Re: Emacsclient, multiple displays and hanging

[Colin S. Miller]

Greg Detre wrote:
> Dear all,
>
> When I'm at work, I want to be able to use that same
> emacs session on my desktop. So I sit at my desktop and ssh into my
> laptop, using emacsclient and 'make-frame-on-display' to bring up a
> new emacsclient session on my desktop, continuing where I left off.
>
> The problem comes when I remove my laptop. If I forgot to close all
> the running emacsclient windows on my desktop, then emacs on my laptop
> hangs (since it's waiting for some kind of X input from the
> emacsclient running on my desktop). Obviously the solution is to
> always shut all the emacsclients on my desktop before unplugging my
> laptop, but I forget about twice a week, and have to kill -9 my laptop
> emacs :(

Greg,

the following function will kill all X-Frames on a named display

(defun csm-kill-frames-on-device (display)
  "kill all frames on display DISPLAY"

  (let ((dvce))
    (loop for frm in (frame-list)
      do
      (progn
        (setq dvce (frame-device frm))
        (if (device-on-window-system-p dvce)
              (if (string-equal (device-connection dvce) display)
                  (delete-frame frm)))))))

or

(defun csm-kill-all-non-local-x-frames ()
  "kill all frames that are not on :0.0"

  (let ((dvce))
    (loop for frm in (frame-list)
      do
      (progn
        (setq dvce (frame-device frm))
        (if (device-on-window-system-p dvce)
              (if (not (string-equal (device-connection dvce) '":0.0"))
          (delete-frame frm)))))))


If you close your laptop's lid before unplugging it, you can catch the
kill -SIGPWR with an external script, have it run emacsclient, calling either 
the
above functions to kill connections from your desktop.

SIGPWR is sent when a UPS connected machine switches to UPS power, I'd assume 
it's also sent
when a machine is hibernated/suspended (or resumed).


I can't see of a way to handle signals inside emacs, so an external script is a 
necessary evil.

HTH,
Colin S. Miller


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