Draft: Genesis exploration

[jasagredo]

The way I implemented prefix selection for now is as follows:

Implemented:

• Currently prefix selection is just a step before BlockFetch decision logic that will provide an updated map of candidates if we are in Syncing mode.
• Genesis window length is now a parameter of the consensus config that for now MUST NOT change between eras (à la k).

Open questions:

• How to define Caught up and Syncing?
• In CaughtUp mode, should BlockFetch receive all the candidates and download them following its own policies (network timing, then length) or should we only provide certain candidates?

Pending changes:

• property tests.
• the TODO @js comments here and there

[dnadales]

Some general and superficial remarks:

• for most of the new functions it'd be great to have:
  • examples in the docstrings
  • property tests
  • unit-tests/doctests to illustrate what they do
• for prefix selection, would it make sense to have:
  • an asymptotic complexity analysis

[nfrisby]

Javier closed this because it's bitrot. He's on UTxO HD now; Esgen and I are on Genesis.

Javier's worked here helped drive some good discussions with me. And I'm hopeful we can harvest some parts when Esgen and I start implementing the design.