select - skynocover/Wiki-for-GoLang GitHub Wiki

使用select來當作chan的switch

func fibonacci(c, quit chan int) {
	x, y := 0, 1
	for {
		select {
		case c <- x:
			x, y = y, x+y
		case <-quit:
			fmt.Println("quit")
			return
		}
	}
}
func main() {
	c := make(chan int)
	quit := make(chan int)
	go func() {
		for i := 0; i < 10; i++ {
			fmt.Println(<-c)
		}
		quit <- 0
	}()
	fibonacci(c, quit)
}

select跟switch相同,只能做case處理 沒辦法當作循環
若要一直循環可以使用無限迴圈

for {
	select {
	case c <- x:
		x, y = y, x+y
	case <-quit:
		fmt.Println("quit")
		return
	}
}

---

超時處理

因為超過一秒等待因此會顯示timeout 1

func main() {
    c1 := make(chan string, 1)
    go func() {
        time.Sleep(time.Second * 2)
        c1 <- "result 1"
    }()
    select {
    case res := <-c1:
        fmt.Println(res)
    case <-time.After(time.Second * 1):
        fmt.Println("timeout 1")
    }
}