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From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: Jonathan Tan <jonathantanmy@google.com>,
	christian.couder@gmail.com, git@vger.kernel.org,
	chriscool@tuxfamily.org, ramsay@ramsayjones.plus.com
Subject: Re: [RFC PATCH 10/10] pack-objects: improve partial packfile reuse
Date: Thu, 17 Oct 2019 16:03:00 +0900	[thread overview]
Message-ID: <xmqq8spj97mj.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <20191013073851.GA7001@sigill.intra.peff.net> (Jeff King's message of "Sun, 13 Oct 2019 03:38:52 -0400")

Jeff King <peff@peff.net> writes:

>> Hmm, I am kind of surprised that the decoding side allowed such a
>> padding.
>
> IIRC, the "padding" is just a sequence of 0-length-plus-continuation-bit
> varint bytes. And for some reason it worked for the size but not for the
> delta offset value.

I think the reason is because they use different varint definition.

The encoding used in builtin/pack-objects.c::write_no_reuse_object()
is for offsets, and it came much later and with an improvement over
the encoding used for delta size in diff-delta.c::create_delta().
The more recent encoding does not allow padding (when I compare the
decoders for these two encodings, I notice there is +1 for each
7-bit iteration; this essentially declares that a byte with "not the
final byte" bit set with all other bits clear does not mean 0 but it
means 1, which breaks the idea of padding to encode filler zero
bits).

  reply	other threads:[~2019-10-17  7:04 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-13 13:02 [RFC PATCH 00/10] Rewrite packfile reuse code Christian Couder
2019-09-13 13:02 ` [RFC PATCH 01/10] builtin/pack-objects: report reused packfile objects Christian Couder
2019-09-13 13:02 ` [RFC PATCH 02/10] packfile: expose get_delta_base() Christian Couder
2019-09-13 13:02 ` [RFC PATCH 03/10] ewah/bitmap: introduce bitmap_word_alloc() Christian Couder
2019-09-13 13:02 ` [RFC PATCH 04/10] ewah/bitmap: always allocate 2 more words Christian Couder
2019-10-10 23:40   ` Jonathan Tan
2019-10-11  7:49     ` Christian Couder
2019-10-11 18:05       ` Jeff King
2019-09-13 13:02 ` [RFC PATCH 05/10] pack-bitmap: don't rely on bitmap_git->reuse_objects Christian Couder
2019-10-10 23:44   ` Jonathan Tan
2019-10-11  7:50     ` Christian Couder
2019-09-13 13:02 ` [RFC PATCH 06/10] pack-bitmap: introduce bitmap_walk_contains() Christian Couder
2019-09-13 13:02 ` [RFC PATCH 07/10] csum-file: introduce hashfile_total() Christian Couder
2019-09-13 13:02 ` [RFC PATCH 08/10] pack-objects: introduce pack.allowPackReuse Christian Couder
2019-09-13 21:37   ` Junio C Hamano
2019-09-13 13:02 ` [RFC PATCH 09/10] builtin/pack-objects: introduce obj_is_packed() Christian Couder
2019-09-13 13:02 ` [RFC PATCH 10/10] pack-objects: improve partial packfile reuse Christian Couder
2019-09-13 22:29   ` Junio C Hamano
2019-09-14  2:02     ` Jeff King
2019-09-14  3:06       ` Junio C Hamano
2019-10-02 15:57         ` Jeff King
2019-10-03  2:06           ` Junio C Hamano
2019-10-03  6:55             ` Christian Couder
2019-10-10 23:59   ` Jonathan Tan
2019-10-11  7:39     ` Christian Couder
2019-10-11 18:01     ` Jeff King
2019-10-11 21:04       ` Jonathan Tan
2019-10-12  0:04       ` Junio C Hamano
2019-10-13  7:38         ` Jeff King
2019-10-17  7:03           ` Junio C Hamano [this message]
2019-10-17  7:23             ` Jeff King

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