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complete re-implmentation of reasonable asymptotic-complexity algorithms from 0.11.3

This commit is contained in:
Dustin Brody 2020-06-09 11:42:53 +02:00 committed by tersec
parent 35f67cec60
commit 36f15a3688
1 changed files with 32 additions and 72 deletions
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104
beacon_chain/spec/state_transition_epoch.nim
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@ -8,17 +8,11 @@
# 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 purpose of this code right is primarily educational, to help piece
# together the mechanics of the beacon state and to discover potential problem
# areas.
#
# The entry point is `process_epoch` which is at the bottom of this file.
# The entry point is `process_epoch`, which is at the bottom of this file.
#
# General notes about the code (TODO):
# * Weird styling - the sections taken from the spec use python styling while
# the others use NEP-1 - helps grepping identifiers in spec
# * We mix procedural and functional styles for no good reason, except that the
# spec does so also.
# * For indices, we get a mix of uint64, ValidatorIndex and int - this is currently
# swept under the rug with casts
# When updating the code, add TODO sections to mark where there are clear
@ -65,11 +59,11 @@ func get_total_active_balance*(state: BeaconState, cache: var StateCache): Gwei
# Note: ``get_total_balance`` returns ``EFFECTIVE_BALANCE_INCREMENT`` Gwei
# minimum to avoid divisions by zero.
# TODO refactor get_empty_per_epoch_cache() not to be, well, empty, so can
# avoid this ever refilling, and raiseAssert, and get rid of var
let
epoch = state.slot.compute_epoch_at_slot
try:
# TODO refactor get_empty_per_epoch_cache() not to be, well, empty, so can
# avoid this ever refilling, and raiseAssert, and get rid of var
if epoch notin cache.shuffled_active_validator_indices:
cache.shuffled_active_validator_indices[epoch] =
get_shuffled_active_validator_indices(state, epoch)
@ -332,15 +326,34 @@ func get_inclusion_delay_deltas(state: BeaconState, cache: var StateCache):
seq[Gwei] =
# Return proposer and inclusion delay micro-rewards/penalties for each validator.
var rewards = repeat(0'u64, len(state.validators))
let matching_source_attestations =
get_matching_source_attestations(state, get_previous_epoch(state))
# TODO some fun big-O's here; see get_attestation_deltas_old() for linear version
let
matching_source_attestations =
get_matching_source_attestations(state, get_previous_epoch(state))
source_attestation_attesting_indices = mapIt(
matching_source_attestations,
get_attesting_indices(state, it.data, it.aggregation_bits, cache))
let total_balance = get_total_active_balance(state, cache)
for index in get_unslashed_attesting_indices(state, matching_source_attestations, cache):
# this is bad; it's to be just-correct-enough to check if v0.12.1 beacon chain is working
let attestations = filterIt(matching_source_attestations, index in get_attesting_indices(state, it.data, it.aggregation_bits, cache))
let admi = minIndex(mapIt(attestations, it.inclusion_delay))
let attestation = attestations[admi]
# Translation of attestation = min([...])
# Start by filtering the right attestations
var filtered_matching_source_attestations: seq[PendingAttestation]
for source_attestation_index, a in matching_source_attestations:
if index notin
source_attestation_attesting_indices[source_attestation_index]:
continue
filtered_matching_source_attestations.add a
if filtered_matching_source_attestations.len == 0:
continue
# The first filtered attestation serves as min until we find something
# better
var attestation = filtered_matching_source_attestations[0]
for source_attestation_index, a in filtered_matching_source_attestations:
if a.inclusion_delay < attestation.inclusion_delay:
attestation = a
# TODO remove duplicate calculation of get_proposer_reward()
rewards[attestation.proposer_index] += get_proposer_reward(state, index, cache)
@ -363,17 +376,18 @@ func get_inactivity_penalty_deltas(state: BeaconState, cache: var StateCache):
get_matching_target_attestations(state, get_previous_epoch(state))
matching_target_attesting_indices =
get_unslashed_attesting_indices(state, matching_target_attestations, cache)
# TODO quadratic or worse behavior, FIXME before merging with devel
for index in get_eligible_validator_indices(state):
# If validator is performing optimally this cancels all rewards for a neutral balance
let base_reward = get_base_reward(state, index, total_balance)
penalties[index] +=
Gwei(BASE_REWARDS_PER_EPOCH * base_reward -
get_proposer_reward(state, index, cache))
# matching_target_attesting_indices is a HashSet
if index notin matching_target_attesting_indices:
let effective_balance = state.validators[index].effective_balance
penalties[index] +=
Gwei(effective_balance * get_finality_delay(state) div INACTIVITY_PENALTY_QUOTIENT)
Gwei(effective_balance * get_finality_delay(state) div
INACTIVITY_PENALTY_QUOTIENT)
# No rewards associated with inactivity penalties
# Spec constructs rewards anyway; this doesn't
@ -399,60 +413,6 @@ func get_attestation_deltas(state: BeaconState, cache: var StateCache): tuple[a:
(rewards, penalties)
func get_attestation_deltas_old(state: BeaconState, stateCache: var StateCache):
tuple[a: seq[Gwei], b: seq[Gwei]] =
when false:
## This depends on matching_source_attestations being an indexable seq, not a
## set, hash table, etc.
let source_attestation_attesting_indices =
mapIt(
matching_source_attestations,
get_attesting_indices(state, it.data, it.aggregation_bits, stateCache))
for index in get_unslashed_attesting_indices(
state, matching_source_attestations, stateCache):
# Translation of attestation = min([...])
doAssert matching_source_attestations.len > 0
# Start by filtering the right attestations
var filtered_matching_source_attestations: seq[PendingAttestation]
for source_attestation_index, a in matching_source_attestations:
if index notin
source_attestation_attesting_indices[source_attestation_index]:
continue
filtered_matching_source_attestations.add a
# The first filtered attestation serves as min until we find something
# better
var attestation = filtered_matching_source_attestations[0]
for source_attestation_index, a in filtered_matching_source_attestations:
if a.inclusion_delay < attestation.inclusion_delay:
attestation = a
let
base_reward = get_base_reward(state, index, total_balance)
proposer_reward = (base_reward div PROPOSER_REWARD_QUOTIENT).Gwei
rewards[attestation.proposer_index.int] += proposer_reward
let max_attester_reward = base_reward - proposer_reward
rewards[index] += max_attester_reward div attestation.inclusion_delay
# Inactivity penalty
let finality_delay = previous_epoch - state.finalized_checkpoint.epoch
if finality_delay > MIN_EPOCHS_TO_INACTIVITY_PENALTY:
let matching_target_attesting_indices =
get_unslashed_attesting_indices(
state, matching_target_attestations, stateCache)
for index in eligible_validator_indices:
penalties[index] +=
BASE_REWARDS_PER_EPOCH.uint64 * get_base_reward(state, index, total_balance)
if index notin matching_target_attesting_indices:
penalties[index] +=
state.validators[index].effective_balance *
finality_delay div INACTIVITY_PENALTY_QUOTIENT
# https://github.com/ethereum/eth2.0-specs/blob/v0.11.3/specs/phase0/beacon-chain.md#rewards-and-penalties-1
func process_rewards_and_penalties(
state: var BeaconState, cache: var StateCache) {.nbench.}=