deduplicateArchiveRevId.php

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<?php
 
use Wikimedia\Rdbms\IDatabase;
 
require_once __DIR__ . '/Maintenance.php';
 
class DeduplicateArchiveRevId extends LoggedUpdateMaintenance {
 
    private $arActorQuery = null;
 
    private $deleted = 0;
    private $reassigned = 0;
 
    public function __construct() {
        parent::__construct();
        $this->addDescription(
            'Clean up duplicate ar_rev_id, both within archive and between archive and revision.'
        );
        $this->setBatchSize( 10000 );
    }
 
    protected function getUpdateKey() {
        return __CLASS__;
    }
 
    protected function doDBUpdates() {
        $this->output( "Deduplicating ar_rev_id...\n" );
        $dbw = $this->getDB( DB_MASTER );
        // Sanity check. If this is a new install, we don't need to do anything here.
        if ( PopulateArchiveRevId::isNewInstall( $dbw ) ) {
            $this->output( "New install, nothing to do here.\n" );
            return true;
        }
 
        PopulateArchiveRevId::checkMysqlAutoIncrementBug( $dbw );
 
        $minId = $dbw->selectField( 'archive', 'MIN(ar_rev_id)', [], __METHOD__ );
        $maxId = $dbw->selectField( 'archive', 'MAX(ar_rev_id)', [], __METHOD__ );
        $batchSize = $this->getBatchSize();
 
        $this->arActorQuery = ActorMigration::newMigration()->getJoin( 'ar_user' );
        $revActorQuery = ActorMigration::newMigration()->getJoin( 'rev_user' );
 
        for ( $id = $minId; $id <= $maxId; $id += $batchSize ) {
            $endId = min( $maxId, $id + $batchSize - 1 );
 
            $this->beginTransaction( $dbw, __METHOD__ );
 
            // Lock the archive and revision table rows for the IDs we're checking
            // to try to prevent deletions or undeletions from confusing things.
            $dbw->selectRowCount(
                'archive',
                '1',
                [ 'ar_rev_id >= ' . (int)$id, 'ar_rev_id <= ' . (int)$endId ],
                __METHOD__,
                [ 'FOR UPDATE' ]
            );
            $dbw->selectRowCount(
                'revision',
                '1',
                [ 'rev_id >= ' . (int)$id, 'rev_id <= ' . (int)$endId ],
                __METHOD__,
                [ 'LOCK IN SHARE MODE' ]
            );
 
            // Figure out the ar_rev_ids we actually need to look at
            $res = $dbw->select(
                [ 'archive', 'revision' ] + $revActorQuery['tables'],
                [ 'rev_id', 'rev_timestamp', 'rev_sha1' ] + $revActorQuery['fields'],
                [ 'ar_rev_id >= ' . (int)$id, 'ar_rev_id <= ' . (int)$endId ],
                __METHOD__,
                [ 'DISTINCT' ],
                [ 'revision' => [ 'JOIN', 'ar_rev_id = rev_id' ] ] + $revActorQuery['joins']
            );
            $revRows = [];
            foreach ( $res as $row ) {
                $revRows[$row->rev_id] = $row;
            }
 
            $arRevIds = $dbw->selectFieldValues(
                [ 'archive' ],
                'ar_rev_id',
                [ 'ar_rev_id >= ' . (int)$id, 'ar_rev_id <= ' . (int)$endId ],
                __METHOD__,
                [ 'GROUP BY' => 'ar_rev_id', 'HAVING' => 'COUNT(*) > 1' ]
            );
            $arRevIds = array_values( array_unique( array_merge( $arRevIds, array_keys( $revRows ) ) ) );
 
            if ( $arRevIds ) {
                $this->processArRevIds( $dbw, $arRevIds, $revRows );
            }
 
            $this->output( "... $id-$endId\n" );
            $this->commitTransaction( $dbw, __METHOD__ );
        }
 
        $this->output(
            "Finished deduplicating ar_rev_id. $this->deleted rows deleted, "
            . "$this->reassigned assigned new IDs.\n"
        );
        return true;
    }
 
    private function processArRevIds( IDatabase $dbw, array $arRevIds, array $revRows ) {
        // Select all the data we need for deduplication
        $res = $dbw->select(
            [ 'archive' ] + $this->arActorQuery['tables'],
            [ 'ar_id', 'ar_rev_id', 'ar_namespace', 'ar_title', 'ar_timestamp', 'ar_sha1' ]
                + $this->arActorQuery['fields'],
            [ 'ar_rev_id' => $arRevIds ],
            __METHOD__,
            [],
            $this->arActorQuery['joins']
        );
 
        // Determine which rows we need to delete or reassign
        $seen = [];
        $toDelete = [];
        $toReassign = [];
        foreach ( $res as $row ) {
            // Revision-table row exists?
            if ( isset( $revRows[$row->ar_rev_id] ) ) {
                $revRow = $revRows[$row->ar_rev_id];
 
                // Record the rev_id as seen, so the code below will always delete or reassign.
                if ( !isset( $seen[$revRow->rev_id] ) ) {
                    $seen[$revRow->rev_id] = [
                        'first' => "revision row",
                    ];
                }
 
                // Delete the archive row if it seems to be the same regardless
                // of page, because moves can change IDs and titles.
                if ( $row->ar_timestamp === $revRow->rev_timestamp &&
                    $row->ar_sha1 === $revRow->rev_sha1 &&
                    $row->ar_user === $revRow->rev_user &&
                    $row->ar_user_text === $revRow->rev_user_text
                ) {
                    $this->output(
                        "Row $row->ar_id duplicates revision row for rev_id $revRow->rev_id, deleting\n"
                    );
                    $toDelete[] = $row->ar_id;
                    continue;
                }
            }
 
            $key = $this->getSeenKey( $row );
            if ( !isset( $seen[$row->ar_rev_id] ) ) {
                // This rev_id hasn't even been seen yet, nothing to do besides record it.
                $seen[$row->ar_rev_id] = [
                    'first' => "archive row $row->ar_id",
                    $key => $row->ar_id,
                ];
            } elseif ( !isset( $seen[$row->ar_rev_id][$key] ) ) {
                // The rev_id was seen, but not this particular change. Reassign it.
                $seen[$row->ar_rev_id][$key] = $row->ar_id;
                $this->output(
                    "Row $row->ar_id conflicts with {$seen[$row->ar_rev_id]['first']} "
                    . "for rev_id $row->ar_rev_id, reassigning\n"
                );
                $toReassign[] = $row->ar_id;
            } else {
                // The rev_id was seen with a row that matches this change. Delete it.
                $this->output(
                    "Row $row->ar_id duplicates archive row {$seen[$row->ar_rev_id][$key]} "
                    . "for rev_id $row->ar_rev_id, deleting\n"
                );
                $toDelete[] = $row->ar_id;
            }
        }
 
        // Perform the updates
        if ( $toDelete ) {
            $dbw->delete( 'archive', [ 'ar_id' => $toDelete ], __METHOD__ );
            $this->deleted += $dbw->affectedRows();
        }
        if ( $toReassign ) {
            $this->reassigned += PopulateArchiveRevId::reassignArRevIds( $dbw, $toReassign );
        }
    }
 
    private function getSeenKey( $row ) {
        return implode( "\n", [
            $row->ar_namespace,
            $row->ar_title,
            $row->ar_timestamp,
            $row->ar_sha1,
            $row->ar_user,
            $row->ar_user_text,
        ] );
    }
 
}
 
$maintClass = DeduplicateArchiveRevId::class;
require_once RUN_MAINTENANCE_IF_MAIN;