定时器的暂停/恢复功能答案

【问题标题】：Pause/Resume functions for timer定时器的暂停/恢复功能
【发布时间】：2014-09-28 20:35:53
【问题描述】：

我需要使用可以暂停和恢复的计时器。据我所知，threading 包中包含的 Python 中只有一个计时器，但我无法暂停或恢复它，只能取消它。

这是在 Python 中使用计时器的标准代码：

from threading import Timer
import time

def timeout():
     print "Game over"

t = Timer(20 * 60, timeout)
t.start()

那么我应该怎么做才能用这个定时器来实现暂停/恢复功能呢？

【问题讨论】：

标签： python python-2.7

【解决方案1】：

import threading, time

class ResumableTimer:
    def __init__(self, timeout, callback):
        self.timeout = timeout
        self.callback = callback
        self.timer = threading.Timer(timeout, callback)
        self.startTime = time.time()

    def start(self):
        self.timer.start()

    def pause(self):
        self.timer.cancel()
        self.pauseTime = time.time()

    def resume(self):
        self.timer = threading.Timer(
            self.timeout - (self.pauseTime - self.startTime),
            self.callback)

        self.timer.start()

你的作业：

继承？
例外？支票？
比可恢复计时器更好的东西

【讨论】：

试试看，t = ResumableTimer(5, someFunction); t.start(); t.pause(); t.resume()，如果可行，请将我的问题标记为正确。

【解决方案2】：

最终课程发布

from threading import Timer
import time


class RenewableTimer:

    def __init__(self, timeout, callback):
        self.timer = Timer(timeout, callback)

        self.start_time = None
        self.cancel_time = None

        # Used for creating a new timer upon renewal
        self.timeout = timeout
        self.callback = callback

    def cancel(self):
        self.timer.cancel()

    def start(self):
        # NOTE: erroneously calling this after pausing causes errors where
        # start_time is updated, and then you get a RuntimeError
        # for trying to restart a thread
        self.start_time = time.time()
        self.timer.start()

    def pause(self):
        self.cancel_time = time.time()
        self.timer.cancel()
        return self.get_remaining_time()

    def resume(self):
        self.timeout = self.get_remaining_time()
        self.timer = Timer(self.timeout, self.callback)
        self.start_time = time.time()
        self.timer.start()

    def get_remaining_time(self):
        if self.start_time is None or self.cancel_time is None:
            return self.timeout
        return self.timeout - (self.cancel_time - self.start_time)

【讨论】：

【解决方案3】：

要考虑的另一种方法是跟踪在每个“停止”计时器但实际上让计时器运行的时间段内经过的时间。然后在任务结束时，从总经过时间中减去总暂停时间。

import keyboard
from timeit import default_timer as timer

elapsedPauseTime = 0;

print("'s' to start task timer")
print("'p' to pause task timer")
print("'r' to resume task timer")
print("'e' to end task timer")

while (1 == 1):
    if keyboard.read_key() == "s":
        print("Task Timer Started")
        timerStart = timer()
    if keyboard.read_key() == "p":
        print("Task Timer pause counter started")
        timerPauseStart = timer()
    if keyboard.read_key() == "r":
        print("Task Timer pause counter stopped")
        timerPauseEnd = timer()
        elapsedPauseTime = elapsedPauseTime + timerPauseEnd - timerPauseStart
    if keyboard.read_key() == "e":
        print("Task Timer Ended")
        timerEnd = timer()
        break

print("Total time: " + str(timerEnd - timerStart))
print("Pause time: " + str(elapsedPauseTime))
print("Task time with pauses: " + str(timerEnd - timerStart - elapsedPauseTime))

【讨论】：