logger.trace("Sending RPC to {}", serverAddr);
final long requestId = Math.abs(UUID.randomUUID().getLeastSignificantBits());
handler.addRpcRequest(requestId, callback);
channel.writeAndFlush(new RpcRequest(requestId, message)).addListener(
new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture future) throws Exception {
if (future.isSuccess()) {
long timeTaken = System.currentTimeMillis() - startTime;