Question

是否可以使截止时间计时器停止并重新启动？

我正在开发一个c ++库中的播放器程序，需要一个能够暂停的计时器。履历，

我发现提升截止时间计时器是一个选项，但如何在停止后重启它？

Answer 1

您的计时器应该异步等待。在这种情况下，您可以使用deadline_timer::cancel()取消计时器，使用deadline_timer :: expires_from_now（）更改计时器到期时间，然后使用deadline_timer::async_wait()再次等待。

C ++ 03的代码示例如下：

#include <iostream>

#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <boost/chrono.hpp>
#include <boost/chrono/duration.hpp>
#include <boost/function.hpp>
#include <boost/thread.hpp>

/// Simple asio::deadline_timer wrapper to aggregate
/// timer, interval and handler function.
class timer
{
    typedef boost::asio::deadline_timer impl;
public:
    typedef impl::duration_type duration;
    typedef boost::function<void (boost::system::error_code, timer&)> handler_function;

    /// Create timer with specified interval and handler
    timer(boost::asio::io_service& io_service, duration interval, handler_function handler)
        : impl_(io_service)
        , interval_(interval)
        , handler_(handler)
    {
    }

    /// Start asynchronous waiting
    void start()
    {
        impl_.expires_from_now(interval_);
        impl_.async_wait(boost::bind(handler_, boost::asio::placeholders::error, boost::ref(*this)));
    }

    /// Stop waiting
    void stop()
    {
        impl_.cancel();
    }

private:
    impl impl_;
    duration interval_;
    handler_function handler_;
};

// Timer handler, just start next tick
void timer_tick(boost::system::error_code err, timer& t)
{
    static int tick_ = 0;
    if (!err)
    {
        std::cout << "tick " << ++tick_ << '\n';
        t.start();
    }
}

boost::asio::io_service io_service;

void timer_thread(timer& t)
{
    t.start();
    io_service.run();
}

int main()
{
    // run a timer in another thread
    timer t(io_service, boost::posix_time::seconds(1), timer_tick);
    boost::thread tthread(&timer_thread, boost::ref(t));

    // stop the timer after some delay
    boost::this_thread::sleep_for(boost::chrono::seconds(3));
    t.stop();

    tthread.join();
}

Answer 2

由于截止日期计时器使用an io service object，您可以通过stopping服务暂停计时器。

如何暂停和;恢复提升deadline_timer？

2 个答案: