[PATCH] nnimap performance improvement for large or old groups

[Daniel Pittman <daniel@rimspace.net>]

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One of the nagging problems with using nnimap as my primary mail store
is that it takes absolutely forever to enter my INBOX, as well as
causing XEmacs to allocate around 150MB of memory.

This is because I have been using the same INBOX for a long while now,
and the 'read' info range starts with '(1 . 695705)'

The code in `nnimap-request-update-info-internal' called
`gnus-uncompress-range' on this, resulting in a list containing around
seven million numbers -- an awful lot of memory, and time spent working
through it.

To address this I rewrote the code in that routine to work with
compressed ranges, rather than uncompressed, which gives me a huge
performance improvement (almost instant entry, vs ten to fifteen
seconds) and reduces the memory use significantly.


I don't think this is too performance-inefficient to include as is, and
it doesn't seem to adversely effect entry into small groups or anything
like that.

	Daniel


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? build.info
? build.sh
? nnimap-performance.patch
? contrib/auto-autoloads.el
? contrib/semantic.cache
Index: lisp/nnimap.el
===================================================================
RCS file: /usr/local/cvsroot/gnus/lisp/nnimap.el,v
retrieving revision 7.30
diff -u -u -r7.30 nnimap.el
--- lisp/nnimap.el	21 Feb 2006 07:14:23 -0000	7.30
+++ lisp/nnimap.el	3 Mar 2006 01:37:36 -0000
@@ -1183,18 +1183,12 @@
 	  (let (seen unseen)
 	    ;; read info could contain articles marked unread by other
 	    ;; imap clients!  we correct this
-	    (setq seen (gnus-uncompress-range (gnus-info-read info))
-		  unseen (imap-search "UNSEEN UNDELETED")
-		  seen (gnus-set-difference seen unseen)
-		  ;; seen might lack articles marked as read by other
-		  ;; imap clients! we correct this
-		  seen (append seen (imap-search "SEEN"))
-		  ;; remove dupes
-		  seen (sort seen '<)
-		  seen (gnus-compress-sequence seen t)
-		  ;; we can't return '(1) since this isn't a "list of ranges",
-		  ;; and we can't return '((1)) since g-list-of-unread-articles
-		  ;; is buggy so we return '((1 . 1)).
+	    (setq unseen (gnus-compress-sequence 
+			  (imap-search "UNSEEN UNDELETED"))
+		  seen (gnus-range-difference (gnus-info-read info) unseen)
+		  seen (gnus-range-add seen 
+				       (gnus-compress-sequence 
+					(imap-search "SEEN")))
 		  seen (if (and (integerp (car seen))
 				(null (cdr seen)))
 			   (list (cons (car seen) (car seen)))