Weighted Rate Limiter

Some API's have usage limits where different endpoints or actions have different costs - this is often implemented as the caller having a certain amount of weight that they are allowed to use per a given time period. This crate allows you to implement a rate limiter that enforces these limits - more specifically by queueing up futures that will be executed when the weight becomes available.

See docs.rs for usage.

To Note

This crate is very new, and has not been thoroughly tested.

lib.rs:

Weighted Rate Limiter

Some API's have usage limits where different endpoints or actions have different costs - this is often implemented as the caller having a certain amount of weight that they are allowed to use per a given time period. This crate allows you to implement a rate limiter that enforces these limits - more specifically by queueing up futures that will be executed when the weight becomes available.

Example

Here, we create a rate limiter that allows a total weight of 2 every 1 second. We then create two futures: one that returns 1 and one that returns "Hello" (note the different return types). We then rate limit these futures with weights 1 and 2 respectively. The first future will be executed immediately, while the second will be executed after 1 second, when the weight allowance has refreshed.

    let rate_limiter = RateLimiter::new(2, Duration::from_secs(1));
    let start = Instant::now();
    let fut1 = async { println!("Returning 1 at {:?}", Instant::now() - start); 1 };
    let fut2 = async { println!("Returning 'Hello' at {:?}", Instant::now() - start); "Hello!" };
    let rate_limited_fut1 = rate_limiter.rate_limit_future(fut1, 1);
    let rate_limited_fut2 = rate_limiter.rate_limit_future(fut2, 2);
    println!("{:?}", join!(rate_limited_fut1, rate_limited_fut2));

    // Returning 1 at 5.2µs
    // Returning 'Hello' at 1.0004935s
    // (1, "Hello!")

Limitations

This crate is very new, and has not been tested in production.

Futures are executed in the order they are rate limited, not in the order they are created.