1 files changed, 31 insertions, 27 deletions

diff --git a/lisp/gnus/gnus-dup.el b/lisp/gnus/gnus-dup.el
index 8342ca86b67..4981614a17f 100644
--- a/lisp/gnus/gnus-dup.el
+++ b/lisp/gnus/gnus-dup.el
@@ -1,4 +1,4 @@
-;;; gnus-dup.el --- suppression of duplicate articles in Gnus
+;;; gnus-dup.el --- suppression of duplicate articles in Gnus  -*- lexical-binding: t -*-
 
 ;; Copyright (C) 1996-2019 Free Software Foundation, Inc.
 
@@ -29,8 +29,6 @@
 
 ;;; Code:
 
-(eval-when-compile (require 'cl))
-
 (require 'gnus)
 (require 'gnus-art)
 
@@ -46,7 +44,7 @@ seen in the same session."
   :type 'boolean)
 
 (defcustom gnus-duplicate-list-length 10000
-  "The number of Message-IDs to keep in the duplicate suppression list."
+  "The maximum number of duplicate Message-IDs to keep track of."
   :group 'gnus-duplicate
   :type 'integer)
 
@@ -57,10 +55,14 @@ seen in the same session."
 
 ;;; Internal variables
 
-(defvar gnus-dup-list nil)
-(defvar gnus-dup-hashtb nil)
+(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)
+(defvar gnus-dup-list-dirty nil
+  "Non-nil if `gnus-dup-list' needs to be saved.")
 
 ;;;
 ;;; Starting and stopping
@@ -80,10 +82,10 @@ seen in the same session."
   (if gnus-save-duplicate-list
       (gnus-dup-read)
     (setq gnus-dup-list nil))
-  (setq gnus-dup-hashtb (gnus-make-hashtable gnus-duplicate-list-length))
+  (setq gnus-dup-hashtb (gnus-make-hashtable))
   ;; Enter all Message-IDs into the hash table.
-  (let ((obarray gnus-dup-hashtb))
-    (mapc 'intern gnus-dup-list)))
+  (dolist (g gnus-dup-list)
+    (puthash g t gnus-dup-hashtb)))
 
 (defun gnus-dup-read ()
   "Read the duplicate suppression list."
@@ -105,7 +107,7 @@ seen in the same session."
 
 (defun gnus-dup-enter-articles ()
   "Enter articles from the current group for future duplicate suppression."
-  (unless gnus-dup-list
+  (unless gnus-dup-hashtb
     (gnus-dup-open))
   (setq gnus-dup-list-dirty t)		; mark list for saving
   (let (msgid)
@@ -118,29 +120,30 @@ seen in the same session."
 		 (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 (intern-soft msgid gnus-dup-hashtb)))
+		 (not (gethash msgid gnus-dup-hashtb)))
 	(push msgid gnus-dup-list)
-	(intern msgid gnus-dup-hashtb))))
-  ;; Chop off excess Message-IDs from the list.
-  (let ((end (nthcdr gnus-duplicate-list-length 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) (unintern id gnus-dup-hashtb)) (cdr end))
-      (setcdr end nil))))
+      (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-list
+  (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 (intern-soft (mail-header-id header) gnus-dup-hashtb)
-		 (gnus-summary-article-unread-p (mail-header-number header)))
-	(setq gnus-newsgroup-unreads
-	      (delq (setq number (mail-header-number header))
-		    gnus-newsgroup-unreads))
+      (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)
@@ -149,12 +152,13 @@ seen in the same session."
 
 (defun gnus-dup-unsuppress-article (article)
   "Stop suppression of ARTICLE."
-  (let* ((header (gnus-data-header (gnus-data-find article)))
-	 (id     (when header (mail-header-id header))))
-    (when id
+  (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))
-      (unintern id gnus-dup-hashtb))))
+      (remhash id gnus-dup-hashtb))))
 
 (provide 'gnus-dup)