slow-http-service.go

package main

import (
	"io/ioutil"
	"net/http"
	"time"
	"log"
	"fmt"
)

const (
	name = "bzip2-1.0.6.tar.gz"
	contentType = "application/x-tar"
	frame = 100
	pause = "5ms"
	longPauseAt = 200000
	longPause = "35s"
)

func main() {
	data, err := ioutil.ReadFile(name)
	if err != nil {
		log.Fatal("Failed to read file: %s", err)
	}
	duration, err := time.ParseDuration(pause)
	if err != nil {
		log.Fatal("Failed to parse pause duration: %s", err)
	}
	longDuration, err := time.ParseDuration(longPause)
	if err != nil {
		log.Fatal("Failed to parse long pause duration: %s", err)
	}
	if longPauseAt >= len(data) {
		log.Fatal("longPauseAt >= len(data): %d >= %d", longPauseAt, len(data))
	}
	http.HandleFunc("/" + name, func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Length", fmt.Sprintf("%d", len(data)))
		w.Header().Set("Content-Type", contentType)
		d := data
		totalSent := 0
		hasLongPaused := false
		for len(d) != 0 {
			f := frame
			if f > len(d) {
				f = len(d)
			}
			n, err := w.Write(d[:f])
			if err != nil || n == 0 {
				return
			}
			totalSent += n
			if totalSent >= longPauseAt && !hasLongPaused {
				time.Sleep(longDuration)
				hasLongPaused = true
			} else {
				time.Sleep(duration)
			}
			d = d[n:]
		}
	})
	log.Fatal(http.ListenAndServe(":8080", nil))
}