From: Jakub Narebski <jnareb@gmail.com>
To: Derrick Stolee <stolee@gmail.com>
Cc: "Junio C Hamano" <gitster@pobox.com>,
"Derrick Stolee" <dstolee@microsoft.com>,
git@vger.kernel.org, "Jeff King" <peff@peff.net>,
"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
"Stefan Beller" <sbeller@google.com>,
"Lars Schneider" <larsxschneider@gmail.com>,
"Brandon Williams" <bmwill@google.com>
Subject: Re: [PATCH v2 07/10] commit-graph.txt: update future work
Date: Fri, 13 Apr 2018 11:53:21 +0200 [thread overview]
Message-ID: <86a7u7mnzi.fsf@gmail.com> (raw)
In-Reply-To: <f557058d-7836-4b66-8fda-7fdfc7484219@gmail.com> (Derrick Stolee's message of "Thu, 12 Apr 2018 07:35:36 -0400")
Derrick Stolee <stolee@gmail.com> writes:
> On 4/12/2018 5:12 AM, Junio C Hamano wrote:
>> Derrick Stolee <dstolee@microsoft.com> writes:
>>
>>> +Here is a diagram to visualize the shape of the full commit graph, and
>>> +how different generation numbers relate:
>>> +
>>> + +-----------------------------------------+
>>> + | GENERATION_NUMBER_INFINITY = 0xFFFFFFFF |
>>> + +-----------------------------------------+
>>> + | | ^
>>> + | | |
>>> + | +------+
>>> + | [gen(A) = gen(B)]
>>> + V
>>> + +-------------------------------------+
>>> + | 0 < commit->generation < 0x40000000 |
>>> + +-------------------------------------+
>>> + | | ^
>>> + | | |
>>> + | +------+
>>> + | [gen(A) > gen(B)]
>>> + V
>>> + +-------------------------------------+
>>> + | GENERATION_NUMBER_ZERO = 0 |
>>> + +-------------------------------------+
>>> + | ^
>>> + | |
>>> + +------+
>>> + [gen(A) = gen(B)]
>>
>> It may be just me but all I can read out of the above is that
It's not just you.
>> commit->generation may store 0xFFFFFFFF, a value between 0 and
>> 0x40000000, or 0. I cannot quite tell what the notation [gen(A)
>> <cmp> gen(B)] is trying to say. I am guessing "Two generation
>> numbers within the 'valid' range can be compared" is what the second
>> one is trying to say, but it is much less interesting to know that
>> two infinities compare equal than how generation numbers from
>> different classes compare, which cannot be depicted in the above
>> notation, I am afraid. For example, don't we want to say that a
>> commit with INF can never be reached by a commit with a valid
>> generation number, or something like that?
>
> My intention with the arrows was to demonstrate where parent
> relationships can go, and the generation-number relation between a
> commit A with parent B. Clearly, this diagram is less than helpful.
Perhaps the following table would make the information clearer (perhaps
in addition to the above graph, but without "gen(A) {cmp} gen(B)"
arrows).
I assume that it is possible to have both GENERATION_NUMBER_ZERO and non
zero generation numbers in one repo, perhaps via alternates. I also
assume that A != B, and that generation numbers (both set, and 0s) are
transitivelu closed under reachability.
gen(A) \ commit B -> | gen(B)
\-----\ |
commit A \ | 0xFFFFFFFF | larger | smaller | 0x00000000
----------------\--------+------------+----------+---------+------------
0xFFFFFFFF | = > > >
0 < larger < 0x40000000 | < N = n > >
0 < smaller < 0x40000000 | < N < N = n >
0x00000000 | < N < N < N =
The "<", "=", ">" denotes result of comparison between gen(A) and gen(B).
Generation numbers create a negative-cut filter: "N" and "n" denote
situation where we know from gen(A) and gen(B) that B is not reachable
from A.
As can be seen if we use gen(A) < gen(B) as cutoff, we don't need to
treat "infinity" and "zero" in a special way.
Best,
--
Jakub Narębski
next prev parent reply other threads:[~2018-04-13 9:53 UTC|newest]
Thread overview: 162+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-03 16:51 [PATCH 0/6] Compute and consume generation numbers Derrick Stolee
2018-04-03 16:51 ` [PATCH 1/6] object.c: parse commit in graph first Derrick Stolee
2018-04-03 18:21 ` Jonathan Tan
2018-04-03 18:28 ` Jeff King
2018-04-03 18:32 ` Derrick Stolee
2018-04-03 16:51 ` [PATCH 2/6] commit: add generation number to struct commmit Derrick Stolee
2018-04-03 18:05 ` Brandon Williams
2018-04-03 18:28 ` Jeff King
2018-04-03 18:31 ` Derrick Stolee
2018-04-03 18:32 ` Brandon Williams
2018-04-03 18:44 ` Stefan Beller
2018-04-03 23:17 ` Ramsay Jones
2018-04-03 23:19 ` Jeff King
2018-04-03 18:24 ` Jonathan Tan
2018-04-03 16:51 ` [PATCH 3/6] commit-graph: compute generation numbers Derrick Stolee
2018-04-03 18:30 ` Jonathan Tan
2018-04-03 18:49 ` Stefan Beller
2018-04-03 16:51 ` [PATCH 4/6] commit: use generations in paint_down_to_common() Derrick Stolee
2018-04-03 18:31 ` Stefan Beller
2018-04-03 18:31 ` Jonathan Tan
2018-04-03 16:51 ` [PATCH 5/6] commit.c: use generation to halt paint walk Derrick Stolee
2018-04-03 19:01 ` Jonathan Tan
2018-04-03 16:51 ` [PATCH 6/6] commit-graph.txt: update future work Derrick Stolee
2018-04-03 19:04 ` Jonathan Tan
2018-04-03 16:56 ` [PATCH 0/6] Compute and consume generation numbers Derrick Stolee
2018-04-03 18:03 ` Brandon Williams
2018-04-03 18:29 ` Derrick Stolee
2018-04-03 18:47 ` Jeff King
2018-04-03 19:05 ` Jeff King
2018-04-04 15:45 ` [PATCH 7/6] ref-filter: use generation number for --contains Derrick Stolee
2018-04-04 15:45 ` [PATCH 8/6] commit: use generation numbers for in_merge_bases() Derrick Stolee
2018-04-04 15:48 ` Derrick Stolee
2018-04-04 17:01 ` Brandon Williams
2018-04-04 18:24 ` Jeff King
2018-04-04 18:53 ` Derrick Stolee
2018-04-04 18:59 ` Jeff King
2018-04-04 18:22 ` [PATCH 7/6] ref-filter: use generation number for --contains Jeff King
2018-04-04 19:06 ` Derrick Stolee
2018-04-04 19:16 ` Jeff King
2018-04-04 19:22 ` Derrick Stolee
2018-04-04 19:42 ` Jeff King
2018-04-04 19:45 ` Derrick Stolee
2018-04-04 19:46 ` Jeff King
2018-04-07 17:09 ` [PATCH 0/6] Compute and consume generation numbers Jakub Narebski
2018-04-07 16:55 ` Jakub Narebski
2018-04-08 1:06 ` Derrick Stolee
2018-04-11 19:32 ` Jakub Narebski
2018-04-11 19:58 ` Derrick Stolee
2018-04-14 16:52 ` Jakub Narebski
2018-04-21 20:44 ` Jakub Narebski
2018-04-23 13:54 ` Derrick Stolee
2018-04-09 16:41 ` [PATCH v2 00/10] " Derrick Stolee
2018-04-09 16:41 ` [PATCH v2 01/10] object.c: parse commit in graph first Derrick Stolee
2018-04-09 16:41 ` [PATCH v2 02/10] merge: check config before loading commits Derrick Stolee
2018-04-11 2:12 ` Junio C Hamano
2018-04-11 12:49 ` Derrick Stolee
2018-04-09 16:42 ` [PATCH v2 03/10] commit: add generation number to struct commmit Derrick Stolee
2018-04-09 17:59 ` Stefan Beller
2018-04-11 2:31 ` Junio C Hamano
2018-04-11 12:57 ` Derrick Stolee
2018-04-11 23:28 ` Junio C Hamano
2018-04-09 16:42 ` [PATCH v2 04/10] commit-graph: compute generation numbers Derrick Stolee
2018-04-11 2:51 ` Junio C Hamano
2018-04-11 13:02 ` Derrick Stolee
2018-04-11 18:49 ` Stefan Beller
2018-04-11 19:26 ` Eric Sunshine
2018-04-09 16:42 ` [PATCH v2 05/10] commit: use generations in paint_down_to_common() Derrick Stolee
2018-04-09 16:42 ` [PATCH v2 06/10] commit.c: use generation to halt paint walk Derrick Stolee
2018-04-11 3:02 ` Junio C Hamano
2018-04-11 13:24 ` Derrick Stolee
2018-04-09 16:42 ` [PATCH v2 07/10] commit-graph.txt: update future work Derrick Stolee
2018-04-12 9:12 ` Junio C Hamano
2018-04-12 11:35 ` Derrick Stolee
2018-04-13 9:53 ` Jakub Narebski [this message]
2018-04-09 16:42 ` [PATCH v2 08/10] ref-filter: use generation number for --contains Derrick Stolee
2018-04-09 16:42 ` [PATCH v2 09/10] commit: use generation numbers for in_merge_bases() Derrick Stolee
2018-04-09 16:42 ` [PATCH v2 10/10] commit: add short-circuit to paint_down_to_common() Derrick Stolee
2018-04-17 17:00 ` [PATCH v3 0/9] Compute and consume generation numbers Derrick Stolee
2018-04-17 17:00 ` [PATCH v3 1/9] commit: add generation number to struct commmit Derrick Stolee
2018-04-17 17:00 ` [PATCH v3 2/9] commit-graph: compute generation numbers Derrick Stolee
2018-04-17 17:00 ` [PATCH v3 3/9] commit: use generations in paint_down_to_common() Derrick Stolee
2018-04-18 14:31 ` Jakub Narebski
2018-04-18 14:46 ` Derrick Stolee
2018-04-17 17:00 ` [PATCH v3 4/9] commit-graph.txt: update design document Derrick Stolee
2018-04-18 19:47 ` Jakub Narebski
2018-04-17 17:00 ` [PATCH v3 5/9] ref-filter: use generation number for --contains Derrick Stolee
2018-04-18 21:02 ` Jakub Narebski
2018-04-23 14:22 ` Derrick Stolee
2018-04-24 18:56 ` Jakub Narebski
2018-04-25 14:11 ` Derrick Stolee
2018-04-17 17:00 ` [PATCH v3 6/9] commit: use generation numbers for in_merge_bases() Derrick Stolee
2018-04-18 22:15 ` Jakub Narebski
2018-04-23 14:31 ` Derrick Stolee
2018-04-17 17:00 ` [PATCH v3 7/9] commit: add short-circuit to paint_down_to_common() Derrick Stolee
2018-04-18 23:19 ` Jakub Narebski
2018-04-23 14:40 ` Derrick Stolee
2018-04-23 21:38 ` Jakub Narebski
2018-04-24 12:31 ` Derrick Stolee
2018-04-19 8:32 ` Jakub Narebski
2018-04-17 17:00 ` [PATCH v3 8/9] commit-graph: always load commit-graph information Derrick Stolee
2018-04-17 17:50 ` Derrick Stolee
2018-04-19 0:02 ` Jakub Narebski
2018-04-23 14:49 ` Derrick Stolee
2018-04-17 17:00 ` [PATCH v3 9/9] merge: check config before loading commits Derrick Stolee
2018-04-19 0:04 ` [PATCH v3 0/9] Compute and consume generation numbers Jakub Narebski
2018-04-23 14:54 ` Derrick Stolee
2018-04-25 14:37 ` [PATCH v4 00/10] " Derrick Stolee
2018-04-25 14:37 ` [PATCH v4 01/10] ref-filter: fix outdated comment on in_commit_list Derrick Stolee
2018-04-28 17:54 ` Jakub Narebski
2018-04-25 14:37 ` [PATCH v4 02/10] commit: add generation number to struct commmit Derrick Stolee
2018-04-28 22:35 ` Jakub Narebski
2018-04-30 12:05 ` Derrick Stolee
2018-04-25 14:37 ` [PATCH v4 03/10] commit-graph: compute generation numbers Derrick Stolee
2018-04-26 2:35 ` Junio C Hamano
2018-04-26 12:58 ` Derrick Stolee
2018-04-26 13:49 ` Derrick Stolee
2018-04-29 9:08 ` Jakub Narebski
2018-05-01 12:10 ` Derrick Stolee
2018-05-02 16:15 ` Jakub Narebski
2018-04-25 14:37 ` [PATCH v4 04/10] commit: use generations in paint_down_to_common() Derrick Stolee
2018-04-26 3:22 ` Junio C Hamano
2018-04-26 9:02 ` Jakub Narebski
2018-04-28 14:38 ` Jakub Narebski
2018-04-29 15:40 ` Jakub Narebski
2018-04-25 14:37 ` [PATCH v4 05/10] commit-graph: always load commit-graph information Derrick Stolee
2018-04-29 22:14 ` Jakub Narebski
2018-05-01 12:19 ` Derrick Stolee
2018-04-29 22:18 ` Jakub Narebski
2018-04-25 14:37 ` [PATCH v4 06/10] ref-filter: use generation number for --contains Derrick Stolee
2018-04-30 16:34 ` Jakub Narebski
2018-04-25 14:37 ` [PATCH v4 07/10] commit: use generation numbers for in_merge_bases() Derrick Stolee
2018-04-30 17:05 ` Jakub Narebski
2018-04-25 14:38 ` [PATCH v4 08/10] commit: add short-circuit to paint_down_to_common() Derrick Stolee
2018-04-30 22:19 ` Jakub Narebski
2018-05-01 11:47 ` Derrick Stolee
2018-05-02 13:05 ` Jakub Narebski
2018-05-02 13:42 ` Derrick Stolee
2018-04-25 14:38 ` [PATCH v4 09/10] merge: check config before loading commits Derrick Stolee
2018-04-30 22:54 ` Jakub Narebski
2018-05-01 11:52 ` Derrick Stolee
2018-05-02 11:41 ` Jakub Narebski
2018-04-25 14:38 ` [PATCH v4 10/10] commit-graph.txt: update design document Derrick Stolee
2018-04-30 23:32 ` Jakub Narebski
2018-05-01 12:00 ` Derrick Stolee
2018-05-02 7:57 ` Jakub Narebski
2018-04-25 14:40 ` [PATCH v4 00/10] Compute and consume generation numbers Derrick Stolee
2018-04-28 17:28 ` Jakub Narebski
2018-05-01 12:47 ` [PATCH v5 00/11] " Derrick Stolee
2018-05-01 12:47 ` [PATCH v5 01/11] ref-filter: fix outdated comment on in_commit_list Derrick Stolee
2018-05-01 12:47 ` [PATCH v5 02/11] commit: add generation number to struct commmit Derrick Stolee
2018-05-01 12:47 ` [PATCH v5 03/11] commit-graph: compute generation numbers Derrick Stolee
2018-05-01 12:47 ` [PATCH v5 04/11] commit: use generations in paint_down_to_common() Derrick Stolee
2018-05-01 12:47 ` [PATCH v5 05/11] commit-graph: always load commit-graph information Derrick Stolee
2018-05-01 12:47 ` [PATCH v5 06/11] ref-filter: use generation number for --contains Derrick Stolee
2018-05-01 12:47 ` [PATCH v5 07/11] commit: use generation numbers for in_merge_bases() Derrick Stolee
2018-05-01 12:47 ` [PATCH v5 08/11] commit: add short-circuit to paint_down_to_common() Derrick Stolee
2018-05-01 12:47 ` [PATCH v5 09/11] commit: use generation number in remove_redundant() Derrick Stolee
2018-05-01 15:37 ` Derrick Stolee
2018-05-03 18:45 ` Jakub Narebski
2018-05-01 12:47 ` [PATCH v5 10/11] merge: check config before loading commits Derrick Stolee
2018-05-01 12:47 ` [PATCH v5 11/11] commit-graph.txt: update design document Derrick Stolee
2018-05-03 11:18 ` [PATCH v5 00/11] Compute and consume generation numbers Jakub Narebski
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