private function saveCache($section) {
    $content = serialize($this->cache[$section]);
    $file = $this->getCacheFile($section);
    $this->fileUtil->mkdirRec(dirname($file));
    $fh = fopen($file, "w");
    if ($fh !== false) {
      fwrite($fh, $content);
      fclose($fh);
    }
    else {
      throw new ConfigurationException("The cache path is not writable: ".$file);
    }
  }