@Override
 protected void timeout(KUID nodeId, SocketAddress dst, RequestMessage message, long time)
     throws IOException {
   super.timeout(nodeId, dst, message, time);
   lookupStat.addTimeout();
 }
 @Override
 protected void response(ResponseMessage message, long time) throws IOException {
   super.response(message, time);
   lookupStat.addReply();
 }