C# event debounce

Question

I\'m listening to a hardware event message, but I need to debounce it to avoid too many queries.

This is an hardware event that sends the machine status and I have t

Answer 1

I needed something like this but in a web-application, so I can't store the Action in a variable, it will be lost between http requests.

Based on other answers and @Collie idea I created a class that looks at a unique string key for throttling.

public static class Debouncer
{
    static ConcurrentDictionary _tokens = new ConcurrentDictionary();
    public static void Debounce(string uniqueKey, Action action, int seconds)
    {
        var token = _tokens.AddOrUpdate(uniqueKey,
            (key) => //key not found - create new
            {
                return new CancellationTokenSource();
            },
            (key, existingToken) => //key found - cancel task and recreate
            {
                existingToken.Cancel(); //cancel previous
                return new CancellationTokenSource();
            }
        );

        Task.Delay(seconds * 1000, token.Token).ContinueWith(task =>
        {
            if (!task.IsCanceled)
            {
                action();
                _tokens.TryRemove(uniqueKey, out _);
            }
        }, token.Token);
    }
}

Usage:

//throttle for 5 secs if it's already been called with this KEY
Debouncer.Debounce("Some-Unique-ID", () => SendEmails(), 5);

As a side bonus, because it's based on a string key, you can use inline lambda's

Debouncer.Debounce("Some-Unique-ID", () => 
{
    //do some work here
}, 5);