Re: [Emacs-diffs] trunk r116304: * lisp/desktop.el (desktop-read): Claim the lock when the owner is not the current process.

[Juri Linkov <juri@jurta.org>]

>> The one that comes last wins.  The last session will do auto-saving,
>> the previous won't.  At least, there should be no conflict of both sessions
>> trying to auto-save to the same file, because auto-saving checks the ownership.
>> The conflict might occur when during exiting both sessions will try writing
>> to the same file.  I see nothing in `desktop-kill' that would prevent saving
>> to a non-locked desktop, except the question "Save desktop?"
>
> That's not what I see today, I think.  When I need to test something
> in a fresh session, I sometimes by mistake invoke "emacs" instead of
> "emacs -Q", which reads my ~/.emacs and activates desktop saving.  The
> main Emacs session is alive, of course.  Then, when I exit, I'm asked
> whether to save desktop and given the opportunity to say NO,

When you invoke "emacs" instead of "emacs -Q" by mistake,
it warns you about the mistake by asking

  "Warning: desktop file appears to be in use by PID %s.
   Using it may cause conflicts.  Use it anyway? "

so you could just say NO.

> because I certainly don't want my main desktop file to be overwritten
> by this mistaken session.  I'm not sure this change doesn't eliminate
> this useful capability.

Even when you answer YES, and a new session will auto-save the desktop,
you still can save the final version of the desktop from the first session
if you exit it later than the auto-saving session, so it will overwrite
the desktop from the latest exited session.