git@vger.kernel.org list mirror (unofficial, one of many)
 help / color / mirror / code / Atom feed
From: Derrick Stolee <stolee@gmail.com>
To: Jakub Narebski <jnareb@gmail.com>
Cc: "Mike Hommey" <mh@glandium.org>,
	"SZEDER Gábor" <szeder.dev@gmail.com>,
	git@vger.kernel.org
Subject: Re: Revision walking, commit dates, slop
Date: Mon, 20 May 2019 21:20:45 -0400	[thread overview]
Message-ID: <88662e18-db51-cb48-3307-0ea2a91c4ebe@gmail.com> (raw)
In-Reply-To: <864l5opuz1.fsf@gmail.com>

On 5/20/2019 7:27 PM, Jakub Narebski wrote:
> Jakub Narebski <jnareb@gmail.com> writes:
>> Derrick Stolee <stolee@gmail.com> writes:
>>> On 5/20/2019 7:02 AM, Jakub Narebski wrote:
>>>>
>>>> Are there any blockers that prevent the switch to this
>>>> "generation number v2"?
> [...]
> 
>>>                      Using the generation number column for the corrected
>>> commit-date offsets (assuming we also guarantee the offset is strictly
>>> increasing from parent to child), these new values will be backwards-
>>> compatible _except_ for 'git commit-graph verify'.
>>
>> O.K., so the "generation number v2 (legacy)" would be incremental and
>> backward-compatibile in use (though not in generation and validation).
>>
>> Do I understand it correctly how it is calculated:
>>
>>   corrected_date(C) = max(committer_date(C),
>>                           max_{P ∈ parents(C)}(corrected_date(P)) + 1)
> 
> This should probably read
> 
>     offset_date(P) = committer_date(P) + gen_v2(P)
>     corrected_date(C) = max(committer_date(C),
>                             max_{P ∈ parents(C)}(offset_date(P)) + 1)  

The final definition needs two conditions on the offset of a commit C for
every parent P:

 1. committer_date(C) + offset(C) > committer_date(P) + offset(P)
 2. offset(C) > offset(P)

Condition (1) will give us the performance benefits related to the
committer-date heuristic. Condition (2) will give us backwards-compatibility
with generation numbers.

Thanks,
-Stolee

  reply	other threads:[~2019-05-21  1:20 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-18  0:54 Mike Hommey
2019-05-18  1:50 ` SZEDER Gábor
2019-05-18  3:58   ` Mike Hommey
2019-05-18  4:17     ` Mike Hommey
2019-05-18 12:01       ` SZEDER Gábor
2019-05-19 22:28         ` Jakub Narebski
2019-05-20  1:33       ` Derrick Stolee
2019-05-20 11:02         ` Jakub Narebski
2019-05-20 11:20           ` Derrick Stolee
2019-05-20 13:42             ` Jakub Narebski
2019-05-20 23:27               ` Jakub Narebski
2019-05-21  1:20                 ` Derrick Stolee [this message]
2019-05-22 18:29                   ` Jakub Narebski
2019-05-22 19:06                     ` Derrick Stolee
2019-05-23 21:04                       ` Jakub Narebski
2019-06-25  7:51               ` Jakub Narebski
2019-06-25 10:54                 ` Derrick Stolee
2019-09-18  8:43                   ` [RFC/PATCH] commit-graph: generation v5 (backward compatible date ceiling) Jakub Narebski
2019-09-18 12:26                     ` Derrick Stolee
2019-05-21 13:14         ` [PATCH] revision: use generation for A..B --topo-order queries Derrick Stolee
2019-05-21 13:59           ` [PATCH 2/2] revision: keep topo-walk free of unintersting commits Derrick Stolee
2019-05-22  2:19             ` Mike Hommey
2019-05-21  2:00   ` Revision walking, commit dates, slop Jonathan Nieder

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

  List information: http://vger.kernel.org/majordomo-info.html

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=88662e18-db51-cb48-3307-0ea2a91c4ebe@gmail.com \
    --to=stolee@gmail.com \
    --cc=git@vger.kernel.org \
    --cc=jnareb@gmail.com \
    --cc=mh@glandium.org \
    --cc=szeder.dev@gmail.com \
    --subject='Re: Revision walking, commit dates, slop' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Code repositories for project(s) associated with this inbox:

	https://80x24.org/mirrors/git.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).