两个协程交替打印

package main

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

//两个goroutine，一个打印A,另一个打印a， 顺序打印AaBbCcDd.....

var wg sync.WaitGroup

func worker1(ch chan struct{},data chan string)  {
	fmt.Println("worker 1")
	defer wg.Done()

	for{
		select {
		case <-ch:
			tmp :=<- data
			time.Sleep(time.Second*1)
			fmt.Println("big:",tmp)
			ch <- struct{}{} //发送信号
		default:

		}
	}
}

func worker2(ch chan struct{},data chan string)  {
	fmt.Println("worker 2")
	defer wg.Done()
	ch<- struct{}{} // 先发送信号给协程1 
	for{
		select {
		case <-ch:
			tmp :=<- data
			time.Sleep(time.Second*1)
			fmt.Println("small:",tmp)
			ch <- struct{}{} //发送信号
		default:
		}
	}
}


func main() {
	done := make(chan struct{})
	dataChan :=make(chan string)
	wg.Add(1)
	go func() {
		defer wg.Done()
		s1 := []string{"A","a","B","b","C","c","D","d","E","e","F","f"}
		for _,v := range s1 {
			dataChan <- v //一个阻塞的channel，数据源
		}

		//for i :=0;i<100;i++{
		//	dataChan <- strconv.Itoa(i)+"_test"
		//}
	}()


	wg.Add(2)

	go worker1(done,dataChan)
	go worker2(done,dataChan)



	wg.Wait()
}