How can I prevent Emacs from auto-reverting only when the file size is over 10 GB? I know that there's the large-file-warning-threshold option but it doesn't work for auto-reverting.
I'm dealing with a file that I frequently overwrite programmatically. It's a small file most of the time, but it sometimes becomes unexpectedly large so I'd like to prevent Emacs from freezing when I leave that file open.
Maybe use add-file-hook to turn off auto-revert-mode for a file buffer that is larger than some limit. This seems to work OK (tested minimally):
(defvar my-max-auto-revert-size 1000000000
"Do not auto-revert file buffers larger than this.")
(add-hook 'find-file-hook
(lambda ()
(when (> (buffer-size) my-max-auto-revert-size)
(setq global-auto-revert-ignore-buffer t))))
(FWIW, I just added an enhancement request to make this kind of thing easier: Emacs bug #25277.)
Assuming you're not using auto-revert-tail-mode, you might be able to just tell Emacs that if the file is too large, then the buffer is not "stale". E.g. something like:
(defun my-not-too-big (&rest _)
(or (not buffer-file-name)
(let ((size (nth 7 (file-attributes buffer-file-name))))
(< size 10000000000))))
(add-function :after-while buffer-stale-function
#'my-not-too-big)
Rather than doing that globally, you could use (add-function :after-while (local buffer-stale-function) #'my-not-too-big) in a mode hook to only do that in the specific buffers you care about.
