MessageGroupCache.php

<?php
declare( strict_types = 1 );
 
namespace MediaWiki\Extension\Translate\MessageGroupProcessing;
 
use Cdb\Reader;
use Cdb\Writer;
use FileBasedMessageGroup;
use RuntimeException;
 
class MessageGroupCache {
    public const NO_SOURCE = 1;
    public const NO_CACHE = 2;
    public const CHANGED = 3;
    private const VERSION = '4';
    private FileBasedMessageGroup $group;
    private ?Reader $cache = null;
    private string $languageCode;
    private string $cacheFilePath;
 
    public function __construct(
        FileBasedMessageGroup $group,
        string $languageCode,
        string $cacheFilePath
    ) {
        $this->group = $group;
        $this->languageCode = $languageCode;
        $this->cacheFilePath = $cacheFilePath;
    }
 
    public function exists(): bool {
        return file_exists( $this->getCacheFilePath() );
    }
 
    public function getKeys(): array {
        $reader = $this->open();
        $keys = [];
 
        $key = $reader->firstkey();
        while ( $key !== false ) {
            if ( ( $key[0] ?? '' ) !== '#' ) {
                $keys[] = $key;
            }
 
            $key = $reader->nextkey();
        }
 
        return $keys;
    }
 
    public function getTimestamp() {
        return $this->open()->get( '#created' );
    }
 
    public function getUpdateTimestamp() {
        return $this->open()->get( '#updated' );
    }
 
    public function get( string $key ) {
        return $this->open()->get( $key );
    }
 
    public function getAuthors(): array {
        $cache = $this->open();
        return $cache->exists( '#authors' ) ?
            $this->unserialize( $cache->get( '#authors' ) ) : [];
    }
 
    public function getExtra(): array {
        $cache = $this->open();
        return $cache->exists( '#extra' ) ? $this->unserialize( $cache->get( '#extra' ) ) : [];
    }
 
    public function create( $created = false ): void {
        $this->close(); // Close the reader instance just to be sure
 
        $parseOutput = $this->group->parseExternal( $this->languageCode );
        $messages = $parseOutput['MESSAGES'];
        if ( $messages === [] ) {
            if ( $this->exists() ) {
                // Delete stale cache files
                unlink( $this->getCacheFilePath() );
            }
 
            return; // Don't create empty caches
        }
        $hash = md5( file_get_contents( $this->group->getSourceFilePath( $this->languageCode ) ) );
 
        wfMkdirParents( dirname( $this->getCacheFilePath() ) );
        $cache = Writer::open( $this->getCacheFilePath() );
 
        foreach ( $messages as $key => $value ) {
            $cache->set( $key, $value );
        }
        $cache->set( '#authors', $this->serialize( $parseOutput['AUTHORS'] ) );
        $cache->set( '#extra', $this->serialize( $parseOutput['EXTRA'] ) );
        $cache->set( '#created', $created ?: wfTimestamp() );
        $cache->set( '#updated', wfTimestamp() );
        $cache->set( '#filehash', $hash );
        $cache->set( '#msghash', md5( serialize( $parseOutput ) ) );
        $cache->set( '#version', self::VERSION );
        $cache->close();
    }
 
    public function isValid( &$reason ): bool {
        $group = $this->group;
        $pattern = $group->getSourceFilePath( '*' );
        $filename = $group->getSourceFilePath( $this->languageCode );
 
        $parseOutput = null;
 
        // If the file pattern is not dependent on the language, we will assume
        // that all translations are stored in one file. This means we need to
        // actually parse the file to know if a language is present.
        if ( !str_contains( $pattern, '*' ) ) {
            $parseOutput = $group->parseExternal( $this->languageCode );
            $source = $parseOutput['MESSAGES'] !== [];
        } else {
            static $globCache = [];
            if ( !isset( $globCache[$pattern] ) ) {
                $globCache[$pattern] = array_flip( glob( $pattern, GLOB_NOESCAPE ) );
                // Definition file might not match the above pattern
                $globCache[$pattern][$group->getSourceFilePath( 'en' )] = true;
            }
            $source = isset( $globCache[$pattern][$filename] );
        }
 
        $cache = $this->exists();
 
        // Timestamp and existence checks
        if ( !$cache && !$source ) {
            return true;
        } elseif ( !$cache && $source ) {
            $reason = self::NO_CACHE;
 
            return false;
        } elseif ( $cache && !$source ) {
            $reason = self::NO_SOURCE;
 
            return false;
        }
 
        if ( $this->get( '#version' ) !== self::VERSION ) {
            $reason = self::CHANGED;
            return false;
        }
 
        if ( filemtime( $filename ) <= $this->get( '#updated' ) ) {
            return true;
        }
 
        // From now on cache and source file exists, but source file mtime is newer
        $created = $this->get( '#created' );
 
        // File hash check
        $newhash = md5( file_get_contents( $filename ) );
        if ( $this->get( '#filehash' ) === $newhash ) {
            // Update cache so that we don't need to compare hashes next time
            $this->create( $created );
 
            return true;
        }
 
        // Parse output hash check
        $parseOutput ??= $group->parseExternal( $this->languageCode );
        if ( $this->get( '#msghash' ) === md5( serialize( $parseOutput ) ) ) {
            // Update cache so that we don't need to do slow checks next time
            $this->create( $created );
 
            return true;
        }
 
        $reason = self::CHANGED;
 
        return false;
    }
 
    public function invalidate(): void {
        $this->close();
        unlink( $this->getCacheFilePath() );
    }
 
    private function serialize( array $data ): string {
        // Using simple prefix for easy future extension
        return 'J' . json_encode( $data );
    }
 
    private function unserialize( string $serialized ): array {
        $type = $serialized[0];
 
        if ( $type !== 'J' ) {
            throw new RuntimeException( 'Unknown serialization format' );
        }
 
        return json_decode( substr( $serialized, 1 ), true );
    }
 
    protected function open(): Reader {
        $this->cache ??= Reader::open( $this->getCacheFilePath() );
 
        return $this->cache;
    }
 
    protected function close(): void {
        if ( $this->cache !== null ) {
            $this->cache->close();
            $this->cache = null;
        }
    }
 
    protected function getCacheFilePath(): string {
        return $this->cacheFilePath;
    }
}