channel.go

package main 

import ("fmt"
	   "net/http"
	   "log"
	   "io/ioutil"
	   "io"
	   "sync"
	   "os"
)

func fetchUrl(url string, send_channel chan<- string){
	response, err := http.Get(url)
	if(err != nil){
		log.Fatal(err)
	}
	bytes, err := io.Copy(ioutil.Discard, response.Body) 
	response.Body.Close()
	if(err != nil){
		log.Fatal(err)
	}
	send_channel <- fmt.Sprintf("Downloaded %d bytes from URL %s", bytes, url)
}

func worker(pid int, wg *sync.WaitGroup, file *os.File){
	defer wg.Done()
	fmt.Printf("Worker Process %d writing to file...\n", pid)
	content := fmt.Sprintf("Worker %d wrote to the file\n", pid)
	file.WriteString(content)
	file.Sync()
}

func main(){
	urls := [2]string{"https://vmware.com", "https://dell.com"}
	var receive_channel string 
	send_channel := make(chan string)
	var wg sync.WaitGroup

	f, err := os.Create("/tmp/concurrency_in_go.txt")
	if err != nil{
		panic(err)
	}
	defer f.Close()

	for i := 1; i <= 3; i++ {
		wg.Add(1)
		go worker(i, &wg, f)
	}
	wg.Wait()

	for _, url := range urls {
		go fetchUrl(url, send_channel)
	}

	for _, url := range urls {
		fmt.Println("Fetching channel content for URL: ", url)
		receive_channel = <-send_channel
		fmt.Println(receive_channel)
	}
}