Description

Before, the state we kept per hash was a bit convoluted. The entry point was a Slot, which contained a tokio mutex to cover the async loading of an entry state from the metadata db. Then inside that, there was the actual entry state, wrapped in an option to cover the case that we don't have anything about the hash.

This was working, but it was an arc in an arc in an arc, and also led to bugs in the case of trying to export a blob that doesn't exist.

Now all these states are flattened into a single enum, and we can easily define what should happen when we e.g. do an export of an entry that does not exist - return an appropriate io error.

Breaking Changes

None

Notes & open questions

Note: you could remove the Initial and Loading state by using a tokio::sync::OnceCell. But that is a true sync primitive, and we want to use an AtomicRefCell, and also using a OnceLock would come with its own sync primitive (a semaphore) just for init, and then we have our own one for the non-load state changes. I don't think it is that bad...

Change checklist

• Self-review.
• Documentation updates following thestyle guide, if relevant.
• Tests if relevant.
• All breaking changes documented.