Re: unifying sequencer's options persisting, was Re: [PATCH v2] sequencer: fix edit handling for cherry-pick and revert messages

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Apr 9, 2021, 13:53 UTC
Message-ID: <nycvar.QRO.7.76.6.2104091548500.54@tvgsbejvaqbjf.bet>
In-Reply-To: <CAP8UFD1WsjB_shHnRUcH3rnQjwh0yodrETq6zh39vnZnHQpVyw@mail.gmail.com>

Hi Christian,

On Thu, 8 Apr 2021, Christian Couder wrote:

Show 17 quoted lines

> On Thu, Apr 8, 2021 at 2:22 PM Johannes Schindelin
> <Johannes.Schindelin@gmx.de> wrote:
> >
> > On Fri, 2 Apr 2021, Junio C Hamano wrote:
> >
> > > Elijah Newren <newren@gmail.com> writes:
> > >
> > > > Even if others now disagree with the above, I know I can get a huge
> > > > speedup by changing sequencer to stop per-commit wasteful work (stop
> > > > forking processes like "git commit", don't write control structures if
> > > > the rebase hasn't ended or hit a conflict, don't update the working
> > > > copy or index or reflog).
>
> It would be interesting to know which of these updates (working copy,
> index or reflog) is the most costly. Of course the best would be to
> compare the costs when updates are done at each step vs only at the
> end.

I would bet that the worktree updates are the most costly thing.

Note: there is also the step where new objects are written to the object
database, but that is a step that we can _not_ skip.

> If the split index could also become the default one day, I guess we
> could be doing pretty well even when some hooks are installed.

Hmm. My opinion about the split index does not match yours.

I'd much rather see us tackle the challenge of allowing truly incremental index updates. That "split index" feature feels like a bandaid that tries to do sort of an incremental update, and fails at it because it is not truly incremental. Granted, that would look much more like a real database and is much, much harder than what the split index code does (think e.g. locking).

Ciao, Dscho