Re: [PATCH] git-remote-mediawiki: better error message when HTTP(S) access fails

From: Jeff King <peff@peff.net>
Date: May 29, 2013, 15:22 UTC
Message-ID: <20130529152216.GA9072@sigill.intra.peff.net>
In-Reply-To: <vpqzjvej8p4.fsf@anie.imag.fr>

On Wed, May 29, 2013 at 02:01:59PM +0200, Matthieu Moy wrote:

Show 11 quoted lines

> > I wonder if we can do something like:
> >
> >   our $mw_operation;
> >   $mediawiki->{config}->{on_error} = sub {
> > [...]
> >           die "$err\n";
> >   };
> 
> Probably, but that would hardcode the fact that mediawiki errors are
> fatal, while in an ideal world, some errors should be recoverable, and
> some would require some cleanups before die-ing.

Fortunately this is perl, not C. We can catch and re-throw die exceptions like:

  my $mw_pages = eval { $mediawiki->list(...) };
  if (!$mw_pages) {
    # possibly continue to something else, or even...
    clean_up();
    die; # propagate $@
  }

but it would require checking all of the call-sites. Another alternative would be a wrapper function that each caller could opt into. But I suspect the norm will be to die, so the exception model should make the code cleaner.

> Also, an error during the first mediawiki operation should not
> necessarily have the same diagnosis hint as the others: if I just
> did a successfull querry, and the next fails, it can hardly be an SSL
> certificate error.

Yeah, my error template was just a sketch; I didn't look too carefully at all of the callers, but the concept should be extensible.

> I'll send a v2 that covers a bit more (at least, push and pull with an
> invalid certificate both give the message).

Thanks.

-Peff