Referenced.h

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/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
 *
 * This library is open source and may be redistributed and/or modified under
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * OpenSceneGraph Public License for more details.
*/

#ifndef OSG_REFERENCED
#define OSG_REFERENCED 1

#include <osg/Export>

#include <OpenThreads/ScopedLock>
#include <OpenThreads/Mutex>
#include <OpenThreads/Atomic>

#if !defined(_OPENTHREADS_ATOMIC_USE_MUTEX)
# define _OSG_REFERENCED_USE_ATOMIC_OPERATIONS
#endif

namespace osg {

// forward declare, declared after Referenced below.
class DeleteHandler;
class Observer;
class ObserverSet;

template <typename T, T M()>
struct depends_on
{
    depends_on() { M(); }
};

class OSG_EXPORT Referenced
{

    public:


        Referenced();

        explicit Referenced(bool threadSafeRefUnref);

        Referenced(const Referenced&);

        inline Referenced& operator = (const Referenced&) { return *this; }

        virtual void setThreadSafeRefUnref(bool threadSafe);

#if defined(_OSG_REFERENCED_USE_ATOMIC_OPERATIONS)
        bool getThreadSafeRefUnref() const { return true; }
#else
        bool getThreadSafeRefUnref() const { return _refMutex!=0; }
#endif

#if defined(_OSG_REFERENCED_USE_ATOMIC_OPERATIONS)
        OpenThreads::Mutex* getRefMutex() const { return getGlobalReferencedMutex(); }
#else
        OpenThreads::Mutex* getRefMutex() const { return _refMutex; }
#endif

        static OpenThreads::Mutex* getGlobalReferencedMutex();

        inline int ref() const;

        inline int unref() const;

        int unref_nodelete() const;

        inline int referenceCount() const { return _refCount; }


        ObserverSet* getObserverSet() const
        {
            #if defined(_OSG_REFERENCED_USE_ATOMIC_OPERATIONS)
                return static_cast<ObserverSet*>(_observerSet.get());
            #else
                return static_cast<ObserverSet*>(_observerSet);
            #endif
        }

        ObserverSet* getOrCreateObserverSet() const;

        void addObserver(Observer* observer) const;

        void removeObserver(Observer* observer) const;

    public:

        static void setThreadSafeReferenceCounting(bool enableThreadSafeReferenceCounting);

        static bool getThreadSafeReferenceCounting();

        friend class DeleteHandler;

        static void setDeleteHandler(DeleteHandler* handler);

        static DeleteHandler* getDeleteHandler();


    protected:

        virtual ~Referenced();

        void signalObserversAndDelete(bool signalDelete, bool doDelete) const;

        void deleteUsingDeleteHandler() const;

#if defined(_OSG_REFERENCED_USE_ATOMIC_OPERATIONS)
        mutable OpenThreads::AtomicPtr  _observerSet;

        mutable OpenThreads::Atomic     _refCount;
#else

        mutable OpenThreads::Mutex*     _refMutex;

        mutable int                     _refCount;

        mutable void*                   _observerSet;
#endif
};

inline int Referenced::ref() const
{
#if defined(_OSG_REFERENCED_USE_ATOMIC_OPERATIONS)
    return ++_refCount;
#else
    if (_refMutex)
    {
        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(*_refMutex);
        return ++_refCount;
    }
    else
    {
        return ++_refCount;
    }
#endif
}

inline int Referenced::unref() const
{
    int newRef;
#if defined(_OSG_REFERENCED_USE_ATOMIC_OPERATIONS)
    newRef = --_refCount;
    bool needDelete = (newRef == 0);
#else
    bool needDelete = false;
    if (_refMutex)
    {
        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(*_refMutex);
        newRef = --_refCount;
        needDelete = newRef==0;
    }
    else
    {
        newRef = --_refCount;
        needDelete = newRef==0;
    }
#endif

    if (needDelete)
    {
        signalObserversAndDelete(true,true);
    }
    return newRef;
}

// intrusive_ptr_add_ref and intrusive_ptr_release allow
// use of osg Referenced classes with boost::intrusive_ptr
inline void intrusive_ptr_add_ref(Referenced* p) { p->ref(); }
inline void intrusive_ptr_release(Referenced* p) { p->unref(); }

}

#endif