DatabaseTtmServer.php

<?php
declare( strict_types = 1 );
 
namespace MediaWiki\Extension\Translate\TtmServer;
 
use MediaWiki\MediaWikiServices;
use MessageHandle;
use Title;
use TTMServer;
use WikiMap;
use Wikimedia\Rdbms\DBQueryError;
use Wikimedia\Rdbms\IDatabase;
use Wikimedia\Rdbms\IResultWrapper;
 
class DatabaseTtmServer extends TTMServer implements WritableTtmServer, ReadableTtmServer {
    private array $sids;
 
    private function getDB( int $mode = DB_REPLICA ): IDatabase {
        return MediaWikiServices::getInstance()->getDBLoadBalancer()->getConnection(
            $mode, 'ttmserver', $this->config['database']
        );
    }
 
    public function update( MessageHandle $handle, ?string $targetText ): bool {
        if ( !$handle->isValid() || $handle->getCode() === '' ) {
            return false;
        }
 
        $mKey = $handle->getKey();
        $group = $handle->getGroup();
        $targetLanguage = $handle->getCode();
        $sourceLanguage = $group->getSourceLanguage();
 
        // Skip definitions to not slow down mass imports etc.
        // These will be added when the first translation is made
        if ( $targetLanguage === $sourceLanguage ) {
            return false;
        }
 
        $definition = $group->getMessage( $mKey, $sourceLanguage );
        if ( !is_string( $definition ) || !strlen( trim( $definition ) ) ) {
            return false;
        }
 
        $context = Title::makeTitle( $handle->getTitle()->getNamespace(), $mKey );
        $dbw = $this->getDB( DB_PRIMARY );
        /* Check that the definition exists and fetch the sid. If not, add
         * the definition and retrieve the sid. If the definition changes,
         * we will create a new entry - otherwise we could at some point
         * get suggestions which do not match the original definition any
         * longer. The old translations are still kept until purged by
         * rerunning the bootstrap script. */
        $conditions = [
            'tms_context' => $context->getPrefixedText(),
            'tms_text' => $definition,
        ];
 
        $sid = $dbw->selectField( 'translate_tms', 'tms_sid', $conditions, __METHOD__ );
        if ( $sid === false ) {
            $sid = $this->insertSource( $context, $sourceLanguage, $definition );
        }
 
        // Delete old translations for this message if any. Could also use replace
        $deleteConditions = [
            'tmt_sid' => $sid,
            'tmt_lang' => $targetLanguage,
        ];
        $dbw->delete( 'translate_tmt', $deleteConditions, __METHOD__ );
 
        // Insert the new translation
        if ( $targetText !== null ) {
            $row = $deleteConditions + [
                'tmt_text' => $targetText,
            ];
 
            $dbw->insert( 'translate_tmt', $row, __METHOD__ );
        }
 
        return true;
    }
 
    private function insertSource( Title $context, string $sourceLanguage, string $text ): int {
        $row = [
            'tms_lang' => $sourceLanguage,
            'tms_len' => mb_strlen( $text ),
            'tms_text' => $text,
            'tms_context' => $context->getPrefixedText(),
        ];
 
        $dbw = $this->getDB( DB_PRIMARY );
        $dbw->insert( 'translate_tms', $row, __METHOD__ );
        $sid = $dbw->insertId();
 
        $fulltext = $this->filterForFulltext( $sourceLanguage, $text );
        if ( count( $fulltext ) ) {
            $row = [
                'tmf_sid' => $sid,
                'tmf_text' => implode( ' ', $fulltext ),
            ];
            $dbw->insert( 'translate_tmf', $row, __METHOD__ );
        }
 
        return $sid;
    }
 
    protected function filterForFulltext( string $languageCode, string $input ): array {
        $lang = MediaWikiServices::getInstance()->getLanguageFactory()->getLanguage( $languageCode );
 
        $text = preg_replace( '/[^[:alnum:]]/u', ' ', $input );
        $text = $lang->segmentByWord( $text );
        $text = $lang->lc( $text );
        $segments = preg_split( '/\s+/', $text, -1, PREG_SPLIT_NO_EMPTY );
        if ( count( $segments ) < 4 ) {
            return [];
        }
 
        foreach ( $segments as $i => $segment ) {
            // Yes strlen
            $len = strlen( $segment );
            if ( $len < 4 || $len > 15 ) {
                unset( $segments[$i] );
            }
        }
 
        return array_slice( array_unique( $segments ), 0, 10 );
    }
 
    public function beginBootstrap(): void {
        $dbw = $this->getDB( DB_PRIMARY );
        $dbw->delete( 'translate_tms', '*', __METHOD__ );
        $dbw->delete( 'translate_tmt', '*', __METHOD__ );
        $dbw->delete( 'translate_tmf', '*', __METHOD__ );
        $table = $dbw->tableName( 'translate_tmf' );
        try {
            $dbw->query( "DROP INDEX tmf_text ON $table", __METHOD__ );
        } catch ( DBQueryError $e ) {
            // Perhaps the script was aborted before it got
            // chance to add the index back.
        }
    }
 
    public function beginBatch(): void {
        $this->sids = [];
    }
 
    public function batchInsertDefinitions( array $batch ): void {
        $mwInstance = MediaWikiServices::getInstance();
        $titleFactory = $mwInstance->getTitleFactory();
        foreach ( $batch as $key => $item ) {
            [ $handle, $language, $text ] = $item;
            $context = $titleFactory->makeTitle( $handle->getTitle()->getNamespace(), $handle->getKey() );
            $this->sids[$key] = $this->insertSource( $context, $language, $text );
        }
 
        $mwInstance->getDBLoadBalancerFactory()->waitForReplication( [ 'ifWritesSince' => 10 ] );
    }
 
    public function batchInsertTranslations( array $batch ): void {
        $rows = [];
        foreach ( $batch as $key => $data ) {
            [ , $language, $text ] = $data;
            $rows[] = [
                'tmt_sid' => $this->sids[$key],
                'tmt_lang' => $language,
                'tmt_text' => $text,
            ];
        }
 
        $dbw = $this->getDB( DB_PRIMARY );
        $dbw->insert( 'translate_tmt', $rows, __METHOD__ );
 
        MediaWikiServices::getInstance()
            ->getDBLoadBalancerFactory()
            ->waitForReplication( [ 'ifWritesSince' => 10 ] );
    }
 
    public function endBatch(): void {
    }
 
    public function endBootstrap(): void {
        $dbw = $this->getDB( DB_PRIMARY );
        $table = $dbw->tableName( 'translate_tmf' );
        $dbw->query( "CREATE FULLTEXT INDEX tmf_text ON $table (tmf_text)", __METHOD__ );
    }
 
    /* Reading interface */
 
    public function isLocalSuggestion( array $suggestion ): bool {
        return true;
    }
 
    public function expandLocation( array $suggestion ): string {
        return Title::newFromText( $suggestion['location'] )->getCanonicalURL();
    }
 
    public function query( string $sourceLanguage, string $targetLanguage, string $text ): array {
        // Calculate the bounds of the string length which are able
        // to satisfy the cutoff percentage in edit distance.
        $len = mb_strlen( $text );
        $min = ceil( max( $len * $this->config['cutoff'], 2 ) );
        $max = floor( $len / $this->config['cutoff'] );
 
        // We could use fulltext index to narrow the results further
        $dbr = $this->getDB();
        $tables = [ 'translate_tmt', 'translate_tms' ];
        $fields = [ 'tms_context', 'tms_text', 'tmt_lang', 'tmt_text' ];
 
        $conditions = [
            'tms_lang' => $sourceLanguage,
            'tmt_lang' => $targetLanguage,
            "tms_len BETWEEN $min AND $max",
            'tms_sid = tmt_sid',
        ];
 
        $fulltext = $this->filterForFulltext( $sourceLanguage, $text );
        if ( $fulltext ) {
            $tables[] = 'translate_tmf';
            $list = implode( ' ', $fulltext );
            $conditions[] = 'tmf_sid = tmt_sid';
            $conditions[] = "MATCH(tmf_text) AGAINST( '$list' )";
        }
 
        $res = $dbr->newSelectQueryBuilder()
            ->tables( $tables )
            ->select( $fields )
            ->where( $conditions )
            ->caller( __METHOD__ )
            ->fetchResultSet();
 
        return $this->processQueryResults( $res, $text, $targetLanguage );
    }
 
    private function processQueryResults( IResultWrapper $res, string $text, string $targetLanguage ): array {
        $timeLimit = microtime( true ) + 5;
 
        $lenA = mb_strlen( $text );
        $results = [];
        foreach ( $res as $row ) {
            if ( microtime( true ) > $timeLimit ) {
                // Having no suggestions is better than preventing translation
                // altogether by timing out the request :(
                break;
            }
 
            $a = $text;
            $b = $row->tms_text;
            $lenB = mb_strlen( $b );
            $len = min( $lenA, $lenB );
            if ( $len > 600 ) {
                // two strings of length 1500 ~ 10s
                // two strings of length 2250 ~ 30s
                $dist = $len;
            } else {
                $dist = self::levenshtein( $a, $b, $lenA, $lenB );
            }
            $quality = 1 - ( $dist * 0.9 / $len );
 
            if ( $quality >= $this->config['cutoff'] ) {
                $results[] = [
                    'source' => $row->tms_text,
                    'target' => $row->tmt_text,
                    'context' => $row->tms_context,
                    'location' => $row->tms_context . '/' . $targetLanguage,
                    'quality' => $quality,
                    'wiki' => $row->tms_wiki ?? WikiMap::getCurrentWikiId(),
                ];
            }
        }
 
        return TTMServer::sortSuggestions( $results );
    }
 
    public function setDoReIndex(): void {
    }
}