1 ;;; gnus-async.el --- asynchronous support for Gnus
3 ;; Copyright (C) 1996, 1997, 1998, 1999, 2000, 2002, 2003, 2004,
4 ;; 2005 Free Software Foundation, Inc.
6 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 2, or (at your option)
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
24 ;; Boston, MA 02110-1301, USA.
30 (eval-when-compile (require 'cl))
37 (when (featurep 'xemacs)
38 (require 'timer-funcs)))
40 (defgroup gnus-asynchronous nil
41 "Support for asynchronous operations."
44 (defcustom gnus-use-article-prefetch 30
45 "*If non-nil, prefetch articles in groups that allow this.
46 If a number, prefetch only that many articles forward;
47 if t, prefetch as many articles as possible."
48 :group 'gnus-asynchronous
49 :type '(choice (const :tag "off" nil)
51 (integer :tag "some" 0)))
53 (defcustom gnus-asynchronous nil
54 "*If nil, inhibit all Gnus asynchronicity.
55 If non-nil, let the other asynch variables be heeded."
56 :group 'gnus-asynchronous
59 (defcustom gnus-prefetched-article-deletion-strategy '(read exit)
60 "List of symbols that say when to remove articles from the prefetch buffer.
61 Possible values in this list are `read', which means that
62 articles are removed as they are read, and `exit', which means
63 that all articles belonging to a group are removed on exit
65 :group 'gnus-asynchronous
66 :type '(set (const read) (const exit)))
68 (defcustom gnus-use-header-prefetch nil
69 "*If non-nil, prefetch the headers to the next group."
70 :group 'gnus-asynchronous
73 (defcustom gnus-async-prefetch-article-p 'gnus-async-unread-p
74 "Function called to say whether an article should be prefetched or not.
75 The function is called with one parameter -- the article data.
76 It should return non-nil if the article is to be prefetched."
77 :group 'gnus-asynchronous
80 ;;; Internal variables.
82 (defvar gnus-async-prefetch-article-buffer " *Async Prefetch Article*")
83 (defvar gnus-async-article-alist nil)
84 (defvar gnus-async-article-semaphore '(nil))
85 (defvar gnus-async-fetch-list nil)
86 (defvar gnus-async-hashtb nil)
87 (defvar gnus-async-current-prefetch-group nil)
88 (defvar gnus-async-current-prefetch-article nil)
89 (defvar gnus-async-timer nil)
91 (defvar gnus-async-prefetch-headers-buffer " *Async Prefetch Headers*")
92 (defvar gnus-async-header-prefetched nil)
94 ;;; Utility functions.
96 (defun gnus-group-asynchronous-p (group)
97 "Say whether GROUP is fetched from a server that supports asynchronicity."
98 (gnus-asynchronous-p (gnus-find-method-for-group group)))
100 ;;; Somewhat bogus semaphores.
102 (defun gnus-async-get-semaphore (semaphore)
103 "Wait until SEMAPHORE is released."
104 (while (/= (length (nconc (symbol-value semaphore) (list nil))) 2)
107 (defun gnus-async-release-semaphore (semaphore)
109 (setcdr (symbol-value semaphore) nil))
111 (defmacro gnus-async-with-semaphore (&rest forms)
114 (gnus-async-get-semaphore 'gnus-async-article-semaphore)
116 (gnus-async-release-semaphore 'gnus-async-article-semaphore)))
118 (put 'gnus-async-with-semaphore 'lisp-indent-function 0)
119 (put 'gnus-async-with-semaphore 'edebug-form-spec '(body))
125 (gnus-add-shutdown 'gnus-async-close 'gnus)
126 (defun gnus-async-close ()
127 (gnus-kill-buffer gnus-async-prefetch-article-buffer)
128 (gnus-kill-buffer gnus-async-prefetch-headers-buffer)
129 (setq gnus-async-hashtb nil
130 gnus-async-article-alist nil
131 gnus-async-header-prefetched nil))
133 (defun gnus-async-set-buffer ()
134 (nnheader-set-temp-buffer gnus-async-prefetch-article-buffer t)
135 (unless gnus-async-hashtb
136 (setq gnus-async-hashtb (gnus-make-hashtable 1023))))
138 (defun gnus-async-halt-prefetch ()
140 (setq gnus-async-fetch-list nil))
142 (defun gnus-async-prefetch-next (group article summary)
143 "Possibly prefetch several articles starting with the article after ARTICLE."
144 (when (and (gnus-buffer-live-p summary)
146 (gnus-group-asynchronous-p group))
148 (set-buffer gnus-summary-buffer)
149 (let ((next (caadr (gnus-data-find-list article))))
151 (if (not (fboundp 'run-with-idle-timer))
152 ;; This is either an older Emacs or XEmacs, so we
153 ;; do this, which leads to slightly slower article
155 (gnus-async-prefetch-article group next summary)
156 (when gnus-async-timer
158 (nnheader-cancel-timer 'gnus-async-timer)))
159 (setq gnus-async-timer
161 0.1 nil 'gnus-async-prefetch-article
162 group next summary))))))))
164 (defun gnus-async-prefetch-article (group article summary &optional next)
165 "Possibly prefetch several articles starting with ARTICLE."
166 (if (not (gnus-buffer-live-p summary))
167 (gnus-async-with-semaphore
168 (setq gnus-async-fetch-list nil))
169 (when (and gnus-asynchronous
172 (gnus-async-with-semaphore
173 (pop gnus-async-fetch-list)))
174 (let ((do-fetch next)
175 (do-message t)) ;(eq major-mode 'gnus-summary-mode)))
176 (when (and (gnus-group-asynchronous-p group)
177 (gnus-buffer-live-p summary)
179 gnus-async-fetch-list))
180 (gnus-async-with-semaphore
182 (setq do-fetch (not gnus-async-fetch-list))
183 ;; Nix out any outstanding requests.
184 (setq gnus-async-fetch-list nil)
185 ;; Fill in the new list.
186 (let ((n gnus-use-article-prefetch)
187 (data (gnus-data-find-list article))
189 (while (and (setq d (pop data))
193 (unless (or (gnus-async-prefetched-article-entry
194 group (setq article (gnus-data-number d)))
195 (not (natnump article))
196 (not (funcall gnus-async-prefetch-article-p d)))
197 ;; Not already fetched -- so we add it to the list.
198 (push article gnus-async-fetch-list)))
199 (setq gnus-async-fetch-list
200 (nreverse gnus-async-fetch-list))))
203 (setq article (car gnus-async-fetch-list))))
205 (when (and do-fetch article)
206 ;; We want to fetch some more articles.
210 (gnus-async-set-buffer)
211 (goto-char (point-max))
212 (setq mark (point-marker))
213 (let ((nnheader-callback-function
214 (gnus-make-async-article-function
215 group article mark summary next))
217 (get-buffer gnus-async-prefetch-article-buffer)))
219 (gnus-message 9 "Prefetching article %d in group %s"
221 (setq gnus-async-current-prefetch-group group)
222 (setq gnus-async-current-prefetch-article article)
223 (gnus-request-article article group))))))))))
225 (defun gnus-make-async-article-function (group article mark summary next)
226 "Return a callback function."
228 (gnus-async-article-callback arg ,group ,article ,mark ,summary ,next)))
230 (defun gnus-async-article-callback (arg group article mark summary next)
231 "Function called when an async article is done being fetched."
233 (setq gnus-async-current-prefetch-article nil)
235 (gnus-async-set-buffer)
236 (gnus-async-with-semaphore
238 gnus-async-article-alist
239 (cons (list (intern (format "%s-%d" group article)
241 mark (set-marker (make-marker) (point-max))
243 gnus-async-article-alist))))
244 (if (not (gnus-buffer-live-p summary))
245 (gnus-async-with-semaphore
246 (setq gnus-async-fetch-list nil))
247 (gnus-async-prefetch-article group next summary t))))
249 (defun gnus-async-unread-p (data)
250 "Return non-nil if DATA represents an unread article."
251 (gnus-data-unread-p data))
253 (defun gnus-async-request-fetched-article (group article buffer)
254 "See whether we have ARTICLE from GROUP and put it in BUFFER."
255 (when (numberp article)
256 (when (and (equal group gnus-async-current-prefetch-group)
257 (eq article gnus-async-current-prefetch-article))
258 (gnus-async-wait-for-article article))
259 (let ((entry (gnus-async-prefetched-article-entry group article)))
262 (gnus-async-set-buffer)
263 (copy-to-buffer buffer (cadr entry) (caddr entry))
264 ;; Remove the read article from the prefetch buffer.
265 (when (memq 'read gnus-prefetched-article-deletion-strategy)
266 (gnus-async-delete-prefetched-entry entry))
269 (defun gnus-async-wait-for-article (article)
270 "Wait until ARTICLE is no longer the currently-being-fetched article."
272 (gnus-async-set-buffer)
273 (let ((proc (nntp-find-connection (current-buffer)))
274 (nntp-server-buffer (current-buffer))
275 (nntp-have-messaged nil)
279 ;; FIXME: we could stop waiting after some
280 ;; timeout, but this is the wrong place to do it.
281 ;; rather than checking time-spent-waiting, we
282 ;; should check time-since-last-output, which
283 ;; needs to be done in nntp.el.
284 (while (eq article gnus-async-current-prefetch-article)
286 (when (nntp-accept-process-output proc)
288 (when (and (not nntp-have-messaged)
290 (gnus-message 5 "Waiting for async article...")
291 (setq nntp-have-messaged t)))
293 ;; if the user interrupted on a slow/hung connection,
294 ;; do something friendly.
296 (setq gnus-async-current-prefetch-article nil))
298 (when nntp-have-messaged
299 (gnus-message 5 ""))))))
301 (defun gnus-async-delete-prefetched-entry (entry)
302 "Delete ENTRY from buffer and alist."
304 (delete-region (cadr entry) (caddr entry))
305 (set-marker (cadr entry) nil)
306 (set-marker (caddr entry) nil))
307 (gnus-async-with-semaphore
308 (setq gnus-async-article-alist
309 (delq entry gnus-async-article-alist))))
311 (defun gnus-async-prefetch-remove-group (group)
312 "Remove all articles belonging to GROUP from the prefetch buffer."
313 (when (and (gnus-group-asynchronous-p group)
314 (memq 'exit gnus-prefetched-article-deletion-strategy))
316 (gnus-async-set-buffer)
317 (dolist (entry gnus-async-article-alist)
318 (when (equal group (nth 3 entry))
319 (gnus-async-delete-prefetched-entry entry))))))
321 (defun gnus-async-prefetched-article-entry (group article)
322 "Return the entry for ARTICLE in GROUP iff it has been prefetched."
323 (let ((entry (save-excursion
324 (gnus-async-set-buffer)
325 (assq (intern (format "%s-%d" group article)
327 gnus-async-article-alist))))
328 ;; Perhaps something has emptied the buffer?
330 (= (cadr entry) (caddr entry)))
333 (set-marker (cadr entry) nil)
334 (set-marker (caddr entry) nil))
335 (setq gnus-async-article-alist
336 (delq entry gnus-async-article-alist))
344 (defun gnus-async-prefetch-headers (group)
345 "Prefetch the headers for group GROUP."
348 (when (and gnus-use-header-prefetch
350 (gnus-group-asynchronous-p group)
351 (listp gnus-async-header-prefetched)
352 (setq unread (gnus-list-of-unread-articles group)))
353 ;; Mark that a fetch is in progress.
354 (setq gnus-async-header-prefetched t)
355 (nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
357 (let ((nntp-server-buffer (current-buffer))
358 (nnheader-callback-function
360 (setq gnus-async-header-prefetched
361 ,(cons group unread)))))
362 (gnus-retrieve-headers unread group gnus-fetch-old-headers))))))
364 (defun gnus-async-retrieve-fetched-headers (articles group)
365 "See whether we have prefetched headers."
366 (when (and gnus-use-header-prefetch
367 (gnus-group-asynchronous-p group)
368 (listp gnus-async-header-prefetched)
369 (equal group (car gnus-async-header-prefetched))
370 (equal articles (cdr gnus-async-header-prefetched)))
372 (nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
374 (copy-to-buffer nntp-server-buffer (point-min) (point-max))
376 (setq gnus-async-header-prefetched nil)
379 (provide 'gnus-async)
381 ;;; gnus-async.el ends here