x.go

package main

import (
	"context"
	"encoding/json"
	"fmt"
	"github.com/hashicorp/go-retryablehttp"
	"io/ioutil"
	"log"
	"net/http"
	"sync"
)

const (
	ProxyAddr = "127.0.0.1:9050"
)

func checkRetry(ctx context.Context, resp *http.Response, err error) (bool, error) {
	return resp.StatusCode >= 403, err
}

func fetch(wg *sync.WaitGroup) {
	// create a socks5 dialer
	//dialer, err := proxy.SOCKS5("tcp", ProxyAddr, nil, proxy.Direct)
	//dialContext := func(ctx context.Context, network, address string) (net.Conn, error) {
	//	return dialer.Dial(network, address)
	//}

	defer wg.Done()

	transport := &http.Transport{
		//DialContext: dialContext,
		DisableKeepAlives: true,
	}

	retryClient := retryablehttp.NewClient()
	retryClient.RetryMax = 100
	retryClient.CheckRetry = checkRetry
	retryClient.HTTPClient.Transport = transport

	resp, err := retryClient.Get("http://127.0.0.1:8000/notify")
	if err != nil {
		log.Fatal(err)
		return
	}

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		fmt.Println("body read failed")
	}

	fmt.Println(string(body))
}

type Server struct {
	Counter int
}

func (s *Server) notify(rw http.ResponseWriter, req *http.Request) {
	s.Counter++

	if s.Counter < 3 {
		rw.WriteHeader(403)
		return
	}

	rw.Header().Set("Content-Type", "application/json")
	rw.WriteHeader(200)

	resp := make(map[string]string)
	resp["message"] = "Status Created"
	jsonResp, err := json.Marshal(resp)
	if err != nil {
		log.Fatalf("Error happened in JSON marshal. Err: %s", err)
	}
	rw.Write(jsonResp)
}

func server()  {
	s := Server{Counter: 0}

	http.HandleFunc("/notify", s.notify)
	log.Fatal(http.ListenAndServe("127.0.0.1:8000", nil))
}

func main() {
	go server()
	var wg sync.WaitGroup

	for i := 0; i < 3; i++ {
		wg.Add(1)

		go func(wg *sync.WaitGroup) {
			fetch(wg)
		}(&wg)
	}

	wg.Wait()
}