lisp/gnus/gnus-async.el

   1 ;;; gnus-async.el --- asynchronous support for Gnus
   2
   3 ;; Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   4 ;;   2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
   5
   6 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
   7 ;; Keywords: news
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  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-use-article-prefetch 30
  39   "*If non-nil, prefetch articles in groups that allow this.
  40 If a number, prefetch only that many articles forward;
  41 if t, prefetch as many articles as possible."
  42   :group 'gnus-asynchronous
  43   :type '(choice (const :tag "off" nil)
  44                  (const :tag "all" t)
  45                  (integer :tag "some" 0)))
  46
  47 (defcustom gnus-asynchronous nil
  48   "*If nil, inhibit all Gnus asynchronicity.
  49 If non-nil, let the other asynch variables be heeded."
  50   :group 'gnus-asynchronous
  51   :type 'boolean)
  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 (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)
  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
 112 (put 'gnus-async-with-semaphore 'lisp-indent-function 0)
 113 (put 'gnus-async-with-semaphore 'edebug-form-spec '(body))
 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)
 123   (setq gnus-async-hashtb nil
 124         gnus-async-article-alist nil
 125         gnus-async-header-prefetched nil))
 126
 127 (defun gnus-async-set-buffer ()
 128   (nnheader-set-temp-buffer gnus-async-prefetch-article-buffer t)
 129   (unless gnus-async-hashtb
 130     (setq gnus-async-hashtb (gnus-make-hashtable 1023))))
 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)
 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))))))))
 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
 162         (setq gnus-async-fetch-list nil))
 163     (when (and gnus-asynchronous
 164                (gnus-alive-p))
 165       (when next
 166         (gnus-async-with-semaphore
 167           (pop gnus-async-fetch-list)))
 168       (let ((do-fetch next)
 169             (do-message t))             ;(eq major-mode 'gnus-summary-mode)))
 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
 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))))
 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))
 215                   (setq gnus-async-current-prefetch-group group)
 216                   (setq gnus-async-current-prefetch-article article)
 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)
 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))))
 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)
 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))
 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)
 260             (gnus-async-delete-prefetched-entry entry))
 261           t)))))
 262
 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       (when proc
 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     (save-excursion
 310       (gnus-async-set-buffer)
 311       (dolist (entry gnus-async-article-alist)
 312         (when (equal group (nth 3 entry))
 313           (gnus-async-delete-prefetched-entry entry))))))
 314
 315 (defun gnus-async-prefetched-article-entry (group article)
 316   "Return the entry for ARTICLE in GROUP if it has been prefetched."
 317   (let ((entry (save-excursion
 318                  (gnus-async-set-buffer)
 319                  (assq (intern (format "%s-%d" group article)
 320                                gnus-async-hashtb)
 321                        gnus-async-article-alist))))
 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 ;; arch-tag: fee61de5-3ea2-4de6-8578-2f90ce89391d
 376 ;;; gnus-async.el ends here