c++ - 线程终止

Question

我无法关闭我的线程。我忘记做某事了吗？该线程似乎正在保存我用于关闭的值，然后从不检查它是否已更改。下面是一些具有相同效果的示例代码:

#include "stdafx.h"
#include "Windows.h"
#include <iostream>
#include <thread>

class test {
private:
    bool user_wants_thread = true;
    bool time_to_close = false;

public:
    bool set_timetoclose(bool in) {
        time_to_close = in;
        if (time_to_close == in) {
            return true;
        }
        return false;
    }
    void function() {
        while (user_wants_thread) {
            // CODE
            std::cout << time_to_close;
            Sleep(100);
            if (time_to_close) {
                goto close;
            }
        }
    close:
        Sleep(1);
    }
};

int main() {
    test t;

    std::thread thread_func(&test::function, t);
    Sleep(1000);

    bool success;
    do {
        success = t.set_timetoclose(true);
    } while (!success);

    thread_func.join();
    std::cout << "Closed";
    std::cin.get();
}

Answer 1

我删除了一些未使用的部分并将实际情况更改为 atomic<bool>它似乎如此链接所示工作:

http://rextester.com/TWHK12491

不过，我并不是说这是绝对正确的，但它显示了使用 atomic 如何导致跨读取/写入值的同步，这可能导致数据竞争。

#include "Windows.h"
#include <iostream>
#include <thread>
#include <atomic>
class test {

public:
    std::atomic<bool> time_to_close = false;

    test()=default;
    void function() {
        while (!time_to_close) {
            std::cout << "Running..." << std::endl;
            Sleep(100);
        }
        std::cout << "closing" << std::endl;
    }
};

int main() {
    test t;
    std::thread thread_func([&t](){t.function();});
    Sleep(500);

    t.time_to_close = true;
    std::cout << "Joining on thread" << std::endl;
    thread_func.join();
    std::cout << "Closed";

    return 0;
}