Asynchronous socket operations in a Task

Question

I have a Threading.Tasks.Task that handles a number of client socket operations (connecting, receiving and sending).

I understand that where possible it's best to use non blocking methods using Await because otherwise I'll end up with "parked threads waiting for their response". However, while the Socket class has async methods (SendAsync and so on) they aren't the same as the usual Task Parallel Library async methods, they don't return a Task and cannot be awaited.

I realise that I can wrap these socket async methods with a TaskCompletionSource but is there any benefit to doing so or will it ultimately still be parking the thread?

Answer 1

As Servy explained. Using TaskCompletionSource as in of itself doesn't create (or park) any threads as long as you're using the asynchronous pattern correctly.

There are 3 different asynchronous patterns in the .Net framework:

1. Asynchronous Programming Model (APM).
2. Event-based Asynchronous Pattern (EAP).
3. Task-based Asynchronous Pattern (TAP).

What you're trying to achieve is "convert" one pattern, the EAP, to another one, TAP. A simpler solution would be to use .Net's built-in "conversion" from the APM pattern to TAP, Task.Factory.FromAsync (which internally uses TaskCompletionSource):

APM

socket.BeginConnect(host, port, asyncResult =>
{
    socket.EndConnect(asyncResult);
    Console.WriteLine("Socket connected");
}, null);

TAP

await Task.Factory.FromAsync(socket.BeginConnect, socket.EndConnect, host, port, null);
Console.WriteLine("Socket connected");