control the rate of messages

main.go

package main

import (
	"fmt"
	"sync/atomic"
	"time"
)

func smoothOutListening(rc <-chan string) {
	var ops atomic.Uint64
	var secondaryRateLimit atomic.Uint64

	for _rc := range rc {
		ops.Add(1)
		if ops.Load() > rateLimit {
			secondaryRateLimit.Add(1)
			fmt.Printf("Rate limit exceeded, waiting for %d seconds\n", secondaryRateLimit.Load())
			t := time.NewTicker(time.Duration(secondaryRateLimit.Load()) * time.Second)
			<-t.C
			ops.Store(0)
		}
		fmt.Println("Do some job" + _rc)
	}
}

const rateLimit = 10

func Listen(c <-chan string, ratelimitedCh chan<- string) {
	go func() {
		for _c := range c {
			ratelimitedCh <- _c
		}
	}()
}

func main() {
	listerCh := make(chan string)
	rateLimitCh := make(chan string, rateLimit)
	go smoothOutListening(rateLimitCh)

	Listen(listerCh, rateLimitCh)

	for i := 0; i < 1e4; i++ {
		listerCh <- fmt.Sprintf("[%d]: Hello\n", i)
	}
}