Re: [PATCH] Add ideas for GSoC 2024

[Christian Couder <christian.couder@gmail.com>]

On Mon, Feb 5, 2024 at 9:39 AM Patrick Steinhardt <ps@pks.im> wrote:
>
> Add project ideas for the GSoC 2024.
> ---
>
> I came up with four different topics:
>
>   - The reftable unit test refactorings. This topic can also be squashed
>     into the preexisting unit test topics, I wouldn't mind. In that case
>     I'd be happy to be a possible mentor, too.
>
>   - Ref consistency checks for git-fsck(1). This should be rather
>     straight forward and make for an interesting topic.
>
>   - Making git-bisect(1)'s state more self-contained as recently
>     discussed. This topic is easy to implement, but the backwards
>     compatibility issues might require a lot of attention.
>
>   - Implementing support for reftables in the "dumb" HTTP protocol. It's
>     quite niche given that the dumb protocol isn't really used much
>     nowadays anymore. But it could make for an interesting project
>     regardless.
>
> It's hard to estimate for me whether their scope is either too small or
> too big. So please feel free to chime in and share your concerns if you
> think that any of those proposals don't make much sense in your opinion.

Thanks a lot for these ideas! I have applied your patch and pushed it.

I have a few concerns though, see below.

>  SoC-2024-Ideas.md | 129 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 129 insertions(+)
>
> diff --git a/SoC-2024-Ideas.md b/SoC-2024-Ideas.md
> index 3efbcaf..286aea0 100644
> --- a/SoC-2024-Ideas.md
> +++ b/SoC-2024-Ideas.md
> @@ -39,3 +39,132 @@ Languages: C, shell(bash)
>  Possible mentors:
>  * Christian Couder < <christian.couder@gmail.com> >
>
> +### Convert reftable unit tests to use the unit testing framework
> +
> +The "reftable" unit tests in "t0032-reftable-unittest.sh"
> +predate the unit testing framework that was recently
> +introduced into Git. These tests should be converted to use
> +the new framework.
> +
> +See:
> +
> +  - this discussion <https://lore.kernel.org/git/cover.1692297001.git.steadmon@google.com/>
> +
> +Expected Project Size: 175 hours or 350 hours
> +
> +Difficulty: Low

"Difficulty: Low" might not be very accurate from the point of view of
contributors. I think it's always quite difficult to contribute
something significant to Git, and sometimes more than we expected.

> +Languages: C, shell(bash)
> +
> +Possible mentors:
> +* Patrick Steinhardt < <ps@pks.im> >
> +* Karthik Nayak < <karthik.188@gmail.com> >
> +
> +### Implement consistency checks for refs
> +
> +The git-fsck(1) command is used to check various data
> +structures for consistency. Notably missing though are
> +consistency checks for the refdb. While git-fsck(1)
> +implicitly checks some of the properties of the refdb
> +because it uses its refs for a connectivity check, these
> +checks aren't sufficient to properly ensure that all refs
> +are properly consistent.
> +
> +The goal of this project would be to introduce consistency
> +checks that can be implemented by the ref backend. Initially
> +these checks may only apply to the "files" backend. With the
> +ongoing efforts to upstream a new "reftable" backend the
> +effort may be extended.
> +
> +See:
> +
> +  - https://lore.kernel.org/git/6cfee0e4-3285-4f18-91ff-d097da9de737@rd10.de/
> +  - https://lore.kernel.org/git/cover.1706601199.git.ps@pks.im/
> +
> +Expected Project Size: 175 hours or 350 hours
> +
> +Difficulty: Medium
> +
> +Languages: C, shell(bash)
> +
> +Possible mentors:
> +* Patrick Steinhardt < <ps@pks.im> >
> +* Karthik Nayak < <karthik.188@gmail.com> >
> +
> +### Refactor git-bisect(1) to make its state self-contained
> +
> +The git-bisect(1) command is used to find a commit in a
> +range of commits that introduced a specific bug. Starting a
> +bisection run creates a set of state files into the Git
> +repository which record various different parameters like
> +".git/BISECT_START". These files look almost like refs
> +due to their names being all-uppercase. This has led to
> +confusion with the new "reftable" backend because it wasn't
> +quite clear whether those files are in fact refs or not.
> +
> +As it turns out they are not refs and should never be
> +treated like one. Overall, it has been concluded that the
> +way those files are currently stored is not ideal. Instead
> +of having a proliferation of files in the Git directory, it
> +was discussed whether the bisect state should be moved into
> +its own "bisect-state" subdirectory. This would make it more
> +self-contained and thereby avoid future confusion. It is
> +also aligned with the sequencer state used by rebases, which
> +is neatly contained in the "rebase-apply" and "rebase-merge"
> +directories.
> +
> +The goal of this project would be to realize this change.
> +While rearchitecting the layout should be comparatively easy
> +to do, the harder part will be to hash out how to handle
> +backwards compatibility.
> +
> +See:
> +
> +  - https://lore.kernel.org/git/Za-gF_Hp_lXViGWw@tanuki/

From reading the discussion it looks like everyone is Ok with doing
this. I really hope that we are not missing something that might make
us decide early not to do this though.

> +Expected Project Size: 175 hours or 350 hours
> +
> +Difficulty: Medium
> +
> +Languages: C, shell(bash)
> +
> +Possible mentors:
> +* Patrick Steinhardt < <ps@pks.im> >
> +* Karthik Nayak < <karthik.188@gmail.com> >