Channel example

channel.go

package main

import (
	"fmt"
	"sync"
	"log"
	"net/http"
)

type Response struct {
	Status int
}

func main() {
	content := make(chan Response)

	urls := []string{
		"https://google.com",
		"https://tutorialedge.net",
		"https://twitter.com",
	}

	var wg sync.WaitGroup
	
	wg.Add(1)
	go fetchWorker(&wg, urls, content)

	wg.Add(1)
	go printResponse(&wg, content)

	wg.Wait()

	fmt.Println("done!")
}

func fetchWorker(mainWG *sync.WaitGroup, urls []string, output chan<- Response) {
	defer mainWG.Done()

	var wg sync.WaitGroup

	for _, url := range urls {
		wg.Add(1)
		go fetch(&wg, url, output)
	}

	wg.Wait()
	close(output)
}

func fetch(wg *sync.WaitGroup, url string, output chan<- Response) {
	defer wg.Done()

	resp, err := http.Get(url)
	if err != nil {
			fmt.Println(err)
	}

	output <- Response{
		Status: resp.StatusCode,
	}
}

func printResponse(wg *sync.WaitGroup, input <-chan Response) {
	defer wg.Done()

	for content := range input {
		log.Printf("content %#v", content)
	}
}