class DFSClientCache {

  DFSClient getDfsClient(String userName) {
    DFSClient client = null;
    try {
      client = clientCache.get(userName);
    } catch (ExecutionException e) {
      LOG.error(
          "Failed to create DFSClient for user:" + userName + " Cause:" + e);
    }
    return client;
  }

    DFSClientCache(Configuration config);
    DFSClientCache(Configuration config, int clientCache);

}