while using server-side stream message, client always got: code = Unknown desc = Unexpected error in RPC handling

[yonnie...@gmail.com]

Hi, all

   I'm using grpc + protobuf with server side written in c++ and client side written in golang.

One grpc method i used server-side stream message, when client connect to the server side, client always got : code = Unknown desc = Unexpected error in RPC handling

The grpc connection inited successfully and other methods worked fine.

Anybody knows why this error means?

The method is the following: client will wait server-side write message to it

rpc RegisterNotification(google.protobuf.Empty) returns (stream Notification);

[Easwar Swaminathan]

Could you please provide relevant snippets of server and client code, for us to be able to debug this issue better.

[yonnie...@gmail.com]

I'm sorry that reply you late.

The service side code was written in c++:

Status RobotControllerServiceImpl::RegisterNotification(::grpc::ServerContext* context, const Empty* request, ServerWriter<Notification>* writer) {

   Notification notification;

   DLOG(INFO) << "Register notification begin , context cancelled:" << context->IsCancelled();

   while ((*run) == 1 && !context->IsCancelled()) {

 

           notification.Clear();

           Notice* notice = notification.add_items();

           

// doing write something      

     

           writer->Write(notification);

           // DLOG(INFO) << "Send notification," << " type: " << n.type << ", id: " << n.id << ", value: " << n.value << ", ret: " << ret;

       }

   }

    context->TryCancel();

   DLOG(INFO) << "Register notification end, maybe exit!";

   return Status::OK;

}

The client side code was written in golang:

func (rc *RobotController) streamRegisterNotification() error {
   ctx := context.Background()
   stream, err := (*rc.client).RegisterNotification(ctx, &empty.Empty{})
   if err != nil {
      log().Errorf("get notification stream err: %v", err)
      return err
   }

   defer func() {
      stream.CloseSend()
   }()
   for {
      
      data, err := stream.Recv()
      if err == io.EOF {
         log().Error("notification run io.EOF")
         break
      }
      if err != nil {
         log().Errorf("notification recv err:%v, data: %v", err.Error(), data)
         return err
      }
      // process the notification
   }

   return nil
}

The protobuf definition defines here

message Notice {
  enum NoticeType {
    NOTICE_STATE = 0; 
    NOTICE_ERROR = 1;  
    NOTICE_BUTTON = 2; 
  }


  enum NoticeId {
    NOTICE_ID_1 = 0;   
    NOTICE_ID_2 = 1;  
  }

  NoticeType type = 1; 
  NoticeId id = 2;
  int32 value = 3; 
  int32 code = 4;
  repeated double lol = 5;
}

message Notification {
 repeated Notice items = 1;
}

service RobotController {