Re: [PATCH v5 01/15] packfile: introduce a new `struct packfile_store`

> across two different structures:
> 
>   - `struct packed_git` contains the `next` pointer as well as the
>     `mru_head`, both of which serve to store the list of packfiles.
> 
>   - `struct object_database` contains several fields that relate to the
>     packfiles.
> 
> 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.
> 
> Introduce a new `struct packfile_store` which is about to become the
> single source of truth for managing packfiles. Right now this data
> structure doesn't yet contain anything, but in subsequent patches we
> will move all data structures that relate to packfiles and that are
> currently contained in `struct object_database` into this new home.
> 
> Note that this is only a first step: most importantly, we won't (yet)
> move the `struct packed_git::next` pointer around. This will happen in a
> subsequent patch series though so that `struct packed_git` will really
> only host information about the specific packfile it represents.
> 
> Further note that the new structure still sits at the wrong level at the
> end of this patch series: as mentioned, it should eventually sit at the
> level of the object database source, not at the object database level.
> But introducing the packfile store now already makes it way easier to
> eventually push down the now-selfcontained data structure by one level.
> 
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---

> @@ -91,6 +91,7 @@ struct odb_source {
>  };
>  
>  struct packed_git;
> +struct packfile_store;