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date Mon, 13 Aug 2007 08:49:20 +0200
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1 ;;; gnus-async.el --- asynchronous support for Gnus
2 ;; Copyright (C) 1996,97 Free Software Foundation, Inc.
3
4 ;; Author: Lars Magne Ingebrigtsen <larsi@ifi.uio.no>
5 ;; Keywords: news
6
7 ;; This file is part of GNU Emacs.
8
9 ;; GNU Emacs is free software; you can redistribute it and/or modify
10 ;; it under the terms of the GNU General Public License as published by
11 ;; the Free Software Foundation; either version 2, or (at your option)
12 ;; any later version.
13
14 ;; GNU Emacs is distributed in the hope that it will be useful,
15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 ;; GNU General Public License for more details.
18
19 ;; You should have received a copy of the GNU General Public License
20 ;; along with GNU Emacs; see the file COPYING. If not, write to the
21 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
22 ;; Boston, MA 02111-1307, USA.
23
24 ;;; Commentary:
25
26 ;;; Code:
27
28 (require 'gnus)
29 (require 'gnus-sum)
30 (require 'nntp)
31
32 (defgroup gnus-asynchronous nil
33 "Support for asynchronous operations."
34 :group 'gnus)
35
36 (defcustom gnus-asynchronous t
37 "*If nil, inhibit all Gnus asynchronicity.
38 If non-nil, let the other asynch variables be heeded."
39 :group 'gnus-asynchronous
40 :type 'boolean)
41
42 (defcustom gnus-use-article-prefetch 30
43 "*If non-nil, prefetch articles in groups that allow this.
44 If a number, prefetch only that many articles forward;
45 if t, prefetch as many articles as possible."
46 :group 'gnus-asynchronous
47 :type '(choice (const :tag "off" nil)
48 (const :tag "all" t)
49 (integer :tag "some" 0)))
50
51 (defcustom gnus-prefetched-article-deletion-strategy '(read exit)
52 "List of symbols that say when to remove articles from the prefetch buffer.
53 Possible values in this list are `read', which means that
54 articles are removed as they are read, and `exit', which means
55 that all articles belonging to a group are removed on exit
56 from that group."
57 :group 'gnus-asynchronous
58 :type '(set (const read) (const exit)))
59
60 (defcustom gnus-use-header-prefetch nil
61 "*If non-nil, prefetch the headers to the next group."
62 :group 'gnus-asynchronous
63 :type 'boolean)
64
65 (defcustom gnus-async-prefetch-article-p 'gnus-async-unread-p
66 "Function called to say whether an article should be prefetched or not.
67 The function is called with one parameter -- the article data.
68 It should return non-nil if the article is to be prefetched."
69 :group 'gnus-asynchronous
70 :type 'function)
71
72 ;;; Internal variables.
73
74 (defvar gnus-async-prefetch-article-buffer " *Async Prefetch Article*")
75 (defvar gnus-async-article-alist nil)
76 (defvar gnus-async-article-semaphore '(nil))
77 (defvar gnus-async-fetch-list nil)
78
79 (defvar gnus-async-prefetch-headers-buffer " *Async Prefetch Headers*")
80 (defvar gnus-async-header-prefetched nil)
81
82 ;;; Utility functions.
83
84 (defun gnus-group-asynchronous-p (group)
85 "Say whether GROUP is fetched from a server that supports asynchronicity."
86 (gnus-asynchronous-p (gnus-find-method-for-group group)))
87
88 ;;; Somewhat bogus semaphores.
89
90 (defun gnus-async-get-semaphore (semaphore)
91 "Wait until SEMAPHORE is released."
92 (while (/= (length (nconc (symbol-value semaphore) (list nil))) 2)
93 (sleep-for 1)))
94
95 (defun gnus-async-release-semaphore (semaphore)
96 "Release SEMAPHORE."
97 (setcdr (symbol-value semaphore) nil))
98
99 (defmacro gnus-async-with-semaphore (&rest forms)
100 `(unwind-protect
101 (progn
102 (gnus-async-get-semaphore 'gnus-async-article-semaphore)
103 ,@forms)
104 (gnus-async-release-semaphore 'gnus-async-article-semaphore)))
105
106 (put 'gnus-asynch-with-semaphore 'lisp-indent-function 0)
107 (put 'gnus-asynch-with-semaphore 'edebug-form-spec '(body))
108
109 ;;;
110 ;;; Article prefetch
111 ;;;
112
113 (gnus-add-shutdown 'gnus-async-close 'gnus)
114 (defun gnus-async-close ()
115 (gnus-kill-buffer gnus-async-prefetch-article-buffer)
116 (gnus-kill-buffer gnus-async-prefetch-headers-buffer)
117 (setq gnus-async-article-alist nil
118 gnus-async-header-prefetched nil))
119
120 (defun gnus-async-set-buffer ()
121 (nnheader-set-temp-buffer gnus-async-prefetch-article-buffer t))
122
123 (defun gnus-async-halt-prefetch ()
124 "Stop prefetching."
125 (setq gnus-async-fetch-list nil))
126
127 (defun gnus-async-prefetch-next (group article summary)
128 "Possibly prefetch several articles starting with the article after ARTICLE."
129 (when (and (gnus-buffer-live-p summary)
130 gnus-asynchronous
131 (gnus-group-asynchronous-p group))
132 (save-excursion
133 (set-buffer gnus-summary-buffer)
134 (let ((next (caadr (gnus-data-find-list article))))
135 (when next
136 (if (not (fboundp 'run-with-idle-timer))
137 ;; This is either an older Emacs or XEmacs, so we
138 ;; do this, which leads to slightly slower article
139 ;; buffer display.
140 (gnus-async-prefetch-article group next summary)
141 (run-with-idle-timer
142 0.1 nil 'gnus-async-prefetch-article group next summary)))))))
143
144 (defun gnus-async-prefetch-article (group article summary &optional next)
145 "Possibly prefetch several articles starting with ARTICLE."
146 (if (not (gnus-buffer-live-p summary))
147 (gnus-async-with-semaphore
148 (setq gnus-async-fetch-list nil))
149 (when (and gnus-asynchronous
150 (gnus-alive-p))
151 (when next
152 (gnus-async-with-semaphore
153 (pop gnus-async-fetch-list)))
154 (let ((do-fetch next)
155 (do-message t)) ;(eq major-mode 'gnus-summary-mode)))
156 (when (and (gnus-group-asynchronous-p group)
157 (gnus-buffer-live-p summary)
158 (or (not next)
159 gnus-async-fetch-list))
160 (gnus-async-with-semaphore
161 (unless next
162 (setq do-fetch (not gnus-async-fetch-list))
163 ;; Nix out any outstanding requests.
164 (setq gnus-async-fetch-list nil)
165 ;; Fill in the new list.
166 (let ((n gnus-use-article-prefetch)
167 (data (gnus-data-find-list article))
168 d)
169 (while (and (setq d (pop data))
170 (if (numberp n)
171 (natnump (decf n))
172 n))
173 (unless (or (gnus-async-prefetched-article-entry
174 group (setq article (gnus-data-number d)))
175 (not (natnump article))
176 (not (funcall gnus-async-prefetch-article-p d)))
177 ;; Not already fetched -- so we add it to the list.
178 (push article gnus-async-fetch-list)))
179 (setq gnus-async-fetch-list
180 (nreverse gnus-async-fetch-list))))
181
182 (when do-fetch
183 (setq article (car gnus-async-fetch-list))))
184
185 (when (and do-fetch article)
186 ;; We want to fetch some more articles.
187 (save-excursion
188 (set-buffer summary)
189 (let (mark)
190 (gnus-async-set-buffer)
191 (goto-char (point-max))
192 (setq mark (point-marker))
193 (let ((nnheader-callback-function
194 (gnus-make-async-article-function
195 group article mark summary next))
196 (nntp-server-buffer
197 (get-buffer gnus-async-prefetch-article-buffer)))
198 (when do-message
199 (gnus-message 7 "Prefetching article %d in group %s"
200 article group))
201 (gnus-request-article article group))))))))))
202
203 (defun gnus-make-async-article-function (group article mark summary next)
204 "Return a callback function."
205 `(lambda (arg)
206 (save-excursion
207 (when arg
208 (gnus-async-set-buffer)
209 (gnus-async-with-semaphore
210 (push (list ',(intern (format "%s-%d" group article))
211 ,mark (set-marker (make-marker) (point-max))
212 ,group ,article)
213 gnus-async-article-alist)))
214 (if (not (gnus-buffer-live-p ,summary))
215 (gnus-async-with-semaphore
216 (setq gnus-async-fetch-list nil))
217 (gnus-async-prefetch-article ,group ,next ,summary t)))))
218
219 (defun gnus-async-unread-p (data)
220 "Return non-nil if DATA represents an unread article."
221 (gnus-data-unread-p data))
222
223 (defun gnus-async-request-fetched-article (group article buffer)
224 "See whether we have ARTICLE from GROUP and put it in BUFFER."
225 (when (numberp article)
226 (let ((entry (gnus-async-prefetched-article-entry group article)))
227 (when entry
228 (save-excursion
229 (gnus-async-set-buffer)
230 (copy-to-buffer buffer (cadr entry) (caddr entry))
231 ;; Remove the read article from the prefetch buffer.
232 (when (memq 'read gnus-prefetched-article-deletion-strategy)
233 (gnus-async-delete-prefected-entry entry))
234 t)))))
235
236 (defun gnus-async-delete-prefected-entry (entry)
237 "Delete ENTRY from buffer and alist."
238 (ignore-errors
239 (delete-region (cadr entry) (caddr entry))
240 (set-marker (cadr entry) nil)
241 (set-marker (caddr entry) nil))
242 (gnus-async-with-semaphore
243 (setq gnus-async-article-alist
244 (delq entry gnus-async-article-alist))))
245
246 (defun gnus-async-prefetch-remove-group (group)
247 "Remove all articles belonging to GROUP from the prefetch buffer."
248 (when (and (gnus-group-asynchronous-p group)
249 (memq 'exit gnus-prefetched-article-deletion-strategy))
250 (let ((alist gnus-async-article-alist))
251 (save-excursion
252 (gnus-async-set-buffer)
253 (while alist
254 (when (equal group (nth 3 (car alist)))
255 (gnus-async-delete-prefected-entry (car alist)))
256 (pop alist))))))
257
258 (defun gnus-async-prefetched-article-entry (group article)
259 "Return the entry for ARTICLE in GROUP iff it has been prefetched."
260 (let ((entry (assq (intern (format "%s-%d" group article))
261 gnus-async-article-alist)))
262 ;; Perhaps something has emptied the buffer?
263 (if (and entry
264 (= (cadr entry) (caddr entry)))
265 (progn
266 (ignore-errors
267 (set-marker (cadr entry) nil)
268 (set-marker (caddr entry) nil))
269 (setq gnus-async-article-alist
270 (delq entry gnus-async-article-alist))
271 nil)
272 entry)))
273
274 ;;;
275 ;;; Header prefetch
276 ;;;
277
278 (defun gnus-async-prefetch-headers (group)
279 "Prefetch the headers for group GROUP."
280 (save-excursion
281 (let (unread)
282 (when (and gnus-use-header-prefetch
283 gnus-asynchronous
284 (gnus-group-asynchronous-p group)
285 (listp gnus-async-header-prefetched)
286 (setq unread (gnus-list-of-unread-articles group)))
287 ;; Mark that a fetch is in progress.
288 (setq gnus-async-header-prefetched t)
289 (nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
290 (erase-buffer)
291 (let ((nntp-server-buffer (current-buffer))
292 (nnheader-callback-function
293 `(lambda (arg)
294 (setq gnus-async-header-prefetched
295 ,(cons group unread)))))
296 (gnus-retrieve-headers unread group gnus-fetch-old-headers))))))
297
298 (defun gnus-async-retrieve-fetched-headers (articles group)
299 "See whether we have prefetched headers."
300 (when (and gnus-use-header-prefetch
301 (gnus-group-asynchronous-p group)
302 (listp gnus-async-header-prefetched)
303 (equal group (car gnus-async-header-prefetched))
304 (equal articles (cdr gnus-async-header-prefetched)))
305 (save-excursion
306 (nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
307 (nntp-decode-text)
308 (copy-to-buffer nntp-server-buffer (point-min) (point-max))
309 (erase-buffer)
310 (setq gnus-async-header-prefetched nil)
311 t)))
312
313 (provide 'gnus-async)
314
315 ;;; gnus-async.el ends here