C++ Boost ASIO simple periodic timer?

问题

I want a very simple periodic timer to call my code every 50ms. I could make a thread that sleeps for 50ms all the time (but that's a pain)... I could start looking into Linux API's for making timers (but it's not portable)...

I'd like to use boost.. I'm just not sure it's possible. Does boost provide this functionality?

回答1:

The second example on Boosts Asio tutorials explains it.
You can find it here.

After that, check the 3rd example to see how you can call it again with a periodic time intervall

回答2:

A very simple, but fully functional example:

#include <iostream>
#include <boost/asio.hpp>

boost::asio::io_service io_service;
boost::posix_time::seconds interval(1);  // 1 second
boost::asio::deadline_timer timer(io_service, interval);

void tick(const boost::system::error_code& /*e*/) {

    std::cout << "tick" << std::endl;

    // Reschedule the timer for 1 second in the future:
    timer.expires_at(timer.expires_at() + interval);
    // Posts the timer event
    timer.async_wait(tick);
}

int main(void) {

    // Schedule the timer for the first time:
    timer.async_wait(tick);
    // Enter IO loop. The timer will fire for the first time 1 second from now:
    io_service.run();
    return 0;
}

Notice that it is very important to call expires_at() to set a new expiration time, otherwise the timer will fire immediately because it's current due time already expired.

回答3:

To further expand on this simple example. It will block the execution as was said in the comments, so if you want more io_services running, you should run them in a thread like so...

boost::asio::io_service io_service;
boost::asio::io_service service2;
timer.async_wait(tick);
boost::thread_group threads;
threads.create_thread(boost::bind(&boost::asio::io_service::run, &io_service));
service2.run();
threads.join_all();

回答4:

As I had some issues with prior answers, here is my example:

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

void print(const boost::system::error_code&, boost::asio::deadline_timer* t,int* count)
{
    if (*count < 5)
    {
        std::cout << *count << std::endl;
        ++(*count);
        t->expires_from_now(boost::posix_time::seconds(1));
        t->async_wait(boost::bind(print, boost::asio::placeholders::error, t, count));
    }
}

int main()
{ 
    boost::asio::io_service io;
    int count = 0;
    boost::asio::deadline_timer t(io, boost::posix_time::seconds(1));

    t.async_wait(boost::bind(print, boost::asio::placeholders::error, &t, &count));

    io.run();
    std::cout << "Final count is " << count << std::endl;

    return 0;

}

it did what it supposed to do: counting to five. May it help someone.

来源：https://stackoverflow.com/questions/4267546/c-boost-asio-simple-periodic-timer

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c++

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boost

boost-asio