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From: Jakub Narebski <jnareb@gmail.com>
To: Derrick Stolee <stolee@gmail.com>
Cc: git@vger.kernel.org, gitster@pobox.com, ramsay@ramsayjones.plus.com, sbeller@google.com, szeder.dev@gmail.com, git@jeffhostetler.com, peff@peff.net, Derrick Stolee <dstolee@microsoft.com>
Subject: Re: [PATCH v8 03/14] commit-graph: add format document
Date: Sat, 14 Apr 2018 00:07:06 +0200
Message-ID: <86woxalq0l.fsf@gmail.com> (raw)
In-Reply-To: <c2f639ba-4832-191e-03ae-fa893796e2a6@gmail.com>

Derrick Stolee <stolee@gmail.com> writes:
> On 4/11/2018 4:58 PM, Jakub Narebski wrote:
>> Derrick Stolee <stolee@gmail.com> writes:
>>
>>> +CHUNK DATA:
>>> +
>>> +  OID Fanout (ID: {'O', 'I', 'D', 'F'}) (256 * 4 bytes)
>>> +      The ith entry, F[i], stores the number of OIDs with first
>>> +      byte at most i. Thus F[255] stores the total
>>> +      number of commits (N).
>>> +
>>> +  OID Lookup (ID: {'O', 'I', 'D', 'L'}) (N * H bytes)
>>> +      The OIDs for all commits in the graph, sorted in ascending order.
>>> +
>>> +  Commit Data (ID: {'C', 'G', 'E', 'T' }) (N * (H + 16) bytes)
>> I think it is a typo, and it should be CDAT, not CGET
>> (CDAT seem to me to stand for Commit DATa):
>>
>>    +  Commit Data (ID: {'C', 'D', 'A', 'T' }) (N * (H + 16) bytes)
>>
>> This is what you use in actual implementation, in PATCH v8 06/14
>>
>> DS> +#define GRAPH_SIGNATURE 0x43475048 /* "CGPH" */
>> DS> +#define GRAPH_CHUNKID_OIDFANOUT 0x4f494446 /* "OIDF" */
>> DS> +#define GRAPH_CHUNKID_OIDLOOKUP 0x4f49444c /* "OIDL" */
>> DS> +#define GRAPH_CHUNKID_DATA 0x43444154 /* "CDAT" */
>> DS> +#define GRAPH_CHUNKID_LARGEEDGES 0x45444745 /* "EDGE" */
>>
>
> Documentation bugs are hard to diagnose. Thanks for finding this. I
> double checked that the hex int "0x43444154" matches "CDAT".

Another possible way of checking the correctness would be to run
`hexdump -C` or equivalent on generated commit-graph file.  File and
chunk headers should be visible in its output.

> Here is a diff to make it match.
>
> diff --git a/Documentation/technical/commit-graph-format.txt
> b/Documentation/technical/commit-graph-format.txt
> index ad6af8105c..af03501834 100644
> --- a/Documentation/technical/commit-graph-format.txt
> +++ b/Documentation/technical/commit-graph-format.txt
> @@ -70,7 +70,7 @@ CHUNK DATA:
>    OID Lookup (ID: {'O', 'I', 'D', 'L'}) (N * H bytes)
>        The OIDs for all commits in the graph, sorted in ascending order.
>
> -  Commit Data (ID: {'C', 'G', 'E', 'T' }) (N * (H + 16) bytes)
> +  Commit Data (ID: {'C', 'D', 'A', 'T' }) (N * (H + 16) bytes)
>      * The first H bytes are for the OID of the root tree.
>      * The next 8 bytes are for the positions of the first two parents
>        of the ith commit. Stores value 0xffffffff if no parent in that

  reply index

Thread overview: 110+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-27  2:32 [PATCH v5 00/13] Serialized Git Commit Graph Derrick Stolee
2018-02-27  2:32 ` [PATCH v5 01/13] commit-graph: add format document Derrick Stolee
2018-02-27  2:32 ` [PATCH v5 02/13] graph: add commit graph design document Derrick Stolee
2018-02-27  2:32 ` [PATCH v5 03/13] commit-graph: create git-commit-graph builtin Derrick Stolee
2018-02-27  2:32 ` [PATCH v5 04/13] csum-file: add CSUM_KEEP_OPEN flag Derrick Stolee
2018-03-12 13:55   ` Derrick Stolee
2018-03-13 21:42     ` Junio C Hamano
2018-03-14  2:26       ` Derrick Stolee
2018-03-14 17:00         ` Junio C Hamano
2018-02-27  2:32 ` [PATCH v5 05/13] commit-graph: implement write_commit_graph() Derrick Stolee
2018-02-27  2:33 ` [PATCH v5 06/13] commit-graph: implement 'git-commit-graph write' Derrick Stolee
2018-02-27  2:33 ` [PATCH v5 07/13] commit-graph: implement git commit-graph read Derrick Stolee
2018-02-27  2:33 ` [PATCH v5 08/13] commit-graph: add core.commitGraph setting Derrick Stolee
2018-02-27  2:33 ` [PATCH v5 09/13] commit-graph: close under reachability Derrick Stolee
2018-02-27  2:33 ` [PATCH v5 10/13] commit: integrate commit graph with commit parsing Derrick Stolee
2018-02-27  2:33 ` [PATCH v5 11/13] commit-graph: read only from specific pack-indexes Derrick Stolee
2018-02-27 20:15   ` Stefan Beller
2018-02-27  2:33 ` [PATCH v5 12/13] commit-graph: build graph from starting commits Derrick Stolee
2018-02-27  2:33 ` [PATCH v5 13/13] commit-graph: implement "--additive" option Derrick Stolee
2018-02-27 18:50 ` [PATCH v5 00/13] Serialized Git Commit Graph Stefan Beller
2018-03-14 19:27 ` [PATCH v6 00/14] " Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 01/14] csum-file: rename hashclose() to finalize_hashfile() Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 02/14] csum-file: refactor finalize_hashfile() method Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 03/14] commit-graph: add format document Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 04/14] graph: add commit graph design document Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 05/14] commit-graph: create git-commit-graph builtin Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 06/14] commit-graph: implement write_commit_graph() Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 07/14] commit-graph: implement 'git-commit-graph write' Derrick Stolee
2018-03-18 13:25     ` Ævar Arnfjörð Bjarmason
2018-03-19 13:12       ` Derrick Stolee
2018-03-19 14:36         ` Ævar Arnfjörð Bjarmason
2018-03-19 18:27           ` Derrick Stolee
2018-03-19 18:48             ` Ævar Arnfjörð Bjarmason
2018-03-14 19:27   ` [PATCH v6 08/14] commit-graph: implement git commit-graph read Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 09/14] commit-graph: add core.commitGraph setting Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 10/14] commit-graph: close under reachability Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 11/14] commit: integrate commit graph with commit parsing Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 12/14] commit-graph: read only from specific pack-indexes Derrick Stolee
2018-03-15 22:50     ` SZEDER Gábor
2018-03-19 13:13       ` Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 13/14] commit-graph: build graph from starting commits Derrick Stolee
2018-03-14 19:27   ` [PATCH v6 14/14] commit-graph: implement "--additive" option Derrick Stolee
2018-03-14 20:10   ` [PATCH v6 00/14] Serialized Git Commit Graph Ramsay Jones
2018-03-14 20:43   ` Junio C Hamano
2018-03-15 17:23     ` Johannes Schindelin
2018-03-15 18:41       ` Junio C Hamano
2018-03-15 21:51         ` Ramsay Jones
2018-03-16 11:50         ` Johannes Schindelin
2018-03-16 17:27           ` Junio C Hamano
2018-03-19 11:41             ` Johannes Schindelin
2018-03-16 16:28     ` Lars Schneider
2018-03-19 13:10       ` Derrick Stolee
2018-03-16 15:06   ` Ævar Arnfjörð Bjarmason
2018-03-16 16:38     ` SZEDER Gábor
2018-03-16 18:33       ` Junio C Hamano
2018-03-16 19:48         ` SZEDER Gábor
2018-03-16 20:06           ` Jeff King
2018-03-16 20:19             ` Jeff King
2018-03-19 12:55               ` Derrick Stolee
2018-03-20  1:17                 ` Derrick Stolee
2018-03-16 20:49         ` Jeff King
2018-04-02 20:34   ` [PATCH v7 " Derrick Stolee
2018-04-02 20:34     ` [PATCH v7 01/14] csum-file: rename hashclose() to finalize_hashfile() Derrick Stolee
2018-04-02 20:34     ` [PATCH v7 02/14] csum-file: refactor finalize_hashfile() method Derrick Stolee
2018-04-07 22:59       ` Jakub Narebski
2018-04-02 20:34     ` [PATCH v7 03/14] commit-graph: add format document Derrick Stolee
2018-04-07 23:49       ` Jakub Narebski
2018-04-02 20:34     ` [PATCH v7 04/14] graph: add commit graph design document Derrick Stolee
2018-04-08 11:06       ` Jakub Narebski
2018-04-02 20:34     ` [PATCH v7 05/14] commit-graph: create git-commit-graph builtin Derrick Stolee
2018-04-02 20:34     ` [PATCH v7 06/14] commit-graph: implement write_commit_graph() Derrick Stolee
2018-04-02 20:34     ` [PATCH v7 07/14] commit-graph: implement git-commit-graph write Derrick Stolee
2018-04-08 11:59       ` Jakub Narebski
2018-04-02 20:34     ` [PATCH v7 08/14] commit-graph: implement git commit-graph read Derrick Stolee
2018-04-02 21:33       ` Junio C Hamano
2018-04-03 11:49         ` Derrick Stolee
2018-04-08 12:59       ` Jakub Narebski
2018-04-02 20:34     ` [PATCH v7 09/14] commit-graph: add core.commitGraph setting Derrick Stolee
2018-04-08 13:39       ` Jakub Narebski
2018-04-02 20:34     ` [PATCH v7 10/14] commit-graph: close under reachability Derrick Stolee
2018-04-02 20:34     ` [PATCH v7 11/14] commit: integrate commit graph with commit parsing Derrick Stolee
2018-04-02 20:34     ` [PATCH v7 12/14] commit-graph: read only from specific pack-indexes Derrick Stolee
2018-04-02 20:34     ` [PATCH v7 13/14] commit-graph: build graph from starting commits Derrick Stolee
2018-04-08 13:50       ` Jakub Narebski
2018-04-02 20:34     ` [PATCH v7 14/14] commit-graph: implement "--additive" option Derrick Stolee
2018-04-05  8:27       ` SZEDER Gábor
2018-04-10 12:55     ` [PATCH v8 00/14] Serialized Git Commit Graph Derrick Stolee
2018-04-10 12:55       ` [PATCH v8 01/14] csum-file: rename hashclose() to finalize_hashfile() Derrick Stolee
2018-04-10 12:55       ` [PATCH v8 02/14] csum-file: refactor finalize_hashfile() method Derrick Stolee
2018-04-10 12:55       ` [PATCH v8 03/14] commit-graph: add format document Derrick Stolee
2018-04-10 19:10         ` Stefan Beller
2018-04-10 19:18           ` Derrick Stolee
2018-04-11 20:58         ` Jakub Narebski
2018-04-12 11:28           ` Derrick Stolee
2018-04-13 22:07             ` Jakub Narebski [this message]
2018-04-10 12:55       ` [PATCH v8 04/14] graph: add commit graph design document Derrick Stolee
2018-04-15 22:48         ` Jakub Narebski
2018-04-10 12:55       ` [PATCH v8 05/14] commit-graph: create git-commit-graph builtin Derrick Stolee
2018-04-10 12:56       ` [PATCH v8 06/14] commit-graph: implement write_commit_graph() Derrick Stolee
2018-04-10 12:56       ` [PATCH v8 07/14] commit-graph: implement git-commit-graph write Derrick Stolee
2018-04-10 12:56       ` [PATCH v8 08/14] commit-graph: implement git commit-graph read Derrick Stolee
2018-04-14 22:15         ` Jakub Narebski
2018-04-15  3:26           ` Eric Sunshine
2018-04-10 12:56       ` [PATCH v8 09/14] commit-graph: add core.commitGraph setting Derrick Stolee
2018-04-14 18:33         ` Jakub Narebski
2018-04-10 12:56       ` [PATCH v8 10/14] commit-graph: close under reachability Derrick Stolee
2018-04-10 12:56       ` [PATCH v8 11/14] commit: integrate commit graph with commit parsing Derrick Stolee
2018-04-10 12:56       ` [PATCH v8 12/14] commit-graph: read only from specific pack-indexes Derrick Stolee
2018-04-10 12:56       ` [PATCH v8 13/14] commit-graph: build graph from starting commits Derrick Stolee
2018-04-10 12:56       ` [PATCH v8 14/14] commit-graph: implement "--append" option Derrick Stolee

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