2013-03-18 03:52 keltezéssel, Tom Lane írta:
Boszormenyi Zoltan <z...@cybertec.at> writes:
2013-03-17 16:07 keltezéssel, Tom Lane írta:
It suddenly occurs to me though that there's more than one way to skin
this cat. We could easily add another static flag variable called
"sigalrm_allowed" or some such, and have the signal handler test that
and immediately return without doing anything if it's off. Clearing
and setting such a variable would be a lot cheaper than an extra
setitimer call, as well as more robust since it would protect us from
all sources of SIGALRM not just ITIMER_REAL.
Something like the attached patch?
Well, something like that, but it still needed some improvements. In
particular I thought it best to leave the signal handler still releasing
the procLatch unconditionally --- that behavior is independent of what
this module is doing. Also you seem to have some odd ideas about what
do-while will accomplish. AFAIK, in this usage it's purely a syntactic
trick without much semantic content. It's the marking of the variable
as "volatile" that counts for telling the compiler not to re-order
operations.
The volatile marking shouldn't even be necessary there.
The signal handler doesn't writes to it, only the main code.
I just put it there saying "why not?" to myself.
IIRC, volatile is needed if both the signal handler and the
main code changes the same variable.
I got the reordering idea from here:
http://yarchive.net/comp/linux/compiler_barriers.html
Thanks for committing,
Zoltán Böszörményi
--
----------------------------------
Zoltán Böszörményi
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt, Austria
Web: http://www.postgresql-support.de
http://www.postgresql.at/
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
