* mu4e-utils: cache the list of maildirs in `mu4e-get-maildirs', document this

emacs/mu4e-utils.el

@@ -172,16 +172,21 @@ paths."
 		       (mu4e~get-maildirs-1 path (concat mdir "/" dir)))))
     maildirs))
 
+(defvar mu4e~maildir-list nil "Cached list of maildirs.")
 
 (defun mu4e-get-maildirs (path)
   "Get maildirs under path, recursively, as a list of relative
 paths (ie., /archive, /sent etc.). Most of the work is done in
-`mu4e-get-maildirs-1'."
-  (sort (mu4e~get-maildirs-1 path)
-    (lambda (m1 m2)
-      (when (string= m1 "/")
-	-1 ;; '/' comes first
-	(compare-strings m1 0 nil m2 0 nil t)))))
+`mu4e-get-maildirs-1'. Note, these results are /cached/, so the
+list of maildirs will not change until you restart mu4e."
+  (unless mu4e~maildir-list
+    (setq mu4e~maildir-list
+      (sort (mu4e~get-maildirs-1 path)
+	(lambda (m1 m2)
+	  (when (string= m1 "/")
+	    -1 ;; '/' comes first
+	    (compare-strings m1 0 nil m2 0 nil t))))))
+  mu4e~maildir-list)
 
 
 (defun mu4e-ask-maildir (prompt)
@@ -616,10 +621,13 @@ FUNC (if non-nil) afterwards."
   "Stop the mu4e session."
   (when mu4e-update-timer
     (cancel-timer mu4e-update-timer)
-    (setq mu4e-update-timer nil))
+    (setq
+      mu4e-update-timer nil 
+      mu4e~maildir-list nil))
   (mu4e~proc-kill)
   (kill-buffer))
 
+
 (defvar mu4e-update-timer nil
   "*internal* The mu4e update timer.")
 

emacs/mu4e.texi

@@ -1082,7 +1082,10 @@ list of maildirs you'd like to have quick access to, for example:
 This would set @key{i} as a shortcut for the @t{/inbox} folder; so effectively
 a query @t{maildir:/inbox}. There is a special shortcut @key{o} for
 @emph{other} (so don't use that one for your own shortcuts!), which allows you
-to choose from @emph{all} maildirs.
+to choose from @emph{all} maildirs. There is support for autocompletion; note
+that the list of maildirs is determined when @t{mu4e} starts; if there are
+changes in the maildirs while @t{mu4e} is running, you need to restart
+@t{mu4e}.
 
 Each of the folder names is relative to your top-level maildir directory; so if
 you keep your mail in @file{~/Maildir}, @file{/inbox} would refer to
@@ -1490,7 +1493,11 @@ them.
 
 @t{mu4e} loads @t{mu4e-speedbar} automatically; all you need to do to activate
 it is @code{M-x speedbar}. Then, when then going to the @ref{Main view}, the
-speedbar-frame will be updated with your bookmarks and maildirs.
+speedbar-frame will be updated with your bookmarks and maildirs. For speed
+reasons, the list of maildirs is determined when @t{mu4e} starts; if the list
+of maildirs changes while @t{mu4e} is running, you need to restart @t{mu4e} to
+reflect those changes in the speedbar and in other places that use this list,
+such as auto-completion when jumping to a maildir.
 
 @code{mu4e-speedbar} was contributed by Antono Vasiljev.