Starts a task, deferring the action until a timeout has elapsed

Defer.cs

private readonly ConcurrentDictionary<Guid, Task> _tasks = new ConcurrentDictionary<Guid, Task>();

public void Defer(Action action, int delay, CancellationToken cancellationToken)
{
    if (action == null) return;
    if (cancellationToken.IsCancellationRequested) return;
    Guid key = Guid.NewGuid();
    _tasks.TryAdd(key, Task.Run(async () =>
    {
        try
        {
            if (delay > 0)
            {
                await Task.Delay(delay, cancellationToken).ConfigureAwait(false);
            }

            if (cancellationToken.IsCancellationRequested)
                return;

            action.Invoke();
        }
        catch (OperationCanceledException)
        {
            return;
        }
        catch (Exception)
        {
            throw;
        }
        finally
        {
            RemoveTask(key);
        }
    }, cancellationToken));
}

private void RemoveTask(Guid key)
{
    Task t;
    _tasks.TryRemove(key, out t);
}