emacs/lisp/gnus/gnus-dup.el

163 lines
5.3 KiB
EmacsLisp

;;; gnus-dup.el --- suppression of duplicate articles in Gnus -*- lexical-binding: t -*-
;; Copyright (C) 1996-2024 Free Software Foundation, Inc.
;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; 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 3 of the License, 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. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; This package tries to mark articles as read the second time the
;; user reads a copy. This is useful if the server doesn't support
;; Xref properly, or if the user reads the same group from several
;; servers.
;;; Code:
(require 'gnus)
(require 'gnus-art)
(defgroup gnus-duplicate nil
"Suppression of duplicate articles."
:group 'gnus)
(defcustom gnus-save-duplicate-list nil
"If non-nil, save the duplicate list when shutting down Gnus.
If nil, duplicate suppression will only work on duplicates
seen in the same session."
:type 'boolean)
(defcustom gnus-duplicate-list-length 10000
"The maximum number of duplicate Message-IDs to keep track of."
:type 'integer)
(defcustom gnus-duplicate-file (nnheader-concat gnus-directory "suppression")
"The name of the file to store the duplicate suppression list."
:type 'file)
;;; Internal variables
(defvar gnus-dup-list nil
"List of seen message IDs, as strings.")
(defvar gnus-dup-hashtb nil
"Hash table of seen message IDs, for fast lookup.")
(defvar gnus-dup-list-dirty nil
"Non-nil if `gnus-dup-list' needs to be saved.")
;;;
;;; Starting and stopping
;;;
(gnus-add-shutdown 'gnus-dup-close 'gnus)
(defun gnus-dup-close ()
"Possibly save the duplicate suppression list and shut down the subsystem."
(gnus-dup-save)
(setq gnus-dup-list nil
gnus-dup-hashtb nil
gnus-dup-list-dirty nil))
(defun gnus-dup-open ()
"Possibly read the duplicate suppression list and start the subsystem."
(if gnus-save-duplicate-list
(gnus-dup-read)
(setq gnus-dup-list nil))
(setq gnus-dup-hashtb (gnus-make-hashtable))
;; Enter all Message-IDs into the hash table.
(dolist (g gnus-dup-list)
(puthash g t gnus-dup-hashtb)))
(defun gnus-dup-read ()
"Read the duplicate suppression list."
(setq gnus-dup-list nil)
(when (file-exists-p gnus-duplicate-file)
(load gnus-duplicate-file t t t)))
(defun gnus-dup-save ()
"Save the duplicate suppression list."
(when (and gnus-save-duplicate-list
gnus-dup-list-dirty)
(with-temp-file gnus-duplicate-file
(gnus-prin1 `(setq gnus-dup-list ',gnus-dup-list))))
(setq gnus-dup-list-dirty nil))
;;;
;;; Interface functions
;;;
(defun gnus-dup-enter-articles ()
"Enter articles from the current group for future duplicate suppression."
(unless gnus-dup-hashtb
(gnus-dup-open))
(setq gnus-dup-list-dirty t) ; mark list for saving
(let (msgid)
;; Enter the Message-IDs of all read articles into the list
;; and hash table.
(dolist (datum gnus-newsgroup-data)
(when (and (not (gnus-data-pseudo-p datum))
(> (gnus-data-number datum) 0)
(not (memq (gnus-data-number datum) gnus-newsgroup-unreads))
(not (= (gnus-data-mark datum) gnus-canceled-mark))
(setq msgid (mail-header-id (gnus-data-header datum)))
(not (nnheader-fake-message-id-p msgid))
(not (gethash msgid gnus-dup-hashtb)))
(push msgid gnus-dup-list)
(puthash msgid t gnus-dup-hashtb))))
;; Remove excess Message-IDs from the list and hash table.
(let* ((dups (cons nil gnus-dup-list))
(end (nthcdr gnus-duplicate-list-length dups)))
(when end
(mapc (lambda (id) (remhash id gnus-dup-hashtb)) (cdr end))
(setcdr end nil))
(setq gnus-dup-list (cdr dups))))
(defun gnus-dup-suppress-articles ()
"Mark duplicate articles as read."
(unless gnus-dup-hashtb
(gnus-dup-open))
(gnus-message 8 "Suppressing duplicates...")
(let ((auto (and gnus-newsgroup-auto-expire
(memq gnus-duplicate-mark gnus-auto-expirable-marks)))
number)
(dolist (header gnus-newsgroup-headers)
(when (and (gethash (mail-header-id header) gnus-dup-hashtb)
(setq number (mail-header-number header))
(gnus-summary-article-unread-p number))
(setq gnus-newsgroup-unreads (delq number gnus-newsgroup-unreads))
(if (not auto)
(push (cons number gnus-duplicate-mark) gnus-newsgroup-reads)
(push number gnus-newsgroup-expirable)
(push (cons number gnus-expirable-mark) gnus-newsgroup-reads)))))
(gnus-message 8 "Suppressing duplicates...done"))
(defun gnus-dup-unsuppress-article (article)
"Stop suppression of ARTICLE."
(let (header id)
(when (and gnus-dup-hashtb
(setq header (gnus-data-header (gnus-data-find article)))
(setq id (mail-header-id header)))
(setq gnus-dup-list-dirty t)
(setq gnus-dup-list (delete id gnus-dup-list))
(remhash id gnus-dup-hashtb))))
(provide 'gnus-dup)
;;; gnus-dup.el ends here