Re: [PATCH 02/17] object-store: rename `object_directory` to `odb_backend`

From: Derrick Stolee <stolee@gmail.com>
Date: May 7, 2025, 00:51 UTC
Message-ID: <e23e7e63-1d66-4a5c-8c4e-19b5078a75ad@gmail.com>
In-Reply-To: <20250506-pks-object-store-wo-the-repository-v1-2-c05b82e7b126@pks.im>

On 5/6/25 7:09 AM, Patrick Steinhardt wrote:

Show 12 quoted lines

> The `object_directory` structure is used as an access point for a single
> object directory like ".git/objects". While the structure isn't yet
> fully self-contained, the intent is for it to eventually contain all
> information required to access objects in one specific location.
> 
> While the name "object directory" is a good fit for now, this will
> change over time as we continue with the agenda to make pluggable object
> databases a thing. Eventually, objects may not be accessed via any kind
> of directory at all anymore, but they could instead be backed by any
> kind of durable storage mechanism. While it seems quite far-fetched for
> now, it is thinkable that eventually this might even be some form of a
> database, for example.

I agree that "object directory" is leaking some of the abstraction, and that we'd want to be able to have pluggable ODB backends.

Show 12 quoted lines

> As such, the current name of this structure will become worse over time
> as we evolve into the direction of pluggable ODBs. Immediate next steps
> will start to carve out proper self-contained object directories, which
> requires us to pass in these object directories as parameters. Based on
> our modern naming schema this means that those functions should then be
> named after their subsystem, which means that we would start to bake the
> current name into the codebase more and more.
> 
> Let's preempt this by renaming the structure to `odb_backend` now
> already. This name is agnostic of how exactly objects are stored and
> allows us to easily introduce e.g. a `files_odb_backend` and other
> specific implementations over time.

But here's where I'll get a little nitpicky and say that these are "odb"s not "odb_backend"s.

* odb: a single object database. A repo can have multiple, currently
   only one that is read/write and multiple read-only alternates.

* odb backend: an _implementation_ of an object database. This would
   be the structure that containts a vtable of implementation methods.
   Each individual 'odb' would point to a single backend describing
   how to access the data in it.

Does that make sense? If we are going through the effort of renaming things, I think it's worth being a little more future-proof here.

Thanks, -Stolee