Go 语言一次性定时器使用方式和实现原理

func main() {
 nowTime := time.Now().Unix()
 fmt.Println(nowTime)
 NewTimerDemo()
}

func NewTimerDemo() {
 timer := time.NewTimer(2 * time.Second)
 select {
 case <-timer.C:
  currentTime := time.Now().Unix()
  fmt.Println(currentTime, "do something")
 }
}

1665894136
1665894138 do something

func main() {
 nowTime := time.Now().Unix()
 fmt.Println(nowTime)
 AfterFuncDemo()
}

func AfterFuncDemo() {
 time.AfterFunc(2 * time.Second, func() {
  currentTime := time.Now().Unix()
  fmt.Println(currentTime, "do something")
 })
 time.Sleep(3 * time.Second)
}

type Timer struct {
    C <-chan Time
    r runtimeTimer
}

type runtimeTimer struct {
    tb     uintptr
    i      int
    when   int64
    period int64
    f      func(interface{}, uintptr)
    arg    interface{}
    seq    uintptr
}

// NewTimer creates a new Timer that will send
// the current time on its channel after at least duration d.
func NewTimer(d Duration) *Timer {
 c := make(chan Time, 1)
 t := &Timer{
  C: c,
  r: runtimeTimer{
   when: when(d),
   f:    sendTime,
   arg:  c,
  },
 }
 startTimer(&t.r)
 return t
}

func sendTime(c interface{}, seq uintptr) {
 // Non-blocking send of time on c.
 // Used in NewTimer, it cannot block anyway (buffer).
 // Used in NewTicker, dropping sends on the floor is
 // the desired behavior when the reader gets behind,
 // because the sends are periodic.
 select {
 case c.(chan Time) <- Now():
 default:
 }
}

// startTimer adds t to the timer heap.
//go:linkname startTimer time.startTimer
func startTimer(t *timer) {
 if raceenabled {
  racerelease(unsafe.Pointer(t))
 }
 addtimer(t)
}