Re: [PATCH 05/16] odb: move MRU list of packfiles into `struct packfile_store`

From: Karthik Nayak <karthik.188@gmail.com>
Date: Aug 20, 2025, 12:44 UTC
Message-ID: <CAOLa=ZRfWamERa_tKenhnxaGnH096p8hGYjauzfw1UzzjA_T_g@mail.gmail.com>
In-Reply-To: <20250819-b4-pks-packfiles-store-v1-5-1660842e125a@pks.im>

Patrick Steinhardt <ps@pks.im> writes:

Show 7 quoted lines

> The object database tracks the list of packfiles in most-recently-used
> order, which is mostly used to favor reading from packfiles that contain
> most of the objects that we're currently accessing. With the
> introduction of the `struct packfile_store` we have a better place to
> host this list though.
>
> Move the list accordingly.

[snip]

Show 17 quoted lines

> diff --git a/packfile.h b/packfile.h
> index 2f84d7d7e6..3022f3a19e 100644
> --- a/packfile.h
> +++ b/packfile.h
> @@ -65,6 +65,9 @@ struct packfile_store {
>  	 */
>  	struct packed_git *packs;
>
> +	/* A most-recently-used ordered version of the packs list. */
> +	struct list_head mru;
> +
>  	/*
>  	 * A map of packfile names to packed_git structs for tracking which
>  	 * packs have been loaded already.
>
> --
> 2.51.0.261.g7ce5a0a67e.dirty

Question: for my understanding, so we maintain a list of `packed_git`
packfiles in `packfile_store.packs` and then the same list is
available in a MRU form in `packfile_store.mru`?

I assume this is to optimize searches to use the mru form? Is there a reason to not pick the mru list?

Thanks