Is it always bad to use Thread.Sleep()?

Question

I created an extension method for the the class Random which executes an Action (void delegate) at random times:

public static clas         


        

Answer 1

One reason I would use Task.Delay over Thread.Sleep is the fact that you can pass a CancellationToken to it. If the user wants to StopExecutor and the random received a long duration span, you'll end up blocking for a long time. On the other hand, in Task.Delay, you can cancel the operation and it will be notified of that cancellation.

I think there are other problems with the design you choose to make. The Random class isn't really fit to be a task scheduler. I would find it a bit odd to find a ExecuteRandomAsync, since it mostly doesn't execute a random, but execute some arbitrary Action every X minutes.

I would instead, go about this another way. While keeping most of the internals you've already created, but putting them in a different class.

public class ActionInvoker
{
    private readonly Action _actionToInvoke;

    public ActionInvoker(Action actionToInvoke)
    {
        _actionToInvoke = actionToInvoke;
        _cancellationTokenSource = new CancellationTokenSource();
    }

    private readonly CancellationTokenSource _cancellationTokenSource;
    private Task _executer;

    public void Start(int min, int max, int minDuration)
    {
        if (_executer != null)
        {
            return;
        }

        _executer = Task.Factory.StartNew(
                    async () => await ExecuteRandomAsync(min, max, _actionToInvoke),
                    _cancellationTokenSource.Token, TaskCreationOptions.LongRunning, 
                    TaskScheduler.Default)
                    .Unwrap();
    }

    private void Stop()
    {
        try
        {
            _cancellationTokenSource.Cancel();
        }
        catch (OperationCanceledException e)
        {
            // Log the cancellation.
        }
    }

    private async Task ExecuteRandomAsync(int min, int max, Action action)
    {
        Random random = new Random();

        while (!_cancellationTokenSource.IsCancellationRequested)
        {
            await Task.Delay(random.Next(min, max), _cancellationTokenSource.Token);
            action();
        }
    }
}