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/**
* @file _refcounted.h
* @brief Atomic, thread-safe ref counting and destruction mixin class
*
* $LicenseInfo:firstyear=2012&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2012, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* 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 GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
#ifndef LLCOREINT__REFCOUNTED_H_
#define LLCOREINT__REFCOUNTED_H_
#include "linden_common.h"
#include "fix_macros.h"
#include <boost/thread.hpp>
#include <boost/intrusive_ptr.hpp>
#include "llatomic.h"
namespace LLCoreInt
{
class RefCounted
{
private:
RefCounted(); // Not defined - may not be default constructed
void operator=(const RefCounted &); // Not defined
public:
explicit RefCounted(bool const implicit)
: mRefCount(implicit)
{}
// ref-count interface
void addRef() const;
void release() const;
bool isLastRef() const;
S32 getRefCount() const;
void noRef() const;
static const S32 NOT_REF_COUNTED = -1;
protected:
virtual ~RefCounted();
virtual void destroySelf();
private:
mutable LLAtomicS32 mRefCount;
}; // end class RefCounted
inline void RefCounted::addRef() const
{
S32 count(++mRefCount);
llassert_always(count >= 0);
}
inline void RefCounted::release() const
{
S32 count(mRefCount);
llassert_always(count != NOT_REF_COUNTED);
llassert_always(count > 0);
count = --mRefCount;
// clean ourselves up if that was the last reference
if (0 == count)
{
const_cast<RefCounted *>(this)->destroySelf();
}
}
inline bool RefCounted::isLastRef() const
{
const S32 count(mRefCount);
llassert_always(count != NOT_REF_COUNTED);
llassert_always(count >= 1);
return (1 == count);
}
inline S32 RefCounted::getRefCount() const
{
const S32 result(mRefCount);
return result;
}
inline void RefCounted::noRef() const
{
llassert_always(mRefCount <= 1);
mRefCount = NOT_REF_COUNTED;
}
inline void RefCounted::destroySelf()
{
delete this;
}
/**
* boost::intrusive_ptr may be used to manage RefCounted classes.
* Unfortunately RefCounted and boost::intrusive_ptr use different conventions
* for the initial refcount value. To avoid leaky (immortal) objects, you
* should really construct boost::intrusive_ptr<RefCounted*>(rawptr, false).
* IntrusivePtr<T> encapsulates that for you.
*/
template <typename T>
struct IntrusivePtr: public boost::intrusive_ptr<T>
{
IntrusivePtr():
boost::intrusive_ptr<T>()
{}
IntrusivePtr(T* p):
boost::intrusive_ptr<T>(p, false)
{}
};
inline void intrusive_ptr_add_ref(RefCounted* p)
{
p->addRef();
}
inline void intrusive_ptr_release(RefCounted* p)
{
p->release();
}
} // end namespace LLCoreInt
#endif // LLCOREINT__REFCOUNTED_H_
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