Asynchronously wait for Task to complete with timeout

Question

I want to wait for a Task to complete with some special rules: If it hasn\'t completed after X milliseconds, I want to display a message to the user. And

Answer 1

I'm recombinging the ideas of some other answers here and this answer on another thread into a Try-style extension method. This has a benefit if you want an extension method, yet avoiding an exception upon timeout.

public static async Task TryWithTimeoutAfter(this Task task,
    TimeSpan timeout, Action successor)
{

    using var timeoutCancellationTokenSource = new CancellationTokenSource();
    var completedTask = await Task.WhenAny(task, Task.Delay(timeout, timeoutCancellationTokenSource.Token))
                                  .ConfigureAwait(continueOnCapturedContext: false);

    if (completedTask == task)
    {
        timeoutCancellationTokenSource.Cancel();

        // propagate exception rather than AggregateException, if calling task.Result.
        var result = await task.ConfigureAwait(continueOnCapturedContext: false);
        successor(result);
        return true;
    }
    else return false;        
}     

async Task Example(Task task)
{
    string result = null;
    if (await task.TryWithTimeoutAfter(TimeSpan.FromSeconds(1), r => result = r))
    {
        Console.WriteLine(result);
    }
}