When mail grows in size, one thing that hurts the most for Gnus users is mail expiration. The default rule, as far as I understand it, is to run the process for a group when you exit it. Some admins/users set gnus-group-expire-all-groups to run when you exit gnus. So, an easy out is
(remove-hook 'gnus-summary-prepare-exit-hook
'gnus-summary-expiry-articles)
(remove-hook 'gnus-Exit-group-hook
'gnus-group-expire-all-groups)
However, the problem now is that you need to remember to manually run expiry once in a while. Someone like me can easily forget that!
Another option is to fetch mail locally before serving to Gnus. I have used offlineimap with pretty good results. But note that the simplest backend to use - nnfolder is also terribly slow when handling large amounts of mail. So, you would have to end up running a local dovecot instance too. On resource starved hardware, this could be a problem.
Another way, I got around this is by timing by expiration process. Mail expiry is meant to be fire-and-forget, but you really don't need to run it more than say, once a day.
On the first run, when exiting a group, create an assoc list of the following format
((group1 . time1) (group2 . time2) ...
Once we have a list with some entries is when the fun starts. We probably don't need to run the expiry process on a group that was just processed. We could check that with this example code snippet
(let ((entry gnus-newsgroup-name)) (if (check-entry-in-ignore-list entry) ;;use the default behavior (gnus-summary-expire-articles) (progn (let ((last-expiry-time (cdr (assoc entry gnus-expiry-table)))) (if (and last-expiry-time ( > (- (float-time) (string-to-number last-expiry-time)) gnus-group-expiry-time-limit)) (progn (let ((time (number-to-string(float-time)))) (setq gnus-expiry-table (acons entry time gnus-expiry-table))) (gnus-summary-expire-articles)))))))And finally, when exiting a group, we check times for all groups. But we are not done yet! We need to store the times we last ran expiration to a file
(defun write-string-to-file (string file) "Simple Function to write a string of the form - \"group value\"" (if string (with-temp-buffer (insert string) (when (file-writable-p file) (write-region (point-min) (point-max) file))))Things are different the next time you fire up Gnus. We need to load up the last known entries from the file we just wrote (I will call it .gnus-expire)
(let ((file gnus-expire-log-file)) (if (file-exists-p file) (let ((entries (with-current-buffer (find-file-noselect file) (split-string (save-restriction (widen) (buffer-substring-no-properties (point-min) (point-max))) "\n" t)))) (mapcar (lambda (tuple) (let ((groupname (car (split-string tuple))) (value (cadr (split-string tuple)))) ;(message "%s %s" groupname value) (setq gnus-expiry-table (acons groupname value gnus-expiry-table)))) entries)))))
And now, we have a populated associative list to perform step 2 above.
Here's the complete source
;;; expiry-hack.el - Don't expire often!
;; Author: Bandan Das <bsd@makefile.in>
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; This assoc list will store the expiry times
;; associated with groups. If there's a .gnus-expiry-file,
;; this gets filled up with the last time expiry was
;; performed
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defvar gnus-expiry-table nil
"This is the run-time assoc list")
(defvar gnus-expire-log-file "~/.gnus-expire"
"The file where the expire times are written")
(defvar gnus-group-ignore-list nil
"Don't apply our expire logic for anything here")
(defvar gnus-group-expiry-time-limit 86400
"When to run expiry")
;; remove some hooks first
(defun gnus-read-last-expiry-times()
"Read the expiry times from the file, populates gnus-expiry-table"
(let ((file gnus-expire-log-file))
(if (file-exists-p file)
(let ((entries (with-current-buffer
(find-file-noselect file)
(split-string
(save-restriction
(widen)
(buffer-substring-no-properties
(point-min)
(point-max)))
"\n" t))))
(mapcar (lambda (tuple)
(let ((groupname (car (split-string tuple)))
(value (cadr (split-string tuple))))
;(message "%s %s" groupname value)
(setq gnus-expiry-table
(acons groupname value gnus-expiry-table))))
entries)))))
(defun write-string-to-file (string file)
"Simple Function to write a string of the form - \"group value\""
(if string
(with-temp-buffer
(insert string)
(when (file-writable-p file)
(write-region (point-min)
(point-max)
file)))))
(defun check-entry-in-ignore-list (entry)
"Just check an entry against the ignore list"
(setq match nil)
(setq count 0)
(setq found nil)
(while
(and (not found) (< count (length gnus-group-ignore-list)))
(when (string-match (elt gnus-group-ignore-list count) entry)
(setq found t))
(setq count (+ count 1)))
found)
(defun gnus-group-custom-expire-single-group()
"This is called when you exit a group, functionally
similar to the function below to expire all groups"
(let ((entry gnus-newsgroup-name))
(if (check-entry-in-ignore-list entry)
;;use the default behavior
(gnus-summary-expire-articles)
(progn
(let ((last-expiry-time (cdr (assoc entry gnus-expiry-table))))
(if (and last-expiry-time
( > (- (float-time) (string-to-number last-expiry-time))
gnus-group-expiry-time-limit))
(progn
(let ((time (number-to-string(float-time))))
(setq gnus-expiry-table
(acons entry time gnus-expiry-table)))
(gnus-summary-expire-articles))))))))
;gnus-group-marked
(defun gnus-group-custom-expire-all-groups ()
"This function gets the list of all groups,
and creates a new list out of it based on -
- if there is an ignore list
- If we have matching entry in gnus-expiry-table
and we need to process expiry"
(interactive)
(setq to-write nil)
(save-excursion
(gnus-message 5 "Running custom expire...")
(let ((gnus-group-tmp-list (mapcar (lambda (info)
(gnus-info-group info))
(cdr gnus-newsrc-alist)))
(to-write nil))
(dolist (entry gnus-group-tmp-list)
(if (check-entry-in-ignore-list entry)
(add-to-list 'gnus-group-marked entry) ;;default behavior - add to expiry list
(progn
(let ((last-expiry-time (cdr (assoc entry gnus-expiry-table))))
(if (and last-expiry-time
( > (- (float-time) (string-to-number last-expiry-time))
gnus-group-expiry-time-limit))
(add-to-list 'gnus-group-marked entry))
;but write it so it gets accounted for the next expiry!
(setq to-write (concat to-write
(concat
entry " "
(number-to-string (float-time))
"\n")))))))
(write-string-to-file to-write gnus-expire-log-file))
(gnus-group-expire-articles nil))
(gnus-group-position-point)
(gnus-message 5 "Expiring...done"))
(provide 'expiry-hack)