Subj : Re: A question about atomic_ptr
To   : comp.programming.threads
From : Peter Dimov
Date : Sun Apr 10 2005 05:23 pm

Chris Thomasson wrote:
>> As a practical matter, I'd think you'd want some mechanism to
>> distinguish between shared global pointers and non-shared local
>> pointers.
>
> Agreed. For instance, I had to separate my atomic pointer into two
> distinguishable classes to address a highly critical performance
> issue:
> shared_smr_ptr<T>
> local_smr_ptr<T>
>
>
> shared_smr_ptr<T> alone is "way to expensive" to be used for a general
> purpose smart pointer.

That's what people tell me all the time, that shared_ptr is too expensive 
and they need an "unsynchronized" variant.

But it's not quite the same as Joe's local_ptr, I think; it still atomically 
updates its count. I think I'll reserve the local_ptr name for a pointer 
that uses a "local" count and non-atomic updates (but is convertible from 
and to a shared_ptr) so that people are free to shoot themselves in the 
foot, if they so insist.

.