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# beacon_chain
# Copyright (c) 2018-2020 Status Research & Development GmbH
# Licensed and distributed under either of
# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
# at your option. This file may not be copied, modified, or distributed except according to those terms.
# State transition - epoch processing, as described in
# https://github.com/ethereum/eth2.0-specs/blob/master/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
#
# The entry point is `process_epoch`, which is at the bottom of this file.
#
# General notes about the code:
# * Weird styling - the sections taken from the spec use python styling while
# the others use NEP-1 - helps grepping identifiers in spec
# * When updating the code, add TODO sections to mark where there are clear
# improvements to be made - other than that, keep things similar to spec unless
# motivated by security or performance considerations
{.push raises: [Defect].}
import
std/[math, sequtils, tables, algorithm],
stew/[bitops2], chronicles, metrics,
../extras,
../ssz/merkleization,
./beaconstate, ./crypto, ./datatypes, ./digest, ./helpers, ./validator,
../../nbench/bench_lab
# Logging utilities
# --------------------------------------------------------
logScope: topics = "consens"
# https://github.com/ethereum/eth2.0-metrics/blob/master/metrics.md#interop-metrics
declareGauge beacon_finalized_epoch, "Current finalized epoch" # On epoch transition
declareGauge beacon_finalized_root, "Current finalized root" # On epoch transition
declareGauge beacon_current_justified_epoch, "Current justified epoch" # On epoch transition
declareGauge beacon_current_justified_root, "Current justified root" # On epoch transition
declareGauge beacon_previous_justified_epoch, "Current previously justified epoch" # On epoch transition
declareGauge beacon_previous_justified_root, "Current previously justified root" # On epoch transition
# Non-spec
declareGauge epoch_transition_justification_and_finalization, "Epoch transition justification and finalization time"
declareGauge epoch_transition_times_rewards_and_penalties, "Epoch transition reward and penalty time"
declareGauge epoch_transition_registry_updates, "Epoch transition registry updates time"
declareGauge epoch_transition_slashings, "Epoch transition slashings time"
declareGauge epoch_transition_final_updates, "Epoch transition final updates time"
declareGauge beacon_current_epoch, "Current epoch"
type
# Caches for computing justificiation, rewards and penalties - based on
# implementation in Lighthouse:
# https://github.com/sigp/lighthouse/blob/master/consensus/state_processing/src/per_epoch_processing/validator_statuses.rs
Delta* = object
rewards*: Gwei
penalties*: Gwei
InclusionInfo = object
# The distance between the attestation slot and the slot that attestation
# was included in block.
delay: uint64
# The index of the proposer at the slot where the attestation was included.
proposer_index: uint64
ValidatorStatus = object
# True if the validator has been slashed, ever.
is_slashed: bool
# True if the validator can withdraw in the current epoch.
is_withdrawable_in_current_epoch: bool
# True if the validator was active in the state's _current_ epoch.
is_active_in_current_epoch: bool
# True if the validator was active in the state's _previous_ epoch.
is_active_in_previous_epoch: bool
# The validator's effective balance in the _current_ epoch.
current_epoch_effective_balance: uint64
# True if the validator had an attestation included in the _current_ epoch.
is_current_epoch_attester: bool
# True if the validator's beacon block root attestation for the first slot
# of the _current_ epoch matches the block root known to the state.
is_current_epoch_target_attester: bool
# True if the validator had an attestation included in the _previous_ epoch.
is_previous_epoch_attester: Option[InclusionInfo]
# Set if the validator's beacon block root attestation for the first slot of
# the _previous_ epoch matches the block root known to the state.
# Information used to reward the block producer of this validators
# earliest-included attestation.
is_previous_epoch_target_attester: bool
# True if the validator's beacon block root attestation in the _previous_
# epoch at the attestation's slot (`attestation_data.slot`) matches the
# block root known to the state.
is_previous_epoch_head_attester: bool
inclusion_info: Option[InclusionInfo]
# Total rewards and penalties for this validator
delta: Delta
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#get_total_balance
TotalBalances = object
# The total effective balance of all active validators during the _current_
# epoch.
current_epoch_raw: Gwei
# The total effective balance of all active validators during the _previous_
# epoch.
previous_epoch_raw: Gwei
# The total effective balance of all validators who attested during the
# _current_ epoch.
current_epoch_attesters_raw: Gwei
# The total effective balance of all validators who attested during the
# _current_ epoch and agreed with the state about the beacon block at the
# first slot of the _current_ epoch.
current_epoch_target_attesters_raw: Gwei
# The total effective balance of all validators who attested during the
# _previous_ epoch.
previous_epoch_attesters_raw: Gwei
# The total effective balance of all validators who attested during the
# _previous_ epoch and agreed with the state about the beacon block at the
# first slot of the _previous_ epoch.
previous_epoch_target_attesters_raw: Gwei
# The total effective balance of all validators who attested during the
# _previous_ epoch and agreed with the state about the beacon block at the
# time of attestation.
previous_epoch_head_attesters_raw: Gwei
ValidatorStatuses* = object
statuses*: seq[ValidatorStatus]
total_balances*: TotalBalances
# Accessors that implement the max condition in `get_total_balance`:
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#get_total_balance
template current_epoch*(v: TotalBalances): Gwei =
max(EFFECTIVE_BALANCE_INCREMENT, v.current_epoch_raw)
template previous_epoch*(v: TotalBalances): Gwei =
max(EFFECTIVE_BALANCE_INCREMENT, v.previous_epoch_raw)
template current_epoch_attesters*(v: TotalBalances): Gwei =
max(EFFECTIVE_BALANCE_INCREMENT, v.current_epoch_attesters_raw)
template current_epoch_target_attesters*(v: TotalBalances): Gwei =
max(EFFECTIVE_BALANCE_INCREMENT, v.current_epoch_target_attesters_raw)
template previous_epoch_attesters*(v: TotalBalances): Gwei =
max(EFFECTIVE_BALANCE_INCREMENT, v.previous_epoch_attesters_raw)
template previous_epoch_target_attesters*(v: TotalBalances): Gwei =
max(EFFECTIVE_BALANCE_INCREMENT, v.previous_epoch_target_attesters_raw)
template previous_epoch_head_attesters*(v: TotalBalances): Gwei =
max(EFFECTIVE_BALANCE_INCREMENT, v.previous_epoch_head_attesters_raw)
func init*(T: type ValidatorStatuses, state: BeaconState): T =
result.statuses = newSeq[ValidatorStatus](state.validators.len)
for i, v in state.validators:
result.statuses[i].is_slashed = v.slashed
result.statuses[i].is_withdrawable_in_current_epoch =
state.get_current_epoch() >= v.withdrawable_epoch
result.statuses[i].current_epoch_effective_balance = v.effective_balance
if v.is_active_validator(state.get_current_epoch()):
result.statuses[i].is_active_in_current_epoch = true
result.total_balances.current_epoch_raw += v.effective_balance
if v.is_active_validator(state.get_previous_epoch()):
result.statuses[i].is_active_in_previous_epoch = true
result.total_balances.previous_epoch_raw += v.effective_balance
func add(a: var Delta, b: Delta) =
a.rewards += b.rewards
a.penalties += b.penalties
func process_attestation(
self: var ValidatorStatuses, state: BeaconState, a: PendingAttestation,
cache: var StateCache) =
# Collect information about the attestation
var
is_current_epoch_attester, is_current_epoch_target_attester: bool
is_previous_epoch_target_attester: bool
is_previous_epoch_head_attester: bool
is_previous_epoch_attester: Option[InclusionInfo]
if a.data.target.epoch == state.get_current_epoch():
is_current_epoch_attester = true
if a.data.target.root == get_block_root(state, state.get_current_epoch()):
is_current_epoch_target_attester = true;
elif a.data.target.epoch == state.get_previous_epoch():
is_previous_epoch_attester = some(InclusionInfo(
delay: a.inclusion_delay,
proposer_index: a.proposer_index,
))
if a.data.target.root == get_block_root(state, state.get_previous_epoch()):
is_previous_epoch_target_attester = true;
if a.data.beacon_block_root == get_block_root_at_slot(state, a.data.slot):
is_previous_epoch_head_attester = true
# Update the cache for all participants
for validator_index in get_attesting_indices(
state, a.data, a.aggregation_bits, cache):
template v(): untyped = self.statuses[validator_index]
if is_current_epoch_attester:
v.is_current_epoch_attester = true
if is_current_epoch_target_attester:
v.is_current_epoch_target_attester = true
if is_previous_epoch_attester.isSome:
if v.is_previous_epoch_attester.isSome:
if is_previous_epoch_attester.get().delay <
v.is_previous_epoch_attester.get().delay:
v.is_previous_epoch_attester = is_previous_epoch_attester
else:
v.is_previous_epoch_attester = is_previous_epoch_attester
if is_previous_epoch_target_attester:
v.is_previous_epoch_target_attester = true
if is_previous_epoch_head_attester:
v.is_previous_epoch_head_attester = true
func process_attestations*(
self: var ValidatorStatuses, state: BeaconState, cache: var StateCache) =
# Walk state attestations and update the status information
for a in state.previous_epoch_attestations:
process_attestation(self, state, a, cache)
for a in state.current_epoch_attestations:
process_attestation(self, state, a, cache)
for idx, v in self.statuses:
if v.is_slashed:
continue
let validator_balance = state.validators[idx].effective_balance
if v.is_current_epoch_attester:
self.total_balances.current_epoch_attesters_raw += validator_balance
if v.is_current_epoch_target_attester:
self.total_balances.current_epoch_target_attesters_raw += validator_balance
if v.is_previous_epoch_attester.isSome():
self.total_balances.previous_epoch_attesters_raw += validator_balance
if v.is_previous_epoch_target_attester:
self.total_balances.previous_epoch_target_attesters_raw += validator_balance
if v.is_previous_epoch_head_attester:
self.total_balances.previous_epoch_head_attesters_raw += validator_balance
func is_eligible_validator*(validator: ValidatorStatus): bool =
validator.is_active_in_previous_epoch or
(validator.is_slashed and (not validator.is_withdrawable_in_current_epoch))
# Spec
# --------------------------------------------------------
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#get_total_active_balance
func get_total_active_balance*(state: BeaconState, cache: var StateCache): Gwei =
## Return the combined effective balance of the active validators.
# Note: ``get_total_balance`` returns ``EFFECTIVE_BALANCE_INCREMENT`` Gwei
# minimum to avoid divisions by zero.
let epoch = state.get_current_epoch()
get_total_balance(
state, cache.get_shuffled_active_validator_indices(state, epoch))
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#justification-and-finalization
proc process_justification_and_finalization*(state: var BeaconState,
total_balances: TotalBalances, updateFlags: UpdateFlags = {}) {.nbench.} =
# 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
let
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
## Spec:
## state.justification_bits[1:] = state.justification_bits[:-1]
## state.justification_bits[0] = 0b0
# TODO JUSTIFICATION_BITS_LENGTH is a constant in spec, move there or fix
# BitVector serialization in SSZ layer
const JUSTIFICATION_BITS_LENGTH = 4
state.justification_bits = (state.justification_bits shl 1) and
cast[uint8]((2^JUSTIFICATION_BITS_LENGTH) - 1)
let total_active_balance = total_balances.current_epoch
if total_balances.previous_epoch_target_attesters * 3 >=
total_active_balance * 2:
state.current_justified_checkpoint =
Checkpoint(epoch: previous_epoch,
root: get_block_root(state, previous_epoch))
state.justification_bits.setBit 1
trace "Justified with previous epoch",
current_epoch = current_epoch,
checkpoint = shortLog(state.current_justified_checkpoint)
elif verifyFinalization in updateFlags:
warn "Low attestation participation in previous epoch",
total_balances, epoch = get_current_epoch(state)
if total_balances.current_epoch_target_attesters * 3 >=
total_active_balance * 2:
state.current_justified_checkpoint =
Checkpoint(epoch: current_epoch,
root: get_block_root(state, current_epoch))
state.justification_bits.setBit 0
trace "Justified with current epoch",
current_epoch = current_epoch,
checkpoint = shortLog(state.current_justified_checkpoint)
# Process finalizations
let bitfield = state.justification_bits
## The 2nd/3rd/4th most recent epochs are justified, the 2nd using the 4th
## as source
if (bitfield and 0b1110) == 0b1110 and
old_previous_justified_checkpoint.epoch + 3 == current_epoch:
state.finalized_checkpoint = old_previous_justified_checkpoint
trace "Finalized with rule 234",
current_epoch = current_epoch,
checkpoint = shortLog(state.finalized_checkpoint)
## The 2nd/3rd most recent epochs are justified, the 2nd using the 3rd as
## source
if (bitfield and 0b110) == 0b110 and
old_previous_justified_checkpoint.epoch + 2 == current_epoch:
state.finalized_checkpoint = old_previous_justified_checkpoint
trace "Finalized with rule 23",
current_epoch = current_epoch,
checkpoint = shortLog(state.finalized_checkpoint)
## The 1st/2nd/3rd most recent epochs are justified, the 1st using the 3rd as
## source
if (bitfield and 0b111) == 0b111 and
old_current_justified_checkpoint.epoch + 2 == current_epoch:
state.finalized_checkpoint = old_current_justified_checkpoint
trace "Finalized with rule 123",
current_epoch = current_epoch,
checkpoint = shortLog(state.finalized_checkpoint)
## The 1st/2nd most recent epochs are justified, the 1st using the 2nd as
## source
if (bitfield and 0b11) == 0b11 and
old_current_justified_checkpoint.epoch + 1 == current_epoch:
state.finalized_checkpoint = old_current_justified_checkpoint
trace "Finalized with rule 12",
current_epoch = current_epoch,
checkpoint = shortLog(state.finalized_checkpoint)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#helpers
func get_base_reward_sqrt*(state: BeaconState, index: ValidatorIndex,
total_balance_sqrt: auto): Gwei =
# Spec function recalculates total_balance every time, which creates an
# O(n^2) situation.
let effective_balance = state.validators[index].effective_balance
effective_balance * BASE_REWARD_FACTOR div
total_balance_sqrt div BASE_REWARDS_PER_EPOCH
func get_proposer_reward(base_reward: Gwei): Gwei =
# Spec version recalculates get_total_active_balance(state) quadratically
base_reward div PROPOSER_REWARD_QUOTIENT
func is_in_inactivity_leak(finality_delay: uint64): bool =
finality_delay > MIN_EPOCHS_TO_INACTIVITY_PENALTY
func get_finality_delay(state: BeaconState): uint64 =
get_previous_epoch(state) - state.finalized_checkpoint.epoch
func get_attestation_component_delta(is_unslashed_attester: bool,
attesting_balance: Gwei,
total_balance: Gwei,
base_reward: uint64,
finality_delay: uint64): Delta =
# Helper with shared logic for use by get source, target, and head deltas
# functions
if is_unslashed_attester:
if is_in_inactivity_leak(finality_delay):
# Since full base reward will be canceled out by inactivity penalty deltas,
# optimal participation receives full base reward compensation here.
Delta(rewards: base_reward)
else:
let reward_numerator =
base_reward * (attesting_balance div EFFECTIVE_BALANCE_INCREMENT)
Delta(rewards:
reward_numerator div (total_balance div EFFECTIVE_BALANCE_INCREMENT))
else:
Delta(penalties: base_reward)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#components-of-attestation-deltas
func get_source_delta*(validator: ValidatorStatus,
base_reward: uint64,
total_balances: TotalBalances,
finality_delay: uint64): Delta =
## Return attester micro-rewards/penalties for source-vote for each validator.
get_attestation_component_delta(
validator.is_previous_epoch_attester.isSome() and (not validator.is_slashed),
total_balances.previous_epoch_attesters,
total_balances.current_epoch,
base_reward,
finality_delay)
func get_target_delta*(validator: ValidatorStatus,
base_reward: uint64,
total_balances: TotalBalances,
finality_delay: uint64): Delta =
## Return attester micro-rewards/penalties for target-vote for each validator.
get_attestation_component_delta(
validator.is_previous_epoch_target_attester and (not validator.is_slashed),
total_balances.previous_epoch_target_attesters,
total_balances.current_epoch,
base_reward,
finality_delay)
func get_head_delta*(validator: ValidatorStatus,
base_reward: uint64,
total_balances: TotalBalances,
finality_delay: uint64): Delta =
## Return attester micro-rewards/penalties for head-vote for each validator.
get_attestation_component_delta(
validator.is_previous_epoch_head_attester and (not validator.is_slashed),
total_balances.previous_epoch_head_attesters,
total_balances.current_epoch,
base_reward,
finality_delay)
func get_inclusion_delay_delta*(validator: ValidatorStatus,
base_reward: uint64):
(Delta, Option[(uint64, Delta)]) =
## Return proposer and inclusion delay micro-rewards/penalties for each validator.
if validator.is_previous_epoch_attester.isSome() and (not validator.is_slashed):
let
inclusion_info = validator.is_previous_epoch_attester.get()
proposer_reward = get_proposer_reward(base_reward)
proposer_delta = Delta(rewards: proposer_reward)
let
max_attester_reward = base_reward - proposer_reward
delta = Delta(rewards: max_attester_reward div inclusion_info.delay)
proposer_index = inclusion_info.proposer_index;
return (delta, some((proposer_index, proposer_delta)))
func get_inactivity_penalty_delta*(validator: ValidatorStatus,
base_reward: Gwei,
finality_delay: uint64): Delta =
## Return inactivity reward/penalty deltas for each validator.
var delta: Delta
if is_in_inactivity_leak(finality_delay):
# If validator is performing optimally this cancels all rewards for a neutral balance
delta.penalties +=
BASE_REWARDS_PER_EPOCH * base_reward - get_proposer_reward(base_reward)
# Additionally, all validators whose FFG target didn't match are penalized extra
# This condition is equivalent to this condition from the spec:
# `index not in get_unslashed_attesting_indices(state, matching_target_attestations)`
if validator.is_slashed or (not validator.is_previous_epoch_target_attester):
delta.penalties +=
validator.current_epoch_effective_balance * finality_delay div
INACTIVITY_PENALTY_QUOTIENT
delta
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#get_attestation_deltas
func get_attestation_deltas(
state: BeaconState, validator_statuses: var ValidatorStatuses) =
## Update validator_statuses with attestation reward/penalty deltas for each validator.
let
finality_delay = get_finality_delay(state)
total_balance = validator_statuses.total_balances.current_epoch
total_balance_sqrt = integer_squareroot(total_balance)
# Filter out ineligible validators. All sub-functions of the spec do this
# except for `get_inclusion_delay_deltas`. It's safe to do so here because
# any validator that is in the unslashed indices of the matching source
# attestations is active, and therefore eligible.
for index, validator in validator_statuses.statuses.mpairs():
if not is_eligible_validator(validator):
continue
let
base_reward = get_base_reward_sqrt(
state, index.ValidatorIndex, total_balance_sqrt)
let
source_delta = get_source_delta(
validator, base_reward, validator_statuses.total_balances, finality_delay)
target_delta = get_target_delta(
validator, base_reward, validator_statuses.total_balances, finality_delay)
head_delta = get_head_delta(
validator, base_reward, validator_statuses.total_balances, finality_delay)
(inclusion_delay_delta, proposer_delta) =
get_inclusion_delay_delta(validator, base_reward)
inactivity_delta = get_inactivity_penalty_delta(
validator, base_reward, finality_delay)
validator.delta.add source_delta
validator.delta.add target_delta
validator.delta.add head_delta
validator.delta.add inclusion_delay_delta
validator.delta.add inactivity_delta
if proposer_delta.isSome:
let proposer_index = proposer_delta.get()[0]
if proposer_index < validator_statuses.statuses.lenu64:
validator_statuses.statuses[proposer_index].delta.add(
proposer_delta.get()[1])
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#process_rewards_and_penalties
func process_rewards_and_penalties(
state: var BeaconState, validator_statuses: var ValidatorStatuses) {.nbench.} =
# No rewards are applied at the end of `GENESIS_EPOCH` because rewards are
# for work done in the previous epoch
doAssert validator_statuses.statuses.len == state.validators.len
if get_current_epoch(state) == GENESIS_EPOCH:
return
get_attestation_deltas(state, validator_statuses)
for idx, v in validator_statuses.statuses:
increase_balance(state, idx.ValidatorIndex, v.delta.rewards)
decrease_balance(state, idx.ValidatorIndex, v.delta.penalties)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#slashings
func process_slashings*(state: var BeaconState, total_balance: Gwei) {.nbench.}=
let
epoch = get_current_epoch(state)
adjusted_total_slashing_balance =
min(sum(state.slashings) * PROPORTIONAL_SLASHING_MULTIPLIER, total_balance)
for index, validator in state.validators:
if validator.slashed and epoch + EPOCHS_PER_SLASHINGS_VECTOR div 2 ==
validator.withdrawable_epoch:
let increment = EFFECTIVE_BALANCE_INCREMENT # Factored out from penalty
# numerator to avoid uint64 overflow
let penalty_numerator =
validator.effective_balance div increment *
adjusted_total_slashing_balance
let penalty = penalty_numerator div total_balance * increment
decrease_balance(state, index.ValidatorIndex, penalty)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#final-updates
func process_final_updates*(state: var BeaconState) {.nbench.}=
let
current_epoch = get_current_epoch(state)
next_epoch = current_epoch + 1
# Reset eth1 data votes
if next_epoch mod EPOCHS_PER_ETH1_VOTING_PERIOD == 0:
state.eth1_data_votes = default(type state.eth1_data_votes)
# Update effective balances with hysteresis
for index, validator in state.validators:
let balance = state.balances[index]
const
HYSTERESIS_INCREMENT =
EFFECTIVE_BALANCE_INCREMENT div HYSTERESIS_QUOTIENT
DOWNWARD_THRESHOLD =
HYSTERESIS_INCREMENT * HYSTERESIS_DOWNWARD_MULTIPLIER
UPWARD_THRESHOLD = HYSTERESIS_INCREMENT * HYSTERESIS_UPWARD_MULTIPLIER
if balance + DOWNWARD_THRESHOLD < validator.effective_balance or
validator.effective_balance + UPWARD_THRESHOLD < balance:
state.validators[index].effective_balance =
min(
balance - balance mod EFFECTIVE_BALANCE_INCREMENT,
MAX_EFFECTIVE_BALANCE)
# Reset slashings
state.slashings[int(next_epoch mod EPOCHS_PER_SLASHINGS_VECTOR)] = 0.Gwei
# Set randao mix
state.randao_mixes[next_epoch mod EPOCHS_PER_HISTORICAL_VECTOR] =
get_randao_mix(state, current_epoch)
# Set historical root accumulator
if next_epoch mod (SLOTS_PER_HISTORICAL_ROOT div SLOTS_PER_EPOCH) == 0:
# Equivalent to hash_tree_root(foo: HistoricalBatch), but without using
# significant additional stack or heap.
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#historicalbatch
# In response to https://github.com/status-im/nimbus-eth2/issues/921
state.historical_roots.add hash_tree_root(
[hash_tree_root(state.block_roots), hash_tree_root(state.state_roots)])
# Rotate current/previous epoch attestations
state.previous_epoch_attestations = state.current_epoch_attestations
state.current_epoch_attestations = default(type state.current_epoch_attestations)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#epoch-processing
proc process_epoch*(state: var BeaconState, updateFlags: UpdateFlags,
cache: var StateCache) {.nbench.} =
let currentEpoch = get_current_epoch(state)
trace "process_epoch",
current_epoch = currentEpoch
var validator_statuses = ValidatorStatuses.init(state)
validator_statuses.process_attestations(state, cache)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#justification-and-finalization
process_justification_and_finalization(
state, validator_statuses.total_balances, updateFlags)
# state.slot hasn't been incremented yet.
if verifyFinalization in updateFlags and currentEpoch >= 2:
doAssert state.current_justified_checkpoint.epoch + 2 >= currentEpoch
if verifyFinalization in updateFlags and currentEpoch >= 3:
# Rule 2/3/4 finalization results in the most pessimal case. The other
# three finalization rules finalize more quickly as long as the any of
# the finalization rules triggered.
doAssert state.finalized_checkpoint.epoch + 3 >= currentEpoch
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#rewards-and-penalties-1
process_rewards_and_penalties(state, validator_statuses)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#registry-updates
process_registry_updates(state, cache)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#slashings
process_slashings(state, validator_statuses.total_balances.current_epoch)
# https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/beacon-chain.md#final-updates
process_final_updates(state)
# Once per epoch metrics
beacon_current_epoch.set(currentEpoch.int64)
beacon_finalized_epoch.set(state.finalized_checkpoint.epoch.int64)
beacon_finalized_root.set(state.finalized_checkpoint.root.toGaugeValue)
beacon_current_justified_epoch.set(
state.current_justified_checkpoint.epoch.int64)
beacon_current_justified_root.set(
state.current_justified_checkpoint.root.toGaugeValue)
beacon_previous_justified_epoch.set(
state.previous_justified_checkpoint.epoch.int64)
beacon_previous_justified_root.set(
state.previous_justified_checkpoint.root.toGaugeValue)
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