bug#51523: 29.0.50; gnus-mime-view-part-externally very slow

[Gregory Heytings <gregory@heytings.org>]

[-- Attachment #1: Type: text/plain, Size: 343 bytes --]


>>> This reminds me of something I've wanted more than a handful of times 
>>> -- it'd be nice to have a function/macro like
>>> 
>>> (when-file-has-changed "/etc/mailcap"
>>>   (do-the-parsing))
>>> 
>> 
>> See attached patch.
>
> And here's another attempt to fix the bug, which uses the 
> when-file-has-changed macro.
>

ENOPATCH catched.

[-- Attachment #2: Type: text/x-diff, Size: 2342 bytes --]

From e8b7530008feb232ead9c91dac2d23e7392b02e3 Mon Sep 17 00:00:00 2001
From: Gregory Heytings <gregory@heytings.org>
Date: Mon, 1 Nov 2021 01:22:51 +0000
Subject: [PATCH] Read mailcaps again only when necessary.

* lisp/net/mailcap.el (mailcap-parse-mailcaps): Read mailcaps again
only when at least one of the mailcap files has changed.  Fixes
bug#51523.
---
 lisp/net/mailcap.el | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/lisp/net/mailcap.el b/lisp/net/mailcap.el
index 83d0eeef9f..a147ee0ce3 100644
--- a/lisp/net/mailcap.el
+++ b/lisp/net/mailcap.el
@@ -447,19 +447,23 @@ mailcap-parse-mailcaps
               ("/etc/mailcap" system)
               ("/usr/etc/mailcap" system)
 	      ("/usr/local/etc/mailcap" system)))))
-    ;; The ~/.mailcap entries will end up first in the resulting data.
-    (dolist (spec (reverse
-                   (if (stringp path)
-                       (split-string path path-separator t)
-                     path)))
-      (let ((source (and (consp spec) (cadr spec)))
-            (file-name (if (stringp spec)
-                           spec
-                         (car spec))))
-        (when (and (file-readable-p file-name)
-                   (file-regular-p file-name))
-          (mailcap-parse-mailcap file-name source))))
-    (setq mailcap-parsed-p t)))
+    (let ((file-has-changed nil))
+      (dolist (file path)
+        (when-file-has-changed (car file) (setq file-has-changed t)))
+      (when file-has-changed
+        ;; The ~/.mailcap entries will end up first in the resulting data.
+        (dolist (spec (reverse
+                       (if (stringp path)
+                           (split-string path path-separator t)
+                         path)))
+          (let ((source (and (consp spec) (cadr spec)))
+                (file-name (if (stringp spec)
+                               spec
+                             (car spec))))
+            (when (and (file-readable-p file-name)
+                       (file-regular-p file-name))
+              (mailcap-parse-mailcap file-name source)))))
+      (setq mailcap-parsed-p t))))
 
 (defun mailcap-parse-mailcap (fname &optional source)
   "Parse out the mailcap file specified by FNAME.
-- 
2.33.0