[libvirt] Re: RFC: API additions for enhanced snapshot support

I was trying to model this after the virDomainSnapshot API, which has a notion of current snapshot, but I guess I don't fully understand what that API was implying by current domain snapshot. After looking more through the code, it looks like the idea was to support the notion of a branching hierarchy of snapshots: A -> B -> D \-> C -> E such that you can revert to the snapshot at point B, start the domain, and create snapshot D; then stop the domain, revert to the snapshot at point C, start the domain, and create snapshot E. Every time you start the domain, you know from which state it was started, so the current snapshot is the snapshot that would be the parent if you were to create a snapshot right now. As long as you can create a branching hierarchy (that is, after creating a snapshot, you can revert to its parent state, then make different changes, and create a new snapshot), then there really is a need to know which snapshot is current - listing all snapshots can show you the parent(s) of each snapshot in that list, but can't tell you which snapshot would be the parent of a new one created right now.