临界区访问的两个类：临界区类，共享临界区类

CSharedCriticalSection 实现临界区的访问：加锁、去锁

CSharedMutex 实现临时窃取临界区对象，然后加锁，对象销毁时又会去锁，然后归还对象

class CSharedCriticalSection {
public:
    CSharedCriticalSection() {
        InitializeCriticalSection(&critical_section_);
    }

    ~CSharedCriticalSection() {
        DeleteCriticalSection(&critical_section_);
    }

    void lock() {
        EnterCriticalSection(&critical_section_);
    }

    void unlock() {
        LeaveCriticalSection(&critical_section_);
    }

private:
    CRITICAL_SECTION critical_section_;
};


class CSharedMutex {
public:
    explicit CSharedMutex(CSharedCriticalSection& critical_section)
    : is_lock_(false)
    , critical_section_(critical_section)
    {
        if(is_lock_ == false) {
            is_lock_ = true;
            critical_section_.lock();
        }
    }

    ~CSharedMutex(){
        if(is_lock_) {
            is_lock_ = false;
            critical_section_.unlock();
        }
    }

    void lock() {
        if(is_lock_ == false) {
            is_lock_ = true;
            critical_section_.lock();
        }
    }

    void unlock() {
        if(is_lock_) {
            is_lock_ = false;
            critical_section_.unlock();
        }
    }

protected:
    CSharedMutex(const CSharedMutex& rhs)
        : critical_section_(rhs.critical_section_)
    {

    }

    CSharedMutex& operator=(const CSharedMutex& rhs) {
        return *this;
    }

private:
    volatile bool is_lock_;
    CSharedCriticalSection& critical_section_;
};