Re: [PATCH 2/2] commit-graph: propagate topo_levels slab to all chain layers

[Taylor Blau <ttaylorr@openai.com>]

On Tue, Jul 07, 2026 at 04:57:13PM +0200, Kristofer Karlsson wrote:
> (b) Move topo_levels to struct object_database. Since
> fill_commit_graph_info() can already reach the odb via
> g->odb_source->odb, no signature changes are needed.
> The write side becomes a single assignment:
>
>     ctx.r->objects->topo_levels = &topo_levels;
>
> and cleanup becomes:
>
>     ctx.r->objects->topo_levels = NULL;
>
> No chain walk needed and the diff is fairly small.
> I am not sure about the semantics of it though -- should the odb
> have a reference to topo_levels?

This seems to be the most promising approach, though I'd be curious what
Patrick's thoughts are. The commit-slab API is really a property of the
object database, but we treat these as a global as I do not recall them
yet being touched by the ODB refactoring effort.

> [...]
>
> I have a prototype of (b) that compiles and passes the test suite.
>
> For now though, I think the minimal bugfix is the right thing to do.

Agreed.

Thanks,
Taylor