Sdk: Can't catch Socket exceptions

[ghost]

//SocketException: OS Error: Broken pipe, errno = 32, address = 0.0.0.0, port = 30100
//SocketException: OS Error: Connection reset by peer, errno = 104, address = 0.0.0.0, port = 30129

Cant catch these exceptions either try/catch blocks or handleError callbacks.

  try {
    ServerSocket.bind('0.0.0.0', port).then((serverSocket) {
      serverSocket.handleError((error){
        print('ERROR: ${error}');
      });

      serverSocket.listen((socket) {
        socket.handleError((error){
          print('ERROR: ${error}');
        });
        socket.transform(UTF8.decoder).listen((buffer) {
          doSomething(socket, buffer)
        });
      });
    });
  } catch(exception, stackTrace) {
    print(exception);
  }

[zoechi]

This might help you http://stackoverflow.com/questions/32810051/cannot-catch-socketexception/32810079#32810079

[ghost]

That might do it, i will check back with the results ASAP.

[ghost]

Yeah it keeps happening, i am probably doing something wrong

  try {
    await ServerSocket.bind('0.0.0.0', port).then((serverSocket) async {
      serverSocket.handleError((error){
        print('ERROR: ${error}');
      });

      await serverSocket.listen((socket) async {
        socket.handleError((error){
          print('ERROR: ${error}');
        });
        await socket.transform(UTF8.decoder).listen((buffer) {
          parse(socket, buffer, db_name);
        });
      }, onError: (error) {
        print('error: $error');
      }, onDone: () {
        print('socket closed.');
      }, cancelOnError: true);
    });

  } catch(exception, stackTrace) {
    print(exception);
  }

If i managed to solve this i will go ahead and write a tutorial or something, i can't find anything about good practices for tcp servers in Dart.

[sgjesse]

Using the Socket interface in dart:io can be a bit tricky. One thing which is not documented particularly, is that the socket have a done getter which returns a Future that one must listen on, as errors can be reported on that as well as on the onError callback on listen.

socket.done.catchError((error) => print('error: $error'));

Also remember when using await you are already waiting for the Future and don't need to use .then as well. You should be able to replace:

await ServerSocket.bind('0.0.0.0', port).then((serverSocket) async {
  ...
}

with:

ServerSocket serverSocket = await ServerSocket.bind('0.0.0.0', port) {
  ...
}

When async errors happen information on the original place where the operation was scheduled is gone. You could take a look at http://news.dartlang.org/2016/01/unboxing-packages-stacktrace.html, to help get more information on async errors.

[ghost]

Thanks for the reply i fixed my future related code everywhere but i am getting this:
[warning] The getter 'done' is not defined for the class 'ServerSocket' (/srv/aries/lib/t.dart, line 403, col 18)

Edit: Just realized the done callback is for the created sockets. Will try it out.

[ghost]

Thanks again, managed to solve it. My main problem was that i did not understood futures as well as i thought i did.

[NTMS2017]

@ghost, can you share solved code that you managed to use correct future? Thanks