nimbus-eth2/beacon_chain/consensus_object_pools/sync_committee_msg_pool.nim

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# beacon_chain
# Copyright (c) 2018-2022 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.
{.push raises: [Defect].}
import
std/[sets, tables],
stew/shims/hashes,
bearssl,
eth/p2p/discoveryv5/random2,
chronicles,
../spec/[crypto, digest],
../spec/datatypes/altair
export hashes, sets, tables, altair
const
syncCommitteeMsgsRetentionSlots = 3
## How many slots to retain sync committee
## messsages before discarding them.
type
SyncCommitteeMsgKey = object
originator: uint64 # ValidatorIndex avoiding mess with invalid values
slot: Slot
subcommitteeIdx: uint64 # SyncSubcommitteeIndex avoiding mess with invalid values
TrustedSyncCommitteeMsg* = object
slot*: Slot
subcommitteeIdx*: SyncSubcommitteeIndex
positionInCommittee*: uint64
signature*: CookedSig
BestSyncSubcommitteeContribution* = object
totalParticipants*: int
participationBits*: SyncCommitteeAggregationBits
signature*: CookedSig
BestSyncSubcommitteeContributions* = object
slot*: Slot
subnets*: array[SYNC_COMMITTEE_SUBNET_COUNT,
BestSyncSubcommitteeContribution]
OnSyncContributionCallback* =
proc(data: SignedContributionAndProof) {.gcsafe, raises: [Defect].}
SyncCommitteeMsgPool* = object
seenSyncMsgByAuthor*: HashSet[SyncCommitteeMsgKey]
seenContributionByAuthor*: HashSet[SyncCommitteeMsgKey]
syncMessages*: Table[Eth2Digest, seq[TrustedSyncCommitteeMsg]]
bestContributions*: Table[Eth2Digest, BestSyncSubcommitteeContributions]
onContributionReceived*: OnSyncContributionCallback
rng: ref BrHmacDrbgContext
syncCommitteeSubscriptions*: Table[ValidatorPubKey, Epoch]
func hash*(x: SyncCommitteeMsgKey): Hash =
hashAllFields(x)
func init*(T: type SyncCommitteeMsgPool,
rng: ref BrHmacDrbgContext,
onSyncContribution: OnSyncContributionCallback = nil
): SyncCommitteeMsgPool =
T(rng: rng, onContributionReceived: onSyncContribution)
func pruneData*(pool: var SyncCommitteeMsgPool, slot: Slot) =
## This should be called at the end of slot.
clear pool.seenContributionByAuthor
clear pool.seenSyncMsgByAuthor
if slot < syncCommitteeMsgsRetentionSlots:
return
let minSlotToRetain = slot - syncCommitteeMsgsRetentionSlots
var syncMsgsToDelete: seq[Eth2Digest]
var contributionsToDelete: seq[Eth2Digest]
for blockRoot, msgs in pool.syncMessages:
if msgs[0].slot < minSlotToRetain:
syncMsgsToDelete.add blockRoot
for blockRoot in syncMsgsToDelete:
pool.syncMessages.del blockRoot
for blockRoot, bestContributions in pool.bestContributions:
if bestContributions.slot < minSlotToRetain:
contributionsToDelete.add blockRoot
for blockRoot in contributionsToDelete:
pool.bestContributions.del blockRoot
func isSeen*(
pool: SyncCommitteeMsgPool,
msg: SyncCommitteeMessage,
subcommitteeIdx: SyncSubcommitteeIndex): bool =
let seenKey = SyncCommitteeMsgKey(
originator: msg.validator_index, # Might be unvalidated at this point
slot: msg.slot,
subcommitteeIdx: subcommitteeIdx.uint64)
seenKey in pool.seenSyncMsgByAuthor
proc addSyncCommitteeMessage*(
pool: var SyncCommitteeMsgPool,
slot: Slot,
blockRoot: Eth2Digest,
validatorIndex: uint64,
signature: CookedSig,
subcommitteeIdx: SyncSubcommitteeIndex,
positionsInCommittee: openArray[uint64]) =
let
seenKey = SyncCommitteeMsgKey(
originator: validatorIndex,
slot: slot,
subcommitteeIdx: subcommitteeIdx.uint64)
pool.seenSyncMsgByAuthor.incl seenKey
for position in positionsInCommittee:
pool.syncMessages.mgetOrPut(blockRoot, @[]).add TrustedSyncCommitteeMsg(
slot: slot,
subcommitteeIdx: subcommitteeIdx,
positionInCommittee: position,
signature: signature)
debug "Sync committee message resolved",
slot = slot, blockRoot = shortLog(blockRoot), validatorIndex
func computeAggregateSig(votes: seq[TrustedSyncCommitteeMsg],
subcommitteeIdx: SyncSubcommitteeIndex,
contribution: var SyncCommitteeContribution): bool =
var
aggregateSig {.noinit.}: AggregateSignature
initialized = false
for vote in votes:
if vote.subcommitteeIdx != subcommitteeIdx:
continue
if not contribution.aggregation_bits[vote.positionInCommittee]:
if not initialized:
initialized = true
aggregateSig.init(vote.signature)
else:
aggregateSig.aggregate(vote.signature)
contribution.aggregation_bits.setBit vote.positionInCommittee
if initialized:
contribution.signature = aggregateSig.finish.toValidatorSig
initialized
func produceContribution*(
pool: SyncCommitteeMsgPool,
slot: Slot,
headRoot: Eth2Digest,
subcommitteeIdx: SyncSubcommitteeIndex,
outContribution: var SyncCommitteeContribution): bool =
if headRoot in pool.syncMessages:
outContribution.slot = slot
outContribution.beacon_block_root = headRoot
outContribution.subcommittee_index = subcommitteeIdx.asUInt64
try:
computeAggregateSig(pool.syncMessages[headRoot],
subcommitteeIdx,
outContribution)
except KeyError:
raiseAssert "We have checked for the key upfront"
else:
false
func addAggregateAux(bestVotes: var BestSyncSubcommitteeContributions,
contribution: SyncCommitteeContribution) =
let
currentBestTotalParticipants =
bestVotes.subnets[contribution.subcommittee_index].totalParticipants
newBestTotalParticipants = countOnes(contribution.aggregation_bits)
if newBestTotalParticipants > currentBestTotalParticipants:
bestVotes.subnets[contribution.subcommittee_index] =
BestSyncSubcommitteeContribution(
totalParticipants: newBestTotalParticipants,
participationBits: contribution.aggregation_bits,
signature: contribution.signature.load.get)
func isSeen*(
pool: SyncCommitteeMsgPool,
msg: ContributionAndProof): bool =
let seenKey = SyncCommitteeMsgKey(
originator: msg.aggregator_index,
slot: msg.contribution.slot,
subcommitteeIdx: msg.contribution.subcommittee_index)
seenKey in pool.seenContributionByAuthor
proc addContribution(pool: var SyncCommitteeMsgPool,
aggregator_index: uint64,
contribution: SyncCommitteeContribution,
signature: CookedSig) =
let seenKey = SyncCommitteeMsgKey(
originator: aggregator_index,
slot: contribution.slot,
subcommitteeIdx: contribution.subcommittee_index)
pool.seenContributionByAuthor.incl seenKey
template blockRoot: auto = contribution.beacon_block_root
if blockRoot notin pool.bestContributions:
let totalParticipants = countOnes(contribution.aggregation_bits)
var initialBestContributions = BestSyncSubcommitteeContributions(
slot: contribution.slot)
initialBestContributions.subnets[contribution.subcommittee_index] =
BestSyncSubcommitteeContribution(
totalParticipants: totalParticipants,
participationBits: contribution.aggregation_bits,
signature: signature)
pool.bestContributions[blockRoot] = initialBestContributions
else:
try:
addAggregateAux(pool.bestContributions[blockRoot], contribution)
except KeyError:
raiseAssert "We have checked for the key upfront"
proc addContribution*(pool: var SyncCommitteeMsgPool,
scproof: SignedContributionAndProof,
signature: CookedSig) =
pool.addContribution(
scproof.message.aggregator_index, scproof.message.contribution, signature)
if not(isNil(pool.onContributionReceived)):
pool.onContributionReceived(scproof)
proc produceSyncAggregateAux(
bestContributions: BestSyncSubcommitteeContributions): SyncAggregate =
var
aggregateSig {.noinit.}: AggregateSignature
initialized = false
startTime = Moment.now
for subcommitteeIdx in SyncSubcommitteeIndex:
if bestContributions.subnets[subcommitteeIdx].totalParticipants == 0:
continue
for pos, value in bestContributions.subnets[subcommitteeIdx].participationBits:
if value:
let globalPos = subcommitteeIdx.asInt * SYNC_SUBCOMMITTEE_SIZE + pos
result.sync_committee_bits.setBit globalPos
if not initialized:
initialized = true
aggregateSig.init(bestContributions.subnets[subcommitteeIdx].signature)
else:
aggregateSig.aggregate(bestContributions.subnets[subcommitteeIdx].signature)
if initialized:
result.sync_committee_signature = aggregateSig.finish.toValidatorSig
else:
result.sync_committee_signature = ValidatorSig.infinity
let duration = Moment.now - startTime
debug "SyncAggregate produced", duration,
bits = result.sync_committee_bits
proc produceSyncAggregate*(
pool: SyncCommitteeMsgPool,
targetRoot: Eth2Digest): SyncAggregate =
if targetRoot in pool.bestContributions:
try:
produceSyncAggregateAux(pool.bestContributions[targetRoot])
except KeyError:
raiseAssert "We have checked for the key upfront"
else:
SyncAggregate.init()
proc isEpochLeadTime*(
pool: SyncCommitteeMsgPool, epochsToSyncPeriod: uint64): bool =
# https://github.com/ethereum/consensus-specs/blob/v1.1.10/specs/altair/validator.md#sync-committee-subnet-stability
# This ensures a uniform distribution without requiring additional state:
# (1/4) = 1/4, 4 slots out
# (3/4) * (1/3) = 1/4, 3 slots out
# (3/4) * (2/3) * (1/2) = 1/4, 2 slots out
# (3/4) * (2/3) * (1/2) * (1/1) = 1/4, 1 slot out
doAssert epochsToSyncPeriod > 0
epochsToSyncPeriod == 1 or pool.rng[].rand(epochsToSyncPeriod - 1) == 0