main.go

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"
	"sync"
)

type JSONSites struct {
	Sites []string `json:"sites"`
}

// list of global top 100 sites by traffic
var SITES_FILE = "sites.json"
var MAX_CONCURRENT_REQUESTS = 10

func CheckSite(host string) (int, error) {
	res, err := http.Get(fmt.Sprintf("http://%s", host))
	if err != nil {
		return -1, err
	}
	return res.StatusCode, nil
}

func main() {
	var wg sync.WaitGroup
	sites_json, _ := ioutil.ReadFile(SITES_FILE)
	s := &JSONSites{}

	if err := json.Unmarshal(sites_json, &s); err != nil {
		panic(err)
	}

	for _, site := range s.Sites {
		wg.Add(1)
		go func(host string) {
			defer wg.Done()
			status, err := CheckSite(host)
			if err != nil {
				fmt.Println("ERROR:", err)
			} else {
				fmt.Printf("%s: %d\n", host, status)
			}
		}(site)
	}

	wg.Wait()
}