# beacon_chain # Copyright (c) 2021-2023 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. import stew/shims/[sets, hashes], chronicles, ../spec/forks from ../spec/validator import compute_subscribed_subnets from ../consensus_object_pools/spec_cache import EpochRef, epoch, get_committee_assignments export forks, tables, sets {.push raises: [].} const SUBNET_SUBSCRIPTION_LEAD_TIME_SLOTS* = 4 ## The number of slots before we're up for aggregation duty that we'll ## actually subscribe to the subnet we're aggregating for - this gives ## the node time to find a mesh etc - can likely be further trimmed KNOWN_VALIDATOR_DECAY* = 3 * SLOTS_PER_EPOCH ## The number of slots before we "forget" about validators that have ## registered for duties - once we've forgotten about a validator, we'll ## eventually decrease the number of stability subnets we're subscribed to. ## Active validators are expected to register for duty every epoch - we use ## 3 epochs here to counter rounding errors and communication delays. ## When known validators decrease, we will keep the stability subnet around ## until it "naturally" expires. type AggregatorDuty* = object subnet_id*: SubnetId slot*: Slot ActionTracker* = object nodeId: UInt256 subscribeAllAttnets: bool currentSlot: Slot ## Duties that we accept are limited to a range around the current slot subscribedSubnets*: AttnetBits ## All subnets we're currently subscribed to nextCycleEpoch: Epoch # Used to track the next attestation and proposal slots using an # epoch-relative coordinate system. Doesn't need initialization. attestingSlots: array[2, uint32] proposingSlots: array[2, uint32] lastCalculatedEpoch*: Epoch attesterDepRoot*: Eth2Digest ## The latest dependent root we used to compute attestation duties ## for internal validators knownValidators*: Table[ValidatorIndex, Slot] ## Validators that we've recently seen - we'll subscribe to one stability ## subnet for each such validator - the slot is used to expire validators ## that no longer are posting duties duties: HashSet[AggregatorDuty] ## Known aggregation duties in the near future - before each such ## duty, we'll subscribe to the corresponding subnet to collect ## attestations for the aggregate lastSyncUpdate*: Opt[SyncCommitteePeriod] syncDuties*: Table[ValidatorPubKey, Epoch] func hash*(x: AggregatorDuty): Hash = hashAllFields(x) proc registerDuty*( tracker: var ActionTracker, slot: Slot, subnet_id: SubnetId, vidx: ValidatorIndex, isAggregator: bool) = # Only register relevant duties if slot < tracker.currentSlot or slot + (SLOTS_PER_EPOCH * 2) <= tracker.currentSlot: debug "Irrelevant duty", slot, subnet_id, vidx return tracker.knownValidators[vidx] = slot # Update validator last-seen registry if isAggregator: let newDuty = AggregatorDuty(slot: slot, subnet_id: subnet_id) if newDuty in tracker.duties: return debug "Registering aggregation duty", slot, subnet_id, vidx tracker.duties.incl(newDuty) proc registerSyncDuty*( tracker: var ActionTracker, pubkey: ValidatorPubKey, until_epoch: Epoch) = if tracker.currentSlot.epoch >= until_epoch: return tracker.syncDuties.withValue(pubkey, entry) do: if entry[] < until_epoch: debug "Updating sync duty", pubkey = shortLog(pubkey), prev_until_epoch = entry[], until_epoch entry[] = until_epoch reset(tracker.lastSyncUpdate) do: debug "Registering sync duty", pubkey = shortLog(pubkey), until_epoch tracker.syncDuties[pubkey] = until_epoch reset(tracker.lastSyncUpdate) proc hasSyncDuty*( tracker: ActionTracker, pubkey: ValidatorPubKey, epoch: Epoch): bool = epoch < tracker.syncDuties.getOrDefault(pubkey, GENESIS_EPOCH) func aggregateSubnets*(tracker: ActionTracker, wallSlot: Slot): AttnetBits = var res: AttnetBits # Subscribe to subnets for upcoming duties for duty in tracker.duties: if wallSlot <= duty.slot and wallSlot + SUBNET_SUBSCRIPTION_LEAD_TIME_SLOTS > duty.slot: res[duty.subnet_id.int] = true res # TODO https://github.com/nim-lang/Nim/issues/12172 keeps from stabilitySubnets const allSubnetBits = block: var res: AttnetBits for i in 0.. 0: for subnetId in compute_subscribed_subnets(tracker.nodeId, slot.epoch): res[subnetId.int] = true res proc updateSlot*(tracker: var ActionTracker, wallSlot: Slot) = # Prune duties from the past - this collection is kept small because there # are only so many slot/subnet combos - prune both internal and API-supplied # duties at the same time tracker.duties.keepItIf(it.slot >= wallSlot) block: var dels: seq[ValidatorPubKey] for k, v in tracker.syncDuties: if wallSlot.epoch >= v: dels.add k for k in dels: tracker.syncDuties.del(k) var toPrune: seq[ValidatorIndex] for k, v in tracker.knownValidators: if v + KNOWN_VALIDATOR_DECAY < wallSlot: toPrune.add k for k in toPrune: debug "Validator no longer active", index = k tracker.knownValidators.del k tracker.currentSlot = wallSlot func getNextValidatorAction( actionSlotSource: auto, lastCalculatedEpoch: Epoch, slot: Slot): Slot = # The relevant actions are in, depending on calculated bounds: # [aS[epoch mod 2], aS[1 - (epoch mod 2)]] # current epoch next epoch let orderedActionSlots = [ actionSlotSource[ slot.epoch mod 2'u64], actionSlotSource[1 - (slot.epoch mod 2'u64)]] static: doAssert MIN_ATTESTATION_INCLUSION_DELAY == 1 # Cleverer ways exist, but a short loop is fine. O(n) vs O(log n) isn't that # important when n is 32 or 64, with early exit on average no more than half # through. for i in [0'u64, 1'u64]: let bitmapEpoch = slot.epoch + i if bitmapEpoch > lastCalculatedEpoch: return FAR_FUTURE_SLOT for slotOffset in 0 ..< SLOTS_PER_EPOCH: let nextActionSlot = start_slot(bitmapEpoch) + slotOffset if ((orderedActionSlots[i] and (1'u32 shl slotOffset)) != 0) and nextActionSlot > slot: return nextActionSlot FAR_FUTURE_SLOT func getNextAttestationSlot*(tracker: ActionTracker, slot: Slot): Slot = getNextValidatorAction( tracker.attestingSlots, tracker.lastCalculatedEpoch, slot) func getNextProposalSlot*(tracker: ActionTracker, slot: Slot): Slot = getNextValidatorAction( tracker.proposingSlots, tracker.lastCalculatedEpoch, slot) func needsUpdate*( tracker: ActionTracker, state: ForkyHashedBeaconState, epoch: Epoch): bool = # Using the attester dependent root here means we lock the action tracking to # the dependent root for attestation duties and not block proposal - # however, the risk of a proposer reordering in the last epoch is small # and the action tracker is speculative in nature. tracker.attesterDepRoot != state.dependent_root(if epoch > Epoch(0): epoch - 1 else: epoch) from std/sequtils import toSeq func updateActions*( tracker: var ActionTracker, epochRef: EpochRef) = # Updates the schedule for upcoming attestation and proposal work let epoch = epochRef.epoch tracker.attesterDepRoot = epochRef.shufflingRef.attester_dependent_root tracker.lastCalculatedEpoch = epoch let validatorIndices = toHashSet(toSeq(tracker.knownValidators.keys())) # Update proposals tracker.proposingSlots[epoch mod 2] = 0 for i, proposer in epochRef.beacon_proposers: if proposer.isSome and proposer.get() in validatorIndices: tracker.proposingSlots[epoch mod 2] = tracker.proposingSlots[epoch mod 2] or (1'u32 shl i) tracker.attestingSlots[epoch mod 2] = 0 # The relevant bitmaps are 32 bits each. static: doAssert SLOTS_PER_EPOCH <= 32 for (committeeIndex, subnet_id, slot) in get_committee_assignments(epochRef.shufflingRef, validatorIndices): doAssert epoch(slot) == epoch # Each get_committee_assignments() call here is on the next epoch. At any # given time, only care about two epochs, the current and next epoch. So, # after it is done for an epoch, [aS[epoch mod 2], aS[1 - (epoch mod 2)]] # provides, sequentially, the current and next epochs' slot schedules. If # get_committee_assignments() has not been called for the next epoch yet, # typically because there hasn't been a block in the current epoch, there # isn't valid information in aS[1 - (epoch mod 2)], and only slots within # the current epoch can be known. Usually, this is not a major issue, but # when there hasn't been a block substantially through an epoch, it might # prove misleading to claim that there aren't attestations known, when it # only might be known either way for 3 more slots. However, it's also not # as important to attest if blocks aren't flowing as only attestations in # blocks garner rewards. tracker.attestingSlots[epoch mod 2] = tracker.attestingSlots[epoch mod 2] or (1'u32 shl (slot mod SLOTS_PER_EPOCH)) func init*( T: type ActionTracker, nodeId: UInt256, subscribeAllAttnets: bool): T = T( nodeId: nodeId, subscribeAllAttnets: subscribeAllAttnets, )