private function getCachePath($cacheKey)
    {
        $folder = $this->cacheDir . substr($cacheKey, 0, 2) . DIRECTORY_SEPARATOR . substr($cacheKey, 2,
                2) . DIRECTORY_SEPARATOR . substr($cacheKey, 4, 2) . DIRECTORY_SEPARATOR;
        if (!is_dir($folder)) {
            mkdir($folder, 0755, true);
        }

        return $folder . $cacheKey;
    }