atomic reference counting primatives.

[Garance A Drosihn]

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?  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