Re: [PATCH 3/3] gc: do not return error for prior errors in daemonized mode

From: Jeff King <peff@peff.net>
Date: Jul 18, 2018, 17:22 UTC
Message-ID: <20180718172225.GA2677@sigill.intra.peff.net>
In-Reply-To: <xmqqk1psldkx.fsf@gitster-ct.c.googlers.com>

On Wed, Jul 18, 2018 at 09:21:18AM -0700, Junio C Hamano wrote:

Show 25 quoted lines

> > I still think that "repo" should probably stop respecting the exit code.
> > But that's no excuse for Git not to have a sensible exit code in the
> > first place.
> 
> I am not yet convinced that this last step to exit with 0 is a good
> change, even though I can understand that it would be more
> convenient, as there currently is no easy way for the calling script
> to tell two error cases apart.
> 
> I think the "sensible exit code" you mention would be something like
> "1 for hard error, 2 for 'I am punting as I see there were previous
> errors---you may want to examine your repository'".  
> 
> If we did that from day one and documented that behaviour, nobody
> would have complained, but adopting that suddenly is of course a
> breaking change.
> 
> Perhaps we should exit with 2 (not 0) in that "previous error" case
> by default, and then have a configuration knob to turn that 2 into 0
> for those who cannot easily modify the calling script?  That way, we
> by default will *not* break those who have been paying attention to
> zero-ness of the exit status, we allow those who want to treat this
> "prior error" case as if there were no error with just a knob, and
> then those who are willing to update their script can tell two cases
> by the exit status and act differently.

I think we have been exiting non-zero with "previous errors" for some time with the daemonizing code. It was just spelled "-1" instead of "2". So just jumping right there does not mean any regression from the current state, I don't think (but it also does not fix existing scripts like "repo" that check the code).

I agree the config you suggest would give people the tools to make that case work. But it somehow rubs me the wrong way. Can you imagine the perspective of a user who is told "oh, your script breaks? Just try setting this option to ignore error codes in this one particular situation". It feels like a weird hack, because it is.

It's also still inconsistent in the daemonize case. The run that yields the error won't return a non-zero exit. But the next run will exit with "2".

-Peff