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get_crosslink_committees_at_slot updates (#95)

This commit is contained in:
Dustin Brody 2019-02-07 19:27:13 +00:00 committed by Mamy Ratsimbazafy
parent 2794181889
commit f2545318db
3 changed files with 56 additions and 10 deletions
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1
beacon_chain/spec/beaconstate.nim
View File

@ -217,6 +217,7 @@ func get_initial_beacon_state*(
state
# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_block_root
func get_block_root*(state: BeaconState,
slot: uint64): Eth2Digest =
doAssert state.slot <= slot + LATEST_BLOCK_ROOTS_LENGTH

23
beacon_chain/spec/helpers.nim
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@ -135,14 +135,20 @@ func get_domain*(
# Get the domain number that represents the fork meta and signature domain.
(get_fork_version(fork, epoch) shl 32) + domain_type.uint32
# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#is_power_of_two
func is_power_of_2*(v: uint64): bool = (v and (v-1)) == 0
# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#merkle_root
func merkle_root*(values: openArray[Eth2Digest]): Eth2Digest =
# o = [0] * len(values) + values
# for i in range(len(values)-1, 0, -1):
# o[i] = hash(o[i*2] + o[i*2+1])
# return o[1]
# TODO
## Merkleize ``values`` (where ``len(values)`` is a power of two) and return
## the Merkle root.
#var o = array[len(values) * 2, Eth2Digest]
#o[len(values) .. 2*len(values)] = values
#for i in countdown(len(values)-1, 0):
# discard
#o[i] = hash(o[i*2] + o[i*2+1])
#return o[1]
#TODO
discard
proc is_double_vote*(attestation_data_1: AttestationData,
@ -194,6 +200,7 @@ func get_epoch_committee_count*(active_validator_count: int): uint64 =
active_validator_count div EPOCH_LENGTH div TARGET_COMMITTEE_SIZE,
1, SHARD_COUNT div EPOCH_LENGTH).uint64 * EPOCH_LENGTH
# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_current_epoch_committee_count
func get_current_epoch_committee_count*(state: BeaconState): uint64 =
let current_active_validators = get_active_validator_indices(
state.validator_registry,
@ -205,9 +212,7 @@ func get_current_epoch_committee_count*(state: BeaconState): uint64 =
func get_current_epoch*(state: BeaconState): EpochNumber =
slot_to_epoch(state.slot)
## TODO I've been moving things into helpers because of layering issues
## but create DAG of which helper functions ref others and topo sort to
## refactor all of this mess.
# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_randao_mix
func get_randao_mix*(state: BeaconState,
epoch: EpochNumber): Eth2Digest =
## Returns the randao mix at a recent ``epoch``.
@ -216,12 +221,14 @@ func get_randao_mix*(state: BeaconState,
state.latest_randao_mixes[epoch mod LATEST_RANDAO_MIXES_LENGTH]
# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_active_index_root
func get_active_index_root(state: BeaconState, epoch: EpochNumber): Eth2Digest =
# Returns the index root at a recent ``epoch``.
assert get_current_epoch(state) - LATEST_INDEX_ROOTS_LENGTH < epoch
assert epoch <= get_current_epoch(state) + 1
state.latest_index_roots[epoch mod LATEST_INDEX_ROOTS_LENGTH]
# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#generate_seed
func generate_seed*(state: BeaconState, epoch: EpochNumber): Eth2Digest =
# Generate a seed for the given ``epoch``.

42
beacon_chain/spec/validator.nim
View File

@ -20,6 +20,7 @@ func xorSeed(seed: Eth2Digest, x: uint64): Eth2Digest =
for i in 0 ..< 8:
result.data[31 - i] = result.data[31 - i] xor byte((x shr i*8) and 0xff)
# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_shuffling
func get_shuffling*(seed: Eth2Digest,
validators: openArray[Validator],
epoch: EpochNumber
@ -59,6 +60,7 @@ func get_new_validator_registry_delta_chain_tip*(
flag: flag
))
# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_previous_epoch_committee_count
func get_previous_epoch_committee_count(state: BeaconState): uint64 =
let previous_active_validators = get_active_validator_indices(
state.validator_registry,
@ -66,9 +68,22 @@ func get_previous_epoch_committee_count(state: BeaconState): uint64 =
)
get_epoch_committee_count(len(previous_active_validators))
func get_crosslink_committees_at_slot*(state: BeaconState, slot: uint64):
# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_next_epoch_committee_count
func get_next_epoch_committee_count(state: BeaconState): uint64 =
let next_active_validators = get_active_validator_indices(
state.validator_registry,
get_current_epoch(state) + 1,
)
get_epoch_committee_count(len(next_active_validators))
# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_crosslink_committees_at_slot
func get_crosslink_committees_at_slot*(state: BeaconState, slot: uint64,
registry_change: bool = false):
seq[CrosslinkCommittee] =
## Returns the list of ``(committee, shard)`` tuples for the ``slot``.
##
## Note: There are two possible shufflings for crosslink committees for a
## ``slot`` in the next epoch -- with and without a `registry_change`
let
epoch = slot_to_epoch(slot)
@ -87,13 +102,35 @@ func get_crosslink_committees_at_slot*(state: BeaconState, slot: uint64):
shuffling_epoch = state.previous_calculation_epoch
shuffling_start_shard = state.previous_epoch_start_shard
(committees_per_epoch, seed, shuffling_epoch, shuffling_start_shard)
else:
elif epoch == current_epoch:
let
committees_per_epoch = get_current_epoch_committee_count(state)
seed = state.current_epoch_seed
shuffling_epoch = state.current_calculation_epoch
shuffling_start_shard = state.current_epoch_start_shard
(committees_per_epoch, seed, shuffling_epoch, shuffling_start_shard)
else:
assert epoch == next_epoch
let
current_committees_per_epoch = get_current_epoch_committee_count(state)
committees_per_epoch = get_next_epoch_committee_count(state)
shuffling_epoch = next_epoch
epochs_since_last_registry_update = current_epoch - state.validator_registry_update_epoch
condition = epochs_since_last_registry_update > 1'u64 and
is_power_of_2(epochs_since_last_registry_update)
seed = if registry_change or condition:
generate_seed(state, next_epoch)
else:
state.current_epoch_seed
shuffling_start_shard =
if registry_change:
(state.current_epoch_start_shard +
current_committees_per_epoch) mod SHARD_COUNT
else:
state.current_epoch_start_shard
(committees_per_epoch, seed, shuffling_epoch, shuffling_start_shard)
let (committees_per_epoch, seed, shuffling_epoch, shuffling_start_shard) =
get_epoch_specific_params()
@ -114,6 +151,7 @@ func get_crosslink_committees_at_slot*(state: BeaconState, slot: uint64):
(slot_start_shard + i.uint64) mod SHARD_COUNT
)
# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_beacon_proposer_index
func get_beacon_proposer_index*(state: BeaconState, slot: uint64): ValidatorIndex =
## From Casper RPJ mini-spec:
## When slot i begins, validator Vidx is expected