GNU bug report logs - #16157
24.3.50; desktop-read doesn't claim the unused lock

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> jurta.org>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.3.50; desktop-read doesn't claim the unused lock
Date: Sun, 15 Dec 2013 23:49:53 +0200

When the previous session crashes or freezes, and .emacs.desktop.lock
contains the PID of the previous process, then `desktop-read' asks

  Warning: desktop file appears to be in use by PID...
  Using it may cause conflicts.  Use it anyway? (y or n)  y

But answering `y' doesn't claim the ownership of the lock,
desktop-owner is still an old nonexistent process, and thus
auto-saving doesn't save the desktop.

Maybe `desktop-read' should call `desktop-claim-lock' in this case?

Message #8 received at 16157 <at> debbugs.gnu.org (full text, mbox):

From: Juri Linkov <juri <at> jurta.org>
To: 16157 <at> debbugs.gnu.org
Subject: Re: bug#16157: 24.3.50; desktop-read doesn't claim the unused lock
Date: Tue, 04 Feb 2014 09:54:58 +0200

> When the previous session crashes or freezes, and .emacs.desktop.lock
> contains the PID of the previous process, then `desktop-read' asks
>
>   Warning: desktop file appears to be in use by PID...
>   Using it may cause conflicts.  Use it anyway? (y or n)  y
>
> But answering `y' doesn't claim the ownership of the lock,
> desktop-owner is still an old nonexistent process, and thus
> auto-saving doesn't save the desktop.
>
> Maybe `desktop-read' should call `desktop-claim-lock' in this case?

I guess the right thing to do here is what its comment suggests to do:
"mark it as in-use, to bother other desktop instances".  Actually it
shouldn't bother other desktop instances when other instances crashed.

=== modified file 'lisp/desktop.el'
--- lisp/desktop.el	2014-01-01 07:43:34 +0000
+++ lisp/desktop.el	2014-02-04 07:53:37 +0000
@@ -1103,9 +1106,12 @@ (defun desktop-read (&optional dirname)
 	    ;; Evaluate desktop buffer and remember when it was modified.
 	    (load (desktop-full-file-name) t t t)
 	    (setq desktop-file-modtime (nth 5 (file-attributes (desktop-full-file-name))))
-	    ;; If it wasn't already, mark it as in-use, to bother other
+	    ;; If it wasn't already owned, mark it as in-use, to bother other
 	    ;; desktop instances.
-	    (unless owner
+	    (unless (eq (emacs-pid) owner)
 	      (condition-case nil
 		  (desktop-claim-lock)
 		(file-error (message "Couldn't record use of desktop file")

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