Port beacon chain

[hwwhww]

I found that #1339 became a huge ticket beyond just "helper functions". Instead, open this one for an overview.

BeaconChainDB

Role

• Provides database interface.

Progress

• DB APIs are done in py-evm#1373
• [TODO] Fork choice rule -> waiting for the spec to be finalized.

BeaconStateMachine

Role

• Provides state transition.

Progress

• Basic forkable architecture: py-evm#1373
• Port functions from beacon_chain: Under construction 🚧

APIs

Process

• import_block: needs to extended compute_state_transition logic.
  • TODO: set state roots of the block
• compute_cycle_transitions
• compute_dynasty_transition
• process_block
• process_updated_crosslinks
• initialize_new_cycle
• fill_recent_block_hashes
• rewarding

Propose

• serenity.blocks.SerenityBlock.from_block(block): setup the context for proposing the block

Validate

• validate_parent_block_proposer
• validate_attestion

BeaconChain

Role

• Provides interfaces for accessing canonical chain and any given block.
• Provides interfaces for accessing the states.

Progress

• BeaconChain #1413

APIs

Pre-process

• validate_block_pre_processing_conditions

Validator (de-)registration

• [TODO] add_validator

Helper functions

Progress

• Port from beacon_chain repo: done
• Update to the latest spec.