C++ implements a thread safe singleton factory implementation code

C++ implements 1 thread-safe singleton factory implementation code

We've seen a lot of people implementing similar singletons using static local objects, and recently found an article that explicitly stated that the compiler is not thread-safe when dealing with static local variables!!

http://blogs.msdn.com/b/oldnewthing/archive/2004/03/08/85901.aspx

Thus, a singleton factory is implemented and thread safe

#ifndef SINGLETONFACTORY_H 
#define SINGLETONFACTORY_H 
#include "windows.h" 
#include <memory> 
namespace Tools 
{ 
template<class T>class SingletonFactory 
{ 
public: 
  virtual ~SingletonFactory() 
  { 
   ::DeleteCriticalSection(&__criticalSection); 
  } 
  std::auto_ptr<T>& GetInstance(); 
  static SingletonFactory<T>* CreateSingletonFactory(); 
private: 
  SingletonFactory() 
  { 
    ::InitializeCriticalSection(&__criticalSection); 
  } 
  std::auto_ptr<T> __singletonObj; 
  CRITICAL_SECTION __criticalSection; 
}; 
 
// Initialization creation   It is used later in multithreading  
// There is another 1 This is written as a separate function that directly returns an internal singleton wrapped in static members   Not safe with multiple threads  
//SingletonFactory::CreateSingletonFactory().GetInstance(); 
template<class T> SingletonFactory<T>* SingletonFactory<T>::CreateSingletonFactory(){ 
  static SingletonFactory<T> temObj; 
  return &temObj; 
} 
// Factory instance  
template<class T> std::auto_ptr<T>& SingletonFactory<T>::GetInstance() 
{ 
  if(__singletonObj.get()==0) 
  { 
    ::EnterCriticalSection(&__criticalSection); 
    if(__singletonObj.get()==0) 
      __singletonObj=std::auto_ptr<T>(new T); 
    ::LeaveCriticalSection(&__criticalSection); 
  } 
  return __singletonObj; 
} 
} 
 
#endif // SINGLETONFACTORY_H 

The test code

SingletonFactory<Data1>*singleton1=SingletonFactory<Data1>::CreateSingletonFactory(); 
singleton1->GetInstance()->x=100; 
cout<<singleton1->GetInstance()->x<<endl; 
singleton1->GetInstance()->y=200; 
cout<<singleton1->GetInstance()->x<<endl; 
cout<<singleton1->GetInstance()->y<<endl; 
 
SingletonFactory<Data2>*singleton2=SingletonFactory<Data2>::CreateSingletonFactory(); 
singleton2->GetInstance()->x=100; 
cout<<singleton2->GetInstance()->x<<endl; 
singleton2->GetInstance()->y=200; 
cout<<singleton2->GetInstance()->x<<endl; 
cout<<singleton2->GetInstance()->y<<endl; 

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