On Oct19, 2011, at 18:05 , Greg Jaskiewicz wrote: > On 19 Oct 2011, at 17:54, Florian Pflug wrote: > >> On Oct19, 2011, at 17:47 , Greg Jaskiewicz wrote: >>> On 15 Oct 2011, at 11:31, Florian Pflug wrote: >>>> >>>> Ok, here's a first cut. >>> >>> So I looked at the patch, and first thing that pops out, >>> is lack of the volatile keyword before the ClientConnectionLostPending >>> variable is defined. Is that done on purpose ? Is that on purpose ? >> >> That's on purpose. volatile is only necessary for variables which are either >> accessed from within signal handlers or which live in shared memory. Neither >> is true for ClientConnectionLostPending, so non-volatile should be fine. > Ok, cool. > I'm aware of the reasons behind volatile, just noticed that some other flags > used in similar way are marked as such. At the end of the day, this is just a > hint to the compiler anyway.
All the other flags which indicate cancellation reasons are set from signal handers, I believe. We could of course mark as ClientConnectionLostPending as volatile just to be consistent. Not sure whether that's a good idea, or not. It might prevent a mistake should we ever add code to detect lost connections asynchronously (i.e., from somewhere else than pq_flush). And the cost is probably negligible, because CHECK_FOR_INTERRUPTS tests for InterruptPending before calling ProcessInterrupts(), so we only pay the cost of volatile if there's actually an interrupt pending. But I still think it's better to add qualifies such a volatile only when really necessary. A comment about why it *isn't* volatile is probably in order, though, so I'll add that in the next version of the patch. best regards, Florian Pflug PS: Thanks for the review. It's very much appreciated! -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
