Simple rate limiter for async tasks.

Provides a structure to control rate of something. Something can be API calls to external resource or anything you want to be limited to requests per interval.

Examples:

// allows 1000 requests every 47 seconds to rick and morty api!
let limiter = RateLimiter::new(1000, Duration::from_secs(47));
for _ in 0..10000 {
    let limiter = limiter.clone();
    tokio::spawn(async move {
        limiter.wait().await;
        let body = reqwest::get("https://rickandmortyapi.com/api/episode/16")
            .await
            .unwrap()
            .text()
            .await
            .unwrap();
    });
}