1 ;;; gnus-async.el --- asynchronous support for Gnus
3 ;; Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
4 ;; 2005, 2006, 2007, 2008, 2009, 2010 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 3 of the License, or
14 ;; (at your option) any later version.
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. If not, see <http://www.gnu.org/licenses/>.
28 (eval-when-compile (require 'cl))
34 (defgroup gnus-asynchronous nil
35 "Support for asynchronous operations."
38 (defcustom gnus-use-article-prefetch 30
39 "*If non-nil, prefetch articles in groups that allow this.
40 If a number, prefetch only that many articles forward;
41 if t, prefetch as many articles as possible."
42 :group 'gnus-asynchronous
43 :type '(choice (const :tag "off" nil)
45 (integer :tag "some" 0)))
47 (defcustom gnus-asynchronous nil
48 "*If nil, inhibit all Gnus asynchronicity.
49 If non-nil, let the other asynch variables be heeded."
50 :group 'gnus-asynchronous
53 (defcustom gnus-prefetched-article-deletion-strategy '(read exit)
54 "List of symbols that say when to remove articles from the prefetch buffer.
55 Possible values in this list are `read', which means that
56 articles are removed as they are read, and `exit', which means
57 that all articles belonging to a group are removed on exit
59 :group 'gnus-asynchronous
60 :type '(set (const read) (const exit)))
62 (defcustom gnus-use-header-prefetch nil
63 "*If non-nil, prefetch the headers to the next group."
64 :group 'gnus-asynchronous
67 (defcustom gnus-async-prefetch-article-p 'gnus-async-unread-p
68 "Function called to say whether an article should be prefetched or not.
69 The function is called with one parameter -- the article data.
70 It should return non-nil if the article is to be prefetched."
71 :group 'gnus-asynchronous
74 (defcustom gnus-async-post-fetch-function nil
75 "Function called after an article has been prefetched.
76 The function will be called narrowed to the region of the article
78 :group 'gnus-asynchronous
81 ;;; Internal variables.
83 (defvar gnus-async-prefetch-article-buffer " *Async Prefetch Article*")
84 (defvar gnus-async-article-alist nil)
85 (defvar gnus-async-article-semaphore '(nil))
86 (defvar gnus-async-fetch-list nil)
87 (defvar gnus-async-hashtb nil)
88 (defvar gnus-async-current-prefetch-group nil)
89 (defvar gnus-async-current-prefetch-article nil)
90 (defvar gnus-async-timer nil)
92 (defvar gnus-async-prefetch-headers-buffer " *Async Prefetch Headers*")
93 (defvar gnus-async-header-prefetched nil)
95 ;;; Utility functions.
97 (defun gnus-group-asynchronous-p (group)
98 "Say whether GROUP is fetched from a server that supports asynchronicity."
99 (gnus-asynchronous-p (gnus-find-method-for-group group)))
101 ;;; Somewhat bogus semaphores.
103 (defun gnus-async-get-semaphore (semaphore)
104 "Wait until SEMAPHORE is released."
105 (while (/= (length (nconc (symbol-value semaphore) (list nil))) 2)
108 (defun gnus-async-release-semaphore (semaphore)
110 (setcdr (symbol-value semaphore) nil))
112 (defmacro gnus-async-with-semaphore (&rest forms)
115 (gnus-async-get-semaphore 'gnus-async-article-semaphore)
117 (gnus-async-release-semaphore 'gnus-async-article-semaphore)))
119 (put 'gnus-async-with-semaphore 'lisp-indent-function 0)
120 (put 'gnus-async-with-semaphore 'edebug-form-spec '(body))
126 (gnus-add-shutdown 'gnus-async-close 'gnus)
127 (defun gnus-async-close ()
128 (gnus-kill-buffer gnus-async-prefetch-article-buffer)
129 (gnus-kill-buffer gnus-async-prefetch-headers-buffer)
130 (setq gnus-async-hashtb nil
131 gnus-async-article-alist nil
132 gnus-async-header-prefetched nil))
134 (defun gnus-async-set-buffer ()
135 (nnheader-set-temp-buffer gnus-async-prefetch-article-buffer t)
136 (unless gnus-async-hashtb
137 (setq gnus-async-hashtb (gnus-make-hashtable 1023))))
139 (defun gnus-async-halt-prefetch ()
141 (setq gnus-async-fetch-list nil))
143 (defun gnus-async-prefetch-next (group article summary)
144 "Possibly prefetch several articles starting with the article after ARTICLE."
145 (when (and (gnus-buffer-live-p summary)
147 (gnus-group-asynchronous-p group))
149 (set-buffer gnus-summary-buffer)
150 (let ((next (caadr (gnus-data-find-list article))))
152 (if (not (fboundp 'run-with-idle-timer))
153 ;; This is either an older Emacs or XEmacs, so we
154 ;; do this, which leads to slightly slower article
156 (gnus-async-prefetch-article group next summary)
157 (when gnus-async-timer
159 (nnheader-cancel-timer 'gnus-async-timer)))
160 (setq gnus-async-timer
162 0.1 nil 'gnus-async-prefetch-article
163 group next summary))))))))
165 (defun gnus-async-prefetch-article (group article summary &optional next)
166 "Possibly prefetch several articles starting with ARTICLE."
167 (if (not (gnus-buffer-live-p summary))
168 (gnus-async-with-semaphore
169 (setq gnus-async-fetch-list nil))
170 (when (and gnus-asynchronous
173 (gnus-async-with-semaphore
174 (pop gnus-async-fetch-list)))
175 (let ((do-fetch next)
176 (do-message t)) ;(eq major-mode 'gnus-summary-mode)))
177 (when (and (gnus-group-asynchronous-p group)
178 (gnus-buffer-live-p summary)
180 gnus-async-fetch-list))
181 (gnus-async-with-semaphore
183 (setq do-fetch (not gnus-async-fetch-list))
184 ;; Nix out any outstanding requests.
185 (setq gnus-async-fetch-list nil)
186 ;; Fill in the new list.
187 (let ((n gnus-use-article-prefetch)
188 (data (gnus-data-find-list article))
190 (while (and (setq d (pop data))
194 (unless (or (gnus-async-prefetched-article-entry
195 group (setq article (gnus-data-number d)))
196 (not (natnump article))
197 (not (funcall gnus-async-prefetch-article-p d)))
198 ;; Not already fetched -- so we add it to the list.
199 (push article gnus-async-fetch-list)))
200 (setq gnus-async-fetch-list
201 (nreverse gnus-async-fetch-list))))
204 (setq article (car gnus-async-fetch-list))))
206 (when (and do-fetch article)
207 ;; We want to fetch some more articles.
211 (gnus-async-set-buffer)
212 (goto-char (point-max))
213 (setq mark (point-marker))
214 (let ((nnheader-callback-function
215 (gnus-make-async-article-function
216 group article mark summary next))
218 (get-buffer gnus-async-prefetch-article-buffer)))
220 (gnus-message 9 "Prefetching article %d in group %s"
222 (setq gnus-async-current-prefetch-group group)
223 (setq gnus-async-current-prefetch-article article)
224 (gnus-request-article article group))))))))))
226 (defun gnus-make-async-article-function (group article mark summary next)
227 "Return a callback function."
229 (gnus-async-article-callback arg ,group ,article ,mark ,summary ,next)))
232 (autoload 'gnus-html-prefetch-images "gnus-html"))
234 (defun gnus-async-article-callback (arg group article mark summary next)
235 "Function called when an async article is done being fetched."
237 (setq gnus-async-current-prefetch-article nil)
239 (gnus-async-set-buffer)
242 (narrow-to-region mark (point-max))
243 ;; Prefetch images for the groups that want that.
244 (when (fboundp 'gnus-html-prefetch-images)
245 (gnus-html-prefetch-images summary))
246 (when gnus-async-post-fetch-function
247 (funcall gnus-async-post-fetch-function summary))))
248 (gnus-async-with-semaphore
250 gnus-async-article-alist
251 (cons (list (intern (format "%s-%d" group article)
253 mark (set-marker (make-marker) (point-max))
255 gnus-async-article-alist))))
256 (if (not (gnus-buffer-live-p summary))
257 (gnus-async-with-semaphore
258 (setq gnus-async-fetch-list nil))
259 (gnus-async-prefetch-article group next summary t))))
261 (defun gnus-async-unread-p (data)
262 "Return non-nil if DATA represents an unread article."
263 (gnus-data-unread-p data))
265 (defun gnus-async-request-fetched-article (group article buffer)
266 "See whether we have ARTICLE from GROUP and put it in BUFFER."
267 (when (numberp article)
268 (when (and (equal group gnus-async-current-prefetch-group)
269 (eq article gnus-async-current-prefetch-article))
270 (gnus-async-wait-for-article article))
271 (let ((entry (gnus-async-prefetched-article-entry group article)))
274 (gnus-async-set-buffer)
275 (copy-to-buffer buffer (cadr entry) (caddr entry))
276 ;; Remove the read article from the prefetch buffer.
277 (when (memq 'read gnus-prefetched-article-deletion-strategy)
278 (gnus-async-delete-prefetched-entry entry))
281 (defun gnus-async-wait-for-article (article)
282 "Wait until ARTICLE is no longer the currently-being-fetched article."
284 (gnus-async-set-buffer)
285 (let ((proc (nntp-find-connection (current-buffer)))
286 (nntp-server-buffer (current-buffer))
287 (nntp-have-messaged nil)
291 ;; FIXME: we could stop waiting after some
292 ;; timeout, but this is the wrong place to do it.
293 ;; rather than checking time-spent-waiting, we
294 ;; should check time-since-last-output, which
295 ;; needs to be done in nntp.el.
296 (while (eq article gnus-async-current-prefetch-article)
298 (when (nntp-accept-process-output proc)
300 (when (and (not nntp-have-messaged)
302 (gnus-message 5 "Waiting for async article...")
303 (setq nntp-have-messaged t)))
305 ;; if the user interrupted on a slow/hung connection,
306 ;; do something friendly.
308 (setq gnus-async-current-prefetch-article nil))
310 (when nntp-have-messaged
311 (gnus-message 5 ""))))))
313 (defun gnus-async-delete-prefetched-entry (entry)
314 "Delete ENTRY from buffer and alist."
316 (delete-region (cadr entry) (caddr entry))
317 (set-marker (cadr entry) nil)
318 (set-marker (caddr entry) nil))
319 (gnus-async-with-semaphore
320 (setq gnus-async-article-alist
321 (delq entry gnus-async-article-alist))))
323 (defun gnus-async-prefetch-remove-group (group)
324 "Remove all articles belonging to GROUP from the prefetch buffer."
325 (when (and (gnus-group-asynchronous-p group)
326 (memq 'exit gnus-prefetched-article-deletion-strategy))
328 (gnus-async-set-buffer)
329 (dolist (entry gnus-async-article-alist)
330 (when (equal group (nth 3 entry))
331 (gnus-async-delete-prefetched-entry entry))))))
333 (defun gnus-async-prefetched-article-entry (group article)
334 "Return the entry for ARTICLE in GROUP if it has been prefetched."
335 (let ((entry (save-excursion
336 (gnus-async-set-buffer)
337 (assq (intern (format "%s-%d" group article)
339 gnus-async-article-alist))))
340 ;; Perhaps something has emptied the buffer?
342 (= (cadr entry) (caddr entry)))
345 (set-marker (cadr entry) nil)
346 (set-marker (caddr entry) nil))
347 (setq gnus-async-article-alist
348 (delq entry gnus-async-article-alist))
356 (defun gnus-async-prefetch-headers (group)
357 "Prefetch the headers for group GROUP."
360 (when (and gnus-use-header-prefetch
362 (gnus-group-asynchronous-p group)
363 (listp gnus-async-header-prefetched)
364 (setq unread (gnus-list-of-unread-articles group)))
365 ;; Mark that a fetch is in progress.
366 (setq gnus-async-header-prefetched t)
367 (nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
369 (let ((nntp-server-buffer (current-buffer))
370 (nnheader-callback-function
372 (setq gnus-async-header-prefetched
373 ,(cons group unread)))))
374 (gnus-retrieve-headers unread group gnus-fetch-old-headers))))))
376 (defun gnus-async-retrieve-fetched-headers (articles group)
377 "See whether we have prefetched headers."
378 (when (and gnus-use-header-prefetch
379 (gnus-group-asynchronous-p group)
380 (listp gnus-async-header-prefetched)
381 (equal group (car gnus-async-header-prefetched))
382 (equal articles (cdr gnus-async-header-prefetched)))
384 (nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
386 (copy-to-buffer nntp-server-buffer (point-min) (point-max))
388 (setq gnus-async-header-prefetched nil)
391 (provide 'gnus-async)
393 ;;; gnus-async.el ends here