Crate leaky_bucket

tokio-based leaky-bucket rate limiter

This implements a leaky bucket from which you can acquire tokens.

If the tokens are already available, the acquisition will be instant (fast path) and the acquired number of tokens will be added to the bucket.

If the bucket overflows (i.e. goes over max), the task that tried to acquire the tokens will be suspended until the required number of tokens has been added.

Example

If the project is built with the static feature (default), you can use LeakyBucket directly as long as you are inside a tokio runtime, like so:

use leaky_bucket::LeakyBucket;
use std::{error::Error, time::Duration};

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let rate_limiter = LeakyBucket::builder()
        .max(5)
        .tokens(5)
        .build()?;

    println!("Waiting for permit...");
    // should take about 5 seconds to acquire.
    rate_limiter.acquire(10).await?;
    println!("I made it!");
    Ok(())
}

Example using explicit coordinator

use leaky_bucket::LeakyBuckets;
use std::{error::Error, time::Duration};

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let mut buckets = LeakyBuckets::new();
    let coordinator = buckets.coordinate()?;
    // spawn the coordinate thread to refill the rate limiter.
    tokio::spawn(async move { coordinator.await.expect("coordinate thread errored") });

    let rate_limiter = buckets
        .rate_limiter()
        .max(5)
        .tokens(5)
        .build()?;

    println!("Waiting for permit...");
    // should take about 5 seconds to acquire.
    rate_limiter.acquire(10).await?;
    println!("I made it!");
    Ok(())
}

Structs

Acquire	Future associated with acquiring a single token.
Builder	Builder for a leaky bucket.
LeakyBucket	The leaky bucket.
LeakyBuckets	Coordinator for rate limiters. Is used to create new rate limiters as needed.

Enums

Error

Error type for the rate limiter.