class Lock  {  private:             CCriticalSection m_cs;  public:      Lock(CCriticalSection  cs) : m_cs(cs)      {          m_cs.Lock();      }      ~Lock()      {          m_cs.Unlock();      }  };    class Singleton  {  private:      Singleton();      Singleton(const Singleton &);      Singleton& operator = (const Singleton &);    public:      static Singleton *Instantialize();      static Singleton *pInstance;      static CCriticalSection cs;  };    Singleton* Singleton::pInstance = 0;    Singleton* Singleton::Instantialize()  {      if(pInstance == NULL)      {   //double check           Lock lock(cs);           //用lock实现线程安全，用资源管理类，实现异常安全           //使用资源管理类，在抛出异常的时候，资源管理类对象会被析构，析构总是发生的无论是因为异常抛出还是语句块结束。           if(pInstance == NULL)          {              pInstance = new Singleton();          }      }      return pInstance;  }