c++11实现异步定时器
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
#ifndef TIMER_H_
#define TIMER_H_
#include
#include
#include
#include
#include
#include
#include
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<void()> 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
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
expired_cond_.wait(locker, [this]{return expired_ == true; });
if (expired_ == true){
// std::cout << "timer expired!" << std::endl;
try_to_expire_ = false;
}
}
}
templateclass... arguments>
void SyncWait(int after, callable&& f, arguments&&... args){
std::function
(std::bind(std::forward
std::this_thread::sleep_for(std::chrono::milliseconds(after));
task();
}
templateclass... arguments>
void AsyncWait(int after, callable&& f, arguments&&... args){
std::function
(std::bind(std::forward
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
#include
#include
#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;
}