Struct rate_limit::Limiter

pub struct Limiter { /* fields omitted */ }

Limiter is a simple token bucket-style rate limiter

When its tokens are exhausted, it will block the current thread until its refilled

The limiter is cheaply-clonable

// limits to 3 `.take()` per 1 second
let limiter = Limiter::full(3, Duration::from_secs(1));
for _ in 0..10 {
    // every 3 calls within 1 second will cause the next .take() to block
    // so this will take ~3 seconds to run (10 / 3 = ~3)
    limiter.take();
}

// initially empty, it will block for 1 second then block for every 3 calls per 1 second
let limiter = Limiter::empty(3, Duration::from_secs(1));
for _ in 0..10 {
    limiter.take();
}

The _unsync() variants create a cheaper, single-threaded form

Methods

impl Limiter

pub fn new(cap: u64, initial: u64, period: Duration) -> Self

Create a new, thread-safe limiter

cap is the number of total tokens available

initial is how many are initially available

period is how long it'll take to refill all of the tokens

pub fn new_unsync(cap: u64, initial: u64, period: Duration) -> Self

Create a new, single-threaded limiter

cap is the number of total tokens available

initial is how many are initially available

period is how long it'll take to refill all of the tokens

pub fn full(cap: u64, period: Duration) -> Self

Create a thread-safe limiter thats pre-filled

cap is the number of total tokens available

period is how long it'll take to refill all of the tokens

pub fn empty(cap: u64, period: Duration) -> Self

Create an empty thread-safe limiter

cap is the number of total tokens available

period is how long it'll take to refill all of the tokens

pub fn full_unsync(cap: u64, period: Duration) -> Self

Create a single-threaded limiter thats pre-filled

cap is the number of total tokens available

period is how long it'll take to refill all of the tokens

pub fn empty_unsync(cap: u64, period: Duration) -> Self

Create an empty single-threaded limiter

cap is the number of total tokens available

period is how long it'll take to refill all of the tokens

pub fn consume(&self, tokens: u64) -> Result<u64, Duration>

Tries to consume tokens

If it will consume more than available then an Error is returned. Otherwise it returns how many tokens are left

This error is the Duration of the next available time

pub fn throttle(&self, tokens: u64) -> u64

Consumes tokens blocking if its trying to consume more than available

Returns how many tokens are available

pub fn take(&self) -> u64

Take a token, blocking if unavailable

Returns how many tokens are available

Trait Implementations

impl Clone for Limiter

fn clone(&self) -> Limiter

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.