Fixes#664
This PR implements the idea described in
https://github.com/agent-substrate/substrate/issues/664#issuecomment-5499311489
It does more than Garbage Collection of snapshots, because we also got
rid of the Snapshot resource (from the DB/API).
Now, an external snapshot is owned by a single resource:
- An Actor owns the snapshot it writes at suspend
- A tag owns a copy taken at tag creation,
- An actor cloned from a tag borrows the tag's snapshot until its own
first suspend.
Garbage Collection: whoever created/owns the snapshot is the only one
who ever deletes them:
i.e., if an actor is deleted and it owns a snapshot. The underlying
snapshot is deleted with the actor.
this PR:
- Drops table actor_snapshots
- Keeps table actor_snapshot_tags
- Adds an object copy at tag creation, and an owned versus borrowed
distinction on the Actor
- Adds synchronous external snapshot deletion at actor suspend, at actor
delete, and at tag delete
> It's a good idea to open an issue first for discussion.
- [x] Tests pass
- [x] Appropriate changes to documentation are included in the PR
Luiz Oliveira
9b333c6fce