Re: [RFC/WIP PATCH] object store classification

From: Junio C Hamano <gitster@pobox.com>
Date: Jul 11, 2017, 20:27 UTC
Message-ID: <xmqq4lui3ei9.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <CAGZ79kaCXLtauL5UNT-8gCpzs5A+LU6Ed41+_LdBO7zDyW1Dyg@mail.gmail.com>

Stefan Beller <sbeller@google.com> writes:

Show 6 quoted lines

>> At the implementation level, it should have a
>> hashtable (lazily populated) for all the objects in a single
>> $GIT_OBJECT_DIRECTORY, grafts/replace info, and a set of pointers to
>> other object-store instances that are its alternate object stores.
>
> So one repository has one or more object stores?

One repository foo/.git/ has one foo/.git/objects/ directory, so it has its own single object store. That object store may refer to another object store by having foo/.git/objects/info/alternates.

Similarly, foo/.git/objects/info/grafts and foo/.git/refs/replace/ would belong to the single object store repository foo/.git/ has.

Show 10 quoted lines

> I would expect that most of the time the question from above
> "give me info on the object I can refer to with this object name"
> is asked with the additional information: "and I know it is in this
> repository", so we rather want to have
>
>   lookup_object(struct *repo, char *name);
>
> instead of
>
>   lookup_object(struct *object_store, char *name);

Absolutely. That is why repository has its own single object_store, which may refer to other object_stores.