"Eric Niebler" <eric@boost-consulting.com> wrote in message news:<443FF065.9020809@boost-consulting.com>...

I'm thinking about replacing some uses of shared_ptr with intrusive_ptr, but I've got questions. One of the nice things about shared_ptr is the

lock-free thread-safe ref counting. I want my intrusive_ptr to have

the

same safety and efficiency, but I don't see how to get it. I see $boost_root/detail/atomic_count.hpp, but shared_ptr doesn't use it. Why not? And why is it in detail/? Should I not consider using it?

Taking in the bigger picture, intrusive_ptr requires people to write their own add_ref and release functions, most of which will probably end up using ++ and -- on a plain integer. This is totally broken in multi-threaded applications, right? Isn't it dangerous to not provide complementary utilities for correctly managing reference counts? It seems to me intrusive_ptr is impossible to use safely and portably. What have I missed?

Check out the policy base smart pointer class in the following link: http://axter.com/smartptr/ This smart pointer uses an intrusive_lock_policy to synchronize both intrusive and non-intrusive smart pointers. Although intrusive_lock_policy uses intrusive logic, it still can work with any type by using the mutex_wrapper class. http://axter.com/smartptr/classmutex__wrapper.htm http://axter.com/smartptr/structintrusive__lock__policy.htm The mutex_wrapper class adds intrusive logic to any type. I believe the same can be done to the boost::intrusive_ptr class. It shouldn't be that hard to add a wrapper-class to boost that would give intrusive logic to any type. Example usage: boost::intrusive_ptr<intrusive_wrapper<vector<int> > > spVect = new boost::intrusive_wrapper<vector<int> >(); See following link for mutex_wrapper implementation: http://axter.com/smartptr/sync__wrapper_8hpp-source.htm