From: Jeff King <peff@peff.net>
To: Duy Nguyen <pclouds@gmail.com>
Cc: Git Mailing List <git@vger.kernel.org>
Subject: Re: [RFC] git checkout $tree -- $path always rewrites files
Date: Fri, 7 Nov 2014 14:15:55 -0500 [thread overview]
Message-ID: <20141107191554.GA5695@peff.net> (raw)
In-Reply-To: <CACsJy8CPLvmbcdHHmfu6g0dUXJVQ8NhwqfGPD=-kcBmzF_ha6g@mail.gmail.com>
On Fri, Nov 07, 2014 at 05:13:47PM +0700, Duy Nguyen wrote:
> > By the way, one other thing I wondered while looking at this code: when
> > we checkout a working tree file, we unlink the old one and write the new
> > one in-place. Is there a particular reason we do this versus writing to
> > a temporary file and renaming it into place? That would give
> > simultaneous readers a more atomic view.
> >
> > I suspect the answer is something like: you cannot always do a rename,
> > because you might have a typechange, directory becoming a file, or vice
> > versa; so anyone relying on an atomic view during a checkout operation
> > is already Doing It Wrong. Handling a content-change of an existing
> > path would complicate the code, so we do not bother.
>
> Not a confirmation, but it looks like Linus did it just to make sure
> he had new permissions right, in e447947 (Be much more liberal about
> the file mode bits. - 2005-04-16).
Thanks for digging that up. I think that only gives us half the story,
though. That explains why we would unlink/open instead of relying on
just open(O_TRUNC). But I think opening a new tempfile would work the
same as the current code in that respect.
-Peff
next prev parent reply other threads:[~2014-11-07 19:16 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-07 8:13 [RFC] git checkout $tree -- $path always rewrites files Jeff King
2014-11-07 8:38 ` Jeff King
2014-11-07 10:13 ` Duy Nguyen
2014-11-07 16:51 ` Junio C Hamano
2014-11-07 19:15 ` Jeff King [this message]
2014-11-07 17:14 ` Junio C Hamano
2014-11-07 19:17 ` Jeff King
[not found] ` <CANiSa6hufp=80TaesNpo1CxCbwVq3LPXvYaUSbcmzPE5pj_GGw@mail.gmail.com>
2014-11-08 7:10 ` Martin von Zweigbergk
[not found] ` <CAPc5daWdzrHr8Rdksr3HycMRQu0=Ji7h=BPYjzZj7MH6Ko0VgQ@mail.gmail.com>
2014-11-08 8:03 ` Martin von Zweigbergk
2014-11-08 8:30 ` Jeff King
2014-11-08 8:45 ` Jeff King
2014-11-09 18:37 ` Junio C Hamano
2014-11-08 16:19 ` Martin von Zweigbergk
2014-11-09 9:42 ` Jeff King
2014-11-09 17:21 ` Junio C Hamano
2014-11-13 18:30 ` Jeff King
2014-11-13 19:15 ` Junio C Hamano
2014-11-13 19:26 ` Jeff King
2014-11-13 20:03 ` Jeff King
2014-11-13 21:18 ` Junio C Hamano
2014-11-13 21:37 ` Jeff King
2014-11-14 5:44 ` David Aguilar
2014-11-14 19:27 ` Junio C Hamano
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