Crate finality_grandpa

Finality gadget for blockchains.

https://github.com/w3f/consensus/blob/master/pdf/grandpa.pdf

Consensus proceeds in rounds. Each round, voters will cast a prevote and precommit message.

Votes on blocks are then applied to the blockchain, being recursively applied to blocks before them. A DAG is superimposed over the blockchain with the vote_graph logic.

Equivocation detection and vote-set management is done in the round module. The work for actually casting votes is done in the voter module.

Modules

• round
  Logic for a single round of GRANDPA.
• vote_graph
  Maintains the vote-graph of the blockchain.
• voter
  A voter in GRANDPA. This transitions between rounds and casts votes.
• voter_set
  Implementation of a VoterSet, representing the complete set of voters and their weights in the context of a round of the protocol.

Structs

• CatchUp
  A catch-up message, which is an aggregate of prevotes and precommits necessary to complete a round.
• Commit
  A commit message which is an aggregate of precommits.
• CommitValidationResult
  Struct returned from validate_commit function with information about the validation result.
• CompactCommit
  A commit message with compact representation of authentication data.
• Equivocation
  An equivocation (double-vote) in a given round.
• HistoricalVotes
  Historical votes seen in a round.
• Precommit
  A precommit for a block and its ancestors.
• Prevote
  A prevote for a block and its ancestors.
• PrimaryPropose
  A primary proposed block, this is a broadcast of the last round’s estimate.
• SignedMessage
  A signed message.
• SignedPrecommit
  A signed precommit message.
• SignedPrevote
  A signed prevote message.

Enums

• Error
  Top-level error type used by this crate.
• Message
  A protocol message or vote.

Traits

• BlockNumberOps
  Arithmetic necessary for a block number.
• Chain
  Chain context necessary for implementation of the finality gadget.

Functions

• process_commit_validation_result
  Runs the callback with the appropriate CommitProcessingOutcome based on the given CommitValidationResult. Outcome is bad if ghost is undefined, good otherwise.
• validate_commit
  Validates a GRANDPA commit message.

Type Definitions

• MultiAuthData
  Authentication data for a set of many messages, currently a set of precommit signatures but in the future could be optimized with BLS signature aggregation.