feat(consensus): HeaviestSubtreeForkChoice

[dadepo]

This PR implements part of the HeaviestSubtreeForkChoice. Specifically part that has been identified as being used in the ReplayStage and does not depend on components not implemented yet (ie Bank, BankFork etc)

The main method identified as being used in the ReplayStage and implemented in this PR are

• HeaviestSubtreeForkChoice.bestOverallSlot
  • Used in Tower::new_from_bankforks
    • Which is used in ReplayStage::load_tower
  • When loading the tower from the bank forks, it is used to determine the best slot which is then used to get the heaviest bank. See
• HeaviestSubtreeForkChoice.setTreeRoot
  • Used in ReplayStage::handle_new_root
  • When a vote is recorded for a bank, there is a possibility it leads to a new root. When that is the case, the new root is also set in the HeaviestSubtreeForkChoice structure. See
• HeaviestSubtreeForkChoice.addNewLeafSlot
  • Used in ReplayStage::process_replay_results
  • When a bank is marked as complete, it is added to the HeaviestSubtreeForkChoice structure as a leave. See
• HeaviestSubtreeForkChoice.containsBlock
  • Used in ReplayStage::process_gossip_verified_vote_hashes
  • Used to check if a slot is frozen (already in fork info) while processing gossip verified votes. See
• HeaviestSubtreeForkChoice.markForkInvalidCandidate
  • Used ReplayStage::initialize_progress_and_fork_choice
  • Used in the instantiation process of the replay stage. When instantiating forkchoice from blockstore and banks, it also loads duplicate slots from the blockstore and mark them as invalid in the heaviest subtree fork choice. See

Apart from the above the following public methods were implemented, either because they were needed as part of the above listed methods or needed for testing.

• HeaviestSubtreeForkChoice.latestInvalidAncestor
• HeaviestSubtreeForkChoice.bestOverallSlot
• HeaviestSubtreeForkChoice.bestSlot
• HeaviestSubtreeForkChoice.deepestSlot
• HeaviestSubtreeForkChoice.deepestOverallSlot
• HeaviestSubtreeForkChoice.stakeVotedSubtree
• HeaviestSubtreeForkChoice.getHeight
• HeaviestSubtreeForkChoice.setTreeRoot
• HeaviestSubtreeForkChoice.isDuplicateConfirmed
• HeaviestSubtreeForkChoice.markForkInvalidCandidate

The PR also contains various private methods which were implemented either because they are needed in the above public methods or needed in tests

[yewman]

A couple of discards from funcs that return void. Also do you think we could add agave permalinks on analogous methods and key logic?

[yewman]

Looks good the me :)

[0xNineteen]

nice