reddit.go

package main

import (
	"time"
	"fmt"
	"context"
	"sync"
)

func web() string {
	time.Sleep(time.Millisecond * 100)
	
	return "web"
}

func video() string {
	time.Sleep(time.Millisecond * 1500)

	return "video"
}

func music() string {
	time.Sleep(time.Millisecond * 1000)

	return "music"
}


func google() []string {
	var result []string
	ch := make(chan string)

	scrapingDone := make(chan bool)
	now := time.Now()

	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	
	go func() {
		for {
			select {
			case i, ok := <- ch:
				if !ok {
					fmt.Println("chan closed")
					scrapingDone <- true
					return
				}
				
				result = append(result, i)
			case <-ctx.Done():
				fmt.Println("done")
				scrapingDone <- true
				return
			}
		}
	}()

	go func() {
		wg := sync.WaitGroup{}

		wg.Add(3)
		
		go func() {
			ch <- web()
			wg.Done()
		}()

		go func() {
			ch <- video()
			wg.Done()
		}()

		go func() {
			ch <- music()
			wg.Done()
		}()

		wg.Wait()
		close(ch)
	}()
	
	<-scrapingDone

	fmt.Println(time.Since(now))
	return result
}

func main() {
	fmt.Println(google())
}