StreamingPingPong.java

// Basically I want to initiate the stream from the client and then whenever I get a message from the server
// I want to respond immediately over the same stream.

private Future<Histogram> doStreamingCalls(Channel channel, final SimpleRequest request,
                                             final long endTime) {
    final TestServiceStub stub = TestServiceGrpc.newStub(channel);
    final Histogram histogram = new Histogram(HISTOGRAM_MAX_VALUE, HISTOGRAM_PRECISION);
    final HistogramFuture future = new HistogramFuture(histogram);

    final StreamObserver<SimpleRequest> requestObserver;
    requestObserver = stub.streamingCall(new StreamObserver<SimpleResponse>() {
          long lastCall = System.nanoTime();

          @Override
          public void onValue(SimpleResponse value) {
            long now = System.nanoTime();
            // Record the latencies in microseconds
            histogram.recordValue((now - lastCall) / 1000);
            lastCall = now;

            if (endTime > now) {
              requestObserver.onValue(request);
            } else {
              requestObserver.onCompleted();
            }
          }

          @Override
          public void onError(Throwable t) {

          }

          @Override
          public void onCompleted() {
            future.done();
          }
        });

    requestObserver.onValue(request);
  }