Generic Cell Rate (GCR) algorithm

A fast, simple, and small Generic Cell Rate (GCR) algorithm implementation with zero dependencies that allows for dynamic rate adjustment.

Usage

use gcr::Gcr;

let mut rate = Gcr::new(10, Duration::from_secs(1), Some(30)).unwrap();
    // 10 units allowed every second with a max burst of 30 units at once

rate.request(20).unwrap(); // Leftover capacity is now 10
rate.request(20).unwrap_err(); // Returns `DeniedFor(1 second)`

Rate adjustment

[Gcr::adjust] can be used to change the rate of the limiter while preserving the current capacity.

It accepts the same parameters as [Gcr::new].

rate.adjust(20, Duration::from_secs(1), Some(30)).unwrap();
    // 20 units allowed every second with a max burst of 30 units at once

Capacity

[Gcr::capacity] can be used to get the current capacity of the rate limiter without making a request.

rate.capacity();