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Re: File watch support in autorevert.el
From: |
Michael Albinus |
Subject: |
Re: File watch support in autorevert.el |
Date: |
Fri, 11 Jan 2013 16:01:14 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3.50 (gnu/linux) |
Eli Zaretskii <address@hidden> writes:
>> > . 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.
I can speak only for the inotify case. According to my tests,
IN_CLOSE_WRITE will always happen once a file has been written on the
filesystem. See for example (commands have been applied in different shells):
--8<---------------cut here---------------start------------->8---
~$ echo xxx >>~/tmp/123
~$ inotifywait -mq ~/tmp/123
/home/albinmic/tmp/123 OPEN
/home/albinmic/tmp/123 MODIFY
/home/albinmic/tmp/123 CLOSE_WRITE,CLOSE
--8<---------------cut here---------------end--------------->8---
Do you (Stefan?) have a use case where just IN_MODIFY has been fired,
w/o a corresponding IN_CLOSE_WRITE?
> I would suggest adding the 'size' filter as well, because Windows
> doesn't update the last write time on every write to a file, only
> after many writes. (It does similar filtering with updating the
> directory entry of the file, so 'size' alone will not do.)
Hmm, as said already I have almost no chance to test it under Windows ...
I would let this implementation to somebody else.
>> 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".
>
> You mean, with a timer?
The timer is still active. The file watch handler just marks buffers
where the related file has been changed. Revert happens when the timer
goes through the buffers markes via `auto-revert-active-p'. That sounds
like an acceptable compromise.
Best regards, Michael.
- File watch support in autorevert.el, Michael Albinus, 2013/01/10
- Re: File watch support in autorevert.el, Stefan Monnier, 2013/01/10
- Re: File watch support in autorevert.el, Eli Zaretskii, 2013/01/11
- Re: File watch support in autorevert.el, Stefan Monnier, 2013/01/11
- Re: File watch support in autorevert.el, Michael Albinus, 2013/01/11
- Re: File watch support in autorevert.el, Eli Zaretskii, 2013/01/12
- Re: File watch support in autorevert.el, Michael Albinus, 2013/01/12
- Re: File watch support in autorevert.el, Eli Zaretskii, 2013/01/12
- Re: File watch support in autorevert.el, Michael Albinus, 2013/01/12