    protected function cleanupRecycledFiles($directory, $timestamp)
    {
        $directory = \TYPO3\CMS\Core\Utility\GeneralUtility::getFileAbsFileName($directory);
        $timestamp = (int)$timestamp;
        // Check if given directory exists
        if (!@is_dir($directory)) {
            throw new \RuntimeException('Given directory "' . $directory . '" does not exist', 1301614535);
        }
        // Find all _recycler_ directories
        $directoryContent = new \RecursiveIteratorIterator(new \RecursiveDirectoryIterator($directory));
        foreach ($directoryContent as $fileName => $file) {
            // Skip directories and files without recycler directory in absolute path