C++中多线程的加锁机制

class singleStance{
private :
singleStance();
public :
static singleStance* onlystance;
static singleStance* getStance(){
lockBase* lockbase = new lockBase();
lockBase->lock();
if(onlystance){
onlystance = new singleStance();
}
lockBase->unlock();
return onlystance;
}

};
class lockBase{
protected:

friend class singleStance;
CRITICAL_SECTION cs;

public :
lockBase(){
::InitializeCriticalSection(&cs);
}
void lock(){
::EnterCriticalSection(&cs);
}
void unlock(){
::LeaveCriticalSection(&cs);
}
~lockBase(){
::DeleteCriticalSection(&cs);
}

};