protected function _clearExpired($time = null){

		if($time === null) $time = time();

		$files = glob("{$this->_cache_path}*.cache");
		$cleared = 0;

		if(is_array($files)){

			foreach($files as $file){

				$path = $this->_cache_path . basename($file);
				$mtime = @filemtime($path);

				// Remove expired files

				if($mtime !== false && $time > $mtime){

					@unlink($path);
					++$cleared;
				}
			}
		}

		return $cleared;
	}