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From: Vicent Marti <vicent@github.com>
To: Shawn Pearce <spearce@spearce.org>
Cc: Jeff King <peff@peff.net>, Colby Ranger <cranger@google.com>,
	Duy Nguyen <pclouds@gmail.com>,
	Git Mailing List <git@vger.kernel.org>
Subject: Re: [PATCH 09/19] documentation: add documentation for the bitmap format
Date: Wed, 30 Oct 2013 17:11:45 +0100	[thread overview]
Message-ID: <CAFFjANSjFRwRYep_itVBAHuR2jYm=nspRWcUY02zXsEK=V5Reg@mail.gmail.com> (raw)
In-Reply-To: <CAJo=hJvOb=oooJ3O0wjxt77caGOMeKwT0VRaV=znMAzm0yNCYw@mail.gmail.com>

On Wed, Oct 30, 2013 at 11:23 AM, Shawn Pearce <spearce@spearce.org> wrote:
> On Wed, Oct 30, 2013 at 7:50 AM, Jeff King <peff@peff.net> wrote:
>> On Fri, Oct 25, 2013 at 01:47:06PM +0000, Shawn O. Pearce wrote:
>>
>>> I think Colby and I talked about having additional optional sections
>>> in this file, but Colby didn't want to overcomplicate the format early
>>> on. So v1 is probably not very extensible and we may have to go to v2
>>> to safely create an extension with the name hash cache used in this
>>> series.
>>>
>>> Given that the JGit v1 bitmap format has been shipping since JGit 3.0
>>> and in Gerrit Code Review 2.6, its in use in the wild. So we aren't
>>> going to go back and redefine v1.
>>
>> I don't think either course of action affects how JGit in the wild will
>> react. If we add a new flag to v1, existing JGit barfs. If we move to
>> v2, existing JGit barfs.  In either case, the simplest fix for JGit is
>> to ignore the new section.
>
> Fair point. Then we can use v1 with the flag for now, JGit will barf and...

Shawn, I'm proposing the following patch to JGit (actually Kevin is,
because I don't have the CLA, but whatevs):

https://git.eclipse.org/r/#/c/17894/

It's a very small change (using an "and" to check for the flags on the
bitmap instead of a switch), but I think it's very clean. In the
spirit of "Be conservative in what you send, be liberal in what you
accept", this patch lets JGit read V1 bitmaps emited from git.git
*even* if they have the extended Name Cache extension, and has no
effect on any JGit bitmap that has been generated up to date, or any
JGit bitmap generated from git.git without name caches.

I don't think it *changes* the semantics of the bitmap V1 format,
because with only one bit value set so far, those semantics weren't
really there, and it'll allow newer versions of JGit to never barf.

Love,
vmg

  reply	other threads:[~2013-10-30 16:12 UTC|newest]

Thread overview: 87+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-10-24 17:59 [PATCH 0/19] pack bitmaps Jeff King
2013-10-24 17:59 ` [PATCH 01/19] sha1write: make buffer const-correct Jeff King
2013-10-24 18:00 ` [PATCH 02/19] revindex: Export new APIs Jeff King
2013-10-24 18:01 ` [PATCH 03/19] pack-objects: Refactor the packing list Jeff King
2013-10-24 18:01 ` [PATCH 04/19] pack-objects: factor out name_hash Jeff King
2013-10-24 18:01 ` [PATCH 05/19] revision: allow setting custom limiter function Jeff King
2013-10-24 18:01 ` [PATCH 06/19] sha1_file: export `git_open_noatime` Jeff King
2013-10-24 18:01 ` [PATCH 07/19] compat: add endianness helpers Jeff King
2013-10-26  7:55   ` Thomas Rast
2013-10-30  8:25     ` Jeff King
2013-10-30 17:06       ` Vicent Martí
2013-10-24 18:02 ` [PATCH 08/19] ewah: compressed bitmap implementation Jeff King
2013-10-24 23:34   ` Junio C Hamano
2013-10-25  3:15     ` Jeff King
2013-10-26  7:55   ` Thomas Rast
2013-10-24 18:03 ` [PATCH 09/19] documentation: add documentation for the bitmap format Jeff King
2013-10-25  1:16   ` Duy Nguyen
2013-10-25  3:21     ` Jeff King
2013-10-25  3:28       ` Duy Nguyen
2013-10-25 13:47       ` Shawn Pearce
2013-10-30  7:50         ` Jeff King
2013-10-30 10:23           ` Shawn Pearce
2013-10-30 16:11             ` Vicent Marti [this message]
2013-10-30 16:14             ` Vicent Marti
2013-10-24 18:03 ` [PATCH 10/19] pack-bitmap: add support for bitmap indexes Jeff King
2013-10-25 13:55   ` Shawn Pearce
2013-10-30  8:10     ` Jeff King
2013-10-30 10:27       ` Shawn Pearce
2013-10-30 15:47       ` Vicent Marti
2013-10-30 16:04         ` Shawn Pearce
2013-10-30 20:25         ` Jeff King
2013-10-24 18:04 ` [PATCH 11/19] pack-objects: use bitmaps when packing objects Jeff King
2013-10-25 14:14   ` Shawn Pearce
2013-10-30  8:21     ` Jeff King
2013-10-30 10:38       ` Shawn Pearce
2013-10-30 16:01         ` Vicent Marti
2013-10-24 18:06 ` [PATCH 12/19] rev-list: add bitmap mode to speed up object lists Jeff King
2013-10-25 14:00   ` Shawn Pearce
2013-10-30  8:12     ` Jeff King
2013-10-24 18:06 ` [PATCH 13/19] pack-objects: implement bitmap writing Jeff King
2013-10-25  1:21   ` Duy Nguyen
2013-10-25  3:22     ` Jeff King
2013-10-24 18:06 ` [PATCH 14/19] repack: stop using magic number for ARRAY_SIZE(exts) Jeff King
2013-10-24 18:07 ` [PATCH 15/19] repack: turn exts array into array-of-struct Jeff King
2013-10-24 18:07 ` [PATCH 16/19] repack: handle optional files created by pack-objects Jeff King
2013-10-24 18:08 ` [PATCH 17/19] repack: consider bitmaps when performing repacks Jeff King
2013-10-24 18:08 ` [PATCH 18/19] t: add basic bitmap functionality tests Jeff King
2013-10-24 18:08 ` [PATCH 19/19] pack-bitmap: implement optional name_hash cache Jeff King
2013-10-24 20:25 ` [PATCH 0/19] pack bitmaps Junio C Hamano
2013-10-25  3:07 ` Junio C Hamano
2013-10-25  5:55 ` [PATCHv2 " Jeff King
2013-10-25  5:57   ` [PATCH v2 01/19] sha1write: make buffer const-correct Jeff King
2013-10-25  6:02   ` [PATCH 02/19] revindex: Export new APIs Jeff King
2013-10-25  6:03   ` [PATCH v2 03/19] pack-objects: Refactor the packing list Jeff King
2013-10-25  6:03   ` [PATCH v2 04/19] pack-objects: factor out name_hash Jeff King
2013-10-25  6:03   ` [PATCH v2 05/19] revision: allow setting custom limiter function Jeff King
2013-10-25  6:03   ` [PATCH v2 06/19] sha1_file: export `git_open_noatime` Jeff King
2013-10-25  6:03   ` [PATCH v2 07/19] compat: add endianness helpers Jeff King
2013-10-25  6:03   ` [PATCH v2 08/19] ewah: compressed bitmap implementation Jeff King
2013-10-25  6:03   ` [PATCH v2 09/19] documentation: add documentation for the bitmap format Jeff King
2013-10-25  6:03   ` [PATCH v2 10/19] pack-bitmap: add support for bitmap indexes Jeff King
2013-10-25 23:06     ` Junio C Hamano
2013-10-26  0:26       ` Jeff King
2013-10-26  6:25         ` Jeff King
2013-10-28 15:22           ` Junio C Hamano
2013-10-30  7:00             ` Jeff King
2013-10-26 10:14     ` Duy Nguyen
2013-10-30  7:27       ` Jeff King
2013-10-25  6:03   ` [PATCH v2 11/19] pack-objects: use bitmaps when packing objects Jeff King
2013-10-26 10:25     ` Duy Nguyen
2013-10-30  7:36       ` Jeff King
2013-10-30 10:28         ` Duy Nguyen
2013-10-30 20:07           ` Jeff King
2013-10-31 12:03             ` Duy Nguyen
2013-10-25  6:04   ` [PATCH v2 12/19] rev-list: add bitmap mode to speed up object lists Jeff King
2013-10-25  6:04   ` [PATCH v2 13/19] pack-objects: implement bitmap writing Jeff King
2013-10-25  6:04   ` [PATCH v2 14/19] repack: stop using magic number for ARRAY_SIZE(exts) Jeff King
2013-10-25  6:04   ` [PATCH v2 15/19] repack: turn exts array into array-of-struct Jeff King
2013-10-25  6:04   ` [PATCH v2 16/19] repack: handle optional files created by pack-objects Jeff King
2013-10-25  6:04   ` [PATCH v2 17/19] repack: consider bitmaps when performing repacks Jeff King
2013-10-25  6:04   ` [PATCH v2 18/19] t: add basic bitmap functionality tests Jeff King
2013-10-28 22:13     ` SZEDER Gábor
2013-10-30  7:39       ` Jeff King
2013-10-25  6:04   ` [PATCH v2 19/19] pack-bitmap: implement optional name_hash cache Jeff King
2013-10-26 10:19     ` [PATCH 20/19] count-objects: consider .bitmap without .pack/.idx pair garbage Nguyễn Thái Ngọc Duy
2013-10-30  6:59       ` Jeff King
2013-10-30 17:36         ` Junio C Hamano

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