Re: desktop.el: autosave?

[Reuben Thomas]

On Fri, 7 Dec 2007, Juri Linkov wrote:

> > > Saving a buffer's file is fast operation comparing to saving the desktop
> > > that takes more time because it is a cpu-intensive task that collects
> > > information from all buffers and some possibly long lists and writes
> > > to the usually large desktop file.  The default timeout for auto-save
> > > is 30 sec which is ok for auto-saving normal files, but I don't see a
> > > need to waste resources to save the desktop so often.
> >
> > It's easy to argue about this, but numbers are more convincing. I don't
> > know anything about instrumenting functions in Emacs; how can I find out
> > how long Emacs spends running desktop-save over a particular time period?
>
> You can evaluate:
>
> (let ((start (float-time))) (desktop-save desktop-dirname) (- (float-time) 
> start))

After about 30 hours, saving the desktop had accumulated about 50s of time 
this way. That seems a reasonable amount to me. I have 137 buffers in my 
session, and my desktop file is about 38,000 bytes long. Hence, I suggest 
that a simple feature "Auto-save desktop" which adds 
desktop-save-in-desktop-dir to auto-save-hook, would satisfy most people 
likely to use this feature. Furthermore those concerned about power usage 
and disk spin-up only have to worry about the same Emacs feature 
(auto-save-hook), and not add another hook or function to their list of 
things to tweak.

To ensure that this doesn't make auto-save-hook ask for input interactively, 
desktop-save-in-desktop-dir should be made only to prompt for the 
desktop-dir (when it's not set) if it's being run interactively.

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