sync.Cond test

CondSpike.go

package main

import (
  "log"
  "time"
  "sync"
)

const NUM = 2
var finished = make(chan bool, NUM)

func tomTask(cond *sync.Cond) {
  cond.L.Lock()
  log.Println(`Tom:
      I locked a room. George won't be able to do task.
      because I locked the room which can accommodate only one person.
  `)
  time.Sleep(2 * time.Second)
  log.Println(`Tom:
      I got some stuff to do. I'm going to let George know that
      he can use this room.
      I will do remaining tasks after Gerge finished.
  `)
  cond.Wait()
  log.Print(`Tom:
      Thanks George.
      I'm going to work on remaining tasks.
  `)
  time.Sleep(2 * time.Second)
  log.Println(`Tom:
      finished!
  `)
  cond.L.Unlock()
  finished <- true
}

func georgeTask(cond *sync.Cond) {
  log.Println(`George:
      Ah, Tom is using the room.
      I can't do my task when Tom is using the room.
  `)
  cond.L.Lock()
  log.Println(`George:
      Thanks Tom. I'll let you know when I finish.
      Let's get started with my work!
  `)
  time.Sleep(2 * time.Second)
  log.Println(`George:
      finished!
  `)
  cond.L.Unlock()
  log.Println(`George:
      I'm going to let Tom know that I've finished my task.
  `)
  cond.Signal()
  finished <- true
}

func main() {
  var m sync.Mutex
  cond := sync.NewCond(&m)
  go tomTask(cond)
  go georgeTask(cond)
  for i := 0; i < NUM; i++ {
    <-finished
  }
}