c ++实现定时回调函数 [英] c++ Implementing Timed Callback function

问题描述

我想在c ++中实现一些系统，这样我可以调用一个函数，并要求另一个函数在X毫秒内调用。像这样：

I want to implement some system in c++ so that I can call a function and ask for another function to be called in X milliseconds. Something like this:

callfunctiontimed(25, funcName);

25是函数调用前的毫秒数。

25 being the amount of milliseconds before the function should be called.

我想知道是否需要多线程，然后使用一些延迟功能？

I would like to know if multithreading is required for this and then use some delay function? Other than using function pointer how would a feature like this work?

推荐答案

对于一个可移植的解决方案，你可以使用boost :: asio 。下面是我写的一个演示。
您可以更改

For a portable solution, you can use boost::asio. Below is a demo I wrote a while ago. You can change

t.expires_from_now(boost::posix_time::seconds(1));

以满足您需要说在200年后调用函数调用。

to suit you need say make function call after 200 milliseonds.

t.expires_from_now(boost::posix_time::milliseconds(200)); 

下面是一个完整的工作示例。它反复呼叫，但我认为应该很容易只调用一次只需更改一点。

Below is a complete working example. It's calling repeatedly but I think it should be easy to call only once by just change a bit.

#include <iostream>
#include <boost/bind.hpp>
#include <boost/thread.hpp>
#include <boost/asio.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>

using namespace boost::asio;
using namespace std;

class Deadline 
{
public:
    Deadline(deadline_timer &timer) : t(timer) {
        wait();
    }

    void timeout(const boost::system::error_code &e) {
        if (e)
            return;
        cout << "tick" << endl;
        wait();
    }

    void cancel() {
        t.cancel();
    }


private:
    void wait() {
        t.expires_from_now(boost::posix_time::seconds(1)); //repeat rate here
        t.async_wait(boost::bind(&Deadline::timeout, this, boost::asio::placeholders::error));
    }

    deadline_timer &t;
};


class CancelDeadline {
public:
    CancelDeadline(Deadline &d) :dl(d) { }
    void operator()() {
        string cancel;
        cin >> cancel;
        dl.cancel();
        return;
    }
private:
    Deadline &dl;
};



int main()
{
    io_service io;
    deadline_timer t(io);
    Deadline d(t);
    CancelDeadline cd(d);
    boost::thread thr1(cd);
    io.run();
    return 0;
}



//result:
//it keeps printing tick every second until you enter cancel and enter in the console
tick
tick
tick

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