定时器timer是多线程编程中经常设计到的工具类
定时器的原理其实很简单：
- 创建一个新线程
- 在那个线程里等待
- 等待指定时长后做任务
这里用C++11实现了一个简单易用的定时器，包含两种模式：
- 周期性定时任务执行
- 单次延时任务执行
timer.hpp
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#ifndef _TIMER_H_#define _TIMER_H_#include <functional>#include <chrono>#include <thread>#include <atomic>#include <memory>#include <mutex>#include <condition_variable>class Timer{public: Timer(): _expired(true), _try_to_expire(false) {} Timer(const Timer& timer) { _expired = timer._expired.load(); _try_to_expire = timer._try_to_expire.load(); } ~Timer() { stop(); } void start(int interval, std::function<void()> task) { // is started, do not start again if (_expired == false) return; // start async timer, launch thread and wait in that thread _expired = false; std::thread([this, interval, task]() { while (!_try_to_expire) { // sleep every interval and do the task again and again until times up std::this_thread::sleep_for(std::chrono::milliseconds(interval)); task(); } { // timer be stopped, update the condition variable expired and wake main thread std::lock_guard<std::mutex> locker(_mutex); _expired = true; _expired_cond.notify_one(); } }).detach(); } void startOnce(int delay, std::function<void()> task) { std::thread([delay, task]() { std::this_thread::sleep_for(std::chrono::milliseconds(delay)); task(); }).detach(); } void stop() { // do not stop again if (_expired) return; if (_try_to_expire) return; // wait until timer _try_to_expire = true; // change this bool value to make timer while loop stop { std::unique_lock<std::mutex> locker(_mutex); _expired_cond.wait(locker, [this] {return _expired == true; }); // reset the timer if (_expired == true) _try_to_expire = false; } }private: std::atomic<bool> _expired; // timer stopped status std::atomic<bool> _try_to_expire; // timer is in stop process std::mutex _mutex; std::condition_variable _expired_cond;};#endif // !_TIMER_H_ |
main.cpp
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#include <iostream>#include "timer.hpp"void func1(){ std::cout << "trigger func1" << std::endl;}void func2(int x){ std::cout << "trigger func2, x: " << x << std::endl;}int main(int argc, char* argv[]){ Timer timer; // execute task every timer interval std::cout << "--- start period timer ----" << std::endl; timer.start(1000, std::bind(func2, 3)); std::this_thread::sleep_for(std::chrono::milliseconds(5000)); timer.stop(); std::cout << "--- stop period timer ----" << std::endl; // execute task once after delay std::cout << "--- start one shot timer ----" << std::endl; timer.startOnce(1000, func1); std::cout << "--- stop one shot timer ----" << std::endl; getchar(); return 0;} |
运行结果
--- start period timer ----
trigger func2, x: 3
trigger func2, x: 3
trigger func2, x: 3
trigger func2, x: 3
trigger func2, x: 3
--- stop period timer ----
--- start one shot timer ----
--- stop one shot timer ----
trigger func1
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原文链接：https://blog.csdn.net/u012234115/article/details/89857431
