Subj : Re: A question about atomic_ptr
To   : comp.programming.threads
From : Peter Dimov
Date : Mon Apr 11 2005 04:40 pm

Joe Seigh wrote:
> On Mon, 11 Apr 2005 14:26:44 +0300, Peter Dimov <pdimov@gmail.com>
> wrote:
>> This is about local_shared_ptr, not about copy/replace. The
>> local_shared_ptrs in an ownership group (which needs to be local to a
>> specific thread) use a local unsynchronized reference count to keep
>> track of their single shared_ptr-like reference into the shared_ptr
>> group. ChrisX got it right, but I still think that there's no need
>> to acquire in the increment, it's an ordinary 'add_ref_strong'.
>
> As a practical matter I don't think you're going to have have more
> than one local pointer copy of a global shared pointer often enought to
> justify the extra overhead of maintaining a separate reference count
> and of the extra indirection.

You may well be right. It's just one idea for a possible extension of 
shared_ptr that could pacify the "we want our unsynchronized pointers" 
portion of the "C++ community". I'm not sure yet whether it's a _good_ idea.

.