c – 重置线程的休眠时间

这有利于支持缩短超时的方案：

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#include <thread>
#include <chrono>
#include <iostream>
#include <condition_variable>

namespace demo
{
    namespace chrono = std::chrono;

    using our_clock = chrono::system_clock;

    struct Worker
    {
        mutable std::mutex _mx;

        // shared,protected by _mx:
        our_clock::time_point _deadline; 
        mutable std::condition_variable _cv;

        Worker(our_clock::time_point deadline) : _deadline(deadline) {}

        void operator()() const {
            std::unique_lock<std::mutex> lk(_mx);
            _cv.wait_until(lk,_deadline,[this] 
                    { 
                        std::cout << "worker: Signaledn";
                        auto now = our_clock::now();
                        if (now >= _deadline)
                            return true;
                        std::cout << "worker: Still waiting " << chrono::duration_cast<chrono::milliseconds>(_deadline - now).count() << "ms...n"; 
                        return false;
                    });
            std::cout << "worker: Donen";
        }
    };
}

int main()
{
    using namespace demo;

    Worker worker(our_clock::now() + chrono::seconds(2));
    auto th = std::thread(std::cref(worker));

    // after 2 seconds,update the timepoint
    std::this_thread::sleep_for(chrono::seconds(1));

    {
        std::lock_guard<std::mutex> lk(worker._mx);
        std::cout << "Updating shared delay value..." << "n";

        worker._deadline = our_clock::now() + chrono::seconds(1);
        worker._cv.notify_all();
    }

    th.join();
}

C 11标准库(无信令)

这是一种仅限标准库的方法,在截止日期前不使用同步.

我更倾向于使用原子time_point作为截止时间值本身,但这不受支持.接下来最好的事情就是shared_ptr< time_point> (使用std :: atomic_load / atomic_store)但我的编译器库尚未实现(grrr).

所以,相反,我从开始时间开始分享’偏移’：

#include <thread>
#include <chrono>
#include <iostream>
#include <atomic>

namespace demo
{
    namespace chrono = std::chrono;

    using our_clock = chrono::system_clock;
    using shared_delay = std::atomic<our_clock::duration>;

    void worker(our_clock::time_point const start,shared_delay const& delay)
    {
        for (our_clock::time_point deadline; our_clock::now() < (deadline = start + delay.load());)
        {
            std::cout << "worker: Sleeping for " << chrono::duration_cast<chrono::milliseconds>(deadline - our_clock::now()).count() << "ms...n";
            std::this_thread::sleep_until(deadline);
        }

        std::cout << "worker: Donen";
    }
}

int main()
{
    using namespace demo;

    shared_delay delay(chrono::seconds(2));
    auto th = std::thread(worker,our_clock::now(),std::cref(delay));

    // after 2 seconds,update the timepoint
    std::this_thread::sleep_for(chrono::seconds(1));
    std::cout << "Updating shared delay value..." << "n";
    delay.store(chrono::seconds(3));

    th.join();
}

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