From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Keeping Subject: Re: [PATCH] rebase: use reflog to find common base with upstream Date: Mon, 21 Oct 2013 12:24:08 +0100 Message-ID: <20131021112408.GA24317@serenity.lan> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: git , Junio C Hamano , Jonathan Nieder To: Martin von Zweigbergk X-From: git-owner@vger.kernel.org Mon Oct 21 13:24:28 2013 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1VYDaz-000453-BP for gcvg-git-2@plane.gmane.org; Mon, 21 Oct 2013 13:24:25 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753263Ab3JULYV (ORCPT ); Mon, 21 Oct 2013 07:24:21 -0400 Received: from coyote.aluminati.org ([72.9.247.114]:36143 "EHLO coyote.aluminati.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753207Ab3JULYU (ORCPT ); Mon, 21 Oct 2013 07:24:20 -0400 Received: from localhost (localhost [127.0.0.1]) by coyote.aluminati.org (Postfix) with ESMTP id 3D3766064D7; Mon, 21 Oct 2013 12:24:20 +0100 (BST) X-Virus-Scanned: Debian amavisd-new at caracal.aluminati.org X-Spam-Flag: NO X-Spam-Score: -2.9 X-Spam-Level: X-Spam-Status: No, score=-2.9 tagged_above=-9999 required=6.31 tests=[ALL_TRUSTED=-1, BAYES_00=-1.9] autolearn=ham Received: from coyote.aluminati.org ([127.0.0.1]) by localhost (coyote.aluminati.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id I+rrSRzKmQp4; Mon, 21 Oct 2013 12:24:19 +0100 (BST) Received: from serenity.lan (banza.aluminati.org [10.0.7.182]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by coyote.aluminati.org (Postfix) with ESMTPSA id DACC16064DD; Mon, 21 Oct 2013 12:24:13 +0100 (BST) Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.22 (2013-10-16) Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Sun, Oct 20, 2013 at 10:03:29PM -0700, Martin von Zweigbergk wrote: > On Wed, Oct 16, 2013 at 11:53 AM, John Keeping wrote: > > Commit 15a147e (rebase: use @{upstream} if no upstream specified, > > 2011-02-09) says: > > > > Make it default to 'git rebase @{upstream}'. That is also what > > 'git pull [--rebase]' defaults to, so it only makes sense that > > 'git rebase' defaults to the same thing. > > > > but that isn't actually the case. Since commit d44e712 (pull: support > > rebased upstream + fetch + pull --rebase, 2009-07-19), pull has actually > > chosen the most recent reflog entry which is an ancestor of the current > > branch if it can find one. > > It is exactly this inconsistency between "git rebase" and "git pull > --rebase" that confused me enough to make me send my first email to > this list almost 4 years ago [1], so thanks for working on this! I > finished that thread with: > > Would it make sense to teach "git rebase" the same tricks as "git > pull --rebase"? > > Then it took me a year before I sent a patch not unlike this one [2]. > To summarize, the patch did not get accepted then because it makes > rebase a little slower (or a lot slower in some cases). "git pull > --rebase" is of course at least as slow in the same cases, but because > it often involves connecting to a remote host, people would probably > blame the connection rather than git itself even in those rare (?) > cases. > > I think > > git merge-base HEAD $(git rev-list -g "$upstream_name") > > is roughly correct and hopefully fast enough. That can lead to too > long a command line, so I was planning on teaching merge-base a > --stdin option, but never got around to it. I'm not sure we should worry about the additional overhead here. In the common case, we should hit a common ancestor within the first couple of reflog entries; and in the case that will be slow, it's likely that there are a lot of differences between the branches so the cherry comparison phase will take a while anyway.