Subj : Re: A question about atomic_ptr
To   : comp.programming.threads
From : Alexander Terekhov
Date : Tue Apr 12 2005 02:07 am


Peter Dimov wrote:
[...]
> But on the other hand "int" offers "basic" thread safety by default and
> "strong" thread safety if I only touch it with atomic_load_acq and
> atomic_store_rel.

Only if you properly isolate (align and pad if nessesary) it.

That's one reason for atomic<> wrapper.

[...]
> This is also why I'm not particularly fond of Alexander's atomic<> dedicated
> wrapper type. Providing atomic access via ordinary functions seems more
> natural.

Another reason is to "enforce" proper labeling for all accesses by
making the type opaque. An exclusive access on atomic<int> doesn't 
need to be isolated/atomic at all, it can be combined with other 
accesses. How are you going to do it all with "extended-for-threads" 
C/C++ volatiles (also mentioned by you in another message not here), 
for example? 

What else?

regards,
alexander.

.