Token Bucket Rate Limiter in Go

A simple implementation of the Token Bucket Algorithm for rate limiting in Go. This rate limiter is used to control the rate of requests to a server by limiting the number of requests a user can make within a specified time frame.

Features

• Token Bucket Algorithm: Efficiently manages request rate using tokens.
• Configurable Capacity and Fill Rate: Set the number of tokens (capacity) and the rate of token refill.
• Concurrency Safe: Uses mutexes to ensure safe access to the token bucket across multiple goroutines.
• Benchmarking: High-performance rate limiter with sub-microsecond response times.

How It Works

The Token Bucket algorithm works by:

• Filling the bucket with tokens at a fixed rate.
• Requests are allowed if there are available tokens in the bucket.
• If no tokens are available, requests are denied until more tokens are added.

The bucket has a defined capacity (maximum tokens) and a fill rate (tokens added per second).

Example:

• Capacity: 5 tokens
• Fill Rate: 1 token per second

If a request is made, and there is a token available, it is allowed. If no tokens are left, the request is denied.

Setup & Installation

1. Clone the repository:

   git clone https://github.com/your-username/token-bucket.git
   cd token-bucket

2. Run the application:

   go run main.go

3. Benchmark the implementation:

   go test -bench .

Example

package main

import (
	"fmt"
	"time"
)

func main() {
	tb := NewTokenBucket(5, 1) // Capacity 5 tokens, 1 token per second

	// Simulate 10 requests
	for i := 0; i < 10; i++ {
		if tb.AllowRequest() {
			fmt.Println("Request allowed!")
		} else {
			fmt.Println("Request denied. No tokens available.")
		}
		time.Sleep(1 * time.Second)
	}
}

Key Methods:

NewTokenBucket(capacity, fillRate int): Initializes a new TokenBucket with a specified capacity and fill rate.

AllowRequest() bool: Returns true if a request is allowed (token available), and false otherwise.

refillTokens(): Refills tokens based on elapsed time.

Benchmark Results

Contribution :

Contribute to the project, report issues, or request features by opening a pull request or an issue.