Crate throttle_kit 

Rate limiting for Rust.

Implements the GCRA (Generic Cell Rate Algorithm) with pluggable backends (in-memory via DashMap, optional Redis) and optional Tower layer integration.

Quick Start

use throttle_kit::{RateLimiter, Quota, InMemoryBackend};

let backend = InMemoryBackend::new();
let limiter = RateLimiter::new(
    Quota::per_second(10),
    backend,
);

let result = limiter.check("user-123").await;
assert!(result.allowed);

Client identity (tower feature)

The Tower layer keys requests by the client’s socket address by default and ignores X-Forwarded-For (secure by default). Behind proxies you control, configure ClientIpConfig; see the client_ip module docs for the resolution algorithm and the README for axum wiring (.into_make_service_with_connect_info).

Re-exports

pub use client_ip::ClientIpConfig;tower

pub use client_ip::ClientIpError;tower

pub use client_ip::ClientIpSource;tower

pub use client_ip::IpNet;tower

pub use client_ip::MissingClientIdentity;tower

pub use client_ip::MissingClientPolicy;tower

pub use client_ip::ResolvedClient;tower

Modules

client_iptower

Client identity resolution for rate limiting behind proxies.

Structs

InMemoryBackendin-memory

In-memory backend backed by a DashMap.

KeyedRateLimiterin-memory

Per-key rate limiter that tracks separate rate limits for each key.

NoopBackendtest-util

No-op backend: allows every request with the quota’s full budget.

Quota

A rate limit quota expressed in the GCRA style.

RateLimitLayertower

Tower layer that applies rate limiting to inner services.

RateLimitResult

Result of a rate limit check.

RateLimitServicetower

Tower service that rate-limits requests by client identity.

RateLimiter

Core rate limiter that delegates to a RateLimitBackend.

RedisBackendredis

Redis-backed rate limiter using the GCRA algorithm via a Lua script.

SlidingWindowBackendsliding-window

In-memory backend using a sliding window algorithm.

SqliteBackendsqlite

SQLite-backed GCRA rate limiter.

Enums

RateLimitError

Errors returned by the rate limiter.

Traits

RateLimitBackend

Backend trait for rate limit state storage.

Functions

gcra_decide

Pure GCRA (Generic Cell Rate Algorithm) conformance decision.

Type Aliases

KeyExtractortower

Custom, non-IP key extractor for callers that key requests by something other than client IP (API key, tenant id, …). Receives the request’s headers and extensions; returns the rate-limit key.