29 KiB
29 KiB
Ethereum 2.0 Altair Beacon chain changes
Table of contents
- Introduction
- Custom types
- Constants
- Configuration
- Containers
- Helper functions
Introduction
Altair is the first beacon chain hard fork. Its main features are:
- sync committees to support light clients
- incentive accounting reforms to reduce spec complexity
- penalty parameter updates towards their planned maximally punitive values
Custom types
| Name | SSZ equivalent | Description |
|---|---|---|
ParticipationFlags |
uint8 |
a succinct representation of 8 boolean participation flags |
Constants
Participation flag indices
| Name | Value |
|---|---|
TIMELY_HEAD_FLAG_INDEX |
0 |
TIMELY_SOURCE_FLAG_INDEX |
1 |
TIMELY_TARGET_FLAG_INDEX |
2 |
Incentivization weights
| Name | Value |
|---|---|
TIMELY_HEAD_WEIGHT |
12 |
TIMELY_SOURCE_WEIGHT |
12 |
TIMELY_TARGET_WEIGHT |
24 |
SYNC_REWARD_WEIGHT |
8 |
WEIGHT_DENOMINATOR |
64 |
Note: The sum of the weight fractions (7/8) plus the proposer inclusion fraction (1/8) equals 1.
Misc
| Name | Value |
|---|---|
G2_POINT_AT_INFINITY |
BLSSignature(b'\xc0' + b'\x00' * 95) |
Configuration
Updated penalty values
This patch updates a few configuration values to move penalty parameters toward their final, maxmium security values.
Note: The spec does not override previous configuration values but instead creates new values and replaces usage throughout.
| Name | Value |
|---|---|
INACTIVITY_PENALTY_QUOTIENT_ALTAIR |
uint64(3 * 2**24) (= 50,331,648) |
MIN_SLASHING_PENALTY_QUOTIENT_ALTAIR |
uint64(2**6) (= 64) |
PROPORTIONAL_SLASHING_MULTIPLIER_ALTAIR |
uint64(2) |
Misc
| Name | Value |
|---|---|
SYNC_COMMITTEE_SIZE |
uint64(2**10) (= 1,024) |
SYNC_SUBCOMMITTEE_SIZE |
uint64(2**6) (= 64) |
INACTIVITY_SCORE_BIAS |
uint64(4) |
Time parameters
| Name | Value | Unit | Duration |
|---|---|---|---|
EPOCHS_PER_SYNC_COMMITTEE_PERIOD |
Epoch(2**8) (= 256) |
epochs | ~27 hours |
Domain types
| Name | Value |
|---|---|
DOMAIN_SYNC_COMMITTEE |
DomainType('0x07000000') |
DOMAIN_SYNC_COMMITTEE_SELECTION_PROOF |
DomainType('0x08000000') |
DOMAIN_CONTRIBUTION_AND_PROOF |
DomainType('0x09000000') |
Containers
Modified containers
BeaconBlockBody
class BeaconBlockBody(Container):
randao_reveal: BLSSignature
eth1_data: Eth1Data # Eth1 data vote
graffiti: Bytes32 # Arbitrary data
# Operations
proposer_slashings: List[ProposerSlashing, MAX_PROPOSER_SLASHINGS]
attester_slashings: List[AttesterSlashing, MAX_ATTESTER_SLASHINGS]
attestations: List[Attestation, MAX_ATTESTATIONS]
deposits: List[Deposit, MAX_DEPOSITS]
voluntary_exits: List[SignedVoluntaryExit, MAX_VOLUNTARY_EXITS]
# [New in Altair]
sync_aggregate: SyncAggregate
BeaconState
class BeaconState(Container):
# Versioning
genesis_time: uint64
genesis_validators_root: Root
slot: Slot
fork: Fork
# History
latest_block_header: BeaconBlockHeader
block_roots: Vector[Root, SLOTS_PER_HISTORICAL_ROOT]
state_roots: Vector[Root, SLOTS_PER_HISTORICAL_ROOT]
historical_roots: List[Root, HISTORICAL_ROOTS_LIMIT]
# Eth1
eth1_data: Eth1Data
eth1_data_votes: List[Eth1Data, EPOCHS_PER_ETH1_VOTING_PERIOD * SLOTS_PER_EPOCH]
eth1_deposit_index: uint64
# Registry
validators: List[Validator, VALIDATOR_REGISTRY_LIMIT]
balances: List[Gwei, VALIDATOR_REGISTRY_LIMIT]
# Randomness
randao_mixes: Vector[Bytes32, EPOCHS_PER_HISTORICAL_VECTOR]
# Slashings
slashings: Vector[Gwei, EPOCHS_PER_SLASHINGS_VECTOR] # Per-epoch sums of slashed effective balances
# Participation
previous_epoch_participation: List[ParticipationFlags, VALIDATOR_REGISTRY_LIMIT] # [Modified in Altair]
current_epoch_participation: List[ParticipationFlags, VALIDATOR_REGISTRY_LIMIT] # [Modified in Altair]
# Finality
justification_bits: Bitvector[JUSTIFICATION_BITS_LENGTH] # Bit set for every recent justified epoch
previous_justified_checkpoint: Checkpoint
current_justified_checkpoint: Checkpoint
finalized_checkpoint: Checkpoint
# Inactivity
inactivity_scores: List[uint64, VALIDATOR_REGISTRY_LIMIT] # [New in Altair]
# Sync
current_sync_committee: SyncCommittee # [New in Altair]
next_sync_committee: SyncCommittee # [New in Altair]
New containers
SyncAggregate
class SyncAggregate(Container):
sync_committee_bits: Bitvector[SYNC_COMMITTEE_SIZE]
sync_committee_signature: BLSSignature
SyncCommittee
class SyncCommittee(Container):
pubkeys: Vector[BLSPubkey, SYNC_COMMITTEE_SIZE]
pubkey_aggregates: Vector[BLSPubkey, SYNC_COMMITTEE_SIZE // SYNC_SUBCOMMITTEE_SIZE]
Helper functions
Predicates
eth2_fast_aggregate_verify
def eth2_fast_aggregate_verify(pubkeys: Sequence[BLSPubkey], message: Bytes32, signature: BLSSignature) -> bool:
"""
Wrapper to ``bls.FastAggregateVerify`` accepting the ``G2_POINT_AT_INFINITY`` signature when ``pubkeys`` is empty.
"""
if len(pubkeys) == 0 and signature == G2_POINT_AT_INFINITY:
return True
return bls.FastAggregateVerify(pubkeys, message, signature)
Misc
get_flag_indices_and_weights
def get_flag_indices_and_weights() -> Sequence[Tuple[int, int]]:
return (
(TIMELY_HEAD_FLAG_INDEX, TIMELY_HEAD_WEIGHT),
(TIMELY_SOURCE_FLAG_INDEX, TIMELY_SOURCE_WEIGHT),
(TIMELY_TARGET_FLAG_INDEX, TIMELY_TARGET_WEIGHT),
)
add_flag
def add_flag(flags: ParticipationFlags, flag_index: int) -> ParticipationFlags:
flag = ParticipationFlags(2**flag_index)
return flags | flag
has_flag
def has_flag(flags: ParticipationFlags, flag_index: int) -> bool:
flag = ParticipationFlags(2**flag_index)
return flags & flag == flag
Beacon state accessors
get_sync_committee_indices
def get_sync_committee_indices(state: BeaconState, epoch: Epoch) -> Sequence[ValidatorIndex]:
"""
Return the sequence of sync committee indices (which may include duplicate indices) for a given state and epoch.
"""
MAX_RANDOM_BYTE = 2**8 - 1
base_epoch = Epoch((max(epoch // EPOCHS_PER_SYNC_COMMITTEE_PERIOD, 1) - 1) * EPOCHS_PER_SYNC_COMMITTEE_PERIOD)
active_validator_indices = get_active_validator_indices(state, base_epoch)
active_validator_count = uint64(len(active_validator_indices))
seed = get_seed(state, base_epoch, DOMAIN_SYNC_COMMITTEE)
i = 0
sync_committee_indices: List[ValidatorIndex] = []
while len(sync_committee_indices) < SYNC_COMMITTEE_SIZE:
shuffled_index = compute_shuffled_index(uint64(i % active_validator_count), active_validator_count, seed)
candidate_index = active_validator_indices[shuffled_index]
random_byte = hash(seed + uint_to_bytes(uint64(i // 32)))[i % 32]
effective_balance = state.validators[candidate_index].effective_balance
if effective_balance * MAX_RANDOM_BYTE >= MAX_EFFECTIVE_BALANCE * random_byte: # Sample with replacement
sync_committee_indices.append(candidate_index)
i += 1
return sync_committee_indices
get_sync_committee
def get_sync_committee(state: BeaconState, epoch: Epoch) -> SyncCommittee:
"""
Return the sync committee for a given state and epoch.
"""
indices = get_sync_committee_indices(state, epoch)
pubkeys = [state.validators[index].pubkey for index in indices]
subcommitees = [pubkeys[i:i + SYNC_SUBCOMMITTEE_SIZE] for i in range(0, len(pubkeys), SYNC_SUBCOMMITTEE_SIZE)]
pubkey_aggregates = [bls.AggregatePKs(subcommitee) for subcommitee in subcommitees]
return SyncCommittee(pubkeys=pubkeys, pubkey_aggregates=pubkey_aggregates)
get_base_reward_per_increment
def get_base_reward_per_increment(state: BeaconState) -> Gwei:
return Gwei(EFFECTIVE_BALANCE_INCREMENT * BASE_REWARD_FACTOR // integer_squareroot(get_total_active_balance(state)))
get_base_reward
Note: The function get_base_reward is modified with the removal of BASE_REWARDS_PER_EPOCH.
def get_base_reward(state: BeaconState, index: ValidatorIndex) -> Gwei:
increments = state.validators[index].effective_balance // EFFECTIVE_BALANCE_INCREMENT
return Gwei(increments * get_base_reward_per_increment(state))
get_unslashed_participating_indices
def get_unslashed_participating_indices(state: BeaconState, flag_index: int, epoch: Epoch) -> Set[ValidatorIndex]:
"""
Return the active and unslashed validator indices for the given epoch and flag index.
"""
assert epoch in (get_previous_epoch(state), get_current_epoch(state))
if epoch == get_current_epoch(state):
epoch_participation = state.current_epoch_participation
else:
epoch_participation = state.previous_epoch_participation
active_validator_indices = get_active_validator_indices(state, epoch)
participating_indices = [i for i in active_validator_indices if has_flag(epoch_participation[i], flag_index)]
return set(filter(lambda index: not state.validators[index].slashed, participating_indices))
get_flag_index_deltas
def get_flag_index_deltas(state: BeaconState, flag_index: int, weight: uint64) -> Tuple[Sequence[Gwei], Sequence[Gwei]]:
"""
Return the deltas for a given flag index by scanning through the participation flags.
"""
rewards = [Gwei(0)] * len(state.validators)
penalties = [Gwei(0)] * len(state.validators)
unslashed_participating_indices = get_unslashed_participating_indices(state, flag_index, get_previous_epoch(state))
increment = EFFECTIVE_BALANCE_INCREMENT # Factored out from balances to avoid uint64 overflow
unslashed_participating_increments = get_total_balance(state, unslashed_participating_indices) // increment
active_increments = get_total_active_balance(state) // increment
for index in get_eligible_validator_indices(state):
base_reward = get_base_reward(state, index)
if index in unslashed_participating_indices:
if is_in_inactivity_leak(state):
# This flag reward cancels the inactivity penalty corresponding to the flag index
rewards[index] += Gwei(base_reward * weight // WEIGHT_DENOMINATOR)
else:
reward_numerator = base_reward * weight * unslashed_participating_increments
rewards[index] += Gwei(reward_numerator // (active_increments * WEIGHT_DENOMINATOR))
else:
penalties[index] += Gwei(base_reward * weight // WEIGHT_DENOMINATOR)
return rewards, penalties
Modified get_inactivity_penalty_deltas
Note: The function get_inactivity_penalty_deltas is modified in the selection of matching target indices
and the removal of BASE_REWARDS_PER_EPOCH.
def get_inactivity_penalty_deltas(state: BeaconState) -> Tuple[Sequence[Gwei], Sequence[Gwei]]:
"""
Return the inactivity penalty deltas by considering timely target participation flags and inactivity scores.
"""
rewards = [Gwei(0) for _ in range(len(state.validators))]
penalties = [Gwei(0) for _ in range(len(state.validators))]
if is_in_inactivity_leak(state):
previous_epoch = get_previous_epoch(state)
matching_target_indices = get_unslashed_participating_indices(state, TIMELY_TARGET_FLAG_INDEX, previous_epoch)
for index in get_eligible_validator_indices(state):
for (_, weight) in get_flag_indices_and_weights():
# This inactivity penalty cancels the flag reward corresponding to the flag index
penalties[index] += Gwei(get_base_reward(state, index) * weight // WEIGHT_DENOMINATOR)
if index not in matching_target_indices:
penalty_numerator = state.validators[index].effective_balance * state.inactivity_scores[index]
penalty_denominator = INACTIVITY_SCORE_BIAS * INACTIVITY_PENALTY_QUOTIENT_ALTAIR
penalties[index] += Gwei(penalty_numerator // penalty_denominator)
return rewards, penalties
Beacon state mutators
Modified slash_validator
Note: The function slash_validator is modified to use MIN_SLASHING_PENALTY_QUOTIENT_ALTAIR.
def slash_validator(state: BeaconState,
slashed_index: ValidatorIndex,
whistleblower_index: ValidatorIndex=None) -> None:
"""
Slash the validator with index ``slashed_index``.
"""
epoch = get_current_epoch(state)
initiate_validator_exit(state, slashed_index)
validator = state.validators[slashed_index]
validator.slashed = True
validator.withdrawable_epoch = max(validator.withdrawable_epoch, Epoch(epoch + EPOCHS_PER_SLASHINGS_VECTOR))
state.slashings[epoch % EPOCHS_PER_SLASHINGS_VECTOR] += validator.effective_balance
decrease_balance(state, slashed_index, validator.effective_balance // MIN_SLASHING_PENALTY_QUOTIENT_ALTAIR)
# Apply proposer and whistleblower rewards
proposer_index = get_beacon_proposer_index(state)
if whistleblower_index is None:
whistleblower_index = proposer_index
whistleblower_reward = Gwei(validator.effective_balance // WHISTLEBLOWER_REWARD_QUOTIENT)
proposer_reward = Gwei(whistleblower_reward // PROPOSER_REWARD_QUOTIENT)
increase_balance(state, proposer_index, proposer_reward)
increase_balance(state, whistleblower_index, Gwei(whistleblower_reward - proposer_reward))
Block processing
def process_block(state: BeaconState, block: BeaconBlock) -> None:
process_block_header(state, block)
process_randao(state, block.body)
process_eth1_data(state, block.body)
process_operations(state, block.body) # [Modified in Altair]
process_sync_committee(state, block.body.sync_aggregate) # [New in Altair]
Modified process_attestation
Note: The function process_attestation is modified to do incentive accounting with epoch participation flags.
def process_attestation(state: BeaconState, attestation: Attestation) -> None:
data = attestation.data
assert data.target.epoch in (get_previous_epoch(state), get_current_epoch(state))
assert data.target.epoch == compute_epoch_at_slot(data.slot)
assert data.slot + MIN_ATTESTATION_INCLUSION_DELAY <= state.slot <= data.slot + SLOTS_PER_EPOCH
assert data.index < get_committee_count_per_slot(state, data.target.epoch)
committee = get_beacon_committee(state, data.slot, data.index)
assert len(attestation.aggregation_bits) == len(committee)
if data.target.epoch == get_current_epoch(state):
epoch_participation = state.current_epoch_participation
justified_checkpoint = state.current_justified_checkpoint
else:
epoch_participation = state.previous_epoch_participation
justified_checkpoint = state.previous_justified_checkpoint
# Matching roots
is_matching_head = data.beacon_block_root == get_block_root_at_slot(state, data.slot)
is_matching_source = data.source == justified_checkpoint
is_matching_target = data.target.root == get_block_root(state, data.target.epoch)
assert is_matching_source
# Verify signature
assert is_valid_indexed_attestation(state, get_indexed_attestation(state, attestation))
# Participation flag indices
participation_flag_indices = []
if is_matching_head and is_matching_target and state.slot <= data.slot + MIN_ATTESTATION_INCLUSION_DELAY:
participation_flag_indices.append(TIMELY_HEAD_FLAG_INDEX)
if is_matching_source and state.slot <= data.slot + integer_squareroot(SLOTS_PER_EPOCH):
participation_flag_indices.append(TIMELY_SOURCE_FLAG_INDEX)
if is_matching_target and state.slot <= data.slot + SLOTS_PER_EPOCH:
participation_flag_indices.append(TIMELY_TARGET_FLAG_INDEX)
# Update epoch participation flags
proposer_reward_numerator = 0
for index in get_attesting_indices(state, data, attestation.aggregation_bits):
for flag_index, weight in get_flag_indices_and_weights():
if flag_index in participation_flag_indices and not has_flag(epoch_participation[index], flag_index):
epoch_participation[index] = add_flag(epoch_participation[index], flag_index)
proposer_reward_numerator += get_base_reward(state, index) * weight
# Reward proposer
proposer_reward = Gwei(proposer_reward_numerator // (WEIGHT_DENOMINATOR * PROPOSER_REWARD_QUOTIENT))
increase_balance(state, get_beacon_proposer_index(state), proposer_reward)
Modified process_deposit
Note: The function process_deposit is modified to initialize inactivity_scores, previous_epoch_participation, current_epoch_participation.
def process_deposit(state: BeaconState, deposit: Deposit) -> None:
# Verify the Merkle branch
assert is_valid_merkle_branch(
leaf=hash_tree_root(deposit.data),
branch=deposit.proof,
depth=DEPOSIT_CONTRACT_TREE_DEPTH + 1, # Add 1 for the List length mix-in
index=state.eth1_deposit_index,
root=state.eth1_data.deposit_root,
)
# Deposits must be processed in order
state.eth1_deposit_index += 1
pubkey = deposit.data.pubkey
amount = deposit.data.amount
validator_pubkeys = [validator.pubkey for validator in state.validators]
if pubkey not in validator_pubkeys:
# Verify the deposit signature (proof of possession) which is not checked by the deposit contract
deposit_message = DepositMessage(
pubkey=deposit.data.pubkey,
withdrawal_credentials=deposit.data.withdrawal_credentials,
amount=deposit.data.amount,
)
domain = compute_domain(DOMAIN_DEPOSIT) # Fork-agnostic domain since deposits are valid across forks
signing_root = compute_signing_root(deposit_message, domain)
# Initialize validator if the deposit signature is valid
if bls.Verify(pubkey, signing_root, deposit.data.signature):
state.validators.append(get_validator_from_deposit(state, deposit))
state.balances.append(amount)
state.previous_epoch_participation.append(ParticipationFlags(0b0000_0000))
state.current_epoch_participation.append(ParticipationFlags(0b0000_0000))
state.inactivity_scores.append(0)
else:
# Increase balance by deposit amount
index = ValidatorIndex(validator_pubkeys.index(pubkey))
increase_balance(state, index, amount)
Sync committee processing
def process_sync_committee(state: BeaconState, aggregate: SyncAggregate) -> None:
# Verify sync committee aggregate signature signing over the previous slot block root
previous_slot = Slot(max(int(state.slot), 1) - 1)
committee_indices = get_sync_committee_indices(state, get_current_epoch(state))
included_indices = [index for index, bit in zip(committee_indices, aggregate.sync_committee_bits) if bit]
committee_pubkeys = state.current_sync_committee.pubkeys
included_pubkeys = [pubkey for pubkey, bit in zip(committee_pubkeys, aggregate.sync_committee_bits) if bit]
domain = get_domain(state, DOMAIN_SYNC_COMMITTEE, compute_epoch_at_slot(previous_slot))
signing_root = compute_signing_root(get_block_root_at_slot(state, previous_slot), domain)
assert eth2_fast_aggregate_verify(included_pubkeys, signing_root, aggregate.sync_committee_signature)
# Compute the maximum sync rewards for the slot
total_active_increments = get_total_active_balance(state) // EFFECTIVE_BALANCE_INCREMENT
total_base_rewards = Gwei(get_base_reward_per_increment(state) * total_active_increments)
max_epoch_rewards = Gwei(total_base_rewards * SYNC_REWARD_WEIGHT // WEIGHT_DENOMINATOR)
max_slot_rewards = Gwei(max_epoch_rewards * len(included_indices) // len(committee_indices) // SLOTS_PER_EPOCH)
# Compute the participant and proposer sync rewards
committee_effective_balance = sum([state.validators[index].effective_balance for index in included_indices])
committee_effective_balance = max(EFFECTIVE_BALANCE_INCREMENT, committee_effective_balance)
for included_index in included_indices:
effective_balance = state.validators[included_index].effective_balance
inclusion_reward = Gwei(max_slot_rewards * effective_balance // committee_effective_balance)
proposer_reward = Gwei(inclusion_reward // PROPOSER_REWARD_QUOTIENT)
increase_balance(state, get_beacon_proposer_index(state), proposer_reward)
increase_balance(state, included_index, inclusion_reward - proposer_reward)
Epoch processing
def process_epoch(state: BeaconState) -> None:
process_justification_and_finalization(state) # [Modified in Altair]
process_inactivity_updates(state) # [New in Altair]
process_rewards_and_penalties(state) # [Modified in Altair]
process_registry_updates(state)
process_slashings(state) # [Modified in Altair]
process_eth1_data_reset(state)
process_effective_balance_updates(state)
process_slashings_reset(state)
process_randao_mixes_reset(state)
process_historical_roots_update(state)
process_participation_flag_updates(state) # [New in Altair]
process_sync_committee_updates(state) # [New in Altair]
Justification and finalization
Note: The function process_justification_and_finalization is modified with matching_target_attestations replaced by matching_target_indices.
def process_justification_and_finalization(state: BeaconState) -> None:
# Initial FFG checkpoint values have a `0x00` stub for `root`.
# Skip FFG updates in the first two epochs to avoid corner cases that might result in modifying this stub.
if get_current_epoch(state) <= GENESIS_EPOCH + 1:
return
previous_epoch = get_previous_epoch(state)
current_epoch = get_current_epoch(state)
old_previous_justified_checkpoint = state.previous_justified_checkpoint
old_current_justified_checkpoint = state.current_justified_checkpoint
# Process justifications
state.previous_justified_checkpoint = state.current_justified_checkpoint
state.justification_bits[1:] = state.justification_bits[:JUSTIFICATION_BITS_LENGTH - 1]
state.justification_bits[0] = 0b0
matching_target_indices = get_unslashed_participating_indices(state, TIMELY_TARGET_FLAG_INDEX, previous_epoch)
if get_total_balance(state, matching_target_indices) * 3 >= get_total_active_balance(state) * 2:
state.current_justified_checkpoint = Checkpoint(epoch=previous_epoch,
root=get_block_root(state, previous_epoch))
state.justification_bits[1] = 0b1
matching_target_indices = get_unslashed_participating_indices(state, TIMELY_TARGET_FLAG_INDEX, current_epoch)
if get_total_balance(state, matching_target_indices) * 3 >= get_total_active_balance(state) * 2:
state.current_justified_checkpoint = Checkpoint(epoch=current_epoch,
root=get_block_root(state, current_epoch))
state.justification_bits[0] = 0b1
# Process finalizations
bits = state.justification_bits
# The 2nd/3rd/4th most recent epochs are justified, the 2nd using the 4th as source
if all(bits[1:4]) and old_previous_justified_checkpoint.epoch + 3 == current_epoch:
state.finalized_checkpoint = old_previous_justified_checkpoint
# The 2nd/3rd most recent epochs are justified, the 2nd using the 3rd as source
if all(bits[1:3]) and old_previous_justified_checkpoint.epoch + 2 == current_epoch:
state.finalized_checkpoint = old_previous_justified_checkpoint
# The 1st/2nd/3rd most recent epochs are justified, the 1st using the 3rd as source
if all(bits[0:3]) and old_current_justified_checkpoint.epoch + 2 == current_epoch:
state.finalized_checkpoint = old_current_justified_checkpoint
# The 1st/2nd most recent epochs are justified, the 1st using the 2nd as source
if all(bits[0:2]) and old_current_justified_checkpoint.epoch + 1 == current_epoch:
state.finalized_checkpoint = old_current_justified_checkpoint
Inactivity scores
Note: The function process_inactivity_updates is new.
def process_inactivity_updates(state: BeaconState) -> None:
for index in get_eligible_validator_indices(state):
if index in get_unslashed_participating_indices(state, TIMELY_TARGET_FLAG_INDEX, get_previous_epoch(state)):
if state.inactivity_scores[index] > 0:
state.inactivity_scores[index] -= 1
elif is_in_inactivity_leak(state):
state.inactivity_scores[index] += INACTIVITY_SCORE_BIAS
Rewards and penalties
Note: The function process_rewards_and_penalties is modified to support the incentive accounting reforms.
def process_rewards_and_penalties(state: BeaconState) -> None:
# No rewards are applied at the end of `GENESIS_EPOCH` because rewards are for work done in the previous epoch
if get_current_epoch(state) == GENESIS_EPOCH:
return
flag_indices_and_numerators = get_flag_indices_and_weights()
flag_deltas = [get_flag_index_deltas(state, index, numerator) for (index, numerator) in flag_indices_and_numerators]
deltas = flag_deltas + [get_inactivity_penalty_deltas(state)]
for (rewards, penalties) in deltas:
for index in range(len(state.validators)):
increase_balance(state, ValidatorIndex(index), rewards[index])
decrease_balance(state, ValidatorIndex(index), penalties[index])
Slashings
Note: The function process_slashings is modified to use PROPORTIONAL_SLASHING_MULTIPLIER_ALTAIR.
def process_slashings(state: BeaconState) -> None:
epoch = get_current_epoch(state)
total_balance = get_total_active_balance(state)
adjusted_total_slashing_balance = min(sum(state.slashings) * PROPORTIONAL_SLASHING_MULTIPLIER_ALTAIR, total_balance)
for index, validator in enumerate(state.validators):
if validator.slashed and epoch + EPOCHS_PER_SLASHINGS_VECTOR // 2 == validator.withdrawable_epoch:
increment = EFFECTIVE_BALANCE_INCREMENT # Factored out from penalty numerator to avoid uint64 overflow
penalty_numerator = validator.effective_balance // increment * adjusted_total_slashing_balance
penalty = penalty_numerator // total_balance * increment
decrease_balance(state, ValidatorIndex(index), penalty)
Participation flags updates
Note: The function process_participation_flag_updates is new.
def process_participation_flag_updates(state: BeaconState) -> None:
state.previous_epoch_participation = state.current_epoch_participation
state.current_epoch_participation = [ParticipationFlags(0b0000_0000) for _ in range(len(state.validators))]
Sync committee updates
Note: The function process_sync_committee_updates is new.
def process_sync_committee_updates(state: BeaconState) -> None:
next_epoch = get_current_epoch(state) + Epoch(1)
if next_epoch % EPOCHS_PER_SYNC_COMMITTEE_PERIOD == 0:
state.current_sync_committee = state.next_sync_committee
state.next_sync_committee = get_sync_committee(state, next_epoch + EPOCHS_PER_SYNC_COMMITTEE_PERIOD)