Re: recovery modules

Hi,

On 2023-02-16 12:15:12 -0800, Nathan Bossart wrote:
> Thanks for reviewing.
>
> On Thu, Feb 16, 2023 at 11:29:56AM -0800, Andres Freund wrote:
> > On 2023-02-15 10:44:07 -0800, Nathan Bossart wrote:
> >> @@ -144,10 +170,12 @@ basic_archive_configured(void)
> >> * Archives one file.
> >> */
> >> static bool
> >> -basic_archive_file(const char *file, const char *path)
> >> +basic_archive_file(ArchiveModuleState *state, const char *file, const char *path)
> >> {
> >> sigjmp_buf local_sigjmp_buf;
> >
> > Not related the things changed here, but this should never have been pushed
> > down into individual archive modules. There's absolutely no way that we're
> > going to keep this up2date and working correctly in random archive
> > modules. And it would break if archive modules are ever called outside of
> > pgarch.c.
>
> Yeah. IIRC I did briefly try to avoid this, but the difficulty was that
> each module will have its own custom cleanup logic.

It can use PG_TRY/CATCH for that, if the top-level sigsetjmp is in pgarch.c.
Or you could add a cleanup callback to the API, to be called after the
top-level cleanup in pgarch.c.

I'm quite baffled by:
/* Close any files left open by copy_file() or compare_files() */
AtEOSubXact_Files(false, InvalidSubTransactionId, InvalidSubTransactionId);

in basic_archive_file(). It seems *really* off to call AtEOSubXact_Files()
completely outside the context of a transaction environment. And it only does
the thing you want because you pass parameters that aren't actually valid in
the normal use in AtEOSubXact_Files(). I really don't understand how that's
supposed to be ok.

Greetings,

Andres Freund