go-rate-limiter

Rate Limiter implemented using Token Bucket Algorithm written in Go.

Overview

The token bucket algorithm allows a certain number of requests to be made in a given time period. It works by refilling a bucket with a fixed number of tokens at a constant rate. Each request consumes one token from the bucket. If the bucket is empty, no more requests can be made until it is refilled.

Implementation

The TokenBucket struct represents the rate limiter. It contains the following fields:

• tokens: The current number of tokens in the bucket.
• refillTime: The time at which the bucket was last refilled.
• maxTokens: The maximum number of tokens the bucket can hold.
• lastRefillTime: The time at which the bucket was last refilled.
• mutex: A mutex to ensure thread safety.

The package provides the following functions:

• NewTokenBucket(tokens int) *TokenBucket: Initializes a new TokenBucket with the specified number of tokens.
• Refill(): Refills the TokenBucket with tokens based on the refill rate.
• IsRequestAllowed() bool: Checks if a request is allowed based on the current number of tokens in the bucket.

Sample usecase

package main

import (
	"fmt"
	"time"

	"github.com/Utkarshn10/go-rate-limiter/src/ratelimiter"
)

func main() {
	// Create a new TokenBucket with 10 tokens
	tb := ratelimiter.NewTokenBucket(10)

	// Periodically refill the bucket
	go func() {
		for {
			tb.Refill()
			time.Sleep(1 * time.Second)
		}
	}()

	// Make requests and check if they are allowed
	for i := 0; i < 15; i++ {
		if tb.IsRequestAllowed() {
			fmt.Println("Request", i+1, "allowed")
		} else {
			fmt.Println("Request", i+1, "blocked")
		}
		time.Sleep(100 * time.Millisecond)
	}
}