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Diffstat (limited to 'lisp/gnus/gnus-async.el')
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diff --git a/lisp/gnus/gnus-async.el b/lisp/gnus/gnus-async.el new file mode 100644 index 0000000000..a87d333b56 --- /dev/null +++ b/lisp/gnus/gnus-async.el @@ -0,0 +1,315 @@ +;;; gnus-async.el --- asynchronous support for Gnus +;; Copyright (C) 1996,97 Free Software Foundation, Inc. + +;; Author: Lars Magne Ingebrigtsen <[email protected]> +;; 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: + +(require 'gnus) +(require 'gnus-sum) +(require 'nntp) + +(defgroup gnus-asynchronous nil + "Support for asynchronous operations." + :group 'gnus) + +(defcustom gnus-asynchronous t + "*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-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-asynch-with-semaphore 'lisp-indent-function 0) +(put 'gnus-asynch-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-article-alist nil + gnus-async-header-prefetched nil)) + +(defun gnus-async-set-buffer () + (nnheader-set-temp-buffer gnus-async-prefetch-article-buffer t)) + +(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) + (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)) + (gnus-request-article article group)))))))))) + +(defun gnus-make-async-article-function (group article mark summary next) + "Return a callback function." + `(lambda (arg) + (save-excursion + (when arg + (gnus-async-set-buffer) + (gnus-async-with-semaphore + (push (list ',(intern (format "%s-%d" group article)) + ,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) + (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-prefected-entry entry)) + t))))) + +(defun gnus-async-delete-prefected-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-prefected-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 (assq (intern (format "%s-%d" group article)) + 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 |