From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-15?Q?Ren=E9_Scharfe?= Subject: [PATCH 1/2] diffcore-pickaxe: use memmem() Date: Tue, 03 Mar 2009 00:00:55 +0100 Message-ID: <49AC6527.5010808@lsrfire.ath.cx> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: git@vger.kernel.org To: Junio C Hamano X-From: git-owner@vger.kernel.org Tue Mar 03 00:02:56 2009 Return-path: Envelope-to: gcvg-git-2@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1LeH9o-00065g-CA for gcvg-git-2@gmane.org; Tue, 03 Mar 2009 00:02:44 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753388AbZCBXBI (ORCPT ); Mon, 2 Mar 2009 18:01:08 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754775AbZCBXBG (ORCPT ); Mon, 2 Mar 2009 18:01:06 -0500 Received: from india601.server4you.de ([85.25.151.105]:54774 "EHLO india601.server4you.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752860AbZCBXBF (ORCPT ); Mon, 2 Mar 2009 18:01:05 -0500 Received: from [10.0.1.101] (p57B7FBAD.dip.t-dialin.net [87.183.251.173]) by india601.server4you.de (Postfix) with ESMTPSA id 2E1632F8055; Tue, 3 Mar 2009 00:01:02 +0100 (CET) User-Agent: Thunderbird 2.0.0.19 (Windows/20081209) In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: Use memmem() instead of open-coding it. The system libraries usually have a much faster version than the memcmp()-loop here. Even our own fall-back in compat/, which is used on Windows, is slightly faster. The following commands were run in a Linux kernel repository and timed, the best of five results is shown: $ STRING='Ensure that the real time constraints are schedulable.' $ git log -S"$STRING" HEAD -- kernel/sched.c >/dev/null On Ubuntu 8.10 x64, before (v1.6.2-rc2): 8.09user 0.04system 0:08.14elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+30952minor)pagefaults 0swaps And with the patch: 1.50user 0.04system 0:01.54elapsed 100%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+30645minor)pagefaults 0swaps On Fedora 10 x64, before: 8.34user 0.05system 0:08.39elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+29268minor)pagefaults 0swaps And with the patch: 1.15user 0.05system 0:01.20elapsed 99%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (0major+32253minor)pagefaults 0swaps On Windows Vista x64, before: real 0m9.204s user 0m0.000s sys 0m0.000s And with the patch: real 0m8.470s user 0m0.000s sys 0m0.000s Signed-off-by: Rene Scharfe --- diffcore-pickaxe.c | 18 ++++++++---------- 1 files changed, 8 insertions(+), 10 deletions(-) diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c index af9fffe..574b3e8 100644 --- a/diffcore-pickaxe.c +++ b/diffcore-pickaxe.c @@ -10,7 +10,7 @@ static unsigned int contains(struct diff_filespec *one, regex_t *regexp) { unsigned int cnt; - unsigned long offset, sz; + unsigned long sz; const char *data; if (diff_populate_filespec(one, 0)) return 0; @@ -33,15 +33,13 @@ static unsigned int contains(struct diff_filespec *one, } } else { /* Classic exact string match */ - /* Yes, I've heard of strstr(), but the thing is *data may - * not be NUL terminated. Sue me. - */ - for (offset = 0; offset + len <= sz; offset++) { - /* we count non-overlapping occurrences of needle */ - if (!memcmp(needle, data + offset, len)) { - offset += len - 1; - cnt++; - } + while (sz) { + const char *found = memmem(data, sz, needle, len); + if (!found) + break; + sz -= found - data + len; + data = found + len; + cnt++; } } diff_free_filespec_data(one); -- 1.6.2.rc2