Switch from Proposer to Slots

[bkchr]

Instead of using Proposer as interface for building the blocks in the collator, we probably want to switch over to Slots as the interface. At the point when we want to support custom authoring, using Slots is easier as Babe and Aura already implemented using this trait.

We would need to change the trait in Substrate to return the Proposal, because we need this in the collator.

[JoshOrndorff]

You mean switching to SlotWorker right? Or maybe SimpleSlotWorker?

Would this change eliminate the possibility of using PoW for collating? Is that a compromise we really want?

[bkchr]

You mean switching to SlotWorker right? Or maybe SimpleSlotWorker?

SlotWorker.

Would this change eliminate the possibility of using PoW for collating? Is that a compromise we really want?

We don't really support PoW at the moment at all. So, yes.

[JoshOrndorff]

I started looking at making the change to the SlotWorker trait, and I have a few questions about it.

1. Proposal is generic over the Transaction type used in the backend. Should I make the SlotWorker trait also generic over this type?

2. Currently the only implementation of the SlotWorker trait come from the blanket implementation over the SimpleSlotWorker trait.
   That means that I'll need to update the provided on_slot method for the SimpleSlotWorker trait. I'm stuck because I can't figure out how to return the proposal here. After it's data has already been moved eg here. It seems Proposal doesn't implement Clone.

3. I see you mentioned on the Babe issue that it wouldn't happen soon. I'm curious if that is true for slots in general, or just for babe. (My main goal right now is Aura)

[bkchr]

I'm already working on AURA, so you don't need to do this.