From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Eli Zaretskii <eliz@gnu.org>
Cc: Michael Albinus <michael.albinus@gmx.de>, emacs-devel@gnu.org
Subject: Re: File watch support in autorevert.el
Date: Fri, 11 Jan 2013 09:34:33 -0500 [thread overview]
Message-ID: <jwva9sf7q7b.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <83fw28uj9c.fsf@gnu.org> (Eli Zaretskii's message of "Fri, 11 Jan 2013 12:05:51 +0200")
> . The code as written is too naive: it blindly assumes that every
> single notification reported by the filesystem for a given watch is
> necessarily the one requested in the auto-revert-notify-add-watch
> call. But that assumption is false, at least on Windows, where the
> implementation actually watches events to the entire parent
> directory of the file we are interested in. So Emacs reverts the
> file whenever _any_ file in the same directory was changed. I
> believe similar problems can happen with inotify, albeit much more
> rarely. For that reason, I think auto-revert-notify-handler should
> filter events by ASPECTS/ACTION member, and on Windows also by FILE
> member of the event.
That seems like a good candidate for something the common API could
hide/provide, I think.
> . It isn't clear to me that using IN_CLOSE_WRITE with inotify is TRT:
> AFAIU, that would mean we only revert a file when the application
> writing to it closes its descriptor. IOW, if the application makes
> several changes to the file during a prolonged operation, and
> doesn't close and reopen the file in between, we will only see the
> changes at the end, but not during the operation. Wouldn't it be
> better to use IN_MODIFY instead?
For auto-revert-tail-mode, IN_CLOSE_WRITE is definitely insufficient
since the common use case is when we watch a log file, so the CLOSE may
never happen.
The non-inotify code does something akin to the IN_MODIFY, indeed.
But at the same time, it's often preferable to wait a bit longer for the
application to finish writing the new version of the file. I think the
perfect behavior lies somewhere in-between: when we get an
IN_CLOSE_WRITE, we should revert immediately, but when we get an
IN_MODIFY we should revert "soon".
Stefan
next prev parent reply other threads:[~2013-01-11 14:34 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-10 14:28 File watch support in autorevert.el Michael Albinus
2013-01-10 17:11 ` Stefan Monnier
2013-01-10 17:14 ` Lennart Borgman
2013-01-10 20:38 ` Michael Albinus
2013-01-11 10:05 ` Eli Zaretskii
2013-01-11 14:34 ` Stefan Monnier [this message]
2013-01-11 14:43 ` Eli Zaretskii
2013-01-11 15:01 ` Michael Albinus
2013-01-11 15:50 ` Eli Zaretskii
2013-01-11 16:09 ` Michael Albinus
2013-01-11 19:19 ` Eli Zaretskii
2013-01-11 16:19 ` Michael Albinus
2013-01-11 16:39 ` Stefan Monnier
2013-01-11 22:43 ` Michael Albinus
2013-01-12 11:28 ` Eli Zaretskii
2013-01-12 13:34 ` Michael Albinus
2013-01-12 15:09 ` Eli Zaretskii
2013-01-12 19:08 ` Michael Albinus
2013-01-17 9:38 ` Michael Albinus
2013-01-17 16:54 ` Eli Zaretskii
2013-01-17 19:19 ` Michael Albinus
2013-01-17 19:39 ` Eli Zaretskii
2013-01-11 15:57 ` Stefan Monnier
2013-01-11 15:18 ` Michael Albinus
2013-01-11 15:57 ` Eli Zaretskii
2013-01-11 16:31 ` Michael Albinus
2013-01-11 18:47 ` Eli Zaretskii
2013-01-11 16:44 ` Stefan Monnier
2013-01-11 22:47 ` Michael Albinus
2013-01-12 11:36 ` Eli Zaretskii
2013-01-12 13:14 ` Michael Albinus
2013-01-12 14:06 ` Eli Zaretskii
2013-01-12 14:16 ` Michael Albinus
2013-01-11 22:39 ` Michael Albinus
2013-01-11 23:01 ` Michael Albinus
2013-01-12 11:31 ` Eli Zaretskii
2013-01-12 13:08 ` Michael Albinus
2013-01-12 13:26 ` Michael Albinus
2013-01-12 14:03 ` Eli Zaretskii
2013-01-12 14:12 ` Michael Albinus
2013-01-12 14:39 ` Eli Zaretskii
2013-01-12 19:04 ` Michael Albinus
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