go 实现timeout功能

package main

import (
  "fmt"
  "math/rand"
  "time"
)

func init() {
  rand.Seed(time.Now().UnixNano())
}

func main() {

  ch1 := make(chan bool)
  timeout := make(chan bool)

  go func() {
  	time.Sleep(time.Second * 5)
  	ch1 <- true
  }()

  go func() {
  	second := rand.Intn(10)
  	fmt.Println(second)
  	time.Sleep(time.Second * time.Duration(second))
  	timeout <- true
  }()

  //select 的 case 里的操作语句只能是【IO 操作】
  select {
  case <-ch1:
  	fmt.Print("ch1 timeout")
  case <-timeout:
  	fmt.Println("timeout")

  }
}