smartptr.h

遗传算法做图像的模式匹配

		GaSmartPtr(const GaSmartPtr<T>& ptr) : _lock(0)
		{
			Lock( ptr );

			// add new reference to smart location
			GaSmartStorage<T>::AddReference( ptr._location );

			_location = ptr._location;
			_data = _location ? _location->_data : NULL;

			Unlock( ptr );
		}

		/// <summary>Default constructor, initializes pointer as <c>NULL</c> pointer.
		/// Creation of smart pointer and counting of references is thread-safe.</summary>
		GaSmartPtr() : _location(NULL),
			_data(NULL),
			_lock(0) { }

		/// <summary>Decrements number of references to data. If there is no more references, memory used my data is freed and object is destroyed.
		/// Destruction of smart pointer is thread-safe.</summary>
		~GaSmartPtr()
		{
			Lock();

			GaSmartStorage<T>::RemoveReference( _location );

			Unlock();
		}

		/// <summary>Operator provides access to data to which smart pointer points. This method is thread safe, but it cannot be guaranteed
		/// that memory will not be freed if some other thread changes pointer after address is returned.</summary>
		/// <returns>Operator returns pointer to user data.</returns>
		inline T* GACALL operator ->() const { return _data; }

		/// <summary>Operator provides access to data to which smart pointer points. This method is thread safe, but it cannot be guaranteed
		/// that memory will not be freed if some other thread changes pointer after address is returned.</summary>
		/// <returns>Operator returns reference to user data.</returns>
		inline T& GACALL operator *() const { return *_data; }

		/// <summary>Sets smart pointer to points to same location as <c>rhs</c> pointer.
		/// It also decrements number of references of old smart locationa and increments number of new smart location.
		/// If number of references of old location reached zero, this operator frees used memory. This operator is thread-safe.</summary>
		/// <param name="rhs">smart pointer which holds address to which <c>this</c> pointer should point.</param>
		/// <returns>Operator returns reference to <c>this</c> object.</returns>
		inline GaSmartPtr<T>& GACALL operator =(const GaSmartPtr<T>& rhs)
		{
			if( this != &rhs )
			{
				Lock( rhs );

				if( rhs._location != _location )
				{
					// remove old reference
					GaSmartStorage<T>::RemoveReference( _location );

					// new reference
					GaSmartStorage<T>::AddReference( rhs._location );

					_location = rhs._location;
					_data = _location ? _location->_data : NULL;
				}

				Unlock( rhs );
			}
			return *this;
		}

		/// <summary>Sets smart pointer to points to <c>rhs</c> smart location for storing data.
		/// It also decrements number of references of old smart locationa and increments number of new smart location.
		/// If number of references of old location reached zero, this operator frees used memory. This operator is thread-safe.</summary>
		/// <param name="rhs">reference to smart location to which <c>this</c> pointer should point.</param>
		/// <returns>Operator returns reference to <c>this</c> object.</returns>
		inline GaSmartPtr<T>& GACALL operator =(GaSmartStorage<T>& rhs)
		{
			Lock();

			if( &rhs != _location )
			{
				// remove old reference
				GaSmartStorage<T>::RemoveReference( _location );

				// new reference
				GaSmartStorage<T>::AddReference( &rhs );

				_location = &rhs;
				_data = _location ? _location->_data : NULL;
			}

			Unlock();

			return *this;
		}

		/// <summary>This operator makes new instance of <see cref="GaSmartStorage" /> and binds unmanaged memory to the smart storage and
		/// sets pointer to it. It also decrements number of references of old smart locationa and increments number of new smart location.
		/// If number of references of old location reached zero, this operator frees used memory. This operator is thread-safe.</summary>
		/// <param name="rhs">raw pointer to user data which should be managed.</param>
		/// <returns>Operator returns reference to <c>this</c> object.</returns>
		inline GaSmartPtr<T>& GACALL operator =(T* rhs)
		{
			Lock();

			if( &rhs != _data )
			{
				GaSmartStorage<T>* location = GaSmartStorage<T>::MakeInstanceDirect( rhs );

				// remove old reference
				GaSmartStorage<T>::RemoveReference( _location );

				// new reference
				GaSmartStorage<T>::AddReference( location );

				_location = location;
				_data = _location ? _location->_data : NULL;
			}

			Unlock();

			return *this;
		}

		// Compare to see if two smart pointer points to same safe location.
		/// <summary>Compares two smart pointers to see they points to same data. This operator is thread-safe.</summary>
		/// <param name="rhs">the second smart pointer in the expression.</param>
		/// <returns>Operator returns true if two pointers point to same location.</returns>
		inline bool GACALL operator ==(const GaSmartPtr<T>& rhs) const { return _location == rhs._location; }

		/// <summary>This method is thread-safe.</summary>
		/// <returns>Method returns raw pointer to user data.</returns>
		inline T* GACALL GetRawPtr() const { return _data; }

		/// <summary>Checks pointer against <c>NULL</c> value. This method is thread-safe.</summary>
		/// <returns>Returns <c>true</c> if this is <c>NULL</c> pointer.</returns>
		inline bool GACALL IsNULL() const { return !_data; }

	private:

		/// <summary>This method prevents concurrent changes of smart pointer by locking it.</summary>
		inline void Lock() const
		{
			// sections are very short so spin-lock is used
			SPINLOCK( _lock );
		}

		/// <summary>This method prevents concurrent changes of <c>this</c> and <c>second</c> smart pointers and it is used
		/// when value of one pointer is assigning to another (<c>operator =</c> or copy constructor). Order of pointer locking is
		/// defined by order of addresses of pointers' objects to prevent deadlocks (first is locked pointer which object has lower address).</summary>
		/// <param name="second">the second pointer which is used in expression.</param>
		inline void Lock(const GaSmartPtr<T>& second) const
		{
			// sections are very short so spin-lock is used
			// pointer sare locked in order in which address are ordered to prevent deadlocks
			if( this < &second )
			{
				SPINLOCK( _lock );
				SPINLOCK( second._lock );
			}
			else
			{
				SPINLOCK( second._lock );
				SPINLOCK( _lock );
			}
		}

		/// <summary>This method unlocks changes of smart pointer.</summary>
		inline void Unlock() const { _lock = 0; }

		/// <summary>This method unlocks changes of this and second smart pointers, it is used after assigning of values
		/// from one smart pointer to another is done (<c>operator =</c> or copy constructor).</summary>
		/// <param name="second">the second pointer whic is used in expression.</param>
		inline void Unlock(const GaSmartPtr<T>& second)
		{
			_lock = 0;
			second._lock = 0;
		}

	public:

		/// <summary><c>NullPtr</c> is global constant <c>NULL</c> pointer for <c>T</c> type.</summary>
		static const GaSmartPtr<T> NullPtr;

	};// END CLASS DEFINITION GaSmartPtr
	
	// NULL pointer
	template <typename T>
	const GaSmartPtr<T> GaSmartPtr<T>::NullPtr;
	
} // Common

#endif //__GA_SMART_PTR_H__