[TOC] 轉載：[https://blog.csdn.net/u012234115/article/details/89857431](https://blog.csdn.net/u012234115/article/details/89857431) 定時器timer是多線程編程中經常設計到的工具類 定時器的原理其實很簡單： * 創建一個新線程 * 在那個線程里等待 * 等待指定時長后做任務 這里用C++11實現了一個簡單易用的定時器，包含兩種模式： * 周期性定時任務執行 * 單次延時任務執行 timer.hpp ``` #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 ``` #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; } ```