producer-consumer.go

package main

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

type HttpResult struct {
	Url        string
	StatusCode int
}

// 3
func producer(ch chan<- HttpResult, url string, wg *sync.WaitGroup) {
	defer wg.Done()
	resp, err := http.Get(url)
	if err != nil {
		fmt.Errorf("url was error: %v", err)
	}
	ch <- HttpResult{Url: url, StatusCode: resp.StatusCode}
}

// 4
func consumer(ch <-chan HttpResult, done chan<- bool) {
	for msg := range ch {
		fmt.Printf("%s -> %d\n", msg.Url, msg.StatusCode)
	}
	done <- true
}

func main() {
	urlChan := make(chan HttpResult)
	// 1
	doneChan := make(chan bool)
	wg := sync.WaitGroup{}

	urls := []string{"https://rogerwelin.github.io/",
		"https://golang.org/",
		"https://news.ycombinator.com/",
		"https://www.google.se/shouldbe404",
		"https://www.cpan.org/"}

	// 2
	for _, url := range urls {
		wg.Add(1)
		go producer(urlChan, url, &wg)
	}
	
	go consumer(urlChan, doneChan)

	// 5
	wg.Wait()
	close(urlChan)
	<-doneChan
}