $id ] )
                                ->caller( __METHOD__ )->execute();
                        $fieldValue = 0;
                } else {
                        $page->insertRedirectEntry( $rt );
                        $fieldValue = 1;
                }

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

        /**
         * Run LinksUpdate for all links on a given page_id
         * @param int $id The page_id
         */
        public static function fixLinksFromArticle( $id ) {
                $services = MediaWikiServices::getInstance();
                $page = $services->getWikiPageFactory()->newFromID( $id );

                // In case the page just got deleted.
                if ( $page === null ) {
                        return;
                }

                // Defer updates to post-send but then immediately execute deferred updates;
                // this is the simplest way to run all updates immediately (including updates
                // scheduled by other updates).
                $page->doSecondaryDataUpdates( [
                        'defer' => DeferredUpdates::POSTSEND,
                        'causeAction' => 'refresh-links-maintenance',
                        'recursive' => false,
                ] );
                DeferredUpdates::doUpdates();
        }

        /**
         * 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 = 100_000
        ) {
                $this->waitForReplication();
                $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->newSelectQueryBuilder()
                                ->select( 'page_id' )
                                ->from( 'page' )
                                ->where( [ self::intervalCond( $dbr, 'page_id', $start, $end ) ] )
                                ->orderBy( 'page_id' )
                                ->offset( $chunkSize )
                                ->caller( __METHOD__ )->fetchField();

                        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->getPrimaryDB();
                $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->newSelectQueryBuilder()
                                        ->select( $field )
                                        ->distinct()
                                        ->from( $table )
                                        ->leftJoin( 'page', null, "$field = page_id" )
                                        ->where( self::intervalCond( $dbr, $field, $tableStart, $end ) )
                                        ->andWhere( [ 'page_id' => null ] )
                                        ->orderBy( $field )
                                        ->limit( $batchSize )
                                        ->caller( __METHOD__ )->fetchFieldValues();

                                $numIds = count( $ids );
                                if ( $numIds ) {
                                        $counter += $numIds;
                                        $dbw->newDeleteQueryBuilder()
                                                ->deleteFrom( $table )
                                                ->where( [ $field => $ids ] )
                                                ->caller( __METHOD__ )->execute();
                                        $this->output( ", $counter" );
                                        $tableStart = $ids[$numIds - 1] + 1;
                                        $this->waitForReplication();
                                }

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

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

        /**
         * Build a SQL expression for a closed interval.
         *
         * By specifying a null $start or $end, it is also possible to create
         * half-bounded or unbounded intervals using this function.
         *
         * @param IReadableDatabase $db
         * @param string $var Field name
         * @param mixed $start First value to include or null
         * @param mixed $end Last value to include or null
         * @return IExpression
         */
        private static function intervalCond( IReadableDatabase $db, $var, $start, $end ) {
                if ( $start === null && $end === null ) {
                        return $db->expr( $var, '!=', null );
                } elseif ( $end === null ) {
                        return $db->expr( $var, '>=', $start );
                } elseif ( $start === null ) {
                        return $db->expr( $var, '<=', $end );
                } else {
                        return $db->expr( $var, '>=', $start )->and( $var, '<=', $end );
                }
        }

        /**
         * Refershes links for pages in a tracking category
         *
         * @param SelectQueryBuilder $builder
         * @param string $category Category key
         */
        private function refreshTrackingCategory( SelectQueryBuilder $builder, $category ) {
                $cats = $this->getPossibleCategories( $category );

                if ( !$cats ) {
                        $this->error( "Tracking category '$category' is disabled\n" );
                        // Output to stderr but don't bail out.
                }

                foreach ( $cats as $cat ) {
                        $this->refreshCategory( clone $builder, $cat );
                }
        }

        /**
         * Refreshes links to a category
         *
         * @param SelectQueryBuilder $builder
         * @param LinkTarget $category
         */
        private function refreshCategory( SelectQueryBuilder $builder, LinkTarget $category ) {
                $this->output( "Refreshing pages in category '{$category->getText()}'...\n" );

                $builder->join( 'categorylinks', null, 'page_id=cl_from' )
                        ->andWhere( [ 'cl_to' => $category->getDBkey() ] );
                $this->doRefreshLinks( $builder, false, [ 'cl_timestamp', 'cl_from' ] );
        }

        /**
         * Returns a list of possible categories for a given tracking category key
         *
         * @param string $categoryKey
         * @return LinkTarget[]
         */
        private function getPossibleCategories( $categoryKey ) {
                $cats = $this->getServiceContainer()->getTrackingCategories()->getTrackingCategories();
                if ( isset( $cats[$categoryKey] ) ) {
                        return $cats[$categoryKey]['cats'];
                }
                $this->fatalError( "Unknown tracking category {$categoryKey}\n" );
        }
}

// @codeCoverageIgnoreStart
$maintClass = RefreshLinks::class;
require_once RUN_MAINTENANCE_IF_MAIN;
// @codeCoverageIgnoreEnd