Re: [RFC PATCH 1/2] notes: support fetching notes from an external repo

[Vegard Nossum <vegard.nossum@oracle.com>]

On 8/30/22 16:17, Philip Oakley wrote:
> Sorry for late comment.

And sorry for late response! I didn't receive your email for some
reason, but I noticed it in the list archives.

> On 02/08/2022 08:54, Vegard Nossum wrote:
>> Notes are currently always fetched from the current repo. However, in
>> certain situations you may want to keep notes in a separate repository
>> altogether.
>>
>> In my specific case, I am using cgit to display notes for repositories
>> that are owned by others but hosted on a shared machine, so I cannot
>> really add the notes directly to their repositories.
>>
>> This patch makes it so that you can do:
>>
>>      const char *notes_repo_path = "path/to/notes.git";
>>      const char *notes_ref = "refs/notes/commits";
>>
>>      struct repository notes_repo;
>>      struct display_notes_opt notes_opt;
>>
>>      repo_init(&notes_repo, notes_repo_path, NULL);
>>      add_to_alternates_memory(notes_repo.objects->odb->path);
>>
>>      init_display_notes(&notes_opt);
>>      notes_opt.repo = &notes_repo;
>>      notes_opt.use_default_notes = 0;
>>
>>      string_list_append(&notes_opt.extra_notes_refs, notes_ref);
>>      load_display_notes(&notes_opt);
>>
>> ...and then notes will be taken from the given ref in the external
>> repository.
>>
>> Given that the functionality is not exposed through the command line,
>> there is currently no way to add regression tests for this.
>>
>> Cc: Johan Herland <johan@herland.net>
>> Cc: Jason A. Donenfeld <Jason@zx2c4.com>
>> Cc: Christian Hesse <mail@eworm.de>
>> Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
>> ---
>>   common-main.c |  2 ++
>>   notes.c       | 15 ++++++++++++---
>>   notes.h       |  3 +++
>>   refs.c        | 12 +++++++++---
>>   refs.h        |  2 ++
>>   5 files changed, 28 insertions(+), 6 deletions(-)
> 
> Where's the documentation? Without a clarity of purpose and usage then,
> for me, it doesn't fly.
> 
> I feel that underlying this there may something that's interesting, but
> without the 'SPIN' narrative (situation, problem, implication, and
> need-payoff) I'm not sure what it's trying to do from a broad user
> perspective. (Spin is just one approach to 'selling' the patches;-)
> 
> I'd agree that Notes are 'odd' in that they are out of sequence relative
> to commits, and may not be common between users viewing the same repo.
> I'd like to understand the issues in a wider context.
> --
> Philip

Perhaps the best way to showcase this is with a screenshot of what we're
trying to upstream:

https://vegard.github.io/cgit/6399f1fae4ec.png

Since git commits cannot be changed without rewriting history, git notes
is the mechanism by which we can attach new information to existing
commits. We're internally using these notes for cross-referencing
information like references to subsequent fixes, backports in other
trees, mailing list discussions, etc.

There is also a bit more information in my cgit patch submission from
today: https://lists.zx2c4.com/pipermail/cgit/2022-October/004764.html

My "problem" is that there are many moving parts to this, and the two
git.git patches sit at the top of the dependency chain:

1. these git patches
2. the cgit patches
3. the Linux kernel-specific notes generation scripts/logic
4. the Linux kernel notes themselves
5. displaying notes on kernel.org

Almost all of these steps involve different people with different
standards, different motivations, different priorities.

As I wrote earlier, I am trying to be a good citizen and upstream as
much of this as I can. But it's hard to justify what Junio asked for:
scrapping my current patches (which we are currently using...) in favour
of a complete rewrite with more functionality that does not buy us
anything from my point of view.

Does this clarify things?

I think my patches are a good cleanup regardless of motivation and
everything was fairly well documented in the changelogs, so I'm
surprised to see skepticism in the git community.


Vegard