Subject: Re: bug#66381: 29.1; Auto-revert not polling files when notifications are enabled

From: Michael Albinus <[email-masked]>
Date: Sun, 08 Oct 2023 10:24:32 +0200

Eli Zaretskii <[email-masked]> writes:

Hi,

>>           (if buffer-file-name
>>               (and (or auto-revert-remote-files
>>                        (not (file-remote-p buffer-file-name)))
>>                    (or (not auto-revert-notify-watch-descriptor)
>>                        auto-revert-notify-modified-p)
>>                    (if auto-revert-tail-mode
>>                        (and (file-readable-p buffer-file-name)
>>                             (/= auto-revert-tail-pos
>>                                 (setq size
>>                                       (file-attribute-size
>>                                        (file-attributes buffer-file-name)))))
>>                      (funcall (or buffer-stale-function
>>                                   #'buffer-stale--default-function)
>>                               t)))
>>
>> When buffer-file-name, revert is true iff:
>>
>> 1. auto-revert-remote-files or the file is not remote
>> AND 2. there is no watch descriptor or a notification was received
>> AND 3. some details about auto-revert-tail-mode OR t
>>
>> If auto-revert-notify-watch-descriptor and not
>> auto-revert-notify-modified-p, then the file won't be reverted.
>> auto-revert-handler does get called by the polling timer, but it
>> doesn't revert.
>
> That's not what your sentence said, which I said wasn't true.  You
> said something much more radical:
>
>   The implementation does not poll if there's a notification registered.
>
> Moreover, the documentation says that "polling is used even if
> notifications are enabled", and that is true regardless of whether the
> file is actually reverted or not.
>
> IOW, the documentation describes the usual case, where notifications
> are enabled and the watch descriptor is valid.  It says nothing at all
> about your situation.

The problem is, that in Daniel's case we get no information that file
notification has ceased to work for the re-mounted file system (no
IN_IGNORED event from inotify). auto-revert-notify-watch-descriptor
still exists, and auto-revert-notify-modified-p isn't modified any
longer. Therefore the file is not reverted even while polling.

You have a wokaround which seems to work. Another approach would be use
polling only for the given mounted file system. Adding "^/google/src" to
auto-revert-notify-exclude-dir-regexp might work.

Best regards, Michael.