Re: [RFC PATCH 1/2] refs: make _advance() check struct repo, not flag

From: Junio C Hamano <gitster@pobox.com>
Date: Sep 16, 2021, 21:56 UTC
Message-ID: <xmqqilz0rxpm.fsf@gitster.g>
In-Reply-To: <20210916172609.1074157-1-jonathantanmy@google.com>

Jonathan Tan <jonathantanmy@google.com> writes:

Show 14 quoted lines

>> On Wed, Sep 15, 2021 at 12:41 AM Glen Choo <chooglen@google.com> wrote:
>> > In the current state of affairs, the files ref store and the packed ref
>> > store seem to behave as a single logical ref database. An example of
>> > this (that I care about in particular) is in refs/files-backend.c where
>> > the files backend validates oids using the_repository's odb.
>> > refs/packed-backend.c doesn't do any such validation, and presumably
>> > just relies on the correctness of refs/files-backend.c. I assume that
>> > this also explains why some functions in refs_be_packed are stubs.
>> 
>> The loose/packed storage is implemented in terms of files backend (the
>> public entry point) that defers to a packed backend in some cases. The
>> latter is implemented as a ref backend, but for no good reason.
>
> Yes, the packed backend doesn't need to be a ref backend.

Sorry, I do not follow. Do you mean we cannot have a version of Git that offers say a read-only access to the repository without any loose refs, with the default ref backend being the packed one?

Or do you mean that we can ignore such a hypothetical use case and could reimplement the files backend that can also understand the $GIT_DIR/packed-refs file directly without "deferring to another ref backend which is 'packed'"?