Rate Limit Module

Rate limiting algorithms with memory exhaustion protection.

What's Included

• Fixed Window — simple counter-based limiting
• Sliding Window — smoother rate limiting
• Token Bucket — burst-friendly limiting
• Memory exhaustion protection with LRU eviction
• HTTP middleware

Quick Copy

cp -r registry/ratelimit/src/go/* yourproject/internal/ratelimit/

Usage

Fixed Window

limiter := ratelimit.NewFixedWindow(100, time.Minute)
handler := ratelimit.Middleware(limiter)(handler)

Sliding Window

limiter := ratelimit.NewSlidingWindow(100, time.Minute)
handler := ratelimit.Middleware(limiter)(handler)

Token Bucket

limiter := ratelimit.NewTokenBucket(100, 10) // 100 tokens/sec, burst 10
handler := ratelimit.Middleware(limiter)(handler)

Custom Key Function

handler := ratelimit.Middleware(limiter, ratelimit.WithKeyFunc(func(r *http.Request) string {
    return r.Header.Get("X-API-Key")
}))(handler)

Configuration

Parameter	Description	Default
maxRequests	Maximum requests per window	Required
window	Time window duration	Required
burst	Burst capacity (token bucket)	Required
maxBuckets	Maximum tracked keys	10000

File Reference

File	Purpose
fixed_window.go	Fixed window algorithm
sliding_window.go	Sliding window algorithm
token_bucket.go	Token bucket algorithm
store.go	In-memory store with LRU eviction
middleware.go	HTTP middleware

Security Features

• Memory exhaustion protection with max buckets
• LRU eviction when limit reached
• Key length limit prevents abuse

Tests

cd registry/ratelimit/src/go
go test -v ./...