RateLimiter

C# client-side rate limiting utility.

Motivation

The initial motivation was to create helper to respect Web Services rate limit in client application. However this helper can also be also in other scenarios where you need to temporally limit the usage of one shared resource.

Features

Easy to use
Fully asynchroneous: lower resource usage than thread sleep
Cancellable via CancellationToken
Thread safe so you can share time contraints object to rate limit diferent threads using the same resource
Composable: ability to compose diferent rate limits in one constraint

Sample usage

Basic

    //Create Time constraint: max five times by second
    var timeconstraint = TimeLimiter.GetFromMaxCountByInterval(5, TimeSpan.FromSeconds(1));

    //Use it
    for(int i=0; i<1000; i++)
    {
        await timeconstraint.Perform(ConsoleIt);
    }       
    
    ....
    private Task ConsoleIt()
    {
        Trace.WriteLine(string.Format("{0:MM/dd/yyy HH:mm:ss.fff}", DateTime.Now));
        return Task.FromResult(0);
    }

Output

05/23/2016 00:14:44.791
05/23/2016 00:14:44.958
05/23/2016 00:14:44.959
05/23/2016 00:14:44.959
05/23/2016 00:14:44.960
05/23/2016 00:14:45.959
05/23/2016 00:14:45.960
05/23/2016 00:14:45.961
05/23/2016 00:14:45.961
05/23/2016 00:14:45.962
05/23/2016 00:14:46.973
...

Composed

    //Create first constraint: max five times by second
    var constraint = new CountByIntervalAwaitableConstraint(5, TimeSpan.FromSeconds(1));
    
    //Create second constraint: one time each 100 ms
    var constraint2 = new CountByIntervalAwaitableConstraint(1, TimeSpan.FromMilliseconds(100));
    
    //Compose the two constraints
    var timeconstraint = TimeLimiter.Compose(constraint, constraint2);

    //Use it
    for(int i=0; i<1000; i++)
    {
        await timeconstraint.Perform(ConsoleIt);
    }