c++11提供了丰富的时间和线程操作函数，比如 std::this_thread::sleep, std::chrono::seconds等。可以利用这些来很方便的实现一个定时器。 定时器要求在固定的时间异步执行一个操作，比如boost库中的boost::asio::deadline_timer，以及MFC中的定时器。这里，利用c++11的thread, mutex, condition_variable 来实现一个定时器： 定时器要求异步执行任务 ----> 开辟独立的线程 定时器要求能够启动和取消 ----> 提供安全的取消操作，使用互斥量和信号量 定时器要求每个定时时刻到达的时候执行的任务要尽可能节省时间 实现

#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& t){    expired_ = t.expired_.load();    try_to_expire_ = t.try_to_expire_.load();}~Timer(){    Expire();    //      std::cout << "timer destructed!" << std::endl;}void StartTimer(int interval, std::function
    
      task){    if (expired_ == false){        //          std::cout << "timer is currently running, please expire it first..." << std::endl;        return;    }    expired_ = false;    std::thread([this, interval, task](){        while (!try_to_expire_){            std::this_thread::sleep_for(std::chrono::milliseconds(interval));            task();        }        //          std::cout << "stop task..." << std::endl;        {            std::lock_guard
     
       locker(mutex_);            expired_ = true;            expired_cond_.notify_one();        }    }).detach();}void Expire(){    if (expired_){        return;    }    if (try_to_expire_){        //          std::cout << "timer is trying to expire, please wait..." << std::endl;        return;    }    try_to_expire_ = true;    {        std::unique_lock
      
        locker(mutex_);        expired_cond_.wait(locker, [this]{return expired_ == true; });        if (expired_ == true){            //              std::cout << "timer expired!" << std::endl;            try_to_expire_ = false;        }    }} template
       
        void SyncWait(int after, callable&& f, arguments&&... args){    std::function
        
         ::type()> task        (std::bind(std::forward
         
          (f), std::forward
          
           (args)...)); std::this_thread::sleep_for(std::chrono::milliseconds(after)); task();}template
           
            void AsyncWait(int after, callable&& f, arguments&&... args){ std::function
            
             ::type()> task (std::bind(std::forward
             
              (f), std::forward
              
               (args)...)); std::thread([after, task](){ std::this_thread::sleep_for(std::chrono::milliseconds(after)); task(); }).detach();}
              
             
            
           
          
         
        
       
      
     
    

private: std::atomic<bool> expired_; std::atomic<bool> try_to_expire_; std::mutex mutex_; std::condition_variable expired_cond_; }; #endif

test.cpp #include<iostream> #include<string> #include<memory> #include"Timer.hpp" using namespace std; void EchoFunc(std::string&& s){ std::cout << "test : " << s << endl; }

int main(){ Timer t; //周期性执行定时任务 t.StartTimer(1000, std::bind(EchoFunc,"hello world!")); std::this_thread::sleep_for(std::chrono::seconds(4)); std::cout << "try to expire timer!" << std::endl; t.Expire();

//周期性执行定时任务t.StartTimer(1000, std::bind(EchoFunc,  "hello c++11!"));std::this_thread::sleep_for(std::chrono::seconds(4));std::cout << "try to expire timer!" << std::endl;t.Expire();std::this_thread::sleep_for(std::chrono::seconds(2));//只执行一次定时任务//同步t.SyncWait(1000, EchoFunc, "hello world!");//异步t.AsyncWait(1000, EchoFunc, "hello c++11!");std::this_thread::sleep_for(std::chrono::seconds(2));return 0;

}