C++通過原子變量代替互斥量

廢話不多說，直接上代碼。

實現類似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一樣。

測試

class student
{
public:student();void move() const{ClockGuard locker(this->m_lockedFlag);std::cout << "自旋鎖" << 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));
}

結果

程序執行后立刻輸出 “自旋鎖”,然后每隔2s輸出一個。

自旋鎖
自旋鎖
自旋鎖
自旋鎖
自旋鎖
自旋鎖
自旋鎖
自旋鎖