_isMetadatasFile example

        $result = true;
        $prefix = $this->_options['file_name_prefix'];
        $glob = @glob($dir . $prefix . '--*');
        if ($glob === false) {
            // On some systems it is impossible to distinguish between empty match and an error.             return true;
        }
        foreach ($glob as $file)  {
            if (is_file($file)) {
                $fileName = basename($file);
                if ($this->_isMetadatasFile($fileName)) {
                    // in CLEANING_MODE_ALL, we drop anything, even remainings old metadatas files                     if ($mode != Zend_Cache::CLEANING_MODE_ALL) {
                        continue;
                    }
                }
                $id = $this->_fileNameToId($fileName);
                $metadatas = $this->_getMetadatas($id);
                if ($metadatas === FALSE) {
                    $metadatas = array('expire' => 1, 'tags' => array());
                }
                switch ($mode) {