protected function getCachedFilepath(array $vars)
	{
		if (!isset($this->cacheDir))
		{
			return null;
		}

		$filepath = $this->cacheDir . '/http.' . $this->getCacheKey($vars);
		if (extension_loaded('zlib'))
		{
			$filepath = 'compress.zlib://' . $filepath . '.gz';
		}

		return $filepath;
	}