[bpt/emacs.git] / lisp / gnus / gnus-async.el

;;; gnus-async.el --- asynchronous support for Gnus
;; Copyright (C) 1996,97 Free Software Foundation, Inc.

;; Author: Lars Magne Ingebrigtsen <larsi@ifi.uio.no>
;; Keywords: news

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;;; Code:

(require 'gnus)
(require 'gnus-sum)
(require 'nntp)

(defgroup gnus-asynchronous nil
  "Support for asynchronous operations."
  :group 'gnus)

(defcustom gnus-asynchronous t
  "*If nil, inhibit all Gnus asynchronicity.
If non-nil, let the other asynch variables be heeded."
  :group 'gnus-asynchronous
  :type 'boolean)

(defcustom gnus-use-article-prefetch 30
  "*If non-nil, prefetch articles in groups that allow this.
If a number, prefetch only that many articles forward;
if t, prefetch as many articles as possible."
  :group 'gnus-asynchronous
  :type '(choice (const :tag "off" nil)
		 (const :tag "all" t)
		 (integer :tag "some" 0)))

(defcustom gnus-prefetched-article-deletion-strategy '(read exit)
  "List of symbols that say when to remove articles from the prefetch buffer.
Possible values in this list are `read', which means that
articles are removed as they are read, and `exit', which means
that all articles belonging to a group are removed on exit
from that group."
  :group 'gnus-asynchronous
  :type '(set (const read) (const exit)))

(defcustom gnus-use-header-prefetch nil
  "*If non-nil, prefetch the headers to the next group."
  :group 'gnus-asynchronous
  :type 'boolean)

(defcustom gnus-async-prefetch-article-p 'gnus-async-unread-p
  "Function called to say whether an article should be prefetched or not.
The function is called with one parameter -- the article data.
It should return non-nil if the article is to be prefetched."
  :group 'gnus-asynchronous
  :type 'function)

;;; Internal variables.

(defvar gnus-async-prefetch-article-buffer " *Async Prefetch Article*")
(defvar gnus-async-article-alist nil)
(defvar gnus-async-article-semaphore '(nil))
(defvar gnus-async-fetch-list nil)

(defvar gnus-async-prefetch-headers-buffer " *Async Prefetch Headers*")
(defvar gnus-async-header-prefetched nil)

;;; Utility functions.

(defun gnus-group-asynchronous-p (group)
  "Say whether GROUP is fetched from a server that supports asynchronicity."
  (gnus-asynchronous-p (gnus-find-method-for-group group)))

;;; Somewhat bogus semaphores.

(defun gnus-async-get-semaphore (semaphore)
  "Wait until SEMAPHORE is released."
  (while (/= (length (nconc (symbol-value semaphore) (list nil))) 2)
    (sleep-for 1)))

(defun gnus-async-release-semaphore (semaphore)
  "Release SEMAPHORE."
  (setcdr (symbol-value semaphore) nil))

(defmacro gnus-async-with-semaphore (&rest forms)
  `(unwind-protect
       (progn
	 (gnus-async-get-semaphore 'gnus-async-article-semaphore)
	 ,@forms)
     (gnus-async-release-semaphore 'gnus-async-article-semaphore)))

(put 'gnus-asynch-with-semaphore 'lisp-indent-function 0)
(put 'gnus-asynch-with-semaphore 'edebug-form-spec '(body))

;;;
;;; Article prefetch
;;;

(gnus-add-shutdown 'gnus-async-close 'gnus)
(defun gnus-async-close ()
  (gnus-kill-buffer gnus-async-prefetch-article-buffer)
  (gnus-kill-buffer gnus-async-prefetch-headers-buffer)
  (setq gnus-async-article-alist nil
	gnus-async-header-prefetched nil))

(defun gnus-async-set-buffer ()
  (nnheader-set-temp-buffer gnus-async-prefetch-article-buffer t))

(defun gnus-async-halt-prefetch ()
  "Stop prefetching."
  (setq gnus-async-fetch-list nil))

(defun gnus-async-prefetch-next (group article summary)
  "Possibly prefetch several articles starting with the article after ARTICLE."
  (when (and (gnus-buffer-live-p summary)
	     gnus-asynchronous
	     (gnus-group-asynchronous-p group))
    (save-excursion
      (set-buffer gnus-summary-buffer)
      (let ((next (caadr (gnus-data-find-list article))))
	(when next
	  (if (not (fboundp 'run-with-idle-timer))
	      ;; This is either an older Emacs or XEmacs, so we
	      ;; do this, which leads to slightly slower article
	      ;; buffer display.
	      (gnus-async-prefetch-article group next summary)
	    (run-with-idle-timer
	     0.1 nil 'gnus-async-prefetch-article group next summary)))))))

(defun gnus-async-prefetch-article (group article summary &optional next)
  "Possibly prefetch several articles starting with ARTICLE."
  (if (not (gnus-buffer-live-p summary))
      (gnus-async-with-semaphore
       (setq gnus-async-fetch-list nil))
    (when (and gnus-asynchronous
	       (gnus-alive-p))
      (when next
	(gnus-async-with-semaphore
	 (pop gnus-async-fetch-list)))
      (let ((do-fetch next)
	    (do-message t)) ;(eq major-mode 'gnus-summary-mode)))
	(when (and (gnus-group-asynchronous-p group)
		   (gnus-buffer-live-p summary)
		   (or (not next)
		       gnus-async-fetch-list))
	  (gnus-async-with-semaphore
	   (unless next
	     (setq do-fetch (not gnus-async-fetch-list))
	     ;; Nix out any outstanding requests.
	     (setq gnus-async-fetch-list nil)
	     ;; Fill in the new list.
	     (let ((n gnus-use-article-prefetch)
		   (data (gnus-data-find-list article))
		   d)
	       (while (and (setq d (pop data))
			   (if (numberp n)
			       (natnump (decf n))
			     n))
		 (unless (or (gnus-async-prefetched-article-entry
			      group (setq article (gnus-data-number d)))
			     (not (natnump article))
			     (not (funcall gnus-async-prefetch-article-p d)))
		   ;; Not already fetched -- so we add it to the list.
		   (push article gnus-async-fetch-list)))
	       (setq gnus-async-fetch-list
		     (nreverse gnus-async-fetch-list))))

	   (when do-fetch
	     (setq article (car gnus-async-fetch-list))))

	  (when (and do-fetch article)
	    ;; We want to fetch some more articles.
	    (save-excursion
	      (set-buffer summary)
	      (let (mark)
		(gnus-async-set-buffer)
		(goto-char (point-max))
		(setq mark (point-marker))
		(let ((nnheader-callback-function
		       (gnus-make-async-article-function
			group article mark summary next))
		      (nntp-server-buffer
		       (get-buffer gnus-async-prefetch-article-buffer)))
		  (when do-message
		    (gnus-message 9 "Prefetching article %d in group %s"
				  article group))
		  (gnus-request-article article group))))))))))

(defun gnus-make-async-article-function (group article mark summary next)
  "Return a callback function."
  `(lambda (arg)
     (save-excursion
       (when arg
	 (gnus-async-set-buffer)
	 (gnus-async-with-semaphore
	  (push (list ',(intern (format "%s-%d" group article))
		      ,mark (set-marker (make-marker) (point-max))
		      ,group ,article)
		gnus-async-article-alist)))
       (if (not (gnus-buffer-live-p ,summary))
	   (gnus-async-with-semaphore
	    (setq gnus-async-fetch-list nil))
	 (gnus-async-prefetch-article ,group ,next ,summary t)))))

(defun gnus-async-unread-p (data)
  "Return non-nil if DATA represents an unread article."
  (gnus-data-unread-p data))

(defun gnus-async-request-fetched-article (group article buffer)
  "See whether we have ARTICLE from GROUP and put it in BUFFER."
  (when (numberp article)
    (let ((entry (gnus-async-prefetched-article-entry group article)))
      (when entry
	(save-excursion
	  (gnus-async-set-buffer)
	  (copy-to-buffer buffer (cadr entry) (caddr entry))
	  ;; Remove the read article from the prefetch buffer.
	  (when (memq 'read gnus-prefetched-article-deletion-strategy)
	    (gnus-async-delete-prefected-entry entry))
	  t)))))

(defun gnus-async-delete-prefected-entry (entry)
  "Delete ENTRY from buffer and alist."
  (ignore-errors
    (delete-region (cadr entry) (caddr entry))
    (set-marker (cadr entry) nil)
    (set-marker (caddr entry) nil))
  (gnus-async-with-semaphore
   (setq gnus-async-article-alist
	 (delq entry gnus-async-article-alist))))

(defun gnus-async-prefetch-remove-group (group)
  "Remove all articles belonging to GROUP from the prefetch buffer."
  (when (and (gnus-group-asynchronous-p group)
	     (memq 'exit gnus-prefetched-article-deletion-strategy))
    (let ((alist gnus-async-article-alist))
      (save-excursion
	(gnus-async-set-buffer)
	(while alist
	  (when (equal group (nth 3 (car alist)))
	    (gnus-async-delete-prefected-entry (car alist)))
	  (pop alist))))))

(defun gnus-async-prefetched-article-entry (group article)
  "Return the entry for ARTICLE in GROUP iff it has been prefetched."
  (let ((entry (assq (intern (format "%s-%d" group article))
		     gnus-async-article-alist)))
    ;; Perhaps something has emptied the buffer?
    (if (and entry
	     (= (cadr entry) (caddr entry)))
	(progn
	  (ignore-errors
	    (set-marker (cadr entry) nil)
	    (set-marker (caddr entry) nil))
	  (setq gnus-async-article-alist
		(delq entry gnus-async-article-alist))
	  nil)
      entry)))

;;;
;;; Header prefetch
;;;

(defun gnus-async-prefetch-headers (group)
  "Prefetch the headers for group GROUP."
  (save-excursion
    (let (unread)
      (when (and gnus-use-header-prefetch
		 gnus-asynchronous
		 (gnus-group-asynchronous-p group)
		 (listp gnus-async-header-prefetched)
		 (setq unread (gnus-list-of-unread-articles group)))
	;; Mark that a fetch is in progress.
	(setq gnus-async-header-prefetched t)
	(nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
	(erase-buffer)
	(let ((nntp-server-buffer (current-buffer))
	      (nnheader-callback-function
	       `(lambda (arg)
		  (setq gnus-async-header-prefetched
			,(cons group unread)))))
	  (gnus-retrieve-headers unread group gnus-fetch-old-headers))))))

(defun gnus-async-retrieve-fetched-headers (articles group)
  "See whether we have prefetched headers."
  (when (and gnus-use-header-prefetch
	     (gnus-group-asynchronous-p group)
	     (listp gnus-async-header-prefetched)
	     (equal group (car gnus-async-header-prefetched))
	     (equal articles (cdr gnus-async-header-prefetched)))
    (save-excursion
      (nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
      (nntp-decode-text)
      (copy-to-buffer nntp-server-buffer (point-min) (point-max))
      (erase-buffer)
      (setq gnus-async-header-prefetched nil)
      t)))

(provide 'gnus-async)

;;; gnus-async.el ends here
Commit	Line	Data
eec82323 LMI	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 9 "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