package main

import (
	"log"
	"sync"
)

func main() {

	inChan := make(chan workToDo, 2)
	outChan := make(chan workResult, 2)
	var wg sync.WaitGroup

	wg.Add(1)
	go startWorker(inChan, outChan, &wg)

	wg.Add(1)
	go startWorker(inChan, outChan, &wg)

	go func() {
		inChan <- workToDo{messageIn: "foo"}
		inChan <- workToDo{messageIn: "bar"}
		inChan <- workToDo{messageIn: "baz"}
		close(inChan)
	}()

	go func() {
		wg.Wait()
		close(outChan)
	}()

	for v := range outChan {
		log.Printf("%#v\n", v)
	}

}

type workToDo struct {
	messageIn string
}
type workResult struct {
	messageOut string
}

func startWorker(in chan workToDo, out chan workResult, wg *sync.WaitGroup) {
	for v := range in {
		log.Printf("%#v\n", v)
		out <- workResult{messageOut: "Echo: " + v.messageIn}
	}
	wg.Done()
}