Re: incorrect xlog.c coverage report

On 2018-Nov-22, Michael Paquier wrote:

> On Thu, Nov 22, 2018 at 10:56:39AM +0900, Masahiko Sawada wrote:
> > On Thu, Nov 22, 2018 at 10:43 AM Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com> wrote:
> >> Presumably you could add your own call to __gcov_flush() in
> >> quickdie(), so that we get GCOV data but no other atexit()-like stuff.
> >> I see that some people advocate doing that in signal handlers, but I
> >> don't know if it's really safe. If that is somehow magically OK,
> >> you'd probably also need the chdir() hack from proc_exit() to get
> >> per-pid files.
> >
> > That's probably a good idea, I'm also not sure if it's really safe
> > though. An alternative approach could be that we can do $node->restart
> > after recovered from $node->teardown_node() to write gcda file surely,
> > although it would make the tests hard to read.
>
> Thanks for looking at the details around that. I'd prefer much if we
> have a solution like what's outline here because we should really try to
> have coverage even for code paths which involve an immediate shutdown
> (mainly for recovery). Manipulating the tests to get a better coverage
> feels more like a band-aid solution, and does not help folks with custom
> TAP tests in their plugins.

I've just realized that we didn't do anything about this (see line 5380
in https://coverage.postgresql.org/src/backend/access/transam/xlog.c.gcov.html)
, and we should. I still prefer the solution I proposed (which is to
edit the test files to avoid immediate shutdown in certain places), but
I admit that adding __gcov_flush() to quickdie() seems to have gotten
more votes.

Are there objections to doing that now on the master branch?

--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services