////////////////////////////////////////////////////////////////////////////////
// Singleton.h
////////////////////////////////////////////////////////////////////////////////

#ifndef __SINGLETON_H__
#define __SINGLETON_H__

#include "ProcessFunction/ProcessConfig.h"
#include "ProcessFunction/UGGuard.h"

namespace UGC{


class Cleanup
{
public:
	/// No-op constructor.
	Cleanup (void){};

	/// Destructor.
	virtual ~Cleanup (void){};

	/// Cleanup method that, by default, simply deletes itself.
	virtual void cleanup () = 0;
};

template <class TYPE, class LOCK>
class SingletonThreadSafe: public Cleanup
{
public:
	/// Global access point to the Singleton.
	static TYPE *instance (void)
	{
		SingletonThreadSafe<TYPE, LOCK> *&singleton = SingletonThreadSafe<TYPE, LOCK>::instance_i();

		// Perform the Double-Check pattern...
		if (singleton == 0)
		{
			static LOCK lock;
			GUARD_RETURN (LOCK, mon, lock, 0);
			/*if (singleton == 0)
			{*/
			NEW_RETURN (singleton, (SingletonThreadSafe<TYPE, LOCK>), 0);
			//}
		}

		return &singleton->instance_;
	}


	/// Cleanup method
	virtual void cleanup ()
	{
		SingletonThreadSafe<TYPE, LOCK> *&singleton = SingletonThreadSafe<TYPE, LOCK>::instance_i();

		if (singleton)
		{
			delete this;
			SingletonThreadSafe<TYPE, LOCK>::instance_i () = 0;
		}
	}

	/// Get pointer to the SingletonThreadSafe instance.
	static SingletonThreadSafe<TYPE, LOCK> *&instance_i(void)
	{
		static SingletonThreadSafe<TYPE, LOCK> *singleton_ = 0;
		return singleton_;
	}

	~SingletonThreadSafe (void){}

protected:
	/// Default constructor.
	SingletonThreadSafe (void){}

	/// Contained instance.
	TYPE instance_;
};


extern "C" void CLEANUP_DESTROYER_NAME (Cleanup *object);
#define DEL_SINGLETON(X) CLEANUP_DESTROYER_NAME(X::instance_i())

}


#endif