Re: [PATCH] commit-graph: retain commit slab when closing NULL commit_graph

Jeff King [off-list ref] writes:

On Wed, Jan 10, 2024 at 08:38:18AM -0800, Junio C Hamano wrote:

quoted

quoted

It should be easy-ish to iterate through the slab and look at the
commits that are mentioned in it. Though maybe not? Each commit knows
its slab-id, but I'm not sure if we have a master list of commits to go
the other way.

We have table of all in-core objects, don't we?

Oh, duh. Yes, we could iterate over obj_hash. I do think the "on demand"
version I showed later in the message is better, though, as the work
both scales with the number of affected commits (rather than the total
number of objects) and can be done lazily (so callers that are not buggy
pay no price at all).

Yeah, it is far more desirable than scanning obj_hash if we can do
the right thing on lazily.

So what if we just tried harder to look it up in the graph file (rather
than the slab) when we see COMMIT_NOT_FROM_GRAPH? And indeed, we even
have a function to do this already!

;-)

but:
...
I somehow sniped myself into thinking about it more, but that has only
reinforced my feeling that I'm afraid to touch it. ;)

Thanks for a nice summary.