Creating a C# like Asynchronous Socket

[DrCataclysm]

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);
         }
     }
}