gRPC C# server side, waiting until client closes connection?

Question

I am creating a gRPC service that allows clients to public interface

My protofile:

syntax = "proto3";
package Tests;
import "google/protobuf/any.proto";
message ListenTest1EventStream {
    uint64 objectId = 1;
}
message EventTestEvent {
}
service Test1ObjectService {
    rpc ListenEvents (ListenTest1EventStream) returns (stream google.protobuf.Any);
}

My C# server:

ISomeService
{
    event EventHandler<EventArgs> TestEvent;
}

public class Server : Test1ObjectService.Test1ObjectServiceBase
{
    private readonly ISomeService _someService;

    public Server(ISomeService someService)
    {
        _someService = someService;
    }

    public override async Task ListenEvents(ListenTest1EventStream request, IServerStreamWriter<Any> responseStream, ServerCallContext context)
    {
        // Begin monitoring event handlers, wait indefinitely 
        var handler = new EventHandler<EventArgs>((sender, args) =>
        {
            responseStream.WriteAsync(Any.Pack(new EventTestEvent()));
        });
        _someService.TestEvent += handler;

        // TODO: Wait until response stream is forcibly closed. How?
        await responseStream.WaitForSatusChangedOrSomething();

        _someService.TestEvent -= handler;
    }
}

How do I know when the client disconnects?

Answer 1

When the client disconnects, context.CancellationToken will be canceled. Pass it to your awaitable method so that it can terminate.

I have a sample here. https://github.com/cactuaroid/GrpcWpfSample/blob/cd0d87ed6ccccac787960e9742aee036a3dc11eb/GrpcWpfSample.Server/Grpc/ChatServiceGrpcServer.cs#L51

ForEachAwaitAsync() will throw TaskCanceledException when the given CancellationToken is canceled, then it catches the exception and log the disconnection.