On 2017-06-06 23:24:50 +0200, Petr Jelinek wrote:
> On 06/06/17 23:17, Andres Freund wrote:
> > Right. I found a couple more instance of similarly iffy, although not
> > quite as broken, patterns in launcher.c. It's easy to get this wrong,
> > but it's a lot easy if you do it differently everywhere you use a
> > latch. It's not good if code in the same file, by the same author(s),
> > has different ways of using latches.
>
> Huh? I see same pattern everywhere in launcher.c, what am I missing?
WaitForReplicationWorkerAttach:
while (...) CHECK_FOR_INTERRUPTS(); /* other stuff including returns */ WaitLatch() WL_POSTMASTER_DEATH
ResetLatch()
logicalrep_worker_stop loop 1:
while (...) /* other stuff */ CHECK_FOR_INTERRUPTS() WaitLatch() POSTMASTER_DEATH ResetLatch() /* other
stuffincluding returns */
logicalrep_worker_stop loop 1:
while (...) /* other stuff including returns */ CHECK_FOR_INTERRUPTS(); WaitLatch() WL_POSTMASTER_DEATH
ResetLatch()
ApplyLauncherMain:
while (!got_SIGTERM) /* lots other stuff */ WaitLatch() WL_POSTMASTER_DEATH /* some other stuff */
ResetLatch()
(note no CFI)
they're not hugely different, but subtely there are differences.
Sometimes you're guaranteed to check for interrupts after resetting the
latch, in other cases not. Sometimes expensive-ish things happen before
a CFI...
Greetings,
Andres Freund
