lisp/gnus/gnus-async.el

   1 ;;; gnus-async.el --- asynchronous support for Gnus
   2 ;; Copyright (C) 1996, 1997, 1998, 1999, 2000, 2003
   3 ;;        Free Software Foundation, Inc.
   4
   5 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
   6 ;; Keywords: news
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  24
  25 ;;; Commentary:
  26
  27 ;;; Code:
  28
  29 (eval-when-compile (require 'cl))
  30
  31 (require 'gnus)
  32 (require 'gnus-sum)
  33 (require 'nntp)
  34
  35 (defgroup gnus-asynchronous nil
  36   "Support for asynchronous operations."
  37   :group 'gnus)
  38
  39 (defcustom gnus-use-article-prefetch 30
  40   "*If non-nil, prefetch articles in groups that allow this.
  41 If a number, prefetch only that many articles forward;
  42 if t, prefetch as many articles as possible."
  43   :group 'gnus-asynchronous
  44   :type '(choice (const :tag "off" nil)
  45                  (const :tag "all" t)
  46                  (integer :tag "some" 0)))
  47
  48 (defcustom gnus-asynchronous nil
  49   "*If nil, inhibit all Gnus asynchronicity.
  50 If non-nil, let the other asynch variables be heeded."
  51   :group 'gnus-asynchronous
  52   :type 'boolean)
  53
  54 (defcustom gnus-prefetched-article-deletion-strategy '(read exit)
  55   "List of symbols that say when to remove articles from the prefetch buffer.
  56 Possible values in this list are `read', which means that
  57 articles are removed as they are read, and `exit', which means
  58 that all articles belonging to a group are removed on exit
  59 from that group."
  60   :group 'gnus-asynchronous
  61   :type '(set (const read) (const exit)))
  62
  63 (defcustom gnus-use-header-prefetch nil
  64   "*If non-nil, prefetch the headers to the next group."
  65   :group 'gnus-asynchronous
  66   :type 'boolean)
  67
  68 (defcustom gnus-async-prefetch-article-p 'gnus-async-unread-p
  69   "Function called to say whether an article should be prefetched or not.
  70 The function is called with one parameter -- the article data.
  71 It should return non-nil if the article is to be prefetched."
  72   :group 'gnus-asynchronous
  73   :type 'function)
  74
  75 ;;; Internal variables.
  76
  77 (defvar gnus-async-prefetch-article-buffer " *Async Prefetch Article*")
  78 (defvar gnus-async-article-alist nil)
  79 (defvar gnus-async-article-semaphore '(nil))
  80 (defvar gnus-async-fetch-list nil)
  81 (defvar gnus-async-hashtb nil)
  82 (defvar gnus-async-current-prefetch-group nil)
  83 (defvar gnus-async-current-prefetch-article nil)
  84 (defvar gnus-async-timer nil)
  85
  86 (defvar gnus-async-prefetch-headers-buffer " *Async Prefetch Headers*")
  87 (defvar gnus-async-header-prefetched nil)
  88
  89 ;;; Utility functions.
  90
  91 (defun gnus-group-asynchronous-p (group)
  92   "Say whether GROUP is fetched from a server that supports asynchronicity."
  93   (gnus-asynchronous-p (gnus-find-method-for-group group)))
  94
  95 ;;; Somewhat bogus semaphores.
  96
  97 (defun gnus-async-get-semaphore (semaphore)
  98   "Wait until SEMAPHORE is released."
  99   (while (/= (length (nconc (symbol-value semaphore) (list nil))) 2)
 100     (sleep-for 1)))
 101
 102 (defun gnus-async-release-semaphore (semaphore)
 103   "Release SEMAPHORE."
 104   (setcdr (symbol-value semaphore) nil))
 105
 106 (defmacro gnus-async-with-semaphore (&rest forms)
 107   `(unwind-protect
 108        (progn
 109          (gnus-async-get-semaphore 'gnus-async-article-semaphore)
 110          ,@forms)
 111      (gnus-async-release-semaphore 'gnus-async-article-semaphore)))
 112
 113 (put 'gnus-async-with-semaphore 'lisp-indent-function 0)
 114 (put 'gnus-async-with-semaphore 'edebug-form-spec '(body))
 115
 116 ;;;
 117 ;;; Article prefetch
 118 ;;;
 119
 120 (gnus-add-shutdown 'gnus-async-close 'gnus)
 121 (defun gnus-async-close ()
 122   (gnus-kill-buffer gnus-async-prefetch-article-buffer)
 123   (gnus-kill-buffer gnus-async-prefetch-headers-buffer)
 124   (setq gnus-async-hashtb nil
 125         gnus-async-article-alist nil
 126         gnus-async-header-prefetched nil))
 127
 128 (defun gnus-async-set-buffer ()
 129   (nnheader-set-temp-buffer gnus-async-prefetch-article-buffer t)
 130   (unless gnus-async-hashtb
 131     (setq gnus-async-hashtb (gnus-make-hashtable 1023))))
 132
 133 (defun gnus-async-halt-prefetch ()
 134   "Stop prefetching."
 135   (setq gnus-async-fetch-list nil))
 136
 137 (defun gnus-async-prefetch-next (group article summary)
 138   "Possibly prefetch several articles starting with the article after ARTICLE."
 139   (when (and (gnus-buffer-live-p summary)
 140              gnus-asynchronous
 141              (gnus-group-asynchronous-p group))
 142     (save-excursion
 143       (set-buffer gnus-summary-buffer)
 144       (let ((next (caadr (gnus-data-find-list article))))
 145         (when next
 146           (if (not (fboundp 'run-with-idle-timer))
 147               ;; This is either an older Emacs or XEmacs, so we
 148               ;; do this, which leads to slightly slower article
 149               ;; buffer display.
 150               (gnus-async-prefetch-article group next summary)
 151             (when gnus-async-timer
 152               (ignore-errors
 153                 (nnheader-cancel-timer 'gnus-async-timer)))
 154             (setq gnus-async-timer
 155                   (run-with-idle-timer
 156                    0.1 nil 'gnus-async-prefetch-article
 157                    group next summary))))))))
 158
 159 (defun gnus-async-prefetch-article (group article summary &optional next)
 160   "Possibly prefetch several articles starting with ARTICLE."
 161   (if (not (gnus-buffer-live-p summary))
 162       (gnus-async-with-semaphore
 163         (setq gnus-async-fetch-list nil))
 164     (when (and gnus-asynchronous
 165                (gnus-alive-p))
 166       (when next
 167         (gnus-async-with-semaphore
 168           (pop gnus-async-fetch-list)))
 169       (let ((do-fetch next)
 170             (do-message t))             ;(eq major-mode 'gnus-summary-mode)))
 171         (when (and (gnus-group-asynchronous-p group)
 172                    (gnus-buffer-live-p summary)
 173                    (or (not next)
 174                        gnus-async-fetch-list))
 175           (gnus-async-with-semaphore
 176             (unless next
 177               (setq do-fetch (not gnus-async-fetch-list))
 178               ;; Nix out any outstanding requests.
 179               (setq gnus-async-fetch-list nil)
 180               ;; Fill in the new list.
 181               (let ((n gnus-use-article-prefetch)
 182                     (data (gnus-data-find-list article))
 183                     d)
 184                 (while (and (setq d (pop data))
 185                             (if (numberp n)
 186                                 (natnump (decf n))
 187                               n))
 188                   (unless (or (gnus-async-prefetched-article-entry
 189                                group (setq article (gnus-data-number d)))
 190                               (not (natnump article))
 191                               (not (funcall gnus-async-prefetch-article-p d)))
 192                     ;; Not already fetched -- so we add it to the list.
 193                     (push article gnus-async-fetch-list)))
 194                 (setq gnus-async-fetch-list
 195                       (nreverse gnus-async-fetch-list))))
 196
 197             (when do-fetch
 198               (setq article (car gnus-async-fetch-list))))
 199
 200           (when (and do-fetch article)
 201             ;; We want to fetch some more articles.
 202             (save-excursion
 203               (set-buffer summary)
 204               (let (mark)
 205                 (gnus-async-set-buffer)
 206                 (goto-char (point-max))
 207                 (setq mark (point-marker))
 208                 (let ((nnheader-callback-function
 209                        (gnus-make-async-article-function
 210                         group article mark summary next))
 211                       (nntp-server-buffer
 212                        (get-buffer gnus-async-prefetch-article-buffer)))
 213                   (when do-message
 214                     (gnus-message 9 "Prefetching article %d in group %s"
 215                                   article group))
 216                   (setq gnus-async-current-prefetch-group group)
 217                   (setq gnus-async-current-prefetch-article article)
 218                   (gnus-request-article article group))))))))))
 219
 220 (defun gnus-make-async-article-function (group article mark summary next)
 221   "Return a callback function."
 222   `(lambda (arg)
 223      (gnus-async-article-callback arg ,group ,article ,mark ,summary ,next)))
 224
 225 (defun gnus-async-article-callback (arg group article mark summary next)
 226   "Function called when an async article is done being fetched."
 227   (save-excursion
 228     (setq gnus-async-current-prefetch-article nil)
 229     (when arg
 230       (gnus-async-set-buffer)
 231       (gnus-async-with-semaphore
 232         (setq
 233          gnus-async-article-alist
 234          (cons (list (intern (format "%s-%d" group article)
 235                              gnus-async-hashtb)
 236                      mark (set-marker (make-marker) (point-max))
 237                      group article)
 238                gnus-async-article-alist))))
 239     (if (not (gnus-buffer-live-p summary))
 240         (gnus-async-with-semaphore
 241           (setq gnus-async-fetch-list nil))
 242       (gnus-async-prefetch-article group next summary t))))
 243
 244 (defun gnus-async-unread-p (data)
 245   "Return non-nil if DATA represents an unread article."
 246   (gnus-data-unread-p data))
 247
 248 (defun gnus-async-request-fetched-article (group article buffer)
 249   "See whether we have ARTICLE from GROUP and put it in BUFFER."
 250   (when (numberp article)
 251     (when (and (equal group gnus-async-current-prefetch-group)
 252                (eq article gnus-async-current-prefetch-article))
 253       (gnus-async-wait-for-article article))
 254     (let ((entry (gnus-async-prefetched-article-entry group article)))
 255       (when entry
 256         (save-excursion
 257           (gnus-async-set-buffer)
 258           (copy-to-buffer buffer (cadr entry) (caddr entry))
 259           ;; Remove the read article from the prefetch buffer.
 260           (when (memq 'read gnus-prefetched-article-deletion-strategy)
 261             (gnus-async-delete-prefetched-entry entry))
 262           t)))))
 263
 264 (defun gnus-async-wait-for-article (article)
 265   "Wait until ARTICLE is no longer the currently-being-fetched article."
 266   (save-excursion
 267     (gnus-async-set-buffer)
 268     (let ((proc (nntp-find-connection (current-buffer)))
 269           (nntp-server-buffer (current-buffer))
 270           (nntp-have-messaged nil)
 271           (tries 0))
 272       (condition-case nil
 273           ;; FIXME: we could stop waiting after some
 274           ;; timeout, but this is the wrong place to do it.
 275           ;; rather than checking time-spent-waiting, we
 276           ;; should check time-since-last-output, which
 277           ;; needs to be done in nntp.el.
 278           (while (eq article gnus-async-current-prefetch-article)
 279             (incf tries)
 280             (when (nntp-accept-process-output proc)
 281               (setq tries 0))
 282             (when (and (not nntp-have-messaged)
 283                        (= tries 3))
 284               (gnus-message 5 "Waiting for async article...")
 285               (setq nntp-have-messaged t)))
 286         (quit
 287          ;; if the user interrupted on a slow/hung connection,
 288          ;; do something friendly.
 289          (when (> tries 3)
 290            (setq gnus-async-current-prefetch-article nil))
 291          (signal 'quit nil)))
 292       (when nntp-have-messaged
 293         (gnus-message 5 "")))))
 294
 295 (defun gnus-async-delete-prefetched-entry (entry)
 296   "Delete ENTRY from buffer and alist."
 297   (ignore-errors
 298     (delete-region (cadr entry) (caddr entry))
 299     (set-marker (cadr entry) nil)
 300     (set-marker (caddr entry) nil))
 301   (gnus-async-with-semaphore
 302     (setq gnus-async-article-alist
 303           (delq entry gnus-async-article-alist))))
 304
 305 (defun gnus-async-prefetch-remove-group (group)
 306   "Remove all articles belonging to GROUP from the prefetch buffer."
 307   (when (and (gnus-group-asynchronous-p group)
 308              (memq 'exit gnus-prefetched-article-deletion-strategy))
 309     (let ((alist gnus-async-article-alist))
 310       (save-excursion
 311         (gnus-async-set-buffer)
 312         (while alist
 313           (when (equal group (nth 3 (car alist)))
 314             (gnus-async-delete-prefetched-entry (car alist)))
 315           (pop alist))))))
 316
 317 (defun gnus-async-prefetched-article-entry (group article)
 318   "Return the entry for ARTICLE in GROUP iff it has been prefetched."
 319   (let ((entry (save-excursion
 320                  (gnus-async-set-buffer)
 321                  (assq (intern (format "%s-%d" group article)
 322                                gnus-async-hashtb)
 323                        gnus-async-article-alist))))
 324     ;; Perhaps something has emptied the buffer?
 325     (if (and entry
 326              (= (cadr entry) (caddr entry)))
 327         (progn
 328           (ignore-errors
 329             (set-marker (cadr entry) nil)
 330             (set-marker (caddr entry) nil))
 331           (setq gnus-async-article-alist
 332                 (delq entry gnus-async-article-alist))
 333           nil)
 334       entry)))
 335
 336 ;;;
 337 ;;; Header prefetch
 338 ;;;
 339
 340 (defun gnus-async-prefetch-headers (group)
 341   "Prefetch the headers for group GROUP."
 342   (save-excursion
 343     (let (unread)
 344       (when (and gnus-use-header-prefetch
 345                  gnus-asynchronous
 346                  (gnus-group-asynchronous-p group)
 347                  (listp gnus-async-header-prefetched)
 348                  (setq unread (gnus-list-of-unread-articles group)))
 349         ;; Mark that a fetch is in progress.
 350         (setq gnus-async-header-prefetched t)
 351         (nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
 352         (erase-buffer)
 353         (let ((nntp-server-buffer (current-buffer))
 354               (nnheader-callback-function
 355                `(lambda (arg)
 356                   (setq gnus-async-header-prefetched
 357                         ,(cons group unread)))))
 358           (gnus-retrieve-headers unread group gnus-fetch-old-headers))))))
 359
 360 (defun gnus-async-retrieve-fetched-headers (articles group)
 361   "See whether we have prefetched headers."
 362   (when (and gnus-use-header-prefetch
 363              (gnus-group-asynchronous-p group)
 364              (listp gnus-async-header-prefetched)
 365              (equal group (car gnus-async-header-prefetched))
 366              (equal articles (cdr gnus-async-header-prefetched)))
 367     (save-excursion
 368       (nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
 369       (nntp-decode-text)
 370       (copy-to-buffer nntp-server-buffer (point-min) (point-max))
 371       (erase-buffer)
 372       (setq gnus-async-header-prefetched nil)
 373       t)))
 374
 375 (provide 'gnus-async)
 376
 377 ;;; arch-tag: fee61de5-3ea2-4de6-8578-2f90ce89391d
 378 ;;; gnus-async.el ends here