From: Duy Nguyen <pclouds@gmail.com>
To: "brian m. carlson" <sandals@crustytoothpaste.net>,
"Duy Nguyen" <pclouds@gmail.com>,
"Martin Ågren" <martin.agren@gmail.com>,
"Git Mailing List" <git@vger.kernel.org>,
"Junio C Hamano" <gitster@pobox.com>,
"Eric Sunshine" <sunshine@sunshineco.com>
Subject: Re: [PATCH 18/41] index-pack: abstract away hash function constant
Date: Sat, 28 Apr 2018 07:41:43 +0200 [thread overview]
Message-ID: <CACsJy8BCSMNRvcPS5HaWjaURpS7abfANVUmrJVrxZ=b0qqGjag@mail.gmail.com> (raw)
In-Reply-To: <20180427210823.GB722934@genre.crustytoothpaste.net>
On Fri, Apr 27, 2018 at 11:08 PM, brian m. carlson
<sandals@crustytoothpaste.net> wrote:
> On Thu, Apr 26, 2018 at 05:46:28PM +0200, Duy Nguyen wrote:
>> On Wed, Apr 25, 2018 at 8:49 PM, Martin Ågren <martin.agren@gmail.com> wrote:
>> > Once that is accomplished, I sort of suspect that this code will want to
>> > be updated to not always blindly use the_hash_algo, but to always work
>> > with SHA-1 sizes. Or rather, this would turn into more generic code to
>> > handle both "v2 with SHA-1" and "v3 with some hash function(s)". This
>> > commit might be a good first step in that direction.
>>
>> I also have an uneasy feeling when things this close to on-disk file
>> format get hash-agnostic treatment. I think we would need to start
>> adding new file formats soon, from bottom up with simple things like
>> loose object files (cat-file and hash-object should be enough to test
>> blobs...), then moving up to pack files and more. This is when we can
>> really decide where to use the new hash and whether we should keep
>> some hashes as sha-1.
>
> I agree that this is work which needs to be done soon. There are
> basically a couple of pieces we need to handle NewHash:
>
> * Remove the dependencies on SHA-1 as much as possible.
> * Get the tests to pass with a different hash (almost done for 160-bit
> hash; in progress for 256-bit hashes).
This step sounds good on paper but realistically could be a nightmare for you.
I tried to implement a simple cat-file/hash-object combination with my
imaginary newhash, which sounded straightforward to me since you have
done a lot of heavylifting. To my surprise I hit a lot more problems.
My point is, when I concentrate on just a few simple cases like this,
I have a smaller scope to work with and could quickly identify
problems. When you work on the scale of the test suite, it's really
hard to know where the problem is (and you don't even know what areas
are newhash-safe).
Anyway my cat-file/hash-object modification could be found here. I
probably will polish and send out a few good patches from it.
https://github.com/pclouds/git/commits/new-hash
--
Duy
next prev parent reply other threads:[~2018-04-28 5:42 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-23 23:39 [PATCH 00/41] object_id part 13 brian m. carlson
2018-04-23 23:39 ` [PATCH 01/41] cache: add a function to read an object ID from a buffer brian m. carlson
2018-04-24 9:39 ` Martin Ågren
2018-05-01 9:36 ` Duy Nguyen
2018-05-01 23:58 ` brian m. carlson
2018-04-23 23:39 ` [PATCH 02/41] server-info: remove unused members from struct pack_info brian m. carlson
2018-04-24 9:41 ` Martin Ågren
2018-05-01 9:39 ` Duy Nguyen
2018-04-23 23:39 ` [PATCH 03/41] Remove unused member in struct object_context brian m. carlson
2018-05-01 9:50 ` Duy Nguyen
2018-04-23 23:39 ` [PATCH 04/41] packfile: remove unused member from struct pack_entry brian m. carlson
2018-05-01 10:01 ` Duy Nguyen
2018-04-23 23:39 ` [PATCH 05/41] packfile: convert has_sha1_pack to object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 06/41] sha1_file: convert freshen functions " brian m. carlson
2018-04-23 23:39 ` [PATCH 07/41] packfile: convert find_pack_entry " brian m. carlson
2018-04-23 23:39 ` [PATCH 08/41] packfile: abstract away hash constant values brian m. carlson
2018-05-01 10:22 ` Duy Nguyen
2018-05-02 0:11 ` brian m. carlson
2018-05-02 15:26 ` Duy Nguyen
2018-05-02 23:05 ` brian m. carlson
2018-04-23 23:39 ` [PATCH 09/41] pack-objects: abstract away hash algorithm brian m. carlson
2018-05-01 10:26 ` Duy Nguyen
2018-04-23 23:39 ` [PATCH 10/41] pack-redundant: " brian m. carlson
2018-04-23 23:39 ` [PATCH 11/41] tree-walk: avoid hard-coded 20 constant brian m. carlson
2018-04-23 23:39 ` [PATCH 12/41] tree-walk: convert get_tree_entry_follow_symlinks to object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 13/41] fsck: convert static functions to struct object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 14/41] submodule-config: convert structures to object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 15/41] split-index: convert struct split_index " brian m. carlson
2018-04-23 23:39 ` [PATCH 16/41] Update struct index_state to use struct object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 17/41] pack-redundant: convert linked lists " brian m. carlson
2018-04-23 23:39 ` [PATCH 18/41] index-pack: abstract away hash function constant brian m. carlson
2018-04-24 9:50 ` Martin Ågren
2018-04-24 23:51 ` brian m. carlson
2018-04-25 18:49 ` Martin Ågren
2018-04-26 15:46 ` Duy Nguyen
2018-04-27 21:08 ` brian m. carlson
2018-04-28 5:41 ` Duy Nguyen [this message]
2018-04-23 23:39 ` [PATCH 19/41] commit: convert uses of get_sha1_hex to get_oid_hex brian m. carlson
2018-04-23 23:39 ` [PATCH 20/41] dir: convert struct untracked_cache_dir to object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 21/41] http: eliminate hard-coded constants brian m. carlson
2018-04-24 9:53 ` Martin Ågren
2018-04-24 23:44 ` Junio C Hamano
2018-04-25 1:29 ` brian m. carlson
2018-04-23 23:39 ` [PATCH 22/41] revision: replace use of " brian m. carlson
2018-04-23 23:39 ` [PATCH 23/41] upload-pack: replace use of several " brian m. carlson
2018-04-24 7:53 ` Simon Ruderich
2018-04-23 23:39 ` [PATCH 24/41] diff: specify abbreviation size in terms of the_hash_algo brian m. carlson
2018-04-23 23:39 ` [PATCH 25/41] builtin/receive-pack: avoid hard-coded constants for push certs brian m. carlson
2018-04-24 9:58 ` Martin Ågren
2018-04-25 2:00 ` brian m. carlson
2018-04-25 5:06 ` Martin Ågren
2018-04-23 23:39 ` [PATCH 26/41] builtin/am: convert uses of EMPTY_TREE_SHA1_BIN to the_hash_algo brian m. carlson
2018-04-23 23:39 ` [PATCH 27/41] builtin/merge: switch tree functions to use object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 28/41] merge: convert empty tree constant to the_hash_algo brian m. carlson
2018-04-23 23:39 ` [PATCH 29/41] sequencer: convert one use of EMPTY_TREE_SHA1_HEX brian m. carlson
2018-04-23 23:39 ` [PATCH 30/41] submodule: convert several uses " brian m. carlson
2018-04-23 23:39 ` [PATCH 31/41] wt-status: convert two " brian m. carlson
2018-04-24 10:03 ` Martin Ågren
2018-05-01 2:29 ` brian m. carlson
2018-04-23 23:39 ` [PATCH 32/41] builtin/receive-pack: convert one use " brian m. carlson
2018-04-23 23:39 ` [PATCH 33/41] builtin/reset: convert use of EMPTY_TREE_SHA1_BIN brian m. carlson
2018-04-23 23:39 ` [PATCH 34/41] sha1_file: convert cached object code to struct object_id brian m. carlson
2018-04-23 23:39 ` [PATCH 35/41] cache-tree: use is_empty_tree_oid brian m. carlson
2018-04-23 23:39 ` [PATCH 36/41] sequencer: use the_hash_algo for empty tree object ID brian m. carlson
2018-04-23 23:39 ` [PATCH 37/41] dir: use the_hash_algo for empty blob " brian m. carlson
2018-04-23 23:39 ` [PATCH 38/41] sha1_file: only expose empty object constants through git_hash_algo brian m. carlson
2018-04-23 23:39 ` [PATCH 39/41] Update shell scripts to compute empty tree object ID brian m. carlson
2018-05-01 10:42 ` Duy Nguyen
2018-05-04 1:29 ` brian m. carlson
2018-04-23 23:39 ` [PATCH 40/41] add--interactive: compute the empty tree value brian m. carlson
2018-04-23 23:39 ` [PATCH 41/41] merge-one-file: compute empty blob object ID brian m. carlson
2018-04-24 1:00 ` SZEDER Gábor
2018-04-24 1:03 ` brian m. carlson
2018-04-30 18:03 ` [PATCH 00/41] object_id part 13 Duy Nguyen
2018-04-30 23:59 ` brian m. carlson
2018-05-01 10:51 ` Duy Nguyen
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