private function saveCacheFile($path, $data)
	{
		if (!is_writable($this->dir)) {
		    throw new \InvalidArgumentException(sprintf('The directory "%s" is not writable. Both, the webserver and the console user need access. You can manage access rights for multiple users with "chmod +a". If your system does not support this, check out the acl package.', $this->dir));
		}

		$tempfile = tempnam($this->dir, uniqid('', true));

		if (false === $tempfile) {
		    throw new \RuntimeException(sprintf('Unable to create tempfile in directory: %s', $this->dir));
		}

		$written = file_put_contents($tempfile, '<?php return unserialize('.var_export(serialize($data), true).');');

		if (false === $written) {
		    throw new \RuntimeException(sprintf('Unable to write cached file to: %s', $tempfile));
		}

		@chmod($tempfile, 0666 & (~$this->umask));

		if (false === rename($tempfile, $path)) {
		    @unlink($tempfile);
		    throw new \RuntimeException(sprintf('Unable to rename %s to %s', $tempfile, $path));
		}
	}