intrusive_ptr.h

#pragma once
//-----------------------------------------------------------------------------
// Class:   Intrusive_ptr
// Authors: LiXizhi
// Emails:  LiXizhi@yeah.net
// Company: ParaEngine
// Date:    2009.6.4
// Desc:  a thread-safe intrusive_ptr to replace boost::shared_ptr. It has smaller memory footprint than shared_ptr.
// since the reference counter is on the object itself. 
//-----------------------------------------------------------------------------
namespace ParaEngine
{
    class intrusive_ptr_thread_safe_base;
    class intrusive_ptr_single_thread_base;
}

namespace boost
{
    // the two function overloads must be in the boost namespace on most compilers:
    PE_CORE_DECL void intrusive_ptr_add_ref(ParaEngine::intrusive_ptr_thread_safe_base* ref);
    PE_CORE_DECL void intrusive_ptr_release(ParaEngine::intrusive_ptr_thread_safe_base* ref);

    PE_CORE_DECL void intrusive_ptr_add_ref(ParaEngine::intrusive_ptr_single_thread_base* ref);
    PE_CORE_DECL void intrusive_ptr_release(ParaEngine::intrusive_ptr_single_thread_base* ref);
}

#include <boost/intrusive_ptr.hpp>
#include <boost/detail/atomic_count.hpp>

#ifndef ParaIntrusivePtr
#define ParaIntrusivePtr boost::intrusive_ptr
#endif

namespace ParaEngine
{
    class PE_CORE_DECL intrusive_ptr_thread_safe_base
    {
        friend void boost::intrusive_ptr_add_ref(intrusive_ptr_thread_safe_base*);
        friend void boost::intrusive_ptr_release(intrusive_ptr_thread_safe_base*);
    public:
#ifdef WIN32
        mutable long m_ref_count;
#else
        mutable boost::detail::atomic_count m_ref_count;
#endif
    protected:
        intrusive_ptr_thread_safe_base() : m_ref_count(0){};
        intrusive_ptr_thread_safe_base(const intrusive_ptr_thread_safe_base&) : m_ref_count(0){};
        intrusive_ptr_thread_safe_base& operator=(const intrusive_ptr_thread_safe_base&) { return *this; }
        virtual ~intrusive_ptr_thread_safe_base(){};
    };

    class PE_CORE_DECL intrusive_ptr_single_thread_base
    {
        friend void boost::intrusive_ptr_add_ref(intrusive_ptr_single_thread_base*);
        friend void boost::intrusive_ptr_release(intrusive_ptr_single_thread_base*);

    public:
        mutable long m_ref_count;

    protected:
        intrusive_ptr_single_thread_base() : m_ref_count(0){};
        intrusive_ptr_single_thread_base(const intrusive_ptr_single_thread_base&) : m_ref_count(0){};
        intrusive_ptr_single_thread_base& operator=(const intrusive_ptr_single_thread_base&) { return *this; }
        virtual ~intrusive_ptr_single_thread_base(){};
    };
}