code.delx.au - gnu-emacs/blob - lisp/gnus/gnus-async.el

   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 (eval-when-compile (require 'cl))
  29
  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
  38 (defcustom gnus-asynchronous t
  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)
  50                  (integer :tag "some" 0)
  51                  (other :tag "all" t)))
  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)
  80
  81 (defvar gnus-async-prefetch-headers-buffer " *Async Prefetch Headers*")
  82 (defvar gnus-async-header-prefetched nil)
  83
  84 ;;; Utility functions.
  85
  86 (defun gnus-group-asynchronous-p (group)
  87   "Say whether GROUP is fetched from a server that supports asynchronicity."
  88   (gnus-asynchronous-p (gnus-find-method-for-group group)))
  89
  90 ;;; Somewhat bogus semaphores.
  91
  92 (defun gnus-async-get-semaphore (semaphore)
  93   "Wait until SEMAPHORE is released."
  94   (while (/= (length (nconc (symbol-value semaphore) (list nil))) 2)
  95     (sleep-for 1)))
  96
  97 (defun gnus-async-release-semaphore (semaphore)
  98   "Release SEMAPHORE."
  99   (setcdr (symbol-value semaphore) nil))
 100
 101 (defmacro gnus-async-with-semaphore (&rest forms)
 102   `(unwind-protect
 103        (progn
 104          (gnus-async-get-semaphore 'gnus-async-article-semaphore)
 105          ,@forms)
 106      (gnus-async-release-semaphore 'gnus-async-article-semaphore)))
 107
 108 (put 'gnus-asynch-with-semaphore 'lisp-indent-function 0)
 109 (put 'gnus-asynch-with-semaphore 'edebug-form-spec '(body))
 110
 111 ;;;
 112 ;;; Article prefetch
 113 ;;;
 114
 115 (gnus-add-shutdown 'gnus-async-close 'gnus)
 116 (defun gnus-async-close ()
 117   (gnus-kill-buffer gnus-async-prefetch-article-buffer)
 118   (gnus-kill-buffer gnus-async-prefetch-headers-buffer)
 119   (setq gnus-async-article-alist nil
 120         gnus-async-header-prefetched nil))
 121
 122 (defun gnus-async-set-buffer ()
 123   (nnheader-set-temp-buffer gnus-async-prefetch-article-buffer t))
 124
 125 (defun gnus-async-halt-prefetch ()
 126   "Stop prefetching."
 127   (setq gnus-async-fetch-list nil))
 128
 129 (defun gnus-async-prefetch-next (group article summary)
 130   "Possibly prefetch several articles starting with the article after ARTICLE."
 131   (when (and (gnus-buffer-live-p summary)
 132              gnus-asynchronous
 133              (gnus-group-asynchronous-p group))
 134     (save-excursion
 135       (set-buffer gnus-summary-buffer)
 136       (let ((next (caadr (gnus-data-find-list article))))
 137         (when next
 138           (if (not (fboundp 'run-with-idle-timer))
 139               ;; This is either an older Emacs or XEmacs, so we
 140               ;; do this, which leads to slightly slower article
 141               ;; buffer display.
 142               (gnus-async-prefetch-article group next summary)
 143             (run-with-idle-timer
 144              0.1 nil 'gnus-async-prefetch-article group next summary)))))))
 145
 146 (defun gnus-async-prefetch-article (group article summary &optional next)
 147   "Possibly prefetch several articles starting with ARTICLE."
 148   (if (not (gnus-buffer-live-p summary))
 149       (gnus-async-with-semaphore
 150        (setq gnus-async-fetch-list nil))
 151     (when (and gnus-asynchronous
 152                (gnus-alive-p))
 153       (when next
 154         (gnus-async-with-semaphore
 155          (pop gnus-async-fetch-list)))
 156       (let ((do-fetch next)
 157             (do-message t)) ;(eq major-mode 'gnus-summary-mode)))
 158         (when (and (gnus-group-asynchronous-p group)
 159                    (gnus-buffer-live-p summary)
 160                    (or (not next)
 161                        gnus-async-fetch-list))
 162           (gnus-async-with-semaphore
 163            (unless next
 164              (setq do-fetch (not gnus-async-fetch-list))
 165              ;; Nix out any outstanding requests.
 166              (setq gnus-async-fetch-list nil)
 167              ;; Fill in the new list.
 168              (let ((n gnus-use-article-prefetch)
 169                    (data (gnus-data-find-list article))
 170                    d)
 171                (while (and (setq d (pop data))
 172                            (if (numberp n)
 173                                (natnump (decf n))
 174                              n))
 175                  (unless (or (gnus-async-prefetched-article-entry
 176                               group (setq article (gnus-data-number d)))
 177                              (not (natnump article))
 178                              (not (funcall gnus-async-prefetch-article-p d)))
 179                    ;; Not already fetched -- so we add it to the list.
 180                    (push article gnus-async-fetch-list)))
 181                (setq gnus-async-fetch-list
 182                      (nreverse gnus-async-fetch-list))))
 183
 184            (when do-fetch
 185              (setq article (car gnus-async-fetch-list))))
 186
 187           (when (and do-fetch article)
 188             ;; We want to fetch some more articles.
 189             (save-excursion
 190               (set-buffer summary)
 191               (let (mark)
 192                 (gnus-async-set-buffer)
 193                 (goto-char (point-max))
 194                 (setq mark (point-marker))
 195                 (let ((nnheader-callback-function
 196                        (gnus-make-async-article-function
 197                         group article mark summary next))
 198                       (nntp-server-buffer
 199                        (get-buffer gnus-async-prefetch-article-buffer)))
 200                   (when do-message
 201                     (gnus-message 9 "Prefetching article %d in group %s"
 202                                   article group))
 203                   (gnus-request-article article group))))))))))
 204
 205 (defun gnus-make-async-article-function (group article mark summary next)
 206   "Return a callback function."
 207   `(lambda (arg)
 208      (save-excursion
 209        (when arg
 210          (gnus-async-set-buffer)
 211          (gnus-async-with-semaphore
 212           (push (list ',(intern (format "%s-%d" group article))
 213                       ,mark (set-marker (make-marker) (point-max))
 214                       ,group ,article)
 215                 gnus-async-article-alist)))
 216        (if (not (gnus-buffer-live-p ,summary))
 217            (gnus-async-with-semaphore
 218             (setq gnus-async-fetch-list nil))
 219          (gnus-async-prefetch-article ,group ,next ,summary t)))))
 220
 221 (defun gnus-async-unread-p (data)
 222   "Return non-nil if DATA represents an unread article."
 223   (gnus-data-unread-p data))
 224
 225 (defun gnus-async-request-fetched-article (group article buffer)
 226   "See whether we have ARTICLE from GROUP and put it in BUFFER."
 227   (when (numberp article)
 228     (let ((entry (gnus-async-prefetched-article-entry group article)))
 229       (when entry
 230         (save-excursion
 231           (gnus-async-set-buffer)
 232           (copy-to-buffer buffer (cadr entry) (caddr entry))
 233           ;; Remove the read article from the prefetch buffer.
 234           (when (memq 'read gnus-prefetched-article-deletion-strategy)
 235             (gnus-async-delete-prefected-entry entry))
 236           t)))))
 237
 238 (defun gnus-async-delete-prefected-entry (entry)
 239   "Delete ENTRY from buffer and alist."
 240   (ignore-errors
 241     (delete-region (cadr entry) (caddr entry))
 242     (set-marker (cadr entry) nil)
 243     (set-marker (caddr entry) nil))
 244   (gnus-async-with-semaphore
 245    (setq gnus-async-article-alist
 246          (delq entry gnus-async-article-alist))))
 247
 248 (defun gnus-async-prefetch-remove-group (group)
 249   "Remove all articles belonging to GROUP from the prefetch buffer."
 250   (when (and (gnus-group-asynchronous-p group)
 251              (memq 'exit gnus-prefetched-article-deletion-strategy))
 252     (let ((alist gnus-async-article-alist))
 253       (save-excursion
 254         (gnus-async-set-buffer)
 255         (while alist
 256           (when (equal group (nth 3 (car alist)))
 257             (gnus-async-delete-prefected-entry (car alist)))
 258           (pop alist))))))
 259
 260 (defun gnus-async-prefetched-article-entry (group article)
 261   "Return the entry for ARTICLE in GROUP iff it has been prefetched."
 262   (let ((entry (assq (intern (format "%s-%d" group article))
 263                      gnus-async-article-alist)))
 264     ;; Perhaps something has emptied the buffer?
 265     (if (and entry
 266              (= (cadr entry) (caddr entry)))
 267         (progn
 268           (ignore-errors
 269             (set-marker (cadr entry) nil)
 270             (set-marker (caddr entry) nil))
 271           (setq gnus-async-article-alist
 272                 (delq entry gnus-async-article-alist))
 273           nil)
 274       entry)))
 275
 276 ;;;
 277 ;;; Header prefetch
 278 ;;;
 279
 280 (defun gnus-async-prefetch-headers (group)
 281   "Prefetch the headers for group GROUP."
 282   (save-excursion
 283     (let (unread)
 284       (when (and gnus-use-header-prefetch
 285                  gnus-asynchronous
 286                  (gnus-group-asynchronous-p group)
 287                  (listp gnus-async-header-prefetched)
 288                  (setq unread (gnus-list-of-unread-articles group)))
 289         ;; Mark that a fetch is in progress.
 290         (setq gnus-async-header-prefetched t)
 291         (nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
 292         (erase-buffer)
 293         (let ((nntp-server-buffer (current-buffer))
 294               (nnheader-callback-function
 295                `(lambda (arg)
 296                   (setq gnus-async-header-prefetched
 297                         ,(cons group unread)))))
 298           (gnus-retrieve-headers unread group gnus-fetch-old-headers))))))
 299
 300 (defun gnus-async-retrieve-fetched-headers (articles group)
 301   "See whether we have prefetched headers."
 302   (when (and gnus-use-header-prefetch
 303              (gnus-group-asynchronous-p group)
 304              (listp gnus-async-header-prefetched)
 305              (equal group (car gnus-async-header-prefetched))
 306              (equal articles (cdr gnus-async-header-prefetched)))
 307     (save-excursion
 308       (nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
 309       (nntp-decode-text)
 310       (copy-to-buffer nntp-server-buffer (point-min) (point-max))
 311       (erase-buffer)
 312       (setq gnus-async-header-prefetched nil)
 313       t)))
 314
 315 (provide 'gnus-async)
 316
 317 ;;; gnus-async.el ends here