def get_attestation_data_slot(state: BeaconState,
data: AttestationData,
config: Eth2Config) -> Slot:
active_validator_indices = get_active_validator_indices(
state.validators,
data.target.epoch,
)
committee_count = get_committee_count(
len(active_validator_indices),
config.SHARD_COUNT,
config.SLOTS_PER_EPOCH,
config.TARGET_COMMITTEE_SIZE,
)
offset = (
data.crosslink.shard + config.SHARD_COUNT - get_start_shard(
state,
data.target.epoch,
CommitteeConfig(config),
)
) % config.SHARD_COUNT
committees_per_slot = committee_count // config.SLOTS_PER_EPOCH
return compute_start_slot_of_epoch(
data.target.epoch,
config.SLOTS_PER_EPOCH,
) + offset // committees_per_slot
def _get_committee_count(state, epoch, config):
active_validators = get_active_validator_indices(state.validators, epoch)
return get_committee_count(
len(active_validators),
config.SHARD_COUNT,
config.SLOTS_PER_EPOCH,
config.TARGET_COMMITTEE_SIZE,
)
def get_crosslink_deltas(
state: BeaconState,
config: Eth2Config) -> Tuple[Sequence[Gwei], Sequence[Gwei]]:
rewards = tuple(0 for _ in range(len(state.validators)))
penalties = tuple(0 for _ in range(len(state.validators)))
epoch = state.previous_epoch(config.SLOTS_PER_EPOCH, config.GENESIS_EPOCH)
active_validators_indices = get_active_validator_indices(
state.validators, epoch)
epoch_committee_count = get_committee_count(
len(active_validators_indices),
config.SHARD_COUNT,
config.SLOTS_PER_EPOCH,
config.TARGET_COMMITTEE_SIZE,
)
epoch_start_shard = get_start_shard(
state,
epoch,
CommitteeConfig(config),
)
for shard_offset in range(epoch_committee_count):
shard = Shard((epoch_start_shard + shard_offset) % config.SHARD_COUNT)
crosslink_committee = set(
get_crosslink_committee(
state,
epoch,
shard,
CommitteeConfig(config),
))
_, attesting_indices = get_winning_crosslink_and_attesting_indices(
state=state,
epoch=epoch,
shard=shard,
config=config,
)
total_attesting_balance = get_total_balance(
state,
attesting_indices,
)
total_committee_balance = get_total_balance(
state,
crosslink_committee,
)
for index in crosslink_committee:
base_reward = get_base_reward(state, index, config)
if index in attesting_indices:
rewards = update_tuple_item_with_fn(
rewards, index, lambda balance, delta: balance + delta,
base_reward * total_attesting_balance //
total_committee_balance)
else:
penalties = update_tuple_item_with_fn(
penalties,
index,
lambda balance, delta: balance + delta,
base_reward,
)
return tuple(Gwei(reward) for reward in rewards), tuple(
Gwei(penalty) for penalty in penalties)
def process_crosslinks(state: BeaconState, config: Eth2Config) -> BeaconState:
current_epoch = state.current_epoch(config.SLOTS_PER_EPOCH)
previous_epoch = state.previous_epoch(config.SLOTS_PER_EPOCH,
config.GENESIS_EPOCH)
new_current_crosslinks = state.current_crosslinks
for epoch in (previous_epoch, current_epoch):
active_validators_indices = get_active_validator_indices(
state.validators, epoch)
epoch_committee_count = get_committee_count(
len(active_validators_indices),
config.SHARD_COUNT,
config.SLOTS_PER_EPOCH,
config.TARGET_COMMITTEE_SIZE,
)
epoch_start_shard = get_start_shard(
state,
epoch,
CommitteeConfig(config),
)
for shard_offset in range(epoch_committee_count):
shard = Shard(
(epoch_start_shard + shard_offset) % config.SHARD_COUNT)
crosslink_committee = set(
get_crosslink_committee(
state,
epoch,
shard,
CommitteeConfig(config),
))
if not crosslink_committee:
# empty crosslink committee this epoch
continue
winning_crosslink, attesting_indices = get_winning_crosslink_and_attesting_indices(
state=state,
epoch=epoch,
shard=shard,
config=config,
)
threshold_met = _is_threshold_met_against_committee(
state,
attesting_indices,
crosslink_committee,
)
if threshold_met:
new_current_crosslinks = update_tuple_item(
new_current_crosslinks,
shard,
winning_crosslink,
)
return state.copy(
previous_crosslinks=state.current_crosslinks,
current_crosslinks=new_current_crosslinks,
)
def test_get_committee_count(active_validator_count, slots_per_epoch,
target_committee_size, shard_count,
expected_committee_count):
assert expected_committee_count == get_committee_count(
active_validator_count=active_validator_count,
shard_count=shard_count,
slots_per_epoch=slots_per_epoch,
target_committee_size=target_committee_size,
)
def _mk_attestation_inputs_in_epoch(epoch, state, config):
active_validators_indices = get_active_validator_indices(state.validators, epoch)
epoch_committee_count = get_committee_count(
len(active_validators_indices),
config.SHARD_COUNT,
config.SLOTS_PER_EPOCH,
config.TARGET_COMMITTEE_SIZE,
)
epoch_start_shard = get_start_shard(
state,
epoch,
CommitteeConfig(config),
)
for shard_offset in random.sample(range(epoch_committee_count), epoch_committee_count):
shard = Shard((epoch_start_shard + shard_offset) % config.SHARD_COUNT)
committee = get_crosslink_committee(
state,
epoch,
shard,
CommitteeConfig(config),
)
if not committee:
# empty crosslink committee this epoch
continue
attestation_data = AttestationData(
target=Checkpoint(
epoch=epoch,
),
crosslink=Crosslink(
shard=shard,
),
)
committee_count = len(committee)
aggregation_bits = bitfield.get_empty_bitfield(committee_count)
for index in range(committee_count):
aggregation_bits = bitfield.set_voted(aggregation_bits, index)
for index in committee:
yield (
index,
(
get_attestation_data_slot(
state,
attestation_data,
config,
),
(
aggregation_bits,
attestation_data,
),
),
)
def get_committee_assignment(
state: BeaconState,
config: Eth2Config,
epoch: Epoch,
validator_index: ValidatorIndex,
) -> CommitteeAssignment:
"""
Return the ``CommitteeAssignment`` in the ``epoch`` for ``validator_index``.
``CommitteeAssignment.committee`` is the tuple array of validators in the committee
``CommitteeAssignment.shard`` is the shard to which the committee is assigned
``CommitteeAssignment.slot`` is the slot at which the committee is assigned
``CommitteeAssignment.is_proposer`` is a bool signalling if the validator is expected to
propose a beacon block at the assigned slot.
"""
next_epoch = state.next_epoch(config.SLOTS_PER_EPOCH)
if epoch > next_epoch:
raise ValidationError(
f"Epoch for committee assignment ({epoch}) must not be after next epoch {next_epoch}."
)
active_validators = get_active_validator_indices(state.validators, epoch)
committees_per_slot = (
get_committee_count(
len(active_validators),
config.SHARD_COUNT,
config.SLOTS_PER_EPOCH,
config.TARGET_COMMITTEE_SIZE,
)
// config.SLOTS_PER_EPOCH
)
epoch_start_slot = compute_start_slot_of_epoch(epoch, config.SLOTS_PER_EPOCH)
epoch_start_shard = get_start_shard(state, epoch, CommitteeConfig(config))
for slot in range(epoch_start_slot, epoch_start_slot + config.SLOTS_PER_EPOCH):
offset = committees_per_slot * (slot % config.SLOTS_PER_EPOCH)
slot_start_shard = (epoch_start_shard + offset) % config.SHARD_COUNT
for i in range(committees_per_slot):
shard = Shard((slot_start_shard + i) % config.SHARD_COUNT)
committee = get_crosslink_committee(
state, epoch, shard, CommitteeConfig(config)
)
if validator_index in committee:
is_proposer = validator_index == get_beacon_proposer_index(
state.copy(slot=slot), CommitteeConfig(config)
)
return CommitteeAssignment(
committee, Shard(shard), Slot(slot), is_proposer
)
raise NoCommitteeAssignment
def _find_collision(state, config, index, epoch):
"""
Given a target epoch, make the attestation expected for the
validator w/ the given index.
"""
active_validators = get_active_validator_indices(state.validators, epoch)
committees_per_slot = get_committee_count(
len(active_validators),
config.SHARD_COUNT,
config.SLOTS_PER_EPOCH,
config.TARGET_COMMITTEE_SIZE,
) // config.SLOTS_PER_EPOCH
epoch_start_slot = compute_start_slot_of_epoch(
epoch,
config.SLOTS_PER_EPOCH,
)
epoch_start_shard = get_start_shard(state, epoch, CommitteeConfig(config))
for slot in range(epoch_start_slot, epoch_start_slot + config.SLOTS_PER_EPOCH):
offset = committees_per_slot * (slot % config.SLOTS_PER_EPOCH)
slot_start_shard = (epoch_start_shard + offset) % config.SHARD_COUNT
for i in range(committees_per_slot):
shard = Shard((slot_start_shard + i) % config.SHARD_COUNT)
committee = get_crosslink_committee(state, epoch, shard, CommitteeConfig(config))
if index in committee:
# TODO(ralexstokes) refactor w/ tools/builder
attestation_data = AttestationData(
target=Checkpoint(
epoch=epoch,
),
crosslink=Crosslink(
shard=shard,
),
)
committee_count = len(committee)
aggregation_bits = bitfield.get_empty_bitfield(committee_count)
for i in range(committee_count):
aggregation_bits = bitfield.set_voted(aggregation_bits, i)
return {
index: (
slot, (aggregation_bits, attestation_data)
)
for index in committee
}
else:
raise Exception("should have found a duplicate validator")
def get_crosslink_committees_at_slot(
state: BeaconState, slot: Slot, config: Eth2Config
) -> Tuple[Tuple[Tuple[ValidatorIndex, ...], Shard], ...]:
epoch = compute_epoch_of_slot(slot, config.SLOTS_PER_EPOCH)
active_validators = get_active_validator_indices(state.validators, epoch)
committees_per_slot = (get_committee_count(
len(active_validators),
config.SHARD_COUNT,
config.SLOTS_PER_EPOCH,
config.TARGET_COMMITTEE_SIZE,
) // config.SLOTS_PER_EPOCH)
results = []
offset = committees_per_slot * (slot % config.SLOTS_PER_EPOCH)
slot_start_shard = Shard(
(get_start_shard(state, epoch, CommitteeConfig(config)) + offset) %
config.SHARD_COUNT)
for i in range(committees_per_slot):
shard = (slot_start_shard + i) % config.SHARD_COUNT
committee = get_crosslink_committee(state, epoch, shard,
CommitteeConfig(config))
results.append((committee, Shard(shard)))
return tuple(results)