Struct ratelimit_meter::state::direct::DirectRateLimiter

pub struct DirectRateLimiter<A: Algorithm = DefaultAlgorithm> { /* private fields */ }

An in-memory rate limiter that makes direct (un-keyed) rate-limiting decisions. Direct rate limiters can be used to e.g. regulate the transmission of packets on a single connection, or to ensure that an API client stays within a server’s rate limit.

Implementations

impl<A> DirectRateLimiter<A>where
    A: Algorithm,

pub fn new(capacity: NonZeroU32, per_time_unit: Duration) -> Self

Construct a new rate limiter that allows capacity cells per time unit through.

Examples

You can construct a GCRA rate limiter like so:

use ratelimit_meter::{DirectRateLimiter, GCRA};
let _gcra = DirectRateLimiter::<GCRA>::new(nonzero!(100u32), Duration::from_secs(5));

and similarly, for a leaky bucket:

use ratelimit_meter::{DirectRateLimiter, LeakyBucket};
let _lb = DirectRateLimiter::<LeakyBucket>::new(nonzero!(100u32), Duration::from_secs(5));

pub fn per_second(capacity: NonZeroU32) -> Self

Construct a new rate limiter that allows capacity cells per second.

Examples

Constructing a GCRA rate limiter that lets through 100 cells per second:

use ratelimit_meter::{DirectRateLimiter, GCRA};
let _gcra = DirectRateLimiter::<GCRA>::per_second(nonzero!(100u32));

and a leaky bucket:

use ratelimit_meter::{DirectRateLimiter, LeakyBucket};
let _gcra = DirectRateLimiter::<LeakyBucket>::per_second(nonzero!(100u32));

pub fn build_with_capacity(capacity: NonZeroU32) -> Builder<A>

Return a builder that can be used to construct a rate limiter using the parameters passed to the Builder.

pub fn check(&mut self) -> Result<(), <A as Algorithm>::NegativeDecision>

Tests if a single cell can be accommodated at Instant::now(). If it can be, check updates the rate limiter state to account for the conforming cell and returns Ok(()).

If the cell is non-conforming (i.e., it can’t be accomodated at this time stamp), check_at returns Err with information about the earliest time at which a cell could be considered conforming.

pub fn check_n(
    &mut self,
    n: u32
) -> Result<(), NegativeMultiDecision<<A as Algorithm>::NegativeDecision>>

Tests if n cells can be accommodated at the current time stamp. If (and only if) all cells in the batch can be accomodated, the MultiDecider updates the internal state to account for all cells and returns Ok(()).

If the entire batch of cells would not be conforming but the rate limiter has the capacity to accomodate the cells at any point in time, check_n_at returns error NegativeMultiDecision::BatchNonConforming, holding the number of cells the rate limiter’s negative outcome result.

If n exceeds the bucket capacity, check_n_at returns NegativeMultiDecision::InsufficientCapacity, indicating that a batch of this many cells can never succeed.

pub fn check_at(
    &mut self,
    at: Instant
) -> Result<(), <A as Algorithm>::NegativeDecision>

Tests whether a single cell can be accommodated at the given time stamp. See check.

pub fn check_n_at(
    &mut self,
    n: u32,
    at: Instant
) -> Result<(), NegativeMultiDecision<<A as Algorithm>::NegativeDecision>>

Tests if n cells can be accommodated at the given time (Instant::now()), using check_n

Trait Implementations

impl<A: Clone + Algorithm> Clone for DirectRateLimiter<A>where
    A::BucketState: Clone,

fn clone(&self) -> DirectRateLimiter<A>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<A: Debug + Algorithm> Debug for DirectRateLimiter<A>where
    A::BucketState: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.