bidir stream example for gatling-grpc - below 0.8 version

gatlingGrpcBidirStreamGist.scala

def connect(productIdFieldName: String, token: String, checkLicenseUpdate:Boolean = false): GrpcCallActionBuilder[ProductConnectionReq, ProductStrmgMessage] = {
    val dT = Calendar.getInstance()

    grpc("connectReq")
      .service(ProductServiceGrpc.stub)
      .rpc(service => { req: ProductConnectionReq =>

        val p = Promise[ProductStrmgMessage]()
        val requestObserver = service.connect(
          new ClientResponseObserver[ProductConnectionReq, ProductStrmgMessage] {

          var requestStream: ClientCallStreamObserver[ProductConnectionReq] = _

          override def beforeStart(requestStream: ClientCallStreamObserver[ProductConnectionReq]): Unit = {
            this.requestStream = requestStream
          }

          override def onNext(value: ProductStrmgMessage): Unit = {
            println(s"[${dT.getTime()}]==================================================>Next " + value.data.isLicenseUpdate)
            if (!checkLicenseUpdate) {
              p.trySuccess(value)
            }

            if(checkLicenseUpdate && value.data.isLicenseUpdate){
              p.trySuccess(value)
            }
          }

          override def onError(throwable: Throwable): Unit = {
            if (p != null) {
              p.tryFailure(throwable)
            }
          }

          override def onCompleted(): Unit = {
            println(s"[${dT.getTime()}]==================>Completed!")
          }
        })
        requestObserver.onNext(req)
        p.future
      })(ProductConnectionReq.defaultInstance.withLastpublicip("192.168.1.9"))
      .header(Metadata.Key.of("authorization", Metadata.ASCII_STRING_MARSHALLER))(token)
      .header(Metadata.Key.of("productId", Metadata.ASCII_STRING_MARSHALLER))($(productIdFieldName))

  // called with this
    val hwIdFeeder = (1 to nbProducts).toStream.map(i => Map("hwid" -> ("perf" + i.toString))).toIterator

    val productsScenario = scenario("Products connect and disconnect after 1 minute")
      .feed(hwIdFeeder)
      .exec(ProductsServiceGrpc.connect("hwid", token))
  
  // the grpc proto rpc method looks like this
  //   rpc connect (stream ProductConnectionReq) returns (stream ProductStrmgMessage);

verified server logs as well, seeing issue in gatling/client end only when "no data" received from serverStream

Below is the normal flow when everything goes okay

15:35:42.711 [DEBUG] i.g.n.NettyClientHandler - [id: 0x70d7beda,  OUTBOUND HEADERS: streamId=13 
headers=GrpcHttp2OutboundHeaders[:authority: example:443, :path: /ServerStreamer/serverStream, :method: POST, 
:scheme: https, content-type: application/grpc, te: trailers, user-agent: grpc-java-netty/1.29.0, grpc-accept-encoding: gzip] 
streamDependency=0 weight=16 exclusive=false padding=0 endStream=false


15:35:42.713 [DEBUG] i.g.n.NettyClientHandler - [id: 0x70d7beda,  OUTBOUND DATA: streamId=13 padding=0 endStream=true length=7 bytes=0000000002081e

15:35:43.481 [DEBUG] i.g.n.NettyClientHandler - [id: 0x70d7beda,  INBOUND WINDOW_UPDATE: streamId=0 windowSizeIncrement=7

15:35:43.714 [DEBUG] i.g.n.NettyClientHandler - [id: 0x70d7beda,  INBOUND HEADERS: streamId=13 headers=GrpcHttp2ResponseHeaders
[:status: 200, content-type: application/grpc, grpc-accept-encoding: gzip, grpc-encoding: identity, date: Wed, 23 Sep 2020 10:05:43 GMT] 
padding=0 endStream=false

15:35:43.715 [DEBUG] i.g.n.NettyClientHandler - [id: 0x70d7beda,  INBOUND DATA: streamId=13 padding=0 endStream=false length=21 bytes=0000000010081e120c08f6bbacfb051080c999ac03


15:35:44.702 [DEBUG] i.g.n.NettyClientHandler - [id: 0x70d7beda, ] INBOUND DATA: streamId=13 padding=0 endStream=false length=21 bytes=0000000010081e120c08f7bbacfb0510c0bcfeec01

15:35:44.827 [DEBUG] i.g.n.NettyClientHandler - [id: 0x70d7beda, ] INBOUND DATA: streamId=13 padding=0 endStream=false length=20 bytes=000000000f081e120b08f8bbacfb0510808cfb29

15:35:44.828 [DEBUG] i.g.n.NettyClientHandler - [id: 0x70d7beda, ] INBOUND HEADERS: streamId=13 headers=GrpcHttp2ResponseHeaders[grpc-status: 0] padding=0 endStream=true

[1600855542707]==================>onCompleted!