LinksDeletionUpdate.php

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<?php
class LinksDeletionUpdate extends SqlDataUpdate implements EnqueueableDataUpdate {
    protected $page;
    protected $pageId;
    protected $timestamp;

    function __construct( WikiPage $page, $pageId = null, $timestamp = null ) {
        parent::__construct( false ); // no implicit transaction

        $this->page = $page;
        if ( $pageId ) {
            $this->pageId = $pageId; // page ID at time of deletion
        } elseif ( $page->exists() ) {
            $this->pageId = $page->getId();
        } else {
            throw new InvalidArgumentException( "Page ID not known. Page doesn't exist?" );
        }

        $this->timestamp = $timestamp ?: wfTimestampNow();
    }

    public function doUpdate() {
        $config = RequestContext::getMain()->getConfig();
        $batchSize = $config->get( 'UpdateRowsPerQuery' );

        // Page may already be deleted, so don't just getId()
        $id = $this->pageId;
        // Make sure all links update threads see the changes of each other.
        // This handles the case when updates have to batched into several COMMITs.
        $scopedLock = LinksUpdate::acquirePageLock( $this->mDb, $id );

        $title = $this->page->getTitle();

        // Delete restrictions for it
        $this->mDb->delete( 'page_restrictions', [ 'pr_page' => $id ], __METHOD__ );

        // Fix category table counts
        $cats = $this->mDb->selectFieldValues(
            'categorylinks',
            'cl_to',
            [ 'cl_from' => $id ],
            __METHOD__
        );
        $catBatches = array_chunk( $cats, $batchSize );
        foreach ( $catBatches as $catBatch ) {
            $this->page->updateCategoryCounts( [], $catBatch, $id );
            if ( count( $catBatches ) > 1 ) {
                $this->mDb->commit( __METHOD__, 'flush' );
                wfGetLBFactory()->waitForReplication( [ 'wiki' => $this->mDb->getWikiID() ] );
            }
        }

        // Refresh the category table entry if it seems to have no pages. Check
        // master for the most up-to-date cat_pages count.
        if ( $title->getNamespace() === NS_CATEGORY ) {
            $row = $this->mDb->selectRow(
                'category',
                [ 'cat_id', 'cat_title', 'cat_pages', 'cat_subcats', 'cat_files' ],
                [ 'cat_title' => $title->getDBkey(), 'cat_pages <= 0' ],
                __METHOD__
            );
            if ( $row ) {
                $cat = Category::newFromRow( $row, $title )->refreshCounts();
            }
        }

        // If using cascading deletes, we can skip some explicit deletes
        if ( !$this->mDb->cascadingDeletes() ) {
            // Delete outgoing links
            $this->batchDeleteByPK(
                'pagelinks',
                [ 'pl_from' => $id ],
                [ 'pl_from', 'pl_namespace', 'pl_title' ],
                $batchSize
            );
            $this->batchDeleteByPK(
                'imagelinks',
                [ 'il_from' => $id ],
                [ 'il_from', 'il_to' ],
                $batchSize
            );
            $this->batchDeleteByPK(
                'categorylinks',
                [ 'cl_from' => $id ],
                [ 'cl_from', 'cl_to' ],
                $batchSize
            );
            $this->batchDeleteByPK(
                'templatelinks',
                [ 'tl_from' => $id ],
                [ 'tl_from', 'tl_namespace', 'tl_title' ],
                $batchSize
            );
            $this->batchDeleteByPK(
                'externallinks',
                [ 'el_from' => $id ],
                [ 'el_id' ],
                $batchSize
            );
            $this->batchDeleteByPK(
                'langlinks',
                [ 'll_from' => $id ],
                [ 'll_from', 'll_lang' ],
                $batchSize
            );
            $this->batchDeleteByPK(
                'iwlinks',
                [ 'iwl_from' => $id ],
                [ 'iwl_from', 'iwl_prefix', 'iwl_title' ],
                $batchSize
            );
            // Delete any redirect entry or page props entries
            $this->mDb->delete( 'redirect', [ 'rd_from' => $id ], __METHOD__ );
            $this->mDb->delete( 'page_props', [ 'pp_page' => $id ], __METHOD__ );
        }

        // If using cleanup triggers, we can skip some manual deletes
        if ( !$this->mDb->cleanupTriggers() ) {
            // Find recentchanges entries to clean up...
            $rcIdsForTitle = $this->mDb->selectFieldValues(
                'recentchanges',
                'rc_id',
                [
                    'rc_type != ' . RC_LOG,
                    'rc_namespace' => $title->getNamespace(),
                    'rc_title' => $title->getDBkey(),
                    'rc_timestamp < ' .
                        $this->mDb->addQuotes( $this->mDb->timestamp( $this->timestamp ) )
                ],
                __METHOD__
            );
            $rcIdsForPage = $this->mDb->selectFieldValues(
                'recentchanges',
                'rc_id',
                [ 'rc_type != ' . RC_LOG, 'rc_cur_id' => $id ],
                __METHOD__
            );

            // T98706: delete by PK to avoid lock contention with RC delete log insertions
            $rcIdBatches = array_chunk( array_merge( $rcIdsForTitle, $rcIdsForPage ), $batchSize );
            foreach ( $rcIdBatches as $rcIdBatch ) {
                $this->mDb->delete( 'recentchanges', [ 'rc_id' => $rcIdBatch ], __METHOD__ );
                if ( count( $rcIdBatches ) > 1 ) {
                    $this->mDb->commit( __METHOD__, 'flush' );
                    wfGetLBFactory()->waitForReplication( [ 'wiki' => $this->mDb->getWikiID() ] );
                }
            }
        }

        // Commit and release the lock
        ScopedCallback::consume( $scopedLock );
    }

    private function batchDeleteByPK( $table, array $conds, array $pk, $bSize ) {
        $dbw = $this->mDb; // convenience
        $res = $dbw->select( $table, $pk, $conds, __METHOD__ );

        $pkDeleteConds = [];
        foreach ( $res as $row ) {
            $pkDeleteConds[] = $this->mDb->makeList( (array)$row, LIST_AND );
            if ( count( $pkDeleteConds ) >= $bSize ) {
                $dbw->delete( $table, $dbw->makeList( $pkDeleteConds, LIST_OR ), __METHOD__ );
                $dbw->commit( __METHOD__, 'flush' );
                wfGetLBFactory()->waitForReplication( [ 'wiki' => $dbw->getWikiID() ] );
                $pkDeleteConds = [];
            }
        }

        if ( $pkDeleteConds ) {
            $dbw->delete( $table, $dbw->makeList( $pkDeleteConds, LIST_OR ), __METHOD__ );
        }
    }

    public function getAsJobSpecification() {
        return [
            'wiki' => $this->mDb->getWikiID(),
            'job'  => new JobSpecification(
                'deleteLinks',
                [ 'pageId' => $this->pageId, 'timestamp' => $this->timestamp ],
                [ 'removeDuplicates' => true ],
                $this->page->getTitle()
            )
        ];
    }
}