Re: atomic reads & writes (with no barriers)

On Fri, Dec 4, 2015 at 6:35 AM, Greg Stark <stark@mit.edu> wrote:
> On Thu, Dec 3, 2015 at 10:10 PM, Kevin Grittner <kgrittn@gmail.com> wrote:
>> Is the c.h change above on anything resembling the right track for
>> a patch for this?  If not, what would such a patch look like?
>
> It would be nicer if we could come up with an interface that didn't
> require #ifdefs everywhere it's used.
>
> Something like
> ...
>   pg_maybe_atomic int64 threshold_timestamp;
> ...
>
> SpinLockAcquire_if_no_atomics(...)
> threshold_timestamp = &oldSnapshotControl->threshold_timestamp;
> SpinLockRelease_if_no_atomics(...)
>
> return threshold_timestamp;

Yeah, I didn't much like including the #ifdefs everywhere; I like
your suggestions.  Will work up a patch for the next CF along those
lines.

Thanks!

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company