package main
import (
  "fmt"
  "math/rand"
  "time"
)
func doSomething(event string,ch chan<-bool) {
  time.Sleep(time.Duration(rand.Intn(500))*time.Millisecond)
  ch<-true
}
func main() {
  ch := make(chan bool)
  go doSomething("event",ch)
  for{
    select {
    case <-ch:
      fmt.Println("finish...")
      return
    }
  }
}

package main
import (
  "fmt"
  "math/rand"
  "time"
)
var food = make(chan string)
func cook(foods []string){
  for _,f := range foods{
    if f == "凉菜"{
      time.Sleep(100*time.Millisecond)
      food<-"凉菜"
    }else {
      time.Sleep(800*time.Millisecond)
      food<-"佛跳墙"
    }
  }
}
func server(finish chan bool){
  for {
    select {
    case name:=<-food:
      time.Sleep(time.Duration(rand.Intn(600))*time.Millisecond)
      fmt.Println("客官，上菜了:",name)
      finish<-true
    default:
      //fmt.Println("服务员在等待...")
    }
  }
}
func main() {
  foods := []string{"凉菜","凉菜","凉菜","凉菜","凉菜","凉菜","佛跳墙","凉菜"}
  n := len(foods)
  cnt := 0
  finish := make(chan bool)
  start := time.Now()
  go cook(foods)
  go server(finish)
  for{
    select {
    case <-finish:{
      cnt += 1
      if cnt == n{
        fmt.Println(time.Since(start))
        return
      }
    }
    }
  }
}