Re: Speeding up IMAP parsing

[Dan Christensen <jdc@uwo.ca>]

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Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> Looking at the rfc, the % character isn't valid in the flags, but it has
> char syntax for the `read' command, so substing \ with % before reading
> should do the trick (and be really fast).

I did a timing comparison between my Dec 2009 version of Gnus and
current git when entering an IMAP group with about 6500 articles.

Dec 2009:  11.1 seconds
git:       10.8 seconds

Great!

With the patch below applied, the time reduces further to 10.4 seconds.
But I don't know if it will break things for others.  (I've used it for
several months now without noticing a problem.)

Interestingly, with my Dec 2009 version, the patch below reduces the
time from 11.1 to 10.5 seconds, a bigger change than with git, and
almost matching the git+patch time.

Did the older nnimap.el use the read trick?  If not, then it must have
been more efficient in some other way to come so close to the time
that the current version uses.

Dan


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diff --git a/lisp/time-date.el b/lisp/time-date.el
index 5dbd08c..01132bc 100644
--- a/lisp/time-date.el
+++ b/lisp/time-date.el
@@ -97,20 +97,20 @@ and type 2 is the list (HIGH LOW MICRO)."
 (autoload 'timezone-make-date-arpa-standard "timezone")
 
 ;;;###autoload
+;; `parse-time-string' isn't sufficiently general or robust.  It fails
+;; to grok some of the formats that timezone does (e.g. dodgy
+;; post-2000 stuff from some Elms) and either fails or returns bogus
+;; values.  timezone-make-date-arpa-standard should help.
 (defun date-to-time (date)
   "Parse a string DATE that represents a date-time and return a time value.
 If DATE lacks timezone information, GMT is assumed."
   (condition-case ()
-      (apply 'encode-time
-	     (parse-time-string
-	      ;; `parse-time-string' isn't sufficiently general or
-	      ;; robust.  It fails to grok some of the formats that
-	      ;; timezone does (e.g. dodgy post-2000 stuff from some
-	      ;; Elms) and either fails or returns bogus values.  Lars
-	      ;; reverted this change, but that loses non-trivially
-	      ;; often for me.  -- fx
-	      (timezone-make-date-arpa-standard date)))
-    (error (error "Invalid date: %s" date))))
+      (apply 'encode-time (parse-time-string date))
+    (error (condition-case ()
+	       (apply 'encode-time 
+		      (parse-time-string
+		       (timezone-make-date-arpa-standard date)))
+	     (error (error "Invalid date: %s" date))))))
 
 ;; Bit of a mess.  Emacs has float-time since at least 21.1.
 ;; This file is synced to Gnus, and XEmacs packages may have been written