Struct TokenBucket

pub struct TokenBucket<I> { /* private fields */ }

A token bucket used for rate limiting.

TokenBucket implements rate limiting by “filling” a bucket with “tokens” at a constant rate, and allowing tokens to be consumed from the bucket until it is empty. This guarantees that a consumer may only maintain a rate of consumption faster than the rate of refilling for a bounded amount of time before they will catch up and find the bucket empty.

Note that the bucket has a maximum size beyond which no new tokens will be added. This prevents a long quiet period from building up a large backlog of tokens which can then be used in an intense and sustained burst.

This implementation does not require any background threads or timers to operate; it refills the bucket during calls to try_take, so no extra infrastructure is required to use it.

Implementations

impl<I> TokenBucket<I>

pub fn new(tokens_per_second: u64) -> TokenBucket<I>

Constructs a new TokenBucket and initializes it with one second’s worth of tokens.

Panics

new panics if tokens_per_second is greater than 2^56 - 1.

impl<I: Instant> TokenBucket<I>

pub fn try_take<BC: InstantContext<Instant = I>>( &mut self, bindings_ctx: &BC, ) -> bool

Attempt to take a token from the bucket.

try_take attempts to take a token from the bucket. If the bucket is currently empty, then no token is available to be taken, and try_take return false.