From mboxrd@z Thu Jan 1 00:00:00 1970 From: Junio C Hamano Subject: Re: [PATCH v3 2/3] patch-id: document new behaviour Date: Mon, 31 Mar 2014 12:08:36 -0700 Message-ID: References: <1396202583-2572-1-git-send-email-mst@redhat.com> <1396202583-2572-2-git-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: git@vger.kernel.org, sunshine@sunshineco.com, jrnieder@gmail.com, peff@peff.net To: "Michael S. Tsirkin" X-From: git-owner@vger.kernel.org Mon Mar 31 21:08:48 2014 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 1WUhZc-0004vi-Pc for gcvg-git-2@plane.gmane.org; Mon, 31 Mar 2014 21:08:45 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754150AbaCaTIk (ORCPT ); Mon, 31 Mar 2014 15:08:40 -0400 Received: from b-pb-sasl-quonix.pobox.com ([208.72.237.35]:44590 "EHLO smtp.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753984AbaCaTIj (ORCPT ); Mon, 31 Mar 2014 15:08:39 -0400 Received: from smtp.pobox.com (unknown [127.0.0.1]) by b-sasl-quonix.pobox.com (Postfix) with ESMTP id C517D77237; Mon, 31 Mar 2014 15:08:38 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; s=sasl; bh=rnKCbjW1nOVz9ypGDBvFOVoA3jw=; b=YiLh7t C2qWf0a9fvJwF1j/wKF2Wunv+DReiHRwjSSLIhME846rHQDYN8eHfjtnp9ZGnTGG CezLaiLDNppo+EO8NiXe9HN6G9AnMuiLkZPI9thqenQY6K6sdKirum1Cmr/eFxGG lxkr6RLb6ojsJHESIPFIg4qb8J1bAMTzQW9zc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=pobox.com; h=from:to:cc :subject:references:date:in-reply-to:message-id:mime-version :content-type; q=dns; s=sasl; b=LIz8gRUNSiJKBsOI+GP1MhjRl/SQzgHv ayDZNdKc5YOavCzgArxTR6UeDvrq0oRiK4r/9vNU6y/iZ8GzoFCXTy4+puKJINj1 L6EHA91afm/5NYhfvbKTSfDZIV5sVvbWPkDXjB/hB6x4ot7BoDPsAuDseqKpx0bE 7FHwdsj5btY= Received: from b-pb-sasl-quonix.pobox.com (unknown [127.0.0.1]) by b-sasl-quonix.pobox.com (Postfix) with ESMTP id AD3CF77236; Mon, 31 Mar 2014 15:08:38 -0400 (EDT) Received: from pobox.com (unknown [72.14.226.9]) (using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by b-sasl-quonix.pobox.com (Postfix) with ESMTPSA id D17BD77234; Mon, 31 Mar 2014 15:08:37 -0400 (EDT) In-Reply-To: <1396202583-2572-2-git-send-email-mst@redhat.com> (Michael S. Tsirkin's message of "Sun, 30 Mar 2014 21:09:26 +0300") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux) X-Pobox-Relay-ID: DD394350-B907-11E3-BDE4-8D19802839F8-77302942!b-pb-sasl-quonix.pobox.com Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: "Michael S. Tsirkin" writes: > Clarify that patch ID is now a sum of hashes, not a hash. > Document --stable and --unstable flags. > > Signed-off-by: Michael S. Tsirkin > --- > > changes from v2: > explicitly list the kinds of changes against which patch ID is stable > > Documentation/git-patch-id.txt | 23 ++++++++++++++++++----- > 1 file changed, 18 insertions(+), 5 deletions(-) > > diff --git a/Documentation/git-patch-id.txt b/Documentation/git-patch-id.txt > index 312c3b1..30923e0 100644 > --- a/Documentation/git-patch-id.txt > +++ b/Documentation/git-patch-id.txt > @@ -8,14 +8,14 @@ git-patch-id - Compute unique ID for a patch > SYNOPSIS > -------- > [verse] > -'git patch-id' < > +'git patch-id' [--stable | --unstable] < Thanks. It seems taht we are fairly inconsistent when writing alternatives on the SYNOPSIS line. A small minority seems to spell the above as "[--stable|--unstable]", which may want to be fixed (outside the context of this series, of course). > > DESCRIPTION > ----------- > -A "patch ID" is nothing but a SHA-1 of the diff associated with a patch, with > -whitespace and line numbers ignored. As such, it's "reasonably stable", but at > -the same time also reasonably unique, i.e., two patches that have the same "patch > -ID" are almost guaranteed to be the same thing. > +A "patch ID" is nothing but a sum of SHA-1 of the diff hunks associated with a > +patch, with whitespace and line numbers ignored. As such, it's "reasonably > +stable", but at the same time also reasonably unique, i.e., two patches that > +have the same "patch ID" are almost guaranteed to be the same thing. Perhaps "nothing but" can go by now? > > IOW, you can use this thing to look for likely duplicate commits. > > @@ -27,6 +27,19 @@ This can be used to make a mapping from patch ID to commit ID. > > OPTIONS > ------- > + > +--stable:: > + Use a symmetrical sum of hashes as the patch ID. > + With this option, reordering file diffs that make up a patch or > + splitting a diff up to multiple diffs that touch the same path > + does not affect the ID. > + This is the default. > + > +--unstable:: > + Use a non-symmetrical sum of hashes, such that reordering > + or splitting the patch does affect the ID. > + This was the default value for git 1.9 and older. I am not sure if swapping the default in this series is a wise decision. We typically introduce a new shiny toy to play with in a release and then later when the shiny toy proves to be useful, start to think about changing the default, but not before. > :: > The diff to create the ID of.