consensuscontext

README

Consensus Context

This file explains non-trivial implementation details in the Consensus Context.

Committees

A committee is a subset of validator nodes, with size between some minimum (currently set at 4) and all of validator nodes. The committee nodes' purpose is to participate in a consensus round, that is to reach consensus for a specific block height.

After consensus is reached, a new committee is chosen.

Committee Selection

See RequestValidationCommittee in committee.go

Algorithm

A weighted random sort over the nodes is used for deciding which nodes become committee members. The random part is achieved by hashing the concatenation of the random seed and the node's public key. The weighted part is achieved by multiplying the node's resulting hash by its reputation, thus increasing its chance of inclusion in a committee. Note that at present, reputation is set to 1, so in effect it is not used by the calculation.

The actual committee is the committeeSize nodes with the highest weighted_grade. The descending weighted_grade ordering is important - the first node is the initial leader of this consensus round.

for each node
   hash = sha256(concat(random_seed, node.public_key))
   low_4_bytes_hash := hash[:4]
   weighted_grade := to_uint32(low_4_bytes_hash) * reputation

sort_nodes := sort(nodes, by descending weighted_grade)
committee = first [committeeSize] sort_nodes

Documentation

Index

• Constants
• Variables
• func NewConsensusContext(transactionPool services.TransactionPool, ...) services.ConsensusContext

Constants

const CALL_ELECTIONS_CONTRACT_INTERVAL = 200 * time.Millisecond

Variables

var ErrFailedTransactionOrdering = errors.New("ErrFailedTransactionOrdering")

var ErrGetStateHash = errors.New("ErrGetStateHash failed in GetStateHash() so cannot retrieve pre-execution state diff merkleRoot from previous block")

var ErrInvalidBlockTimestamp = errors.New("ErrInvalidBlockTimestamp")

var ErrMismatchedBlockHeight = errors.New("ErrMismatchedBlockHeight")

var ErrMismatchedPreExecutionStateMerkleRoot = errors.New("ErrMismatchedPreExecutionStateMerkleRoot pre-execution state diff merkleRoot is different between results block header and extracted from state storage for previous block")

var ErrMismatchedPrevBlockHash = errors.New("ErrMismatchedPrevBlockHash")

var ErrMismatchedProtocolVersion = errors.New("ErrMismatchedProtocolVersion")

var ErrMismatchedTxHashPtrToActualTxBlock = errors.New("ErrMismatchedTxHashPtrToActualTxBlock mismatched tx block hash ptr to actual tx block hash")

var ErrMismatchedTxRxBlockHeight = errors.New("ErrMismatchedTxRxBlockHeight mismatched block height between transactions and results")

var ErrMismatchedTxRxTimestamps = errors.New("ErrMismatchedTxRxTimestamps mismatched timestamp between transactions and results")

var ErrMismatchedVirtualChainID = errors.New("ErrMismatchedVirtualChainID")

var ErrProcessTransactionSet = errors.New("ErrProcessTransactionSet failed in ProcessTransactionSet()")

var LogTag = log.Service("consensus-context")

Functions

func NewConsensusContext

func NewConsensusContext(
	transactionPool services.TransactionPool,
	virtualMachine services.VirtualMachine,
	stateStorage services.StateStorage,
	config config.ConsensusContextConfig,
	logger log.BasicLogger,
	metricFactory metric.Factory,
) services.ConsensusContext