382 lines
13 KiB
EmacsLisp
382 lines
13 KiB
EmacsLisp
;;; gnus-async.el --- asynchronous support for Gnus -*- lexical-binding:t -*-
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;; Copyright (C) 1996-2024 Free Software Foundation, Inc.
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;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
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;; Keywords: news
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;;; Code:
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(eval-when-compile (require 'cl-lib))
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(require 'gnus)
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(require 'gnus-sum)
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(require 'nntp)
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(defgroup gnus-asynchronous nil
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"Support for asynchronous operations."
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:group 'gnus)
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(defcustom gnus-use-article-prefetch 30
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"If non-nil, prefetch articles in groups that allow this.
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If a number, prefetch only that many articles forward;
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if t, prefetch as many articles as possible."
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:type '(choice (const :tag "off" nil)
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(const :tag "all" t)
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(integer :tag "some" 0)))
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(defcustom gnus-asynchronous nil
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"If nil, inhibit all Gnus asynchronicity.
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If non-nil, let the other asynch variables be heeded."
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:type 'boolean)
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(defcustom gnus-prefetched-article-deletion-strategy '(read exit)
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"List of symbols that say when to remove articles from the prefetch buffer.
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Possible values in this list are `read', which means that
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articles are removed as they are read, and `exit', which means
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that all articles belonging to a group are removed on exit
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from that group."
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:type '(set (const read) (const exit)))
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(defcustom gnus-use-header-prefetch nil
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"If non-nil, prefetch the headers to the next group."
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:type 'boolean)
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(defcustom gnus-async-prefetch-article-p #'gnus-async-unread-p
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"Function called to say whether an article should be prefetched or not.
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The function is called with one parameter -- the article data.
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It should return non-nil if the article is to be prefetched."
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:type 'function)
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(defcustom gnus-async-post-fetch-function #'ignore
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"Function called after an article has been prefetched.
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The function will be called narrowed to the region of the article
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that was fetched."
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:version "27.1"
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:type 'function)
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;;; Internal variables.
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(defvar gnus-async-prefetch-article-buffer " *Async Prefetch Article*")
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(defvar gnus-async-article-alist nil)
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(defvar gnus-async-article-semaphore '(nil))
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(defvar gnus-async-fetch-list nil)
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(defvar gnus-async-current-prefetch-group nil)
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(defvar gnus-async-current-prefetch-article nil)
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(defvar gnus-async-timer nil)
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(defvar gnus-async-prefetch-headers-buffer " *Async Prefetch Headers*")
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(defvar gnus-async-header-prefetched nil)
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;;; Utility functions.
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(defun gnus-group-asynchronous-p (group)
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"Say whether GROUP is fetched from a server that supports asynchronicity."
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(gnus-asynchronous-p (gnus-find-method-for-group group)))
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;;; Somewhat bogus semaphores.
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(defun gnus-async-get-semaphore (semaphore)
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"Wait until SEMAPHORE is released."
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(while (/= (length (nconc (symbol-value semaphore) (list nil))) 2)
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(sleep-for 1)))
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(defun gnus-async-release-semaphore (semaphore)
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"Release SEMAPHORE."
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(setcdr (symbol-value semaphore) nil))
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(defmacro gnus-async-with-semaphore (&rest forms)
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(declare (indent 0) (debug t))
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`(unwind-protect
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(progn
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(gnus-async-get-semaphore 'gnus-async-article-semaphore)
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,@forms)
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(gnus-async-release-semaphore 'gnus-async-article-semaphore)))
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;;;
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;;; Article prefetch
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;;;
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(gnus-add-shutdown 'gnus-async-close 'gnus)
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(defun gnus-async-close ()
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(gnus-kill-buffer gnus-async-prefetch-article-buffer)
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(gnus-kill-buffer gnus-async-prefetch-headers-buffer)
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(setq gnus-async-article-alist nil
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gnus-async-header-prefetched nil))
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(defun gnus-async-set-buffer ()
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(nnheader-set-temp-buffer gnus-async-prefetch-article-buffer t))
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(defun gnus-async-halt-prefetch ()
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"Stop prefetching."
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(setq gnus-async-fetch-list nil))
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(defun gnus-async-prefetch-next (group article summary)
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"Possibly prefetch several articles starting with the article after ARTICLE."
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(when (and (gnus-buffer-live-p summary)
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gnus-asynchronous
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(gnus-group-asynchronous-p group))
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(with-current-buffer gnus-summary-buffer
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(let ((next (cadr (gnus-data-find-list article))))
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(when next
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(when gnus-async-timer
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(ignore-errors
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(cancel-timer 'gnus-async-timer)))
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(setq gnus-async-timer
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(run-with-idle-timer
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0.1 nil
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(lambda ()
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;; When running from a timer, `C-g' is inhibited.
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;; But the prefetch action may (when there's a
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;; network problem or the like) hang (or take a
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;; long time), so allow quitting anyway.
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(let ((inhibit-quit nil))
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(gnus-async-prefetch-article
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group (gnus-data-number next) summary))))))))))
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(defun gnus-async-prefetch-article (group article summary &optional next)
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"Possibly prefetch several articles starting with ARTICLE."
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(if (not (gnus-buffer-live-p summary))
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(gnus-async-with-semaphore
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(setq gnus-async-fetch-list nil))
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(when (and gnus-asynchronous
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(gnus-alive-p))
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(when next
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(gnus-async-with-semaphore
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(pop gnus-async-fetch-list)))
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(let ((do-fetch next)
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(do-message t)) ;(eq major-mode 'gnus-summary-mode)))
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(when (and (gnus-group-asynchronous-p group)
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(gnus-buffer-live-p summary)
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(or (not next)
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gnus-async-fetch-list))
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(gnus-async-with-semaphore
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(unless next
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(setq do-fetch (not gnus-async-fetch-list))
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;; Nix out any outstanding requests.
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(setq gnus-async-fetch-list nil)
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;; Fill in the new list.
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(let ((n gnus-use-article-prefetch)
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(data (gnus-data-find-list article))
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d)
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(while (and (setq d (pop data))
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(if (numberp n)
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(natnump (cl-decf n))
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n))
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(unless (or (gnus-async-prefetched-article-entry
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group (setq article (gnus-data-number d)))
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(not (natnump article))
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(not (funcall gnus-async-prefetch-article-p d)))
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;; Not already fetched -- so we add it to the list.
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(push article gnus-async-fetch-list)))
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(setq gnus-async-fetch-list
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(nreverse gnus-async-fetch-list))))
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(when do-fetch
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(setq article (car gnus-async-fetch-list))))
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(when (and do-fetch article)
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;; We want to fetch some more articles.
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(with-current-buffer summary
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(let (mark)
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(gnus-async-set-buffer)
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(goto-char (point-max))
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(setq mark (point-marker))
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(let ((nnheader-callback-function
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(gnus-make-async-article-function
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group article mark summary next))
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(nntp-server-buffer
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(get-buffer gnus-async-prefetch-article-buffer)))
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(when do-message
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(gnus-message 9 "Prefetching article %d in group %s"
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article group))
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(setq gnus-async-current-prefetch-group group)
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(setq gnus-async-current-prefetch-article article)
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(gnus-request-article article group))))))))))
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(defun gnus-make-async-article-function (group article mark summary next)
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"Return a callback function."
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(lambda (arg)
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(gnus-async-article-callback arg group article mark summary next)))
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(defun gnus-async-article-callback (arg group article mark summary next)
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"Function called when an async article is done being fetched."
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(save-excursion
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(setq gnus-async-current-prefetch-article nil)
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(when arg
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(gnus-async-set-buffer)
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(save-excursion
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(save-restriction
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(narrow-to-region mark (point-max))
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;; Put the articles into the agent, if they aren't already.
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(when (and gnus-agent
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gnus-agent-eagerly-store-articles
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(gnus-agent-group-covered-p group))
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(save-restriction
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(narrow-to-region mark (point-max))
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(gnus-agent-store-article article group)))
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;; Prefetch images for the groups that want that.
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(when (fboundp 'gnus-html-prefetch-images)
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(gnus-html-prefetch-images summary))
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(when gnus-async-post-fetch-function
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(funcall gnus-async-post-fetch-function summary))))
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(gnus-async-with-semaphore
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(push (list (format "%s-%d" group article)
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mark (point-max-marker)
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group article)
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gnus-async-article-alist)))
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(if (not (gnus-buffer-live-p summary))
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(gnus-async-with-semaphore
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(setq gnus-async-fetch-list nil))
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(gnus-async-prefetch-article group next summary t))))
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(defun gnus-async-unread-p (data)
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"Return non-nil if DATA represents an unread article."
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(gnus-data-unread-p data))
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(defun gnus-async-request-fetched-article (group article buffer)
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"See whether we have ARTICLE from GROUP and put it in BUFFER."
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(when (numberp article)
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(when (and (equal group gnus-async-current-prefetch-group)
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(eq article gnus-async-current-prefetch-article))
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(gnus-async-wait-for-article article))
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(let ((entry (gnus-async-prefetched-article-entry group article)))
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(when entry
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(save-excursion
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(gnus-async-set-buffer)
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(copy-to-buffer buffer (cadr entry) (caddr entry))
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;; Remove the read article from the prefetch buffer.
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(when (memq 'read gnus-prefetched-article-deletion-strategy)
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(gnus-async-delete-prefetched-entry entry))
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t)))))
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(defun gnus-async-wait-for-article (article)
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"Wait until ARTICLE is no longer the currently-being-fetched article."
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(save-excursion
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(gnus-async-set-buffer)
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(let ((proc (nntp-find-connection (current-buffer)))
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(nntp-server-buffer (current-buffer))
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(nntp-have-messaged nil)
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(tries 0))
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(when proc
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(condition-case nil
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;; FIXME: we could stop waiting after some
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;; timeout, but this is the wrong place to do it.
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;; rather than checking time-spent-waiting, we
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;; should check time-since-last-output, which
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;; needs to be done in nntp.el.
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(while (eq article gnus-async-current-prefetch-article)
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(cl-incf tries)
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(when (nntp-accept-process-output proc)
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(setq tries 0))
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(when (and (not nntp-have-messaged)
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(= tries 3))
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(gnus-message 5 "Waiting for async article...")
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(setq nntp-have-messaged t)))
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(quit
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;; if the user interrupted on a slow/hung connection,
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;; do something friendly.
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(when (> tries 3)
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(setq gnus-async-current-prefetch-article nil))
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(signal 'quit nil)))
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(when nntp-have-messaged
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(gnus-message 5 ""))))))
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(defun gnus-async-delete-prefetched-entry (entry)
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"Delete ENTRY from buffer and alist."
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(ignore-errors
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(delete-region (cadr entry) (caddr entry))
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(set-marker (cadr entry) nil)
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(set-marker (caddr entry) nil))
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(gnus-async-with-semaphore
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(setq gnus-async-article-alist
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(delete entry gnus-async-article-alist))))
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(defun gnus-async-prefetch-remove-group (group)
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"Remove all articles belonging to GROUP from the prefetch buffer."
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(when (and (gnus-group-asynchronous-p group)
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(memq 'exit gnus-prefetched-article-deletion-strategy))
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(save-excursion
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(gnus-async-set-buffer)
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(dolist (entry gnus-async-article-alist)
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(when (equal group (nth 3 entry))
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(gnus-async-delete-prefetched-entry entry))))))
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(defun gnus-async-prefetched-article-entry (group article)
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"Return the entry for ARTICLE in GROUP if it has been prefetched."
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(let ((entry (save-excursion
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(gnus-async-set-buffer)
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(assoc (format "%s-%d" group article)
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gnus-async-article-alist))))
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;; Perhaps something has emptied the buffer?
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(if (and entry
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(= (cadr entry) (caddr entry)))
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(progn
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(ignore-errors
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(set-marker (cadr entry) nil)
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(set-marker (caddr entry) nil))
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(setq gnus-async-article-alist
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(delete entry gnus-async-article-alist))
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nil)
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entry)))
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;;;
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;;; Header prefetch
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;;;
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(defun gnus-async-prefetch-headers (group)
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"Prefetch the headers for group GROUP."
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(save-excursion
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(let (unread)
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(when (and gnus-use-header-prefetch
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gnus-asynchronous
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(gnus-group-asynchronous-p group)
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(listp gnus-async-header-prefetched)
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(setq unread (gnus-list-of-unread-articles group)))
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;; Mark that a fetch is in progress.
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(setq gnus-async-header-prefetched t)
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(nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
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(erase-buffer)
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(let ((nntp-server-buffer (current-buffer))
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(nnheader-callback-function
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(lambda (_arg)
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(setq gnus-async-header-prefetched
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(cons group unread)))))
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(gnus-retrieve-headers unread group gnus-fetch-old-headers))))))
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(defun gnus-async-retrieve-fetched-headers (articles group)
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"See whether we have prefetched headers."
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(when (and gnus-use-header-prefetch
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(gnus-group-asynchronous-p group)
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(listp gnus-async-header-prefetched)
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(equal group (car gnus-async-header-prefetched))
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(equal articles (cdr gnus-async-header-prefetched)))
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(save-excursion
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(nnheader-set-temp-buffer gnus-async-prefetch-headers-buffer t)
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(nntp-decode-text)
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(copy-to-buffer nntp-server-buffer (point-min) (point-max))
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(erase-buffer)
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(setq gnus-async-header-prefetched nil)
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t)))
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(provide 'gnus-async)
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;;; gnus-async.el ends here
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