algorithm - 进入循环倒数计时器

Question

我目前有这段代码试图计算触发特定条件的耗时。 (伪):

timeDelay = 900000 // time.Microsecond
for {
   // if a certain something happens, start a counting (time)
   if (certainSomething) {
      startTime = time.Now();

      if !prevTime.IsZero() {
        // add the time elapsed time to timeTick
        diffTime = time.Since(prevTime)
        timeTick = timeTick + diffTime
      }

      prevTime = startTime
   }

   if (timeTick < timeDelay) { // lessThan()
      // still has not reached target count (time elapsed)
      fmt.Println("Not Yet")
      // we dont want to get to the end of the loop yet
      continue
   }

   if (timeTick > timeDelay) { // greaterThan()
      // has finally reached the target count (time elapsed)
      fmt.Println("Yes! Finally")
      // yes the delay has been reached lets reset the time
      // and if `thisHappened` is triggered again, lets start counting again
      timeTick = time.Duration(0 * time.Microsecond)
   }

   // function shouldn't be called if the elapsed amount
   //      of time required has not yet been reached
   iShouldOnlyBeCalledWhenDelayHasBeenReached();
}

我还将这些用作辅助函数(实际代码)

func lessThan(diff time.Duration, upper int) bool {
    return diff < time.Duration(upper)*time.Microsecond && diff != 0
}

func greaterThan(diff time.Duration, upper int) bool {
    return diff > time.Duration(upper)*time.Microsecond
}

但是，我对自己的做法不太满意。我不应该数数，对吧？我应该倒计时...我只是很困惑，需要帮助我应该使用什么方法。

我想要发生的事情:
1. 当certainSomething发生时，从timeDelay开始倒计时到0。
2. 在倒计时达到 0 之前，不要调用 iShouldOnlyBeCalledWhenDelayHasBeenReached。
3. 这应该都发生在一个循环内，确切地说是一个服务器循环接收数据包。

我的问题:
1. 我应该怎么做才能实现这种倒计时风格？

谢谢，任何建议或示例代码都会有很大帮助。

Note: There are other functions in the loop. Doing other things. This is the main loop. I can't make it Sleep.

Answer 1

您可以设置一个 channel ，让您知道何时超过了时间。

这是一个例子 on play

它还有一个额外的好处，就是在 select 语句中，您可以有其他 channel 用于其他目的。例如，如果您在此循环中做其他工作，您也可以在 goroutine 中生成该工作并将结果发送回另一个 channel 。
然后在 timeDelay 之后或其他工作完成时退出，或者其他什么。

package main

import (
    "fmt"
    "time"
)

func main() {
    certainSomething := true // will cause time loop to repeat

    timeDelay := 900 * time.Millisecond // == 900000 * time.Microsecond

    var endTime <-chan time.Time // signal for when timer us up

    for {
        // if a certain something happens, start a timer
        if certainSomething && endTime == nil {
            endTime = time.After(timeDelay)
        }
        select {
        case <-endTime:
            fmt.Println("Yes Finally!")
            endTime = nil
        default:
            fmt.Println("not yet")
            time.Sleep(50 * time.Millisecond) // simulate work
            continue
        }

        // function shouldn't be called if the elapsed amount
        //      of time required has not yet been reached
        iShouldOnlyBeCalledWhenDelayHasBeenReached() // this could also just be moved to the <- endtime block above
    }
}

func iShouldOnlyBeCalledWhenDelayHasBeenReached() {
    fmt.Println("I've been called")
}