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

;;; gnus-async.el --- asynchronous support for Gnus
;; Copyright (C) 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.

;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; 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:

(eval-when-compile (require 'cl))

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

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

(defcustom gnus-asynchronous nil
  "*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-hashtb nil)
(defvar gnus-async-current-prefetch-group nil)
(defvar gnus-async-current-prefetch-article nil)
(defvar gnus-async-timer 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-async-with-semaphore 'lisp-indent-function 0)
(put 'gnus-async-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-hashtb nil
	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)
  (unless gnus-async-hashtb
    (setq gnus-async-hashtb (gnus-make-hashtable 1023))))

(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)
	    (when gnus-async-timer
	      (ignore-errors
		(nnheader-cancel-timer 'gnus-async-timer)))
	    (setq gnus-async-timer
		  (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))
		  (setq gnus-async-current-prefetch-group group)
		  (setq gnus-async-current-prefetch-article article)
		  (gnus-request-article article group))))))))))

(defun gnus-make-async-article-function (group article mark summary next)
  "Return a callback function."
  `(lambda (arg)
     (gnus-async-article-callback arg ,group ,article ,mark ,summary ,next)))

(defun gnus-async-article-callback (arg group article mark summary next)
  "Function called when an async article is done being fetched."
  (save-excursion
    (setq gnus-async-current-prefetch-article nil)
    (when arg
      (gnus-async-set-buffer)
      (gnus-async-with-semaphore
	(setq
	 gnus-async-article-alist
	 (cons (list (intern (format "%s-%d" group article)
			     gnus-async-hashtb)
		     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)
    (when (and (equal group gnus-async-current-prefetch-group)
	       (eq article gnus-async-current-prefetch-article))
      (gnus-async-wait-for-article 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-prefetched-entry entry))
	  t)))))

(defun gnus-async-wait-for-article (article)
  "Wait until ARTICLE is no longer the currently-being-fetched article."
  (save-excursion
    (gnus-async-set-buffer)
    (let ((proc (nntp-find-connection (current-buffer)))
	  (nntp-server-buffer (current-buffer))
	  (nntp-have-messaged nil)
	  (tries 0))
      (condition-case nil
	  ;; FIXME: we could stop waiting after some
	  ;; timeout, but this is the wrong place to do it.
	  ;; rather than checking time-spent-waiting, we
	  ;; should check time-since-last-output, which
	  ;; needs to be done in nntp.el.
	  (while (eq article gnus-async-current-prefetch-article)
	    (incf tries)
	    (when (nntp-accept-process-output proc 1)
	      (setq tries 0))
	    (when (and (not nntp-have-messaged) (eq 3 tries))
	      (gnus-message 5 "Waiting for async article...")
	      (setq nntp-have-messaged t)))
	(quit
	 ;; if the user interrupted on a slow/hung connection,
	 ;; do something friendly.
	 (when (< 3 tries)
	   (setq gnus-async-current-prefetch-article nil))
	 (signal 'quit nil)))
      (when nntp-have-messaged
	(gnus-message 5 "")))))

(defun gnus-async-delete-prefetched-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-prefetched-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 (save-excursion
		 (gnus-async-set-buffer)
		 (assq (intern (format "%s-%d" group article)
			       gnus-async-hashtb)
		       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	1	;;; gnus-async.el --- asynchronous support for Gnus
16409b0b	2	;; Copyright (C) 1996, 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
eec82323	3
6748645f	4	;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
eec82323 LMI	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
5ab7173c RS	28	(eval-when-compile (require 'cl))
5ab7173c RS	29
eec82323 LMI	30	(require 'gnus)
	31	(require 'gnus-sum)
	32	(require 'nntp)
	33
	34	(defgroup gnus-asynchronous nil
	35	"Support for asynchronous operations."
	36	:group 'gnus)
	37
16409b0b	38	(defcustom gnus-asynchronous nil
eec82323 LMI	39	"*If nil, inhibit all Gnus asynchronicity.
	40	If non-nil, let the other asynch variables be heeded."
	41	:group 'gnus-asynchronous
	42	:type 'boolean)
	43
	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)
16409b0b GM	50	(const :tag "all" t)
16409b0b GM	51	(integer :tag "some" 0)))
eec82323 LMI	52
	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
	58	from that group."
	59	:group 'gnus-asynchronous
	60	:type '(set (const read) (const exit)))
	61
	62	(defcustom gnus-use-header-prefetch nil
	63	"*If non-nil, prefetch the headers to the next group."
	64	:group 'gnus-asynchronous
	65	:type 'boolean)
	66
	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
	72	:type 'function)
	73
	74	;;; Internal variables.
	75
	76	(defvar gnus-async-prefetch-article-buffer " Async Prefetch Article")
	77	(defvar gnus-async-article-alist nil)
	78	(defvar gnus-async-article-semaphore '(nil))
	79	(defvar gnus-async-fetch-list nil)
16409b0b GM	80	(defvar gnus-async-hashtb nil)
	81	(defvar gnus-async-current-prefetch-group nil)
	82	(defvar gnus-async-current-prefetch-article nil)
	83	(defvar gnus-async-timer nil)
eec82323 LMI	84
	85	(defvar gnus-async-prefetch-headers-buffer " Async Prefetch Headers")
	86	(defvar gnus-async-header-prefetched nil)
	87
	88	;;; Utility functions.
	89
	90	(defun gnus-group-asynchronous-p (group)
	91	"Say whether GROUP is fetched from a server that supports asynchronicity."
	92	(gnus-asynchronous-p (gnus-find-method-for-group group)))
	93
	94	;;; Somewhat bogus semaphores.
	95
	96	(defun gnus-async-get-semaphore (semaphore)
	97	"Wait until SEMAPHORE is released."
	98	(while (/= (length (nconc (symbol-value semaphore) (list nil))) 2)
	99	(sleep-for 1)))
	100
	101	(defun gnus-async-release-semaphore (semaphore)
	102	"Release SEMAPHORE."
	103	(setcdr (symbol-value semaphore) nil))
	104
	105	(defmacro gnus-async-with-semaphore (&rest forms)
	106	`(unwind-protect
	107	(progn
	108	(gnus-async-get-semaphore 'gnus-async-article-semaphore)
	109	,@forms)
	110	(gnus-async-release-semaphore 'gnus-async-article-semaphore)))
	111
16409b0b GM	112	(put 'gnus-async-with-semaphore 'lisp-indent-function 0)
16409b0b GM	113	(put 'gnus-async-with-semaphore 'edebug-form-spec '(body))
eec82323 LMI	114
	115	;;;
	116	;;; Article prefetch
	117	;;;
	118
	119	(gnus-add-shutdown 'gnus-async-close 'gnus)
	120	(defun gnus-async-close ()
	121	(gnus-kill-buffer gnus-async-prefetch-article-buffer)
	122	(gnus-kill-buffer gnus-async-prefetch-headers-buffer)
16409b0b GM	123	(setq gnus-async-hashtb nil
16409b0b GM	124	gnus-async-article-alist nil
eec82323 LMI	125	gnus-async-header-prefetched nil))
	126
	127	(defun gnus-async-set-buffer ()
6748645f	128	(nnheader-set-temp-buffer gnus-async-prefetch-article-buffer t)
16409b0b GM	129	(unless gnus-async-hashtb
16409b0b GM	130	(setq gnus-async-hashtb (gnus-make-hashtable 1023))))
eec82323 LMI	131
	132	(defun gnus-async-halt-prefetch ()
	133	"Stop prefetching."
	134	(setq gnus-async-fetch-list nil))
	135
	136	(defun gnus-async-prefetch-next (group article summary)
	137	"Possibly prefetch several articles starting with the article after ARTICLE."
	138	(when (and (gnus-buffer-live-p summary)
	139	gnus-asynchronous
	140	(gnus-group-asynchronous-p group))
	141	(save-excursion
	142	(set-buffer gnus-summary-buffer)
	143	(let ((next (caadr (gnus-data-find-list article))))
	144	(when next
	145	(if (not (fboundp 'run-with-idle-timer))
	146	;; This is either an older Emacs or XEmacs, so we
	147	;; do this, which leads to slightly slower article
	148	;; buffer display.
	149	(gnus-async-prefetch-article group next summary)
16409b0b GM	150	(when gnus-async-timer
	151	(ignore-errors
	152	(nnheader-cancel-timer 'gnus-async-timer)))
	153	(setq gnus-async-timer
	154	(run-with-idle-timer
	155	0.1 nil 'gnus-async-prefetch-article
	156	group next summary))))))))
eec82323 LMI	157
	158	(defun gnus-async-prefetch-article (group article summary &optional next)
	159	"Possibly prefetch several articles starting with ARTICLE."
	160	(if (not (gnus-buffer-live-p summary))
	161	(gnus-async-with-semaphore
16409b0b	162	(setq gnus-async-fetch-list nil))
eec82323 LMI	163	(when (and gnus-asynchronous
	164	(gnus-alive-p))
	165	(when next
	166	(gnus-async-with-semaphore
16409b0b	167	(pop gnus-async-fetch-list)))
eec82323	168	(let ((do-fetch next)
16409b0b	169	(do-message t)) ;(eq major-mode 'gnus-summary-mode)))
eec82323 LMI	170	(when (and (gnus-group-asynchronous-p group)
	171	(gnus-buffer-live-p summary)
	172	(or (not next)
	173	gnus-async-fetch-list))
	174	(gnus-async-with-semaphore
16409b0b GM	175	(unless next
	176	(setq do-fetch (not gnus-async-fetch-list))
	177	;; Nix out any outstanding requests.
	178	(setq gnus-async-fetch-list nil)
	179	;; Fill in the new list.
	180	(let ((n gnus-use-article-prefetch)
	181	(data (gnus-data-find-list article))
	182	d)
	183	(while (and (setq d (pop data))
	184	(if (numberp n)
	185	(natnump (decf n))
	186	n))
	187	(unless (or (gnus-async-prefetched-article-entry
	188	group (setq article (gnus-data-number d)))
	189	(not (natnump article))
	190	(not (funcall gnus-async-prefetch-article-p d)))
	191	;; Not already fetched -- so we add it to the list.
	192	(push article gnus-async-fetch-list)))
	193	(setq gnus-async-fetch-list
	194	(nreverse gnus-async-fetch-list))))
	195
	196	(when do-fetch
	197	(setq article (car gnus-async-fetch-list))))
eec82323 LMI	198
	199	(when (and do-fetch article)
	200	;; We want to fetch some more articles.
	201	(save-excursion
	202	(set-buffer summary)
	203	(let (mark)
	204	(gnus-async-set-buffer)
	205	(goto-char (point-max))
	206	(setq mark (point-marker))
	207	(let ((nnheader-callback-function
	208	(gnus-make-async-article-function
	209	group article mark summary next))
	210	(nntp-server-buffer
	211	(get-buffer gnus-async-prefetch-article-buffer)))
	212	(when do-message
	213	(gnus-message 9 "Prefetching article %d in group %s"
	214	article group))
16409b0b GM	215	(setq gnus-async-current-prefetch-group group)
16409b0b GM	216	(setq gnus-async-current-prefetch-article article)
eec82323 LMI	217	(gnus-request-article article group))))))))))
	218
	219	(defun gnus-make-async-article-function (group article mark summary next)
	220	"Return a callback function."
	221	`(lambda (arg)
16409b0b GM	222	(gnus-async-article-callback arg ,group ,article ,mark ,summary ,next)))
	223
	224	(defun gnus-async-article-callback (arg group article mark summary next)
	225	"Function called when an async article is done being fetched."
	226	(save-excursion
	227	(setq gnus-async-current-prefetch-article nil)
	228	(when arg
	229	(gnus-async-set-buffer)
	230	(gnus-async-with-semaphore
	231	(setq
	232	gnus-async-article-alist
	233	(cons (list (intern (format "%s-%d" group article)
	234	gnus-async-hashtb)
	235	mark (set-marker (make-marker) (point-max))
	236	group article)
	237	gnus-async-article-alist))))
	238	(if (not (gnus-buffer-live-p summary))
	239	(gnus-async-with-semaphore
	240	(setq gnus-async-fetch-list nil))
	241	(gnus-async-prefetch-article group next summary t))))
eec82323 LMI	242
	243	(defun gnus-async-unread-p (data)
	244	"Return non-nil if DATA represents an unread article."
	245	(gnus-data-unread-p data))
	246
	247	(defun gnus-async-request-fetched-article (group article buffer)
	248	"See whether we have ARTICLE from GROUP and put it in BUFFER."
	249	(when (numberp article)
16409b0b GM	250	(when (and (equal group gnus-async-current-prefetch-group)
	251	(eq article gnus-async-current-prefetch-article))
	252	(gnus-async-wait-for-article article))
eec82323 LMI	253	(let ((entry (gnus-async-prefetched-article-entry group article)))
	254	(when entry
	255	(save-excursion
	256	(gnus-async-set-buffer)
	257	(copy-to-buffer buffer (cadr entry) (caddr entry))
	258	;; Remove the read article from the prefetch buffer.
	259	(when (memq 'read gnus-prefetched-article-deletion-strategy)
16409b0b	260	(gnus-async-delete-prefetched-entry entry))
eec82323 LMI	261	t)))))
eec82323 LMI	262
16409b0b GM	263	(defun gnus-async-wait-for-article (article)
	264	"Wait until ARTICLE is no longer the currently-being-fetched article."
	265	(save-excursion
	266	(gnus-async-set-buffer)
	267	(let ((proc (nntp-find-connection (current-buffer)))
	268	(nntp-server-buffer (current-buffer))
	269	(nntp-have-messaged nil)
	270	(tries 0))
	271	(condition-case nil
	272	;; FIXME: we could stop waiting after some
	273	;; timeout, but this is the wrong place to do it.
	274	;; rather than checking time-spent-waiting, we
	275	;; should check time-since-last-output, which
	276	;; needs to be done in nntp.el.
	277	(while (eq article gnus-async-current-prefetch-article)
	278	(incf tries)
	279	(when (nntp-accept-process-output proc 1)
	280	(setq tries 0))
	281	(when (and (not nntp-have-messaged) (eq 3 tries))
	282	(gnus-message 5 "Waiting for async article...")
	283	(setq nntp-have-messaged t)))
	284	(quit
	285	;; if the user interrupted on a slow/hung connection,
	286	;; do something friendly.
	287	(when (< 3 tries)
	288	(setq gnus-async-current-prefetch-article nil))
	289	(signal 'quit nil)))
	290	(when nntp-have-messaged
	291	(gnus-message 5 "")))))
	292
	293	(defun gnus-async-delete-prefetched-entry (entry)
eec82323 LMI	294	"Delete ENTRY from buffer and alist."
	295	(ignore-errors
	296	(delete-region (cadr entry) (caddr entry))
	297	(set-marker (cadr entry) nil)
	298	(set-marker (caddr entry) nil))
	299	(gnus-async-with-semaphore
16409b0b GM	300	(setq gnus-async-article-alist
16409b0b GM	301	(delq entry gnus-async-article-alist))))
eec82323 LMI	302
	303	(defun gnus-async-prefetch-remove-group (group)
	304	"Remove all articles belonging to GROUP from the prefetch buffer."
	305	(when (and (gnus-group-asynchronous-p group)
	306	(memq 'exit gnus-prefetched-article-deletion-strategy))
	307	(let ((alist gnus-async-article-alist))
	308	(save-excursion
	309	(gnus-async-set-buffer)
	310	(while alist
	311	(when (equal group (nth 3 (car alist)))
16409b0b	312	(gnus-async-delete-prefetched-entry (car alist)))
eec82323 LMI	313	(pop alist))))))
	314
	315	(defun gnus-async-prefetched-article-entry (group article)
	316	"Return the entry for ARTICLE in GROUP iff it has been prefetched."
6748645f LMI	317	(let ((entry (save-excursion
	318	(gnus-async-set-buffer)
	319	(assq (intern (format "%s-%d" group article)
16409b0b	320	gnus-async-hashtb)
6748645f	321	gnus-async-article-alist))))
eec82323 LMI	322	;; Perhaps something has emptied the buffer?
	323	(if (and entry
	324	(= (cadr entry) (caddr entry)))
	325	(progn
	326	(ignore-errors
	327	(set-marker (cadr entry) nil)
	328	(set-marker (caddr entry) nil))
	329	(setq gnus-async-article-alist
	330	(delq entry gnus-async-article-alist))
	331	nil)
	332	entry)))
	333
	334	;;;
	335	;;; Header prefetch
	336	;;;
	337
	338	(defun gnus-async-prefetch-headers (group)
	339	"Prefetch the headers for group GROUP."
	340	(save-excursion
	341	(let (unread)
	342	(when (and gnus-use-header-prefetch
	343	gnus-asynchronous
	344	(gnus-group-asynchronous-p group)
	345	(listp gnus-async-header-prefetched)
	346	(setq unread (gnus-list-of-unread-articles group)))
	347	;; Mark that a fetch is in progress.
	348	(setq gnus-async-header-prefetched t)
	349	(nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
	350	(erase-buffer)
	351	(let ((nntp-server-buffer (current-buffer))
	352	(nnheader-callback-function
	353	`(lambda (arg)
	354	(setq gnus-async-header-prefetched
	355	,(cons group unread)))))
	356	(gnus-retrieve-headers unread group gnus-fetch-old-headers))))))
	357
	358	(defun gnus-async-retrieve-fetched-headers (articles group)
	359	"See whether we have prefetched headers."
	360	(when (and gnus-use-header-prefetch
	361	(gnus-group-asynchronous-p group)
	362	(listp gnus-async-header-prefetched)
	363	(equal group (car gnus-async-header-prefetched))
	364	(equal articles (cdr gnus-async-header-prefetched)))
	365	(save-excursion
	366	(nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
	367	(nntp-decode-text)
	368	(copy-to-buffer nntp-server-buffer (point-min) (point-max))
	369	(erase-buffer)
	370	(setq gnus-async-header-prefetched nil)
	371	t)))
	372
	373	(provide 'gnus-async)
	374
	375	;;; gnus-async.el ends here