wikimedia/mediawiki-core

<?php

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

/**
 * Maintenance script that cleans unused rows in linktarget table
 *
 * @ingroup Maintenance
 * @since 1.39
 */
class PruneUnusedLinkTargetRows extends Maintenance {
    public function __construct() {
        parent::__construct();
        $this->addDescription(
            'Clean unused rows in linktarget table'
        );
        $this->addOption(
            'sleep',
            'Sleep time (in seconds) between every batch. Default: 0',
            false,
            true
        );
        $this->addOption( 'dry', 'Dry run', false );
        $this->addOption( 'start', 'Start after this lt_id', false, true );
        $this->setBatchSize( 50 );
    }

    public function execute() {
        $dbw = $this->getPrimaryDB();
        $dbr = $this->getReplicaDB();
        $maxLtId = (int)$dbr->newSelectQueryBuilder()
            ->select( 'MAX(lt_id)' )
            ->from( 'linktarget' )
            ->caller( __METHOD__ )
            ->fetchField();
        // To avoid race condition of newly added linktarget rows
        // being deleted before getting a chance to be used, let's ignore the newest ones.
        $maxLtId = min( [ $maxLtId - 1, (int)( $maxLtId * 0.99 ) ] );

        $ltCounter = (int)$this->getOption( 'start', 0 );

        $this->output( "Deleting unused linktarget rows...\n" );
        $deleted = 0;
        $linksMigration = $this->getServiceContainer()->getLinksMigration();
        while ( $ltCounter < $maxLtId ) {
            $batchMaxLtId = min( $ltCounter + $this->getBatchSize(), $maxLtId ) + 1;
            $this->output( "Checking lt_id between $ltCounter and $batchMaxLtId...\n" );
            $queryBuilder = $dbr->newSelectQueryBuilder()
                ->select( [ 'lt_id' ] )
                ->from( 'linktarget' );
            $queryBuilder->where( [
                $dbr->expr( 'lt_id', '<', $batchMaxLtId ),
                $dbr->expr( 'lt_id', '>', $ltCounter )
            ] );
            foreach ( $linksMigration::$mapping as $table => $tableData ) {
                $queryBuilder->leftJoin( $table, null, $tableData['target_id'] . '=lt_id' );
                $queryBuilder->andWhere( [
                    $tableData['target_id'] => null
                ] );
            }
            $ltIdsToDelete = $queryBuilder->caller( __METHOD__ )->fetchFieldValues();
            if ( !$ltIdsToDelete ) {
                $ltCounter += $this->getBatchSize();
                continue;
            }

            // Run against primary as well with a faster query plan, just to be safe.
            // Also having a bit of time in between helps in cases of immediate removal and insertion of use.
            $queryBuilder = $dbr->newSelectQueryBuilder()
                ->select( [ 'lt_id' ] )
                ->from( 'linktarget' )
                ->where( [
                    'lt_id' => $ltIdsToDelete,
                ] );
            foreach ( $linksMigration::$mapping as $table => $tableData ) {
                $queryBuilder->leftJoin( $table, null, $tableData['target_id'] . '=lt_id' );
                $queryBuilder->andWhere( [
                    $tableData['target_id'] => null
                ] );
            }
            $ltIdsToDelete = $queryBuilder->caller( __METHOD__ )->fetchFieldValues();
            if ( !$ltIdsToDelete ) {
                $ltCounter += $this->getBatchSize();
                continue;
            }

            if ( !$this->getOption( 'dry' ) ) {
                $dbw->newDeleteQueryBuilder()
                    ->deleteFrom( 'linktarget' )
                    ->where( [ 'lt_id' => $ltIdsToDelete ] )
                    ->caller( __METHOD__ )->execute();
            }
            $deleted += count( $ltIdsToDelete );
            $ltCounter += $this->getBatchSize();

            // Sleep between batches for replication to catch up
            $this->waitForReplication();
            $sleep = (int)$this->getOption( 'sleep', 0 );
            if ( $sleep > 0 ) {
                sleep( $sleep );
            }
        }

        $this->output(
            "Completed clean up linktarget table, "
            . "$deleted rows deleted.\n"
        );

        return true;
    }

}

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