设计模式学习之单件模式

class CSingleton
{
public:
    static CSingleton* GetInstance();

    /**
    释放单例，应仅限于所有对单例对象的使用完成后调用
    */
    static void ReleaseInstance();

    void DoSomething();

private:
    CSingleton();
	CSingleton(const CSingleton&);  // private and not implemented copy constructor
	CSingleton& operator=(const CSingleton&); // private and not implemented = operator

    volatile static CSingleton* m_sUniqueInstance;
    static HANDLE m_hSync;
};

volatile CSingleton* CSingleton::m_sUniqueInstance = NULL;
HANDLE CSingleton::m_hSync = ::CreateEvent(NULL, FALSE, TRUE, NULL);

CSingleton* CSingleton::GetInstance()
{
    if (NULL == m_sUniqueInstance)
	{
        WaitForSingleObject(m_hSync, INFINITE);
        if (NULL == m_sUniqueInstance)
		{
            m_sUniqueInstance = new CSingleton();
		}
        SetEvent(m_hSync);
	}

    return (CSingleton*)m_sUniqueInstance;
}

void CSingleton::ReleaseInstance()
{
    if (0 != m_sUniqueInstance)
	{
        delete m_sUniqueInstance;
        m_sUniqueInstance = NULL;
	}

    if (NULL != m_hSync)
	{
        CloseHandle(m_hSync);
	}
}