Re: [PATCH 1/2] diffcore-rename: no point trying to find a match better than exact

From: Elijah Newren <newren@gmail.com>
Date: Feb 3, 2021, 19:10 UTC
Message-ID: <CABPp-BH45RzNjo_Xj9uTpLj5f00dWwXun4m+mob25FJ0sPprWg@mail.gmail.com>
In-Reply-To: <xmqqft2dc7lj.fsf@gitster.c.googlers.com>

On Wed, Feb 3, 2021 at 10:46 AM Junio C Hamano <gitster@pobox.com> wrote:

Show 12 quoted lines

>
> Derrick Stolee <stolee@gmail.com> writes:
>
> >>      /* All done? */
> >> -    if (!num_destinations)
> >> +    if (!num_destinations || !num_sources)
> >>              goto cleanup;
> >
> > And add an extra quit condition which is very possible to hit.
> > Is it only hit when every "delete" is actually a rename?
>
> When every delete is actually an unmodified exact rename, I think.

Yes, exactly.

> If this simple change gives us good performance gain, that is
> superb.
>
> Nicely done.

Thanks.

I probably should have separated this from the speculative not-quite-working changes that weren't ready yet and pushed just it sooner.[1] But I kinda wanted to get all the performance changes together, and...well, all the other performance changes took a while to complete (especially given multiple starts and stops).

[1] https://lore.kernel.org/git/20171110222156.23221-2-newren@gmail.com/