#include <mutex>
#include <condition_variable>


class Event {
public:
    Event() {};
    ~Event() {};

    bool wait(std::chrono::milliseconds millisec) {

        std::unique_lock<std::mutex> l(m_lock);
        auto cv = m_cond.wait_for(l, millisec);
        if (cv == std::cv_status::no_timeout) {
            return true;
        }
        return false;
    };
    void notify() {
        m_cond.notify_all();
    };

private:
    std::mutex m_lock;
    std::condition_variable m_cond;
};
class MyClass
{
public:
    MyClass() {};
    ~MyClass() {};
    void start() {
        std::thread run_thread(std::bind(&MyClass::run, this));
        run_thread.detach();
    };
    void run() {
        while (true)
        {
            if (m_event.wait(std::chrono::milliseconds(500)))
            {
                printf("end thread!\n");
                break;
            }
            else
            {
                printf("do something,continue thread!\n");
                continue;
            }
        }
    };
    void stop() {
        m_event.notify();
    };
private:
    Event    m_event;
};



int main()
{
    MyClass test;
    test.start();
    std::this_thread::sleep_for(std::chrono::milliseconds(1000*10));
    printf("before stop!\n");
    test.stop();

    system("pause");
    return 0;
}

上面这段代码，本意是想当调用stop的时候通知线程退出，但是实际情况是不到调用stop之前，线程就被通知退出了。而且退出时机是随机的，有时早有时晚，可能是我对condition_variable理解的不够，请问哪里的问题。谢谢
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