C++通过原子变量代替互斥量

C++通过原子变量代替互斥量

废话不多说，直接上代码。

实现类似lock_guard功能

#include <atomic>
#include <thread>

class ClockGuard
{
public:
    ClockGuard(std::atomic_flag & atomic):m_lockedFlag(atomic)
    {
        lock();
    }

    ~ClockGuard()
    {
        unlock();
    }

    void lock() const
    {
        while(m_lockedFlag.test_and_set(std::memory_order_acquire))
        {
            std::this_thread::sleep_for(std::chrono::microseconds(10));
        }
    }

    void unlock() const
    {
        m_lockedFlag.clear(std::memory_order_release);
    }
private:
    std::atomic_flag &m_lockedFlag;
};

ClockGuard的用法和lock_guard一样。

测试

class student
{
public:
    student();

    void move() const
    {
        ClockGuard locker(this->m_lockedFlag);
        std::cout << "自旋锁" << std::endl;
        std::this_thread::sleep_for(std::chrono::milliseconds(2000));
    }

private:
    mutable std::atomic_flag m_lockedFlag = ATOMIC_FLAG_INIT;

};

int main()
{
    student st;
    unsigned int count = 8;
    for (unsigned int i = 0; i < count; ++i)
    {
        std::thread t(&student::move, &st);
        t.detach();
    }
    
    std::this_thread::sleep_for(std::chrono::milliseconds(20000));
}

结果

程序执行后立刻输出 “自旋锁”,然后每隔2s输出一个。

自旋锁
自旋锁
自旋锁
自旋锁
自旋锁
自旋锁
自旋锁
自旋锁