ratelimit

Overview ¶

Package ratelimit provides rate limiting primitives for Go applications.

This package offers three main types of rate limiters:

• bucket: Token bucket rate limiter allowing burst traffic
• leakybucket: Leaky bucket rate limiter for smooth traffic flow
• concurrency: Concurrency limiter for controlling concurrent operations

Rate Limiter Types:

Token Bucket vs Leaky Bucket:

Token bucket allows controlled bursts and is ideal for interactive applications:

tokenLimiter := bucket.New(10, 5) // 10 tokens/sec, burst of 5
if tokenLimiter.Allow() {
	// Process request (allows immediate burst)
}

Leaky bucket enforces smooth flow and is ideal for traffic shaping:

leakyLimiter := leakybucket.New(10, 5) // 10 requests/sec, capacity 5
if leakyLimiter.Allow() {
	// Process request (smooth flow, no bursts)
}

Concurrency limiter controls the number of simultaneous operations:

concLimiter := concurrency.New(10) // Max 10 concurrent operations
if concLimiter.Acquire() {
	defer concLimiter.Release()
	// Process operation (limited by concurrency, not time)
}

All rate limiters support:

• Context-aware blocking operations (Wait/WaitN)
• Dynamic configuration changes
• Comprehensive state inspection
• Safe concurrent access

Rate vs Concurrency Limiting:

• Rate limiters control operations per unit of time
• Concurrency limiters control simultaneous operations
• Rate limiters include reservation patterns for advance booking
• Concurrency limiters provide semaphore-like functionality

All rate limiters integrate with the context package for cancellation and timeouts.