Re: [PATCH 00/16] packfile: carve out a new packfile store

From: Junio C Hamano <gitster@pobox.com>
Date: Aug 19, 2025, 17:13 UTC
Message-ID: <xmqqldnfdyku.fsf@gitster.g>
In-Reply-To: <20250819-b4-pks-packfiles-store-v1-0-1660842e125a@pks.im>

Patrick Steinhardt <ps@pks.im> writes:

Show 9 quoted lines

> So we don't really have a central data structure that tracks our
> packfiles, and consequently responsibilities aren't always clear cut.
> A consequence for the upcoming pluggable object databases is that this
> makes it very hard to move management of packfiles from the object
> database level down into the object database source.
>
> This patch series introduces a new `struct packfile_store`, which is
> about to become the single source of truth for managing packfiles, and
> carves out the packfile store subsystem.

Nice.

Show 10 quoted lines

> This is the first step to make packfiles work with pluggable object
> databases. Next steps will be to:
>
>   - Move the `struct packed_git::next` and `struct packed::mru_head`
>     pointers into the packfile store so that `struct packed_git` only
>     tracks a single packfile.
>
>   - Push the `struct packfile_store` down one level so that it's not
>     hosted by the object database anymore, but instead by the object
>     database source.

Makes sense. Each packfile belong to a single $GIT_DIR/objects/ and together with loose object files in there form a set of objects in a single object store. When alternates are in effect, I think we still out of convenience link these packfiles taken from multiple places into a single list, which a series like this one may have to untangle.

Thanks.