1 ;;; gnus-async.el --- asynchronous support for Gnus
3 ;; Copyright (C) 1996-2011 Free Software Foundation, Inc.
5 ;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
8 ;; This file is part of GNU Emacs.
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 3 of the License, or
13 ;; (at your option) any later version.
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.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
27 (eval-when-compile (require 'cl))
33 (defgroup gnus-asynchronous nil
34 "Support for asynchronous operations."
37 (defcustom gnus-use-article-prefetch 30
38 "*If non-nil, prefetch articles in groups that allow this.
39 If a number, prefetch only that many articles forward;
40 if t, prefetch as many articles as possible."
41 :group 'gnus-asynchronous
42 :type '(choice (const :tag "off" nil)
44 (integer :tag "some" 0)))
46 (defcustom gnus-asynchronous nil
47 "*If nil, inhibit all Gnus asynchronicity.
48 If non-nil, let the other asynch variables be heeded."
49 :group 'gnus-asynchronous
52 (defcustom gnus-prefetched-article-deletion-strategy '(read exit)
53 "List of symbols that say when to remove articles from the prefetch buffer.
54 Possible values in this list are `read', which means that
55 articles are removed as they are read, and `exit', which means
56 that all articles belonging to a group are removed on exit
58 :group 'gnus-asynchronous
59 :type '(set (const read) (const exit)))
61 (defcustom gnus-use-header-prefetch nil
62 "*If non-nil, prefetch the headers to the next group."
63 :group 'gnus-asynchronous
66 (defcustom gnus-async-prefetch-article-p 'gnus-async-unread-p
67 "Function called to say whether an article should be prefetched or not.
68 The function is called with one parameter -- the article data.
69 It should return non-nil if the article is to be prefetched."
70 :group 'gnus-asynchronous
73 (defcustom gnus-async-post-fetch-function nil
74 "Function called after an article has been prefetched.
75 The function will be called narrowed to the region of the article
77 :group 'gnus-asynchronous
80 ;;; Internal variables.
82 (defvar gnus-async-prefetch-article-buffer " *Async Prefetch Article*")
83 (defvar gnus-async-article-alist nil)
84 (defvar gnus-async-article-semaphore '(nil))
85 (defvar gnus-async-fetch-list nil)
86 (defvar gnus-async-hashtb nil)
87 (defvar gnus-async-current-prefetch-group nil)
88 (defvar gnus-async-current-prefetch-article nil)
89 (defvar gnus-async-timer nil)
91 (defvar gnus-async-prefetch-headers-buffer " *Async Prefetch Headers*")
92 (defvar gnus-async-header-prefetched nil)
94 ;;; Utility functions.
96 (defun gnus-group-asynchronous-p (group)
97 "Say whether GROUP is fetched from a server that supports asynchronicity."
98 (gnus-asynchronous-p (gnus-find-method-for-group group)))
100 ;;; Somewhat bogus semaphores.
102 (defun gnus-async-get-semaphore (semaphore)
103 "Wait until SEMAPHORE is released."
104 (while (/= (length (nconc (symbol-value semaphore) (list nil))) 2)
107 (defun gnus-async-release-semaphore (semaphore)
109 (setcdr (symbol-value semaphore) nil))
111 (defmacro gnus-async-with-semaphore (&rest forms)
114 (gnus-async-get-semaphore 'gnus-async-article-semaphore)
116 (gnus-async-release-semaphore 'gnus-async-article-semaphore)))
118 (put 'gnus-async-with-semaphore 'lisp-indent-function 0)
119 (put 'gnus-async-with-semaphore 'edebug-form-spec '(body))
125 (gnus-add-shutdown 'gnus-async-close 'gnus)