alpha-10-concurrent-sleep-service-leaky-bucket.go

package main

import (
	"flag"
	"fmt"
	"net/http"
	"time"
)

var port string
var limit chan int

func main() {
	// initaite rate limit
	limit = make(chan int, 10)

	// service flags
	flag.StringVar(&port, "port", "8000", "service http port")
	flag.Parse()

	// starting server
	fmt.Printf("Starting server on :%s\n", port)
	http.HandleFunc("/", handler)
	http.ListenAndServe(fmt.Sprintf(":%s", port), nil)
}

func handler(w http.ResponseWriter, req *http.Request) {
  limit <- 1 // push request if there is capacity, if not then wait

	fmt.Println("Receiving a request")
	time.Sleep(200 * time.Millisecond)
	fmt.Fprintf(w, "hello\n")

	// pull the request from the limiter
	<-limit
}

alpha-10-concurrent-sleep-service.go

package main

import (
	"flag"
	"fmt"
	"net/http"
	"time"
)

var port string
var limit chan int

func main() {
	// initaite rate limit
	limit = make(chan int, 10)

	// service flags
	flag.StringVar(&port, "port", "8000", "service http port")
	flag.Parse()

	// starting server
	fmt.Printf("Starting server on :%s\n", port)
	http.HandleFunc("/", handler)
	http.ListenAndServe(fmt.Sprintf(":%s", port), nil)
}

func handler(w http.ResponseWriter, req *http.Request) {
	// rate limit 10 concurrent
	select {
	case limit <- 1: // push request if there is capacity
	default: // if not return server error
		w.WriteHeader(http.StatusServiceUnavailable)
		w.Write([]byte("503 - Maximum concurrent reatched!"))
		return
	}

	fmt.Println("Receiving a request")
	time.Sleep(200 * time.Millisecond)
	fmt.Fprintf(w, "hello\n")

	// pull the request from the limiter
	<-limit
}