定時器timer是多執行緒程式設計中經常設計到的工具類

定時器的原理其實很簡單：

• 建立一個新執行緒
• 在那個執行緒裡等待
• 等待指定時長後做任務

這裡用C++11實現了一個簡單易用的定時器，包含兩種模式：

• 週期性定時任務執行
• 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;
}

執行結果

--- start period timer ----
trigger func2,x: 3
trigger func2,x: 3
--- stop period timer ----
--- start one shot timer ----
--- stop one shot timer ----
trigger func1

到此這篇關於C++11實現簡易定時器的示例程式碼的文章就介紹到這了,更多相關C++11 定時器 內容請搜尋我們以前的文章或繼續瀏覽下面的相關文章希望大家以後多多支援我們！