TaskCompletionSource throws “An attempt was made to transition a task to a final state when it had already completed”

Question

I want to use TaskCompletionSource to wrap MyService which is a simple service:

public static Task ProcessAsync(MyService         


        

Answer 1

An alternative solution to i3arnon's answer would be:

public async static Task ProcessAsync(MyService service, int parameter)
{
    var tcs = new TaskCompletionSource();

    EventHandler callback = 
        (s, e) => tcs.SetResult(e.Result);

    try
    {
        contacts.Completed  += callback;

        contacts.RunAsync(parameter);

        return await tcs.Task;
    }
    finally
    {
        contacts.Completed  -= callback;
    }
}

However, this solution will have a compiler generated state machine. It will use more memory and CPU.