def process_attestations(state: BeaconState,
block: BaseBeaconBlock,
config: Eth2Config) -> BeaconState:
"""
Implements 'per-block-processing.operations.attestations' portion of Phase 0 spec:
https://github.com/ethereum/eth2.0-specs/blob/master/specs/core/0_beacon-chain.md#attestations-1
Validate the ``attestations`` contained within the ``block`` in the context of ``state``.
If any invalid, throw ``ValidationError``.
Otherwise, append a ``PendingAttestationRecords`` for each to ``previous_epoch_attestations``
or ``current_epoch_attestations``.
Return resulting ``state``.
"""
if len(block.body.attestations) > config.MAX_ATTESTATIONS:
raise ValidationError(
f"The block ({block}) has too many attestations:\n"
f"\tFound {len(block.body.attestations)} attestations, "
f"maximum: {config.MAX_ATTESTATIONS}"
)
for attestation in block.body.attestations:
validate_attestation(
state,
attestation,
config.MIN_ATTESTATION_INCLUSION_DELAY,
config.SLOTS_PER_HISTORICAL_ROOT,
CommitteeConfig(config),
)
# update attestations
previous_epoch = state.previous_epoch(config.SLOTS_PER_EPOCH, config.GENESIS_EPOCH)
current_epoch = state.current_epoch(config.SLOTS_PER_EPOCH)
new_previous_epoch_pending_attestations = []
new_current_epoch_pending_attestations = []
for attestation in block.body.attestations:
if slot_to_epoch(attestation.data.slot, config.SLOTS_PER_EPOCH) == current_epoch:
new_current_epoch_pending_attestations.append(
PendingAttestationRecord(
data=attestation.data,
aggregation_bitfield=attestation.aggregation_bitfield,
custody_bitfield=attestation.custody_bitfield,
slot_included=state.slot,
)
)
elif slot_to_epoch(attestation.data.slot, config.SLOTS_PER_EPOCH) == previous_epoch:
new_previous_epoch_pending_attestations.append(
PendingAttestationRecord(
data=attestation.data,
aggregation_bitfield=attestation.aggregation_bitfield,
custody_bitfield=attestation.custody_bitfield,
slot_included=state.slot,
)
)
state = state.copy(
previous_epoch_attestations=(
state.previous_epoch_attestations + tuple(new_previous_epoch_pending_attestations)
),
current_epoch_attestations=(
state.current_epoch_attestations + tuple(new_current_epoch_pending_attestations)
),
)
return state
def process_crosslinks(state: BeaconState, config: Eth2Config) -> BeaconState:
"""
Implement 'per-epoch-processing.crosslinks' portion of Phase 0 spec:
https://github.com/ethereum/eth2.0-specs/blob/master/specs/core/0_beacon-chain.md#crosslinks
For each shard from the past two epochs, find the shard block
root that has been attested to by the most stake.
If enough(>= 2/3 total stake) attesting stake, update the crosslink record of that shard.
Return resulting ``state``
"""
latest_crosslinks = state.latest_crosslinks
effective_balances = {
ValidatorIndex(index): get_effective_balance(
state.validator_balances,
ValidatorIndex(index),
config.MAX_DEPOSIT_AMOUNT,
)
for index in range(len(state.validator_registry))
}
previous_epoch_start_slot = get_epoch_start_slot(
state.previous_epoch(config.SLOTS_PER_EPOCH),
config.SLOTS_PER_EPOCH,
)
next_epoch_start_slot = get_epoch_start_slot(
state.next_epoch(config.SLOTS_PER_EPOCH),
config.SLOTS_PER_EPOCH,
)
for slot in range(previous_epoch_start_slot, next_epoch_start_slot):
crosslink_committees_at_slot = get_crosslink_committees_at_slot(
state,
slot,
CommitteeConfig(config),
)
for crosslink_committee, shard in crosslink_committees_at_slot:
winning_root, attesting_validator_indices = get_winning_root_and_participants(
state=state,
shard=shard,
effective_balances=effective_balances,
committee_config=CommitteeConfig(config),
)
if len(attesting_validator_indices) > 0:
total_attesting_balance = get_total_balance(
state.validator_balances,
attesting_validator_indices,
config.MAX_DEPOSIT_AMOUNT,
)
total_balance = get_total_balance(
state.validator_balances,
crosslink_committee,
config.MAX_DEPOSIT_AMOUNT,
)
if 3 * total_attesting_balance >= 2 * total_balance:
latest_crosslinks = update_tuple_item(
latest_crosslinks,
shard,
CrosslinkRecord(
epoch=slot_to_epoch(Slot(slot),
config.SLOTS_PER_EPOCH),
crosslink_data_root=winning_root,
),
)
state = state.copy(latest_crosslinks=latest_crosslinks, )
return state