Max requests per second limiter

max-requests-per-second-limiter.go

package main

import (
	"fmt"
	"sync"
	"time"
)

func main() {
	// Start request limiter
	// Only 10 requests are able to be sent out in every second interval
	maxRequestPerSecondLimiterChannel := maxRequestsPerSecondLimiter(10)

	var waitGroup sync.WaitGroup

	for i := 0; i < 50; i++ {
		waitGroup.Add(1)

		go func(id int) {
			fmt.Printf("Waiting to request %d\n", id)
			// Will wait until below limit of requests per second
			maxRequestPerSecondLimiterChannel <- true

			fmt.Printf("Making request %d\n", id)
			<-time.After(3 * time.Second)
			fmt.Printf("Maked request %d\n", id)

			waitGroup.Done()
		}(i)
	}

	waitGroup.Wait()
}

func maxRequestsPerSecondLimiter(requestsPerSecond uint) chan bool {
	maxRequestsPerSecondLimiterChannel := make(chan bool, requestsPerSecond)

	// 1. If channel is fully available -> for loop will block
	// 2. If channnel has at least one value -> allow another request after a second
	// 		for desired amount of requests per second
	for i := uint(0); i < requestsPerSecond; i++ {
		go func() {
			for {
				<-time.After(time.Second)
				<-maxRequestsPerSecondLimiterChannel
			}
		}()
	}

	return maxRequestsPerSecondLimiterChannel
}