From: Jeff King <peff@peff.net>
To: Jonathan Nieder <jrnieder@gmail.com>
Cc: Nathan Neulinger <nneul@neulinger.org>,
Santiago Torres <santiago@nyu.edu>,
git@vger.kernel.org,
Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: Re: git status always modifies index?
Date: Wed, 22 Nov 2017 16:17:29 -0500 [thread overview]
Message-ID: <20171122211729.GA2854@sigill> (raw)
In-Reply-To: <20171122202720.GD11671@aiede.mtv.corp.google.com>
On Wed, Nov 22, 2017 at 12:27:20PM -0800, Jonathan Nieder wrote:
> Nathan Neulinger wrote[1]:
>
> > I just got an answer to my stackoverflow question on this,
> > apparently it's already implemented:
> >
> > https://stackoverflow.com/questions/47436939/how-to-run-git-status-without-modifying-git-index-such-as-in-a-prompt-command
> >
> > There is a "--no-optional-locks" command in 2.15 that looks like it
> > does exactly what I need.
>
> I was about to point to
> https://public-inbox.org/git/20170921043214.pyhdsrpy4omy54rm@sigill.intra.peff.net/
> about exactly this thing. :)
>
> That said, I wonder if this use case is an illustration that a name
> like --no-lock-index (as was used in Git for Windows when this feature
> first appeared) or --no-refresh-on-disk-index (sorry, I am terrible at
> coming up with option names) would make the feature easier to
> discover.
Yeah, it's interesting that Nathan does not care about the simultaneous
locking here, but rather about the effect of writing to the repo for
what would otherwise be a read-only operation.
Under the original intent of --no-optional-locks I think if we could
somehow magically update the on-disk index without lock contention, it
would be OK to do so. But that would make it no longer work for this
particular case.
And I would also not be surprised if there are other cases where we
write in a lockless way that would best be avoided in a multi-user
setup. I'm thinking specifically of the way that some merge-y operations
may write out intermediate objects, even though they're only needed
inside the process. It _should_ be a read-only operation to ask "can
these two things be merged cleanly", and you should be able to ask that
without accidentally creating root-owned files in .git/objects.
So I actually think what Nathan wants is not exactly the same as
--no-optional-locks in the first place. But in practice, for a limited
set of operations and with the way that locks work in Git, it
accomplishes the same thing. Maybe that points to having a broader
option. Or maybe having two separate options that largely have the same
effect. Or maybe just living with the minor philosophical rough edges,
since it seems OK in practice.
-Peff
next prev parent reply other threads:[~2017-11-22 21:17 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-22 15:19 git status always modifies index? Nathan Neulinger
2017-11-22 15:30 ` Santiago Torres
2017-11-22 15:37 ` Nathan Neulinger
2017-11-22 16:10 ` Santiago Torres
2017-11-22 16:20 ` Nathan Neulinger
2017-11-22 16:24 ` Santiago Torres
2017-11-22 20:27 ` Jonathan Nieder
2017-11-22 21:17 ` Jeff King [this message]
2017-11-22 21:56 ` Jonathan Nieder
2017-11-22 22:06 ` Jeff King
2017-11-25 21:55 ` Johannes Schindelin
2017-11-26 19:25 ` Jeff King
2017-11-26 21:55 ` Johannes Schindelin
2017-11-27 5:24 ` Jeff King
2017-11-27 6:03 ` Junio C Hamano
2017-11-27 20:50 ` Johannes Schindelin
2017-11-27 6:04 ` [PATCH] git-status.txt: mention --no-optional-locks Jeff King
2017-11-27 6:07 ` Junio C Hamano
2017-11-27 10:22 ` Kaartic Sivaraam
2017-11-27 20:54 ` Johannes Schindelin
2017-11-27 20:44 ` git status always modifies index? Johannes Schindelin
2017-11-27 20:49 ` Jonathan Nieder
2017-11-26 3:32 ` Junio C Hamano
2017-11-26 9:35 ` Junio C Hamano
2017-11-27 4:43 ` Jeff King
2017-11-27 4:56 ` Junio C Hamano
2017-11-27 5:00 ` Jeff King
2017-11-27 20:57 ` Jonathan Nieder
2017-11-27 22:50 ` Jeff King
2017-12-03 0:37 ` Junio C Hamano
2017-11-26 19:27 ` Jeff King
2017-11-27 0:47 ` Junio C Hamano
2017-11-27 6:12 ` Jeff King
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