https://github.com/pacak/htb-rs

https://github.com/pacak/htb-rs

Last synced: 3 months ago
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• Host: GitHub
• URL: https://github.com/pacak/htb-rs
• Owner: pacak
• License: apache-2.0
• Created: 2021-09-01T05:46:32.000Z (over 3 years ago)
• Default Branch: master
• Last Pushed: 2023-12-11T15:30:55.000Z (about 1 year ago)
• Last Synced: 2024-09-17T18:05:35.287Z (4 months ago)
• Language: Rust
• Size: 23.4 KB
• Stars: 5
• Watchers: 2
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: Changelog.md
  • License: LICENSE-APACHE

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README

        
# Hierarchical token Bucket

This crate implements Hierarchical Token Bucket algorithm with fixed structure

Crate does not rely on periodic updates to maintain the token buckets which

means it can be updated right before requesting tokens

```rust

use htb::*;

use std::time::Duration;

#[derive(Clone, Copy, Eq, PartialEq)]

enum Rate {

    Long,

    Short,

}

impl From for usize {

    fn from(rate: Rate) -> Self {

        match rate {

            Rate::Long => 0,

            Rate::Short => 1,

        }

    }

}

// let's implement a rate limiter with two required properties:

// - packet rate should not exceed 250 msg per second

// - packet rate should not exceed 1500 msg per 15 seconds

let mut htb = HTB::new(&[

    BucketCfg {

        this: Rate::Long,

        parent: None,

        rate: (1500, Duration::from_secs(15)),

        capacity: 0,

    },

    BucketCfg {

        this: Rate::Short,

        parent: Some(Rate::Long),

        rate: (250, Duration::from_secs(1)),

        capacity: 250,

    },

])?;

// we are allowed a single 250 token burst

assert!(htb.take_n(Rate::Short, 250));

assert!(!htb.peek(Rate::Short));

htb.advance(Duration::from_secs(1));

// after this point established packet rate obeys "long" indefinitely

for _ in 0..10 {

    assert!(htb.take_n(Rate::Short, 100));

    assert!(!htb.peek(Rate::Short));

    htb.advance(Duration::from_secs(1));

}

// if we stop consuming tokens for some time

htb.advance(Duration::from_secs(10));

assert!(htb.take_n(Rate::Short, 250));

// we get more bursts

assert!(!htb.peek(Rate::Short));

# Ok::<(), Error>(())

```