159 lines
6.4 KiB
Nim
159 lines
6.4 KiB
Nim
# Copyright (c) 2018 Status Research & Development GmbH
|
|
# Licensed and distributed under either of
|
|
# * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
|
|
# * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
|
|
# at your option. This file may not be copied, modified, or distributed except according to those terms.
|
|
|
|
# Helpers and functions pertaining to managing the validator set
|
|
|
|
import
|
|
options, nimcrypto, sequtils, math,
|
|
eth_common,
|
|
../ssz,
|
|
./crypto, ./datatypes, ./digest, ./helpers
|
|
|
|
func min_empty_validator_index*(
|
|
validators: seq[Validator],
|
|
validator_balances: seq[uint64],
|
|
current_slot: uint64): Option[int] =
|
|
for i, v in validators:
|
|
if validator_balances[i] == 0 and
|
|
v.latest_status_change_slot +
|
|
ZERO_BALANCE_VALIDATOR_TTL.uint64 <= current_slot:
|
|
return some(i)
|
|
|
|
func xorSeed(seed: Eth2Digest, x: uint64): Eth2Digest =
|
|
## Integers are all encoded as bigendian
|
|
## Helper for get_shuffling in lieu of generally better bitwise handling
|
|
## xor least significant/highest-index 8 bytes in place (after copy)
|
|
result = seed
|
|
for i in 0 ..< 8:
|
|
result.data[31 - i] = result.data[31 - i] xor byte((x shr i*8) and 0xff)
|
|
|
|
func get_shuffling*(seed: Eth2Digest,
|
|
validators: openArray[Validator],
|
|
epoch: EpochNumber
|
|
): seq[seq[ValidatorIndex]] =
|
|
## Shuffles ``validators`` into crosslink committees seeded by ``seed`` and ``slot``.
|
|
## Returns a list of ``EPOCH_LENGTH * committees_per_slot`` committees where each
|
|
## committee is itself a list of validator indices.
|
|
## Implementation should do the following: http://vitalik.ca/files/ShuffleAndAssign.png
|
|
|
|
let
|
|
active_validator_indices = get_active_validator_indices(validators, epoch)
|
|
|
|
committees_per_epoch = get_epoch_committee_count(len(active_validator_indices)).int
|
|
|
|
# Shuffle
|
|
shuffled_active_validator_indices = shuffle(
|
|
active_validator_indices,
|
|
xorSeed(seed, epoch))
|
|
|
|
# Split the shuffled list into committees_per_epoch pieces
|
|
result = split(shuffled_active_validator_indices, committees_per_epoch)
|
|
assert result.len() == committees_per_epoch # what split should do..
|
|
|
|
func get_new_validator_registry_delta_chain_tip*(
|
|
current_validator_registry_delta_chain_tip: Eth2Digest,
|
|
index: ValidatorIndex,
|
|
pubkey: ValidatorPubKey,
|
|
slot: uint64,
|
|
flag: ValidatorSetDeltaFlags): Eth2Digest =
|
|
## Compute the next hash in the validator registry delta hash chain.
|
|
|
|
hash_tree_root_final(ValidatorRegistryDeltaBlock(
|
|
latest_registry_delta_root: current_validator_registry_delta_chain_tip,
|
|
validator_index: index,
|
|
pubkey: pubkey,
|
|
slot: slot,
|
|
flag: flag
|
|
))
|
|
|
|
func get_previous_epoch_committee_count(state: BeaconState): uint64 =
|
|
let previous_active_validators = get_active_validator_indices(
|
|
state.validator_registry,
|
|
state.previous_calculation_epoch,
|
|
)
|
|
get_epoch_committee_count(len(previous_active_validators))
|
|
|
|
func get_current_epoch_committee_count_per_slot(state: BeaconState): uint64 =
|
|
let current_active_validators = get_active_validator_indices(
|
|
state.validator_registry,
|
|
state.current_calculation_epoch,
|
|
)
|
|
get_epoch_committee_count(len(current_active_validators))
|
|
|
|
func get_crosslink_committees_at_slot*(state: BeaconState, slot: uint64) : seq[tuple[a: seq[ValidatorIndex], b: uint64]] =
|
|
## Returns the list of ``(committee, shard)`` tuples for the ``slot``.
|
|
|
|
let
|
|
epoch = slot_to_epoch(slot)
|
|
current_epoch = get_current_epoch(state)
|
|
previous_epoch = if current_epoch > GENESIS_EPOCH: (current_epoch - 1) else: current_epoch
|
|
next_epoch = current_epoch + 1
|
|
|
|
assert previous_epoch <= epoch
|
|
assert epoch < next_epoch
|
|
|
|
func get_epoch_specific_params() : auto =
|
|
if epoch < current_epoch:
|
|
let
|
|
committees_per_epoch = get_previous_epoch_committee_count(state)
|
|
seed = state.previous_epoch_seed
|
|
shuffling_epoch = state.previous_calculation_epoch
|
|
shuffling_start_shard = state.previous_epoch_start_shard
|
|
(committees_per_epoch, seed, shuffling_epoch, shuffling_start_shard)
|
|
else:
|
|
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)
|
|
|
|
let (committees_per_epoch, seed, shuffling_epoch, shuffling_start_shard) = get_epoch_specific_params()
|
|
|
|
let
|
|
shuffling = get_shuffling(
|
|
seed,
|
|
state.validator_registry,
|
|
shuffling_epoch,
|
|
)
|
|
offset = slot mod EPOCH_LENGTH
|
|
committees_per_slot = committees_per_epoch div EPOCH_LENGTH
|
|
slot_start_shard = (shuffling_start_shard + committees_per_slot * offset) mod SHARD_COUNT
|
|
|
|
for i in 0 ..< committees_per_slot.int:
|
|
result.add (
|
|
shuffling[(committees_per_slot * offset + i.uint64).int],
|
|
(slot_start_shard + i.uint64) mod SHARD_COUNT
|
|
)
|
|
|
|
func get_shard_committees_at_slot*(
|
|
state: BeaconState, slot: uint64): seq[ShardCommittee] =
|
|
# TODO temporary adapter; remove when all users gone
|
|
# where ShardCommittee is: shard*: uint64 / committee*: seq[ValidatorIndex]
|
|
let index = state.get_shard_committees_index(slot)
|
|
#state.shard_committees_at_slots[index]
|
|
for crosslink_committee in get_crosslink_committees_at_slot(state, slot):
|
|
var sac: ShardCommittee
|
|
sac.shard = crosslink_committee.b
|
|
sac.committee = crosslink_committee.a
|
|
result.add sac
|
|
|
|
func get_beacon_proposer_index*(state: BeaconState, slot: uint64): ValidatorIndex =
|
|
## From Casper RPJ mini-spec:
|
|
## When slot i begins, validator Vidx is expected
|
|
## to create ("propose") a block, which contains a pointer to some parent block
|
|
## that they perceive as the "head of the chain",
|
|
## and includes all of the **attestations** that they know about
|
|
## that have not yet been included into that chain.
|
|
##
|
|
## idx in Vidx == p(i mod N), pi being a random permutation of validators indices (i.e. a committee)
|
|
## Returns the beacon proposer index for the ``slot``.
|
|
# TODO this index is invalid outside of the block state transition function
|
|
# because presently, `state.slot += 1` happens before this function
|
|
# is called - see also testutil.getNextBeaconProposerIndex
|
|
let first_committee = get_crosslink_committees_at_slot(state, slot)[0][0]
|
|
first_committee[slot.int mod len(first_committee)]
|