async org-agenda

Question

I have a lot of org files in emacs 27.1 so when I do an agenda listing for the week it takes about 20seconds. Is there a nice way to do this in the background? I've put together the following function and it sort of works. The Org Agenda buffer that it shows in the finish lambda is blank, but the agenda.org file is correct but it's just an org file not the special Org Agenda buffer.

(defun async-org-agenda-list()
  (interactive)
  (async-start

   ;; start
   (lambda ()
     (setq org-agenda-files '("~/org/" "~/org/projects"))
     (org-agenda-list)
     (switch-to-buffer "*Org Agenda*")
     (append-to-file (point-min) (point-max) "~/agenda.org")
     )

   ;; finish
   (lambda (msg)
     (message "done")
     )
   )
  )

Is there a way to do the Agenda in the background and display it in the Org Agenda buffer in the correct mode?

Answer 1

SECOND EDIT

A solution that also fixes the links has been posted/implemented here.

Thanks Thierry!

EDIT

Okay, so you can fix it by adding the following two lines before just before the (goto-char (point-max)) in the async-when-done function (see the comment to this answer also):

(goto-char (point-min))
(replace-string "#" "")

I will send a mail about it to the emacs-devel mailing list.

END EDIT

Nice idea!

The following answer works for simple org files. However, the async API seems to error on some more complex org files (bug?). Anyway, would be nice to hear back how it works on your files.

Okay, then here follows the code:

(defun map-text-properties (props)
  (let ((plist (caddr props)))
    (while plist
      (put-text-property (1+ (nth 0 props))
                         (1+ (nth 1 props))
                         (car plist)
                         (cadr plist))
      (setq plist (cddr plist)))
    (when props
      (map-text-properties (nthcdr 3 props)))))

(async-start
 ;; What to do in the child process
 (lambda ()
   (setq org-agenda-files '("~/spacemacs/diary.org"))
   (org-agenda-list)
   (buffer-string))

 ;; What to do when it finishes
 (lambda (result)
   (switch-to-buffer-other-window "*Org Agenda*")
   (insert (car result))
   (map-text-properties (cdr result))
   (org-agenda-mode)))

The map-text-properties properties function is required because the async API returns the text object as a list. There is probably an easier way to convert the list back into a text object (but I did not look very much into that).