Re: Run function in background.

[Deniz Dogan]

On 2011-06-01 12:40, Oleksandr Gavenko wrote:
> On 01.06.2011 13:19, Oleksandr Gavenko wrote:
> > I need use auto update for GNU Global:
> >
> > $ global -u
> >
> > There described how this done:
> >
> > http://www.emacswiki.org/emacs/GnuGlobal
> >
> > But this:
> >
> > (defun gtags-root-dir ()
> > "Returns GTAGS root directory or nil if doesn't exist."
> > (with-temp-buffer
> > (if (zerop (call-process "global" nil t nil "-pr"))
> > (buffer-substring (point-min) (1- (point-max)))
> > nil)))
> >
> > (defun gtags-update ()
> > "Make GTAGS incremental update"
> > (call-process "global" nil nil nil "-u"))
> >
> > (defun gtags-update-hook ()
> > (when (gtags-root-dir)
> > (gtags-update)))
> >
> > (add-hook 'after-save-hook #'gtags-update-hook)
> >
> > cause freezing Emacs for about 2-3 sec. How run this in background
> > so I can still complete Emacs editing?
> >
> > Write sh script and start-process-shell-command for asynchronous job?
> I write:
>
> (defun gtags-update ()
>   (start-process-shell-command "/bin/sh" nil "if global -pr; then 
> global -u; fi")
>   )
>
> (add-hook 'after-save-hook #'gtags-update)
> ; (remove-hook 'after-save-hook #'gtags-update)
>
> Seems this help but how in general case when I need run elisp code
> in background (synchronization issue is not essential).

Read: (info "(elisp) Asynchronous Processes")

I haven't really tested this, but I think something like this should work:

(defun gtags-process-sentinel (process event)
  (when (string= event "finished\n"))
    (kill-buffer (process-buffer process))))

(defun gtags-update ()
  "Make GTAGS incremental update."
  (let ((gtags-process (start-process "Global" "*Global output*" "dir")))
    (set-process-sentinel gtags-process 'gtags-process-sentinel)))

/Deniz