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 and returns the ghost calculated using the precommits in the commit message and using the commit target as a base.

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.