Server does not want to stop on us_listen_socket_close

[quirm]

Hi, I'm trying to gracefully stop a websocket server but it seems I need to call close on every connected client.

A simple example in main.cpp:

#include "App.h"
#include <iostream>
#include <csignal> // std::signal

struct us_listen_socket_t *gSocket;

int main()
{
  int port = 9001;
  int nonce = 0;

  std::signal(SIGINT, [](int) {
    std::cout << "Closing down the server, press again to kill." << std::endl;
    std::signal(SIGINT, SIG_DFL);
    us_listen_socket_close(0, gSocket);
    std::cout << "Is it dead?" << std::endl;
  });

  struct PerSocketData {
    int id;
  };

  auto app = uWS::App().ws<PerSocketData>("/ws", {
    .open = [&nonce](auto *ws) {
      ws->subscribe("broadcast");
      auto *data = static_cast<PerSocketData *>(ws->getUserData());
      data->id = ++nonce;
      std::cout << "[open] [" << nonce << "]" << std::endl;
    },
    .message = [](auto *ws, std::string_view message, uWS::OpCode opCode) {
      auto *data = static_cast<PerSocketData *>(ws->getUserData());
      std::cout << "[message] [" << data->id << "] " << message << " " << opCode << std::endl;

      if (message == "stop") {
        std::cout << "closing by a client's request...\n";
        us_listen_socket_close(0, gSocket);
        ws->close();
      } else {
        ws->publish("broadcast", message, opCode);
      }
    }
  }).listen(port, [&port](auto *socket) {
    std::cout << "Listening on port " << port << std::endl;
    gSocket = socket;
	}).run();

  std::cout << "Graceful exit..." << std::endl;

  return 0;
}

A client that can run from a console in about:blank page:

const connect = () => {
  const ws = window.ws = new WebSocket('ws://localhost:9001/ws');
  console.log('connecting...');

  ws.addEventListener('open', () => console.log('[connected]'));
  ws.addEventListener('error', () => console.log('[error]'));
  ws.addEventListener('message', evt => console.log('[message]', evt.data));
  ws.addEventListener('close', evt => console.log('[closed]', evt.code, evt.wasClean));
};

connect();

Steps:

1. start a server
2. connect with a client
3. interrupt in terminal or call from one client ws.send('stop') when two or more clients are connected.

Expected:
The server disconnects all clients and an event loop is stopped.

What is happening:
It just goes through us_listen_socket_close(0, gSocket); but the server is still running and all clients are connected. When I disconnect all connected clients, it will stop. Also, after calling us_listen_socket_close, I can't connect with a new client which makes sense but I can still keep messaging with currently active clients and the server is publishing messages to all participants.

Could you please point me to the right API on how to gracefully stop the server or whether I have to manually keep all connected clients and call close on every one of them? Thank you

[ghost]

us_listen_socket_close shuts the listen socket down. All other established sockets are unaffected. So you need to close them (or gracefully end them) yourself.

It had been brought up that we could add us_socket_context_close as a way to close all sockets in a context, but I haven't added it since it is quite easy to do this on your own.

[ElectroluxV2]

Could you post implementation of us_socket_context_close?

[quirm]

It would be nice-to-have in cases where everything can be handled just through subscription. Thank you for the clarification.

[z16166]

1.How to close all client sockets from CTRL + C handler routine?
2. Can we safely call us_listen_socket_close() from the CTRL + C handler thread to close the listening socket while the listening thread is using it? no race there? I randomly get access violation inside us_listen_socket_close().

[ghost]

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