Re: shared-memory based stats collector

Thank you for looking this.

At Fri, 27 Mar 2020 12:34:02 -0300, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> wrote in
> On 2020-Mar-27, Kyotaro Horiguchi wrote:
>
> > +/*
> > + * XLogArchiveWakeupEnd - Set up archiver wakeup stuff
> > + */
> > +void
> > +XLogArchiveWakeupStart(void)
> > +{
> > + Latch *old_latch PG_USED_FOR_ASSERTS_ONLY;
> > +
> > + SpinLockAcquire(&XLogCtl->info_lck);
> > + old_latch = XLogCtl->archiverWakeupLatch;
> > + XLogCtl->archiverWakeupLatch = MyLatch;
> > + SpinLockRelease(&XLogCtl->info_lck);
> > + Assert (old_latch == NULL);
> > +}
>
> Comment is wrong about the function name; OTOH I don't think the

Oops! I found a similar mistake in another place. (pgstat_flush_funcentry)

> old_latch assigment in the fourth line won't work well in non-assert
> builds. But why do you need those shenanigans? Surely
> "Assert(XLogCtl->archiverWakeupLatch == NULL)" in the locked region
> before assigning MyLatch should be sufficient and acceptable?

Right. Maybe I wanted to move the assertion out of the lock section,
but that's actually useless.

Fixed them and rebased.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center