wikimedia/mediawiki-extensions-Wikibase

<?php

declare( strict_types = 1 );

namespace Wikibase\Repo\Store\Sql;

use Wikibase\Lib\Rdbms\RepoDomainDb;
use Wikimedia\Rdbms\IReadableDatabase;

/**
 * Utility class for collecting dispatch statistics.
 *
 * @license GPL-2.0-or-later
 */
class DispatchStats {

    private RepoDomainDb $db;

    public function __construct( RepoDomainDb $repoDomainDb ) {
        $this->db = $repoDomainDb;
    }

    public function getDispatchStats(): array {
        $db = $this->db->connections()->getReadConnection();
        $limit = 5000;

        $limitedNumberOfChanges = $this->loadLimitedNumberOfChanges( $db, $limit );
        if ( $limitedNumberOfChanges === 0 ) {
            return [ 'numberOfChanges' => 0 ];
        }
        $changeTimesStats = $this->loadChangeTimes( $db );
        if ( $limitedNumberOfChanges > $limit ) {
            $estimate = $this->getWbChangesRowEstimate( $db );
            if ( $estimate < $limit ) {
                // estimate is outdated
                return $this->buildMinimumNumberOfChangesStats( $limitedNumberOfChanges, $changeTimesStats );
            }
            return $this->buildEstimateStats( $estimate, $changeTimesStats );
        }

        $numberOfEntities = $this->loadNumberOfEntities( $db );

        return $this->buildExactNumberOfChangesStats( $limitedNumberOfChanges, $numberOfEntities, $changeTimesStats );
    }

    private function loadLimitedNumberOfChanges( IReadableDatabase $db, $limit ): int {
        return $db->newSelectQueryBuilder()
            ->select( '*' )
            ->from( 'wb_changes' )
            ->limit( $limit + 1 )
            ->caller( __METHOD__ )
            ->fetchRowCount();
    }

    private function getWbChangesRowEstimate( IReadableDatabase $db ): int {
        return $db->newSelectQueryBuilder()
            ->select( '*' )
            ->from( 'wb_changes' )
            ->caller( __METHOD__ )
            ->estimateRowCount();
    }

    private function loadNumberOfEntities( IReadableDatabase $db ): int {
        return (int)$db->newSelectQueryBuilder()
            ->select( 'COUNT( DISTINCT change_object_id )' )
            ->from( 'wb_changes' )
            ->caller( __METHOD__ )
            ->fetchField();
    }

    private function loadChangeTimes( IReadableDatabase $db ): array {
        $statsRow = $db->newSelectQueryBuilder()
            ->select( [
                'stalestTime' => 'MIN( change_time )',
                'freshestTime' => 'MAX( change_time )',
            ] )
            ->from( 'wb_changes' )
            ->caller( __METHOD__ )
            ->fetchRow();

        return get_object_vars( $statsRow );
    }

    private function buildMinimumNumberOfChangesStats( int $limitedNumberOfChanges, array $changeTimesStats ): array {
        return [
                'minimumNumberOfChanges' => $limitedNumberOfChanges,
            ] + $changeTimesStats;
    }

    private function buildEstimateStats( int $estimate, array $changeTimesStats ): array {
        return [
                'estimatedNumberOfChanges' => $estimate,
            ] + $changeTimesStats;
    }

    private function buildExactNumberOfChangesStats( int $numberOfChanges, int $numberOfEntities, array $changeTimesStats ): array {
        return [
                'numberOfChanges' => $numberOfChanges,
                'numberOfEntities' => $numberOfEntities,
            ] + $changeTimesStats;
    }

}