Module rate_limit 

Token-bucket rate limiter as a ServerInterceptor.

Provides RateLimitInterceptor, a ready-made interceptor that limits request throughput per caller. The caller key is derived from CallContext::caller_identity or the x-forwarded-for / peer IP header.

Example

use std::sync::Arc;
use a2a_protocol_server::rate_limit::{RateLimitInterceptor, RateLimitConfig};

let limiter = Arc::new(RateLimitInterceptor::new(RateLimitConfig {
    requests_per_window: 100,
    window_secs: 60,
}));

Then add it to the handler builder:

let handler = RequestHandlerBuilder::new(executor)
    .with_interceptor(limiter)
    .build()?;

Design

Uses a fixed-window counter per caller key. Windows are aligned to wall clock seconds. When a request exceeds the per-window limit, the before hook returns an error with code -32029 (“rate limit exceeded”).

For production deployments requiring sliding windows, distributed counters, or more sophisticated algorithms, implement a custom ServerInterceptor or use a reverse proxy (nginx, Envoy).

Structs

RateLimitConfig

Configuration for RateLimitInterceptor.

RateLimitInterceptor

A fixed-window rate limiting ServerInterceptor.