Re: Exec upload-pack on remote with what parameters to get direntries.

From: Bruno Albuquerque <bga@google.com>
Date: Aug 31, 2021, 15:35 UTC
Message-ID: <CAPeR6H7_V+ypzyN39e27+NCRqG-nA17sgq=qtefzFF3Dg50bnA@mail.gmail.com>
In-Reply-To: <87sfypwuwx.fsf@evledraar.gmail.com>

On Tue, Aug 31, 2021 at 7:28 AM Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:

[Replying again as I used HTML mail by mistake. Sorry.]

Show 5 quoted lines

> I.e. someone setting up a git server probably isn't going to suspect
> that one day their server load is going to go up by some big % because
> some developer somewhere is using a local IDE whose every file click on
> a directory is a new remote server request (i.e. the case where
> "object-info"'s functionality is expanded like this).

Do you mean by someone directly sending object-info requests? I am working on wiring object-info to some of the existing tools (cat-file/ls-tree) so this is the general idea about how I see this being used:

- object-info would be used when it made sense but only if the actual
object being queried is not already fetched locally. If you think of a
virtual filesystem that is backed by, say, partial clones, this mostly
means retrieving metadata information to be displayed to the user.
- Still in the context of a virtual filesystem, metadata is usually
cached locally independently of Git itself, further reducing the need
to call object-info (but, of course, this is a brittle assumption as
it is not controlled by Git).
- git cat-file, for example, would be changed to support real batching
and then send a single request instead of the multiple requests it
does currently.

My point is that I understand where your worry is coming from and as long as someone can send arbitrary requests then it is possible your scenario of a heavier server load can potentially happen but as far as the expected canonical usage, I do not think this would be a problem and, in fact, under some usage patterns it might make things better (mostly due to batching support in object-info).

With all that being said, I don' t think making it optional would be an issue so I have no strong feelings about this. I am fine with whatever is agreed to be the best approach.

> I found myself wondering this when reading serve.c the other day,
> i.e. why we have "always_advertise" for object-info, but it seemed
> innocuous enough given how it's described in a2ba162cda2 (object-info:
> support for retrieving object info, 2021-04-20).

For what it is worth, The same change is now being reviewed in JGit and there the feature is conditionally enabled. But that was a side-effect of needing to deploy it to multiple servers before making the feature available to clients.

--

Bruno Albuquerque | Software Engineer | bga@google.com | +1 650-395-8242