Re: Interruptible sleeps (was Re: CommitFest 2009-07: Yay, Kevin! Thanks, reviewers!)

Jeff Davis <pgsql@j-davis.com> writes:
> However, that also means that the whole concept of OwnLatch/DisownLatch
> is entirely redundant, and only there for asserts because it doesn't do
> anything else. That seems a little strange to me, as well, so (at
> minimum) it should be documented that the functions really have no
> effect on execution and are required only to support debugging.

Uh, this is nonsense.  You have to have something like these functions
to support transferring ownership of a latch from one process to
another, which is required at least for the walreceiver usage.

It's correct that the latch code itself isn't trying very hard to avoid
a race condition in acquiring ownership, but that doesn't make the whole
thing useless, it just means that we're assuming that will be avoided
by logic elsewhere.  If there is a bug elsewhere that allows two
different processes to try to take ownership of the same latch, the
current coding will expose that bug soon enough.
        regards, tom lane