From: Mitchel Humpherys <mitch.special@gmail.com>
To: Ben Gamari <ben@smart-cactus.org>
Cc: 21559@debbugs.gnu.org
Subject: bug#21559: 25.0.50; auto-revert-mode breaks git rebase
Date: Sat, 06 Feb 2016 17:34:49 -0800 [thread overview]
Message-ID: <87zivd8fra.fsf@gmail.com> (raw)
In-Reply-To: <87oabu9fwh.fsf@smart-cactus.org> (Ben Gamari's message of "Sat, 06 Feb 2016 13:34:06 +0100")
On Sat, Feb 06 2016 at 01:34:06 PM, Ben Gamari <ben@smart-cactus.org> wrote:
> Mitchel Humpherys <mitch.special@gmail.com> writes:
>
>> On Fri, Sep 25 2015 at 03:45:56 PM, Ben Gamari <ben@smart-cactus.org> wrote:
>>> Arguably `git rebase` should be holding the `index.lock` for the entire
>>> duration of the process (or be more resilient to the lock being taken)
>>> but sadly this isn't the case. Emacs should behave appropriately to
>>> accomodate this behavior.
>>
>> I don't think this is quite right. As I understand it, git only takes
>> index.lock for operations that mutate the index [1].
>>
>> It wouldn't make sense for git to hold index.lock for the entirety of
>> the rebase operation since you can stop in the middle of an interactive
>> rebase and do anything you want (mess with the index, add new commits,
>> anything).
>>
> Ahh, yes. You are quite right.
>
>> I think the real question is: why is vc-find-file-hook (or
>> vc-refresh-state) trying to mutate the index? Shouldn't refreshing a
>> buffer be a read-only operation (at least with respect to the VCS)?
>>
> As far as I can tell vc-find-file-hook is merely calling `git ls-files
> -c -z -- $FILE`, which sounds to me like it should indeed be a read-only
> operation.
I'm able to reliably reproduce this on the tip of the emacs-25 branch
with emacs -Q with:
$ cd /path/to/emacs
$ ./src/emacs -Q lisp/*.el
[ M-x global-auto-revert-mode ]
$ for i in $(seq 30); do for f in lisp/*.el; do echo "; $i" >> $f; done; git commit -am "test $i"; done
You might need to increase the `30' value in order to see it happen
depending on your disk speed, etc.
I took a quick look at the git source and the main source of this
particular error seems to be from the `git update-index' command. I see
that vc-git.el is calling `git update-index' in a few places but my
attempts at instrumenting the code to track down where it was coming
from were fruitless. I tried:
(setq vc-command-messages t)
as well as:
(defun vc-git-command (buffer okstatus file-or-list &rest flags)
"A wrapper around `vc-do-command' for use in vc-git.el.
The difference to vc-do-command is that this function always invokes
`vc-git-program'."
(let ((coding-system-for-read vc-git-commits-coding-system)
(coding-system-for-write vc-git-commits-coding-system))
+ (message "git: %s %s" file-or-list flags)
Any ideas on how we can trace every git command that vc-git.el is
running? I'm suspicious that we're calling `git update-index' in the
auto revert path somewhere...
next prev parent reply other threads:[~2016-02-07 1:34 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-25 12:45 bug#21559: 25.0.50; auto-revert-mode breaks git rebase Ben Gamari
2015-09-26 7:41 ` Eli Zaretskii
2015-09-28 14:11 ` Ben Gamari
2015-09-28 14:35 ` Eli Zaretskii
2015-09-28 15:05 ` Ben Gamari
2015-09-29 8:47 ` Michael Albinus
2015-10-26 18:43 ` bug#21559: [PATCH] autorevert: Wait for repository to become idle before calling vc-find-file-hook Ben Gamari
2015-10-26 18:43 ` bug#21559: [PATCH] autorevert: Wait a while " Ben Gamari
2015-10-27 8:25 ` Michael Albinus
2015-10-28 11:59 ` Ben Gamari
2015-10-28 14:45 ` Michael Albinus
2015-10-28 17:05 ` Ben Gamari
2015-10-29 8:20 ` Michael Albinus
2016-02-06 0:01 ` bug#21559: 25.0.50; auto-revert-mode breaks git rebase Mitchel Humpherys
2016-02-06 12:34 ` Ben Gamari
2016-02-07 1:34 ` Mitchel Humpherys [this message]
2016-02-07 5:03 ` Mitchel Humpherys
2016-02-07 5:21 ` Mitchel Humpherys
2016-02-07 10:22 ` Ben Gamari
2016-02-07 10:55 ` Ben Gamari
2016-02-07 17:06 ` Mitchel Humpherys
2016-02-07 17:22 ` Ben Gamari
2016-02-08 21:19 ` Daniel Colascione
2016-09-09 20:56 ` Jason Merrill
2018-02-14 10:08 ` Alexei Khlebnikov
2018-02-15 19:08 ` Alexei Khlebnikov
2018-02-15 22:32 ` Alexei Khlebnikov
2018-02-19 23:41 ` Dmitry Gutov
2018-02-20 0:06 ` Alexei Khlebnikov
2018-02-20 0:17 ` Dmitry Gutov
2018-02-20 4:07 ` Eli Zaretskii
2018-02-20 7:40 ` Michael Albinus
2018-02-20 11:37 ` Dmitry Gutov
2018-02-20 11:53 ` Michael Albinus
2018-02-20 22:28 ` Dmitry Gutov
2018-02-21 22:07 ` Alexei Khlebnikov
2018-02-22 11:24 ` Michael Albinus
2018-02-22 11:45 ` Dmitry Gutov
2018-02-19 10:24 ` bug#21559: PATCH review needed: lisp/vc/vc-git.el (vc-git-state, vc-git-conflicted-files) Alexei Khlebnikov
2018-02-19 12:39 ` Michael Albinus
2018-02-19 15:29 ` Eli Zaretskii
2018-02-19 18:39 ` Alexei Khlebnikov
2018-02-19 18:50 ` Michael Albinus
2018-02-19 19:05 ` Alexei Khlebnikov
2018-02-19 23:35 ` Dmitry Gutov
2018-09-25 12:23 ` bug#21559: additional patch needed to set GIT_OPTIONAL_LOCKS=0 in all cases Andrew Ruder
2018-09-26 3:16 ` Phil Sainty
2018-09-26 9:45 ` Michael Albinus
2018-09-29 11:16 ` Michael Albinus
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