[boost] shared_ptr changes

From: Peter Dimov (pdimov_at_[hidden])
Date: 2005-03-17 20:38:21

I've made some pretty extensive changes to the implementation of shared_ptr. 
It now uses a lock-free algorithm (originally invented by Alexander 
Terekhov) on Windows, and the old detail/shared_count.hpp has been 
refactored into a number of smaller headers. A per-count pthread_mutex is 
still being used on non-Windows platforms, but this is also going to change 
soon.

Now is the time to test the new implementation; please report any errors you 
encounter. Some of you have posted patches against the old implementation; 
these will need to be reexamined, too.

detail/lightweight_mutex will also change "soon"; it will just map into a 
CRITICAL_SECTION or a pthread_mutex depending on the platform. The spin 
locks will disappear. shared_ptr no longer uses lightweight_mutex.

If you use some of the undocumented features of shared_ptr - 
BOOST_SP_USE_STD_ALLOCATOR, BOOST_SP_ENABLE_DEBUG_HOOKS, sp_collector.cpp - 
please say so. During the refactoring I may drop some of these features in 
order to simplify and streamline the implementation.

Thanks,

--
Peter Dimov
http://www.pdimov.com