From: Junio C Hamano <gitster@pobox.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: git@vger.kernel.org, sunshine@sunshineco.com, jrnieder@gmail.com,
peff@peff.net
Subject: Re: [PATCH v3 2/3] patch-id: document new behaviour
Date: Mon, 31 Mar 2014 12:08:36 -0700 [thread overview]
Message-ID: <xmqqmwg65gp7.fsf@gitster.dls.corp.google.com> (raw)
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")
"Michael S. Tsirkin" <mst@redhat.com> 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 <mst@redhat.com>
> ---
>
> 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' < <patch>
> +'git patch-id' [--stable | --unstable] < <patch>
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.
> <patch>::
> The diff to create the ID of.
next prev parent reply other threads:[~2014-03-31 19:08 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-30 18:09 [PATCH v3 1/3] patch-id: make it stable against hunk reordering Michael S. Tsirkin
2014-03-30 18:09 ` [PATCH v3 2/3] patch-id: document new behaviour Michael S. Tsirkin
2014-03-31 19:08 ` Junio C Hamano [this message]
2014-03-31 19:26 ` Michael S. Tsirkin
2014-03-31 19:54 ` Junio C Hamano
2014-03-31 20:42 ` Michael S. Tsirkin
2014-04-02 18:18 ` Junio C Hamano
2014-04-02 19:02 ` Michael S. Tsirkin
2014-04-03 15:42 ` Junio C Hamano
2014-03-30 18:09 ` [PATCH v3 3/3] patch-id-test: test --stable and --unstable flags Michael S. Tsirkin
2014-03-31 19:29 ` Junio C Hamano
2014-03-31 17:59 ` [PATCH v3 1/3] patch-id: make it stable against hunk reordering Junio C Hamano
2014-03-31 19:04 ` Michael S. Tsirkin
2014-03-31 19:35 ` Junio C Hamano
2014-03-31 22:05 ` Junio C Hamano
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