Re: Creating a C# like Asynchronous Socket

[DrCataclysm via Digitalmars-d-learn]

On Sunday, 5 November 2017 at 14:47:37 UTC, DrCataclysm wrote:
I am trying to build something like the asynchronous Sockets 
from C# .NET but I'm stuck at the accepting phase.

....

The client created by _socket.accept() cannot receive any data.

client.receive() immediately returns 0 like a non-blocking 
socket. I think it has something to do with the original socket 
being owned by a different thread.

I am not very familiar with multitasking/multithreading in D so 
any help would be appreciated.

// I removed all multithreading and cleaned up the example. It 
still does not work.
// Sockets don't seem to work as class fields, is there a reason 
for this?
// Has anyone a better idea to accomplish this?

import std.socket;
import std.stdio;

void main(){
    TCPListener test = new TCPListener("127.0.0.1", 9001);
    test.startListening();
    while (true){}
}

public class TCPListener {
    ushort _port;
    string _address;
    bool _active;
    Socket _socket = null;
    Socket _connection = null;

    this(string address, ushort port, string lineEnd = "\n") {
        _port = port;
        _address = address;
        _socket = new TcpSocket();
        _socket.setOption(SocketOptionLevel.SOCKET, 
SocketOption.REUSEADDR, true);
    }

    void startListening(){
        // bind the port in the main thread
        try{
            assert(_socket !is null);
            _socket.bind(new InternetAddress(_port));
            _socket.listen(3);
        }
        catch (Exception e){
            writeln(e.msg);
        }
        //auto _connectionTask = task(&this.Accept);
        //_connectionTask.executeInNewThread();
        Accept();
    }

    private void Accept(){
        bool error = false;
        // start accepting in a different thread
        try{
            _connection = _socket.accept();
            assert(_connection !is null); // this works
            ubyte[] buffer;

            // this does not block, even if the socket is 
explicitly markes
            // as blocking
            auto receive = _connection.receive(buffer);

            // this always fails
            assert(receive != 0);
        }
        catch (SocketAcceptException e){
            writeln("Error while accepting connection: " ~ e.msg);
            error = true;
        }
        finally{
            //emit(error);
        }
    }
}