RoundTripper demo

sleep.go

package main

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

type sleepTransport struct {
	maxSecond         int
	originalTransport http.RoundTripper
}

func (c *sleepTransport) RoundTrip(r *http.Request) (*http.Response, error) {
	rand.Seed(time.Now().Unix())
	n := rand.Intn(c.maxSecond)
	log.Println("sleep second is ", n)
	time.Sleep(time.Duration(n) * time.Second)
	resp, err := c.originalTransport.RoundTrip(r)

	if err != nil {
		return nil, err
	}

	return resp, nil
}

func main() {
	client := &http.Client{
		Transport: &sleepTransport{
			maxSecond:         20,
			originalTransport: http.DefaultTransport,
		},
		Timeout: time.Second * 20,
	}
	req, err := http.NewRequest(http.MethodGet, "http://localhost:8000", strings.NewReader(""))

	if err != nil {
		log.Fatalf("An error occurred ... %v", err)
	}

	resp, err := client.Do(req)

	if err != nil {
		log.Fatalf("An error occurred ... %v", err)
	}

	buf, err := ioutil.ReadAll(resp.Body)

	if err != nil {
		log.Fatalf("An error occurred ... %v", err)
	}

	fmt.Printf("The body of the response is \"%s\" \n\n", string(buf))

}