[Golang channels] Golang channels example #go #golang

main.go

package tasks

type Task struct {
	Name string
}

func (t *Task) Finish() {
	// what actually can finish the task
}

func AssignTasks(ch chan *Task) {
	// we have 100 tasks to assigned.
	// all we need to do is throw them all to the channel.
	// when we finish, close the channel, the read end of channel will stop  reading.
	for i := 0; i < 100; i++ {
		task := new(Task)
		ch <- task
	}
	close(ch)
}

func WorkerFinishTasks(ch chan *Task, done chan struct{}) {
	// Worker doesn't care what and how many tasks he do.
	// He just finish all the tasks as possible as he can.
	// when the channel closed, he will know all the task done.
	for task := range ch {
		task.Finish()
	}

	// send a signal the indicate that his work is done.
	done <- struct{}{}
}

func main() {
    workerNum := 4
    ch := make(chan *Task, workerNum)

    // use channel as an signal here, the struct{} type take zero byte in memory.
    done := make(chan struct{}, workerNum)

    go AssignTasks(ch)
    for i:=0; i<workerNum; i++ {
        go WorkerFinishTasks(ch, done)
    }

    // we hire 4 worker to work, so we need to receive 4 signal when they all done.
    for i:=0; i<workerNum; i++ {
        <-done
    }
    fmt.Println("all task done!")
}