From: Abhishek Kumar <abhishekkumar8222@gmail.com>
To: "Jakub Narębski" <jnareb@gmail.com>
Cc: abhishekkumar8222@gmail.com, git@vger.kernel.org,
gitgitgadget@gmail.com, stolee@gmail.com
Subject: Re: [PATCH v3 03/11] commit-graph: consolidate fill_commit_graph_info
Date: Tue, 1 Sep 2020 17:05:24 +0530 [thread overview]
Message-ID: <20200901113524.GD10388@Abhishek-Arch> (raw)
In-Reply-To: <85mu2jc75c.fsf@gmail.com>
On Tue, Aug 25, 2020 at 01:11:11PM +0200, Jakub Narębski wrote:
> Hello,
>
> ...
>
> All right.
>
> We might want to add here the information that we also move loading the
> commit date from the commit-graph file from fill_commit_in_graph() down
> the [new] call chain into fill_commit_graph_info(). The commit date
> would be needed in fill_commit_graph_info() in the next commit to
> compute corrected commit date out of corrected commit date offset, and
> store it as generation number.
>
>
> NOTE that this means that if we switch to storing 64-bit corrected
> commit date directly in the commit-graph file, instead of storing 32-bit
> offsets, neither this Move Statement Into Function Out of Caller
> refactoring nor change to the 'generate tar with future mtime' test
> would be necessary.
>
> >
> > The test 'generate tar with future mtime' creates a commit with commit
> > time of (2 ^ 36 + 1) seconds since EPOCH. The CDAT chunk provides
> > 34-bits for storing commiter date, thus committer time overflows into
> > generation number (within CDAT chunk) and has undefined behavior.
> >
> > The test used to pass as fill_commit_graph_info() would not set struct
> > member `date` of struct commit and loads committer date from the object
> > database, generating a tar file with the expected mtime.
>
> I guess that in the case of generating a tar file we would read the
> commit out of 'object database', and then only add commit-graph specific
> info with fill_commit_graph_info(). Possibly because we need more
> information that commit-graph provides for a commit.
>
> >
> > However, with corrected commit date, we will load the committer date
> > from CDAT chunk (truncated to lower 34-bits) to populate the generation
> > number. Thus, fill_commit_graph_info() sets date and generates tar file
> > with the truncated mtime and the test fails.
> >
> > Let's fix the test by setting a timestamp of (2 ^ 34 - 1) seconds, which
> > will not be truncated.
>
> Now I got interested why the value of (2 ^ 36 + 1) seconds since EPOCH
> was used.
>
> The commit that introduced the 'generate tar with future mtime' test,
> namely e51217e15 (t5000: test tar files that overflow ustar headers,
> 30-06-2016), says:
>
> The ustar format only has room for 11 (or 12, depending on
> some implementations) octal digits for the size and mtime of
> each file. For values larger than this, we have to add pax
> extended headers to specify the real data, and git does not
> yet know how to do so.
>
> Before fixing that, let's start off with some test
> infrastructure [...]
>
> The value of 2 ^ 36 equals 2 ^ 3*12 = (2 ^ 3) ^ 12 = 8 ^ 12.
> So we need the value of (2 ^ 36 + 1) for this test do do its job.
> Possibly the value of 8 ^ 11 + 1 = 2 ^ 33 + 1 would be enough
> (if we skip testing "some implementations").
>
> So I think to make this test more clear (for inquisitive minds) we
> should set a timestamp of (2 ^ 33 + 1), not (2 ^ 34 - 1) seconds
> since EPOCH. Maybe even add a variant of this test that uses the
> origial value of (2 ^ 36 + 1) seconds since EPOCH, but turns off
> use of serialized commit-graph.
That's pretty interesting! I didn't look into this either, will modify
the existing test and add a new test for it.
Thanks for investigating this further.
>
> I'm sorry for not checking this earlier.
>
> Best,
> --
> Jakub Narębski
Thanks
- Abhishek
next prev parent reply other threads:[~2020-09-01 11:42 UTC|newest]
Thread overview: 211+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-28 9:13 [PATCH 0/6] [GSoC] Implement Corrected Commit Date Abhishek Kumar via GitGitGadget
2020-07-28 9:13 ` [PATCH 1/6] commit-graph: fix regression when computing bloom filter Abhishek Kumar via GitGitGadget
2020-07-28 15:28 ` Taylor Blau
2020-07-30 5:24 ` Abhishek Kumar
2020-08-04 0:46 ` Jakub Narębski
2020-08-04 0:56 ` Taylor Blau
2020-08-04 10:10 ` Jakub Narębski
2020-08-04 7:55 ` Jakub Narębski
2020-07-28 9:13 ` [PATCH 2/6] revision: parse parent in indegree_walk_step() Abhishek Kumar via GitGitGadget
2020-07-28 13:00 ` Derrick Stolee
2020-07-28 15:30 ` Taylor Blau
2020-08-05 23:16 ` Jakub Narębski
2020-07-28 9:13 ` [PATCH 3/6] commit-graph: consolidate fill_commit_graph_info Abhishek Kumar via GitGitGadget
2020-07-28 13:14 ` Derrick Stolee
2020-07-28 15:19 ` René Scharfe
2020-07-28 15:58 ` Derrick Stolee
2020-07-28 16:01 ` Taylor Blau
2020-07-30 6:07 ` Abhishek Kumar
2020-07-28 9:13 ` [PATCH 4/6] commit-graph: consolidate compare_commits_by_gen Abhishek Kumar via GitGitGadget
2020-07-28 16:03 ` Taylor Blau
2020-07-28 9:13 ` [PATCH 5/6] commit-graph: implement generation data chunk Abhishek Kumar via GitGitGadget
2020-07-28 16:12 ` Taylor Blau
2020-07-30 6:52 ` Abhishek Kumar
2020-07-28 9:13 ` [PATCH 6/6] commit-graph: implement corrected commit date offset Abhishek Kumar via GitGitGadget
2020-07-28 15:55 ` Derrick Stolee
2020-07-28 16:23 ` Taylor Blau
2020-07-30 7:27 ` Abhishek Kumar
2020-07-28 14:54 ` [PATCH 0/6] [GSoC] Implement Corrected Commit Date Taylor Blau
2020-07-30 7:47 ` Abhishek Kumar
2020-07-28 16:35 ` Derrick Stolee
2020-08-09 2:53 ` [PATCH v2 00/10] " Abhishek Kumar via GitGitGadget
2020-08-09 2:53 ` [PATCH v2 01/10] commit-graph: fix regression when computing bloom filter Abhishek Kumar via GitGitGadget
2020-08-09 2:53 ` [PATCH v2 02/10] revision: parse parent in indegree_walk_step() Abhishek Kumar via GitGitGadget
2020-08-09 2:53 ` [PATCH v2 03/10] commit-graph: consolidate fill_commit_graph_info Abhishek Kumar via GitGitGadget
2020-08-09 2:53 ` [PATCH v2 04/10] commit-graph: consolidate compare_commits_by_gen Abhishek Kumar via GitGitGadget
2020-08-09 2:53 ` [PATCH v2 05/10] commit-graph: implement generation data chunk Abhishek Kumar via GitGitGadget
2020-08-10 16:28 ` Derrick Stolee
2020-08-11 11:03 ` Abhishek Kumar
2020-08-11 12:27 ` Derrick Stolee
2020-08-11 18:58 ` Taylor Blau
2020-08-09 2:53 ` [PATCH v2 06/10] commit-graph: return 64-bit generation number Abhishek Kumar via GitGitGadget
2020-08-09 2:53 ` [PATCH v2 07/10] commit-graph: implement corrected commit date Abhishek Kumar via GitGitGadget
2020-08-10 14:23 ` Derrick Stolee
2020-08-14 4:59 ` Abhishek Kumar
2020-08-14 12:24 ` Derrick Stolee
2020-08-09 2:53 ` [PATCH v2 08/10] commit-graph: handle mixed generation commit chains Abhishek Kumar via GitGitGadget
2020-08-10 16:42 ` Derrick Stolee
2020-08-11 11:36 ` Abhishek Kumar
2020-08-11 12:43 ` Derrick Stolee
2020-08-09 2:53 ` [PATCH v2 09/10] commit-reach: use corrected commit dates in paint_down_to_common() Abhishek Kumar via GitGitGadget
2020-08-09 2:53 ` [PATCH v2 10/10] doc: add corrected commit date info Abhishek Kumar via GitGitGadget
2020-08-10 16:47 ` [PATCH v2 00/10] [GSoC] Implement Corrected Commit Date Derrick Stolee
2020-08-15 16:39 ` [PATCH v3 00/11] " Abhishek Kumar via GitGitGadget
2020-08-15 16:39 ` [PATCH v3 01/11] commit-graph: fix regression when computing bloom filter Abhishek Kumar via GitGitGadget
2020-08-17 22:30 ` Jakub Narębski
2020-08-15 16:39 ` [PATCH v3 02/11] revision: parse parent in indegree_walk_step() Abhishek Kumar via GitGitGadget
2020-08-18 14:18 ` Jakub Narębski
2020-08-15 16:39 ` [PATCH v3 03/11] commit-graph: consolidate fill_commit_graph_info Abhishek Kumar via GitGitGadget
2020-08-19 17:54 ` Jakub Narębski
2020-08-21 4:11 ` Abhishek Kumar
2020-08-25 11:11 ` Jakub Narębski
2020-09-01 11:35 ` Abhishek Kumar [this message]
2020-08-15 16:39 ` [PATCH v3 04/11] commit-graph: consolidate compare_commits_by_gen Abhishek Kumar via GitGitGadget
2020-08-17 13:22 ` Derrick Stolee
2020-08-21 11:05 ` Jakub Narębski
2020-08-15 16:39 ` [PATCH v3 05/11] commit-graph: return 64-bit generation number Abhishek Kumar via GitGitGadget
2020-08-21 13:14 ` Jakub Narębski
2020-08-25 5:04 ` Abhishek Kumar
2020-08-25 12:18 ` Jakub Narębski
2020-09-01 12:06 ` Abhishek Kumar
2020-09-03 13:42 ` Jakub Narębski
2020-09-05 17:21 ` Abhishek Kumar
2020-09-13 15:39 ` Jakub Narębski
2020-09-28 21:48 ` Jakub Narębski
2020-10-05 5:25 ` Abhishek Kumar
2020-08-15 16:39 ` [PATCH v3 06/11] commit-graph: add a slab to store topological levels Abhishek Kumar via GitGitGadget
2020-08-21 18:43 ` Jakub Narębski
2020-08-25 6:14 ` Abhishek Kumar
2020-08-25 7:33 ` Jakub Narębski
2020-08-25 7:56 ` Jakub Narębski
2020-09-01 10:26 ` Abhishek Kumar
2020-09-03 9:25 ` Jakub Narębski
2020-08-15 16:39 ` [PATCH v3 07/11] commit-graph: implement corrected commit date Abhishek Kumar via GitGitGadget
2020-08-22 0:05 ` Jakub Narębski
2020-08-25 6:49 ` Abhishek Kumar
2020-08-25 10:07 ` Jakub Narębski
2020-09-01 11:01 ` Abhishek Kumar
2020-08-15 16:39 ` [PATCH v3 08/11] commit-graph: implement generation data chunk Abhishek Kumar via GitGitGadget
2020-08-22 13:09 ` Jakub Narębski
2020-08-15 16:39 ` [PATCH v3 09/11] commit-graph: use generation v2 only if entire chain does Abhishek Kumar via GitGitGadget
2020-08-22 17:14 ` Jakub Narębski
2020-08-26 7:15 ` Abhishek Kumar
2020-08-26 10:38 ` Jakub Narębski
2020-08-15 16:39 ` [PATCH v3 10/11] commit-reach: use corrected commit dates in paint_down_to_common() Abhishek Kumar via GitGitGadget
2020-08-22 19:09 ` Jakub Narębski
2020-09-01 10:08 ` Abhishek Kumar
2020-09-03 19:11 ` Jakub Narębski
2020-08-15 16:39 ` [PATCH v3 11/11] doc: add corrected commit date info Abhishek Kumar via GitGitGadget
2020-08-22 22:20 ` Jakub Narębski
2020-08-27 6:39 ` Abhishek Kumar
2020-08-27 12:43 ` Jakub Narębski
2020-08-27 13:15 ` Derrick Stolee
2020-09-01 13:01 ` Abhishek Kumar
2020-08-17 0:13 ` [PATCH v3 00/11] [GSoC] Implement Corrected Commit Date Jakub Narębski
[not found] ` <CANQwDwdKp7oKy9BeKdvKhwPUiq0R5MS8TCw-eWGCYCoMGv=G-g@mail.gmail.com>
2020-08-17 1:32 ` Fwd: " Taylor Blau
2020-08-17 7:56 ` Jakub Narębski
2020-08-18 6:12 ` Abhishek Kumar
2020-08-23 15:27 ` Jakub Narębski
2020-08-24 2:49 ` Abhishek Kumar
2020-10-07 14:09 ` [PATCH v4 00/10] " Abhishek Kumar via GitGitGadget
2020-10-07 14:09 ` [PATCH v4 01/10] commit-graph: fix regression when computing Bloom filters Abhishek Kumar via GitGitGadget
2020-10-24 23:16 ` Jakub Narębski
2020-10-25 20:58 ` Taylor Blau
2020-11-03 5:36 ` Abhishek Kumar
2020-10-07 14:09 ` [PATCH v4 02/10] revision: parse parent in indegree_walk_step() Abhishek Kumar via GitGitGadget
2020-10-24 23:41 ` Jakub Narębski
2020-10-07 14:09 ` [PATCH v4 03/10] commit-graph: consolidate fill_commit_graph_info Abhishek Kumar via GitGitGadget
2020-10-25 10:52 ` Jakub Narębski
2020-10-27 6:33 ` Abhishek Kumar
2020-10-07 14:09 ` [PATCH v4 04/10] commit-graph: return 64-bit generation number Abhishek Kumar via GitGitGadget
2020-10-25 13:48 ` Jakub Narębski
2020-11-03 6:40 ` Abhishek Kumar
2020-10-07 14:09 ` [PATCH v4 05/10] commit-graph: add a slab to store topological levels Abhishek Kumar via GitGitGadget
2020-10-25 22:17 ` Jakub Narębski
2020-10-07 14:09 ` [PATCH v4 06/10] commit-graph: implement corrected commit date Abhishek Kumar via GitGitGadget
2020-10-27 18:53 ` Jakub Narębski
2020-11-03 11:44 ` Abhishek Kumar
2020-11-04 16:45 ` Jakub Narębski
2020-11-05 14:05 ` Philip Oakley
2020-11-05 18:22 ` Junio C Hamano
2020-11-06 18:26 ` Extending and updating gitglossary (was: Re: [PATCH v4 06/10] commit-graph: implement corrected commit date) Jakub Narębski
2020-11-06 19:33 ` Extending and updating gitglossary Junio C Hamano
2020-11-08 17:23 ` Extending and updating gitglossary (was: Re: [PATCH v4 06/10] commit-graph: implement corrected commit date) Philip Oakley
2020-11-10 1:35 ` Extending and updating gitglossary Jakub Narębski
2020-11-10 14:04 ` Philip Oakley
2020-11-10 23:52 ` Jakub Narębski
2020-10-07 14:09 ` [PATCH v4 07/10] commit-graph: implement generation data chunk Abhishek Kumar via GitGitGadget
2020-10-30 12:45 ` Jakub Narębski
2020-11-06 11:25 ` Abhishek Kumar
2020-11-06 17:56 ` Jakub Narębski
2020-10-07 14:09 ` [PATCH v4 08/10] commit-graph: use generation v2 only if entire chain does Abhishek Kumar via GitGitGadget
2020-11-01 0:55 ` Jakub Narębski
2020-11-12 10:01 ` Abhishek Kumar
2020-11-13 9:59 ` Jakub Narębski
2020-10-07 14:09 ` [PATCH v4 09/10] commit-reach: use corrected commit dates in paint_down_to_common() Abhishek Kumar via GitGitGadget
2020-11-03 17:59 ` Jakub Narębski
2020-11-03 18:19 ` Junio C Hamano
2020-11-20 10:33 ` Abhishek Kumar
2020-10-07 14:09 ` [PATCH v4 10/10] doc: add corrected commit date info Abhishek Kumar via GitGitGadget
2020-11-04 1:37 ` Jakub Narębski
2020-11-21 6:30 ` Abhishek Kumar
2020-11-04 23:37 ` [PATCH v4 00/10] [GSoC] Implement Corrected Commit Date Jakub Narębski
2020-11-22 5:31 ` Abhishek Kumar
2020-12-28 11:15 ` [PATCH v5 00/11] " Abhishek Kumar via GitGitGadget
2020-12-28 11:15 ` [PATCH v5 01/11] commit-graph: fix regression when computing Bloom filters Abhishek Kumar via GitGitGadget
2020-12-30 1:35 ` Derrick Stolee
2021-01-08 5:45 ` Abhishek Kumar
2021-01-05 9:45 ` SZEDER Gábor
2021-01-05 9:47 ` SZEDER Gábor
2021-01-08 5:51 ` Abhishek Kumar
2020-12-28 11:15 ` [PATCH v5 02/11] revision: parse parent in indegree_walk_step() Abhishek Kumar via GitGitGadget
2020-12-28 11:16 ` [PATCH v5 03/11] commit-graph: consolidate fill_commit_graph_info Abhishek Kumar via GitGitGadget
2020-12-28 11:16 ` [PATCH v5 04/11] t6600-test-reach: generalize *_three_modes Abhishek Kumar via GitGitGadget
2020-12-28 11:16 ` [PATCH v5 05/11] commit-graph: add a slab to store topological levels Abhishek Kumar via GitGitGadget
2020-12-28 11:16 ` [PATCH v5 06/11] commit-graph: return 64-bit generation number Abhishek Kumar via GitGitGadget
2020-12-28 11:16 ` [PATCH v5 07/11] commit-graph: implement corrected commit date Abhishek Kumar via GitGitGadget
2020-12-30 1:53 ` Derrick Stolee
2021-01-10 12:21 ` Abhishek Kumar
2020-12-28 11:16 ` [PATCH v5 08/11] commit-graph: implement generation data chunk Abhishek Kumar via GitGitGadget
2020-12-28 11:16 ` [PATCH v5 09/11] commit-graph: use generation v2 only if entire chain does Abhishek Kumar via GitGitGadget
2020-12-30 3:23 ` Derrick Stolee
2021-01-10 13:13 ` Abhishek Kumar
2021-01-11 12:43 ` Derrick Stolee
2020-12-28 11:16 ` [PATCH v5 10/11] commit-reach: use corrected commit dates in paint_down_to_common() Abhishek Kumar via GitGitGadget
2020-12-28 11:16 ` [PATCH v5 11/11] doc: add corrected commit date info Abhishek Kumar via GitGitGadget
2020-12-30 4:35 ` [PATCH v5 00/11] [GSoC] Implement Corrected Commit Date Derrick Stolee
2021-01-10 14:06 ` Abhishek Kumar
2021-01-16 18:11 ` [PATCH v6 " Abhishek Kumar via GitGitGadget
2021-01-16 18:11 ` [PATCH v6 01/11] commit-graph: fix regression when computing Bloom filters Abhishek Kumar via GitGitGadget
2021-01-16 18:11 ` [PATCH v6 02/11] revision: parse parent in indegree_walk_step() Abhishek Kumar via GitGitGadget
2021-01-16 18:11 ` [PATCH v6 03/11] commit-graph: consolidate fill_commit_graph_info Abhishek Kumar via GitGitGadget
2021-01-16 18:11 ` [PATCH v6 04/11] t6600-test-reach: generalize *_three_modes Abhishek Kumar via GitGitGadget
2021-01-16 18:11 ` [PATCH v6 05/11] commit-graph: add a slab to store topological levels Abhishek Kumar via GitGitGadget
2021-01-16 18:11 ` [PATCH v6 06/11] commit-graph: return 64-bit generation number Abhishek Kumar via GitGitGadget
2021-01-16 18:11 ` [PATCH v6 07/11] commit-graph: implement corrected commit date Abhishek Kumar via GitGitGadget
2021-01-16 18:11 ` [PATCH v6 08/11] commit-graph: implement generation data chunk Abhishek Kumar via GitGitGadget
2021-01-16 18:11 ` [PATCH v6 09/11] commit-graph: use generation v2 only if entire chain does Abhishek Kumar via GitGitGadget
2021-01-16 18:11 ` [PATCH v6 10/11] commit-reach: use corrected commit dates in paint_down_to_common() Abhishek Kumar via GitGitGadget
2021-01-16 18:11 ` [PATCH v6 11/11] doc: add corrected commit date info Abhishek Kumar via GitGitGadget
2021-01-27 0:04 ` SZEDER Gábor
2021-01-30 5:29 ` Abhishek Kumar
2021-01-31 1:45 ` Taylor Blau
2021-01-18 21:04 ` [PATCH v6 00/11] [GSoC] Implement Corrected Commit Date Derrick Stolee
2021-01-18 22:00 ` Taylor Blau
2021-01-23 12:11 ` Abhishek Kumar
2021-01-19 0:02 ` Junio C Hamano
2021-01-23 12:07 ` Abhishek Kumar
2021-02-01 6:58 ` [PATCH v7 " Abhishek Kumar via GitGitGadget
2021-02-01 6:58 ` [PATCH v7 01/11] commit-graph: fix regression when computing Bloom filters Abhishek Kumar via GitGitGadget
2021-02-01 6:58 ` [PATCH v7 02/11] revision: parse parent in indegree_walk_step() Abhishek Kumar via GitGitGadget
2021-02-01 6:58 ` [PATCH v7 03/11] commit-graph: consolidate fill_commit_graph_info Abhishek Kumar via GitGitGadget
2021-02-01 6:58 ` [PATCH v7 04/11] t6600-test-reach: generalize *_three_modes Abhishek Kumar via GitGitGadget
2021-02-01 6:58 ` [PATCH v7 05/11] commit-graph: add a slab to store topological levels Abhishek Kumar via GitGitGadget
2021-02-01 6:58 ` [PATCH v7 06/11] commit-graph: return 64-bit generation number Abhishek Kumar via GitGitGadget
2021-02-01 6:58 ` [PATCH v7 07/11] commit-graph: document generation number v2 Abhishek Kumar via GitGitGadget
2021-02-01 6:58 ` [PATCH v7 08/11] commit-graph: implement corrected commit date Abhishek Kumar via GitGitGadget
2021-02-01 6:58 ` [PATCH v7 09/11] commit-graph: implement generation data chunk Abhishek Kumar via GitGitGadget
2021-02-01 6:58 ` [PATCH v7 10/11] commit-graph: use generation v2 only if entire chain does Abhishek Kumar via GitGitGadget
2021-02-01 6:58 ` [PATCH v7 11/11] commit-reach: use corrected commit dates in paint_down_to_common() Abhishek Kumar via GitGitGadget
2021-02-01 13:14 ` [PATCH v7 00/11] [GSoC] Implement Corrected Commit Date Derrick Stolee
2021-02-01 18:26 ` Junio C Hamano
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