`std::lock_guard` for `std::counting_semaphore`和`std::binary_semaphore`

Question

是否有类似于std::lock_guard、std::scoped_lock或std::unique_lock的标准所提供的与std::binary_semaphore和std::counting_semaphore相结合使用的RAII护卫？

Answer 1

与std::mutex不同，std::counting_semaphore的获取和释放调用可以发生在不同的线程上。因此，我认为在同一范围内锁定和解锁不是信号量的主要用例。但是，您可以像这样轻松地创建自定义lock_guard：

#include <semaphore>
#include <iostream>

template <typename T>
class custom_lock_guard
{
    T &m_;

public:
    custom_lock_guard(T &m) : m_(m)
    {
        m_.acquire();
        std::cout << "Lock acquired" << std::endl;
    }
    ~custom_lock_guard()
    {
        m_.release();
        std::cout << "Lock released" << std::endl;
    }
};

std::counting_semaphore<10> m(5);
std::binary_semaphore n(1);

int main()
{
    custom_lock_guard g(m);
    custom_lock_guard h(n);

    return 0;
}