atomic reference counting primatives.

[Julian Elischer]

On Fri, 21 May 2004, Garance A Drosihn wrote:

> At 1:56 PM -0700 5/20/04, Julian Elischer wrote:
> >This has been raised before but I have come across uses for
> >it again and again so I'm raising it again.   JHB once posted
> >some atomic reference counting primitives. (Do you still have
> >them John?)   Alfred once said he had some somewhere too, and
> >others have commented on this before, but we still don't seem
> >to have any.
> 
> Btw, does this thread have anything to do with the present
> buuldworld-breakage for sparc64?

Not specifically, but for the reasons you outline below, 
it's an example of the kind of reason one might have for doing it..




>  I notice the compile-time
> errors are something like:
> 
> /usr/src/lib/libthr/thread/thr_cancel.c: In function `testcancel':
> /usr/src/lib/libthr/thread/thr_cancel.c:123: warning: passing
>       arg 1 of `atomic_cmpset_int' from incompatible pointer type
> 
> My guess is that this is related to Mike's change to "Make libthr 
> async-signal-safe without costly signal masking. [...etc...]".
> 
> This breakage underlines one reason that it would be mighty
> convenient to have some "official" set of primitives.  It is
> one thing if a developer has to roll-their-own solution for
> i386, but somewhat more challenging if that solution has to
> work across a half-dozen different hardware platforms.
> 
> This also suggests that it would be nice if the primitives
> could be written so that if the wrong type-of-parameters are
> given, the compiles will fail on *all* platforms.
> 
> -- 
> Garance Alistair Drosehn            =   gad at gilead.netel.rpi.edu
> Senior Systems Programmer           or  gad at freebsd.org
> Rensselaer Polytechnic Institute    or  drosih at rpi.edu
>