nimbus-eth2/beacon_chain/consensus_object_pools/blockchain_dag_light_client...

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# beacon_chain
# Copyright (c) 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].}
# This implements the pre-release proposal of the libp2p based light client sync
# protocol. See https://github.com/ethereum/consensus-specs/pull/2802
import
# Status libraries
stew/[bitops2, objects],
# Beacon chain internals
../spec/datatypes/[phase0, altair, bellatrix],
../beacon_chain_db_light_client,
"."/[block_pools_types, blockchain_dag]
logScope: topics = "chaindag"
type
HashedBeaconStateWithSyncCommittee =
bellatrix.HashedBeaconState |
altair.HashedBeaconState
TrustedSignedBeaconBlockWithSyncAggregate =
bellatrix.TrustedSignedBeaconBlock |
altair.TrustedSignedBeaconBlock
template nextEpochBoundarySlot(slot: Slot): Slot =
## Compute the first possible epoch boundary state slot of a `Checkpoint`
## referring to a block at given slot.
(slot + (SLOTS_PER_EPOCH - 1)).epoch.start_slot
proc updateExistingState(
dag: ChainDAGRef, state: var ForkedHashedBeaconState, bsi: BlockSlotId,
save: bool, cache: var StateCache): bool =
## Wrapper around `updateState` for states expected to exist.
let ok = dag.updateState(state, bsi, save, cache)
if not ok:
error "State failed to load unexpectedly", bsi, tail = dag.tail.slot
doAssert verifyFinalization notin dag.updateFlags
ok
template withUpdatedExistingState(
dag: ChainDAGRef, stateParam: var ForkedHashedBeaconState,
bsiParam: BlockSlotId, okBody: untyped, failureBody: untyped): untyped =
## Wrapper around `withUpdatedState` for states expected to exist.
block:
let bsi = bsiParam
dag.withUpdatedState(stateParam, bsiParam) do:
okBody
do:
error "State failed to load unexpectedly", bsi, tail = dag.tail.slot
doAssert verifyFinalization notin dag.updateFlags
failureBody
proc getExistingBlockIdAtSlot(dag: ChainDAGRef, slot: Slot): Opt[BlockSlotId] =
## Wrapper around `getBlockIdAtSlot` for blocks expected to exist.
let bsi = dag.getBlockIdAtSlot(slot)
if bsi.isErr:
error "Block failed to load unexpectedly", slot, tail = dag.tail.slot
doAssert verifyFinalization notin dag.updateFlags
bsi
proc existingParent(dag: ChainDAGRef, bid: BlockId): Opt[BlockId] =
## Wrapper around `parent` for parents known to exist.
let parent = dag.parent(bid)
if parent.isErr:
error "Parent failed to load unexpectedly", bid, tail = dag.tail.slot
doAssert verifyFinalization notin dag.updateFlags
parent
proc getExistingForkedBlock(
dag: ChainDAGRef, bid: BlockId): Opt[ForkedTrustedSignedBeaconBlock] =
## Wrapper around `getForkedBlock` for blocks expected to exist.
let bdata = dag.getForkedBlock(bid)
if bdata.isErr:
error "Block failed to load unexpectedly", bid, tail = dag.tail.slot
doAssert verifyFinalization notin dag.updateFlags
bdata
proc existingCurrentSyncCommitteeForPeriod(
dag: ChainDAGRef,
tmpState: var ForkedHashedBeaconState,
period: SyncCommitteePeriod): Opt[SyncCommittee] =
## Wrapper around `currentSyncCommitteeForPeriod` for states known to exist.
let syncCommittee = dag.currentSyncCommitteeForPeriod(tmpState, period)
if syncCommittee.isErr:
error "Current sync committee failed to load unexpectedly",
period, tail = dag.tail.slot
doAssert verifyFinalization notin dag.updateFlags
syncCommittee
template syncCommitteeRoot(
state: HashedBeaconStateWithSyncCommittee): Eth2Digest =
## Compute a root to uniquely identify `current_sync_committee` and
## `next_sync_committee`.
withEth2Hash:
h.update state.data.current_sync_committee.hash_tree_root().data
h.update state.data.next_sync_committee.hash_tree_root().data
proc syncCommitteeRootForPeriod(
dag: ChainDAGRef,
tmpState: var ForkedHashedBeaconState,
period: SyncCommitteePeriod): Opt[Eth2Digest] =
## Compute a root to uniquely identify `current_sync_committee` and
## `next_sync_committee` for a given sync committee period.
## For non-finalized periods, follow the chain as selected by fork choice.
let lowSlot = max(dag.tail.slot, dag.cfg.ALTAIR_FORK_EPOCH.start_slot)
if period < lowSlot.sync_committee_period:
return err()
let
periodStartSlot = period.start_slot
syncCommitteeSlot = max(periodStartSlot, lowSlot)
bsi = ? dag.getExistingBlockIdAtSlot(syncCommitteeSlot)
dag.withUpdatedExistingState(tmpState, bsi) do:
withState(state):
when stateFork >= BeaconStateFork.Altair:
ok state.syncCommitteeRoot
else: raiseAssert "Unreachable"
do: err()
proc initLightClientDataStore*(
config: LightClientDataConfig,
cfg: RuntimeConfig,
db: LightClientDataDB): LightClientDataStore =
## Initialize light client data store.
LightClientDataStore(
db: db,
serve: config.serve,
importMode: config.importMode,
maxPeriods: config.maxPeriods.get(cfg.defaultLightClientDataMaxPeriods),
onLightClientFinalityUpdate: config.onLightClientFinalityUpdate,
onLightClientOptimisticUpdate: config.onLightClientOptimisticUpdate)
func targetLightClientTailSlot(dag: ChainDAGRef): Slot =
## Earliest slot for which light client data is retained.
let
maxPeriods = dag.lcDataStore.maxPeriods
headPeriod = dag.head.slot.sync_committee_period
lowSlot = max(dag.tail.slot, dag.cfg.ALTAIR_FORK_EPOCH.start_slot)
tail = max(headPeriod + 1, maxPeriods.SyncCommitteePeriod) - maxPeriods
max(tail.start_slot, lowSlot)
func handleUnexpectedLightClientError(dag: ChainDAGRef, buggedSlot: Slot) =
## If there is an unexpected error, adjust `tailSlot` to keep track of the
## section for which complete light client data is available, and to avoid
## failed lookups of cached light client data.
doAssert verifyFinalization notin dag.updateFlags
if buggedSlot >= dag.lcDataStore.cache.tailSlot:
dag.lcDataStore.cache.tailSlot = buggedSlot + 1
proc initLightClientBootstrapForPeriod(
dag: ChainDAGRef,
period: SyncCommitteePeriod): Opt[void] =
## Compute and cache `LightClientBootstrap` data for all finalized
## epoch boundary blocks within a given sync committee period.
if not dag.isNextSyncCommitteeFinalized(period):
return ok()
if dag.lcDataStore.db.isPeriodSealed(period):
return ok()
let startTick = Moment.now()
debug "Caching historic LC bootstrap data", period
defer:
let endTick = Moment.now()
debug "Historic LC bootstrap data cached", period,
cacheDur = endTick - startTick
let
periodStartSlot = period.start_slot
periodEndSlot = periodStartSlot + SLOTS_PER_SYNC_COMMITTEE_PERIOD - 1
lowSlot = max(periodStartSlot, dag.targetLightClientTailSlot)
highSlot = min(periodEndSlot, dag.finalizedHead.blck.slot)
lowBoundarySlot = lowSlot.nextEpochBoundarySlot
highBoundarySlot = highSlot.nextEpochBoundarySlot
var
res = ok()
tmpState = assignClone(dag.headState)
tmpCache: StateCache
nextBoundarySlot = lowBoundarySlot
while nextBoundarySlot <= highBoundarySlot:
defer: nextBoundarySlot += SLOTS_PER_EPOCH
let
bsi = dag.getExistingBlockIdAtSlot(nextBoundarySlot).valueOr:
dag.handleUnexpectedLightClientError(nextBoundarySlot)
res.err()
continue
bid = bsi.bid
boundarySlot = bid.slot.nextEpochBoundarySlot
if boundarySlot == nextBoundarySlot and bid.slot >= lowSlot and
not dag.lcDataStore.db.hasCurrentSyncCommitteeBranch(bid.slot):
if not dag.updateExistingState(
tmpState[], bid.atSlot, save = false, tmpCache):
dag.handleUnexpectedLightClientError(bid.slot)
res.err()
continue
let branch = withState(tmpState[]):
when stateFork >= BeaconStateFork.Altair:
state.data.build_proof(altair.CURRENT_SYNC_COMMITTEE_INDEX).get
else: raiseAssert "Unreachable"
dag.lcDataStore.db.putCurrentSyncCommitteeBranch(bid.slot, branch)
res
proc initLightClientUpdateForPeriod(
dag: ChainDAGRef, period: SyncCommitteePeriod): Opt[void] =
## Compute and cache the best `LightClientUpdate` within a given
## sync committee period up through the finalized head block.
## Non-finalized blocks are processed incrementally by other functions.
if not dag.isNextSyncCommitteeFinalized(period):
return ok()
if dag.lcDataStore.db.isPeriodSealed(period):
return ok()
let startTick = Moment.now()
debug "Computing best historic LC update", period
proc logBest(endTick = Moment.now()) =
# Using a helper function reduces code size as the `defer` beneath is
# replicated on every `return`, and the log statement allocates another
# copy of the arguments on the stack for each instantiation (~1 MB stack!)
debug "Best historic LC update computed",
period, update = dag.lcDataStore.db.getBestUpdate(period),
computeDur = endTick - startTick
defer: logBest()
proc maxParticipantsBlock(
dag: ChainDAGRef, highBid: BlockId, lowSlot: Slot
): tuple[bid: Opt[BlockId], res: Opt[void]] =
## Determine the earliest block with most sync committee signatures among
## ancestors of `highBid` with at least `lowSlot` as parent block slot.
## Return `err` if no block with `MIN_SYNC_COMMITTEE_PARTICIPANTS` exists.
## `res` in result indicates whether no unexpected errors occurred.
var
maxParticipants = MIN_SYNC_COMMITTEE_PARTICIPANTS
maxBid: Opt[BlockId]
res = Opt[void].ok()
bid = highBid
while true:
if bid.slot <= lowSlot:
break
let parentBid = dag.existingParent(bid).valueOr:
dag.handleUnexpectedLightClientError(bid.slot)
res.err()
break
if parentBid.slot < lowSlot:
break
let
bdata = dag.getExistingForkedBlock(bid).valueOr:
dag.handleUnexpectedLightClientError(bid.slot)
res.err()
break
numParticipants =
withBlck(bdata):
when stateFork >= BeaconStateFork.Altair:
countOnes(blck.message.body.sync_aggregate.sync_committee_bits)
else: raiseAssert "Unreachable"
if numParticipants >= maxParticipants:
maxParticipants = numParticipants
maxBid.ok bid
bid = parentBid
(bid: maxBid, res: res)
# Determine the block in the period with highest sync committee participation
let
periodStartSlot = period.start_slot
periodEndSlot = periodStartSlot + SLOTS_PER_SYNC_COMMITTEE_PERIOD - 1
lowSlot = max(periodStartSlot, dag.targetLightClientTailSlot)
highSlot = min(periodEndSlot, dag.finalizedHead.blck.slot)
fullPeriodCovered = (dag.finalizedHead.slot > periodEndSlot)
highBsi = dag.getExistingBlockIdAtSlot(highSlot).valueOr:
dag.handleUnexpectedLightClientError(highSlot)
return err()
highBid = highBsi.bid
maxParticipantsRes = dag.maxParticipantsBlock(highBid, lowSlot)
maxParticipantsBid = maxParticipantsRes.bid.valueOr:
const update = default(altair.LightClientUpdate)
if fullPeriodCovered and maxParticipantsRes.res.isOk: # No block in period
dag.lcDataStore.db.putBestUpdate(period, update)
else:
dag.lcDataStore.db.putUpdateIfBetter(period, update)
return maxParticipantsRes.res
# The block with highest participation may refer to a `finalized_checkpoint`
# in a different sync committee period. If that is the case, search for a
# later block with a `finalized_checkpoint` within the given sync committee
# period, despite it having a lower sync committee participation
var
res = ok()
tmpState = assignClone(dag.headState)
signatureBid {.noinit.}, finalizedBid {.noinit.}: BlockId
signatureBid.slot = FAR_FUTURE_SLOT
finalizedBid.slot = FAR_FUTURE_SLOT
while true:
if signatureBid.slot == FAR_FUTURE_SLOT:
signatureBid = maxParticipantsBid
else:
let
nextLowSlot = signatureBid.slot + 1
signatureRes = dag.maxParticipantsBlock(highBid, nextLowSlot)
if signatureRes.res.isErr:
res.err()
signatureBid = signatureRes.bid.valueOr:
signatureBid = maxParticipantsBid
break
let
attestedBid = dag.existingParent(signatureBid).valueOr:
dag.handleUnexpectedLightClientError(signatureBid.slot)
res.err()
continue
finalizedEpoch = block:
dag.withUpdatedExistingState(tmpState[], attestedBid.atSlot) do:
withState(state):
when stateFork >= BeaconStateFork.Altair:
state.data.finalized_checkpoint.epoch
else: raiseAssert "Unreachable"
do:
dag.handleUnexpectedLightClientError(attestedBid.slot)
res.err()
continue
finalizedSlot = finalizedEpoch.start_slot
finalizedBsi =
if finalizedSlot >= dag.tail.slot:
dag.getExistingBlockIdAtSlot(finalizedSlot).valueOr:
dag.handleUnexpectedLightClientError(finalizedSlot)
res.err()
continue
else:
continue
if finalizedBid.slot >= lowSlot:
finalizedBid = finalizedBsi.bid
break
if signatureBid == maxParticipantsBid:
finalizedBid = finalizedBsi.bid # For fallback `break` at start of loop
# Save best light client data for given period
var update {.noinit.}: altair.LightClientUpdate
let attestedBid = dag.existingParent(signatureBid).valueOr:
dag.handleUnexpectedLightClientError(signatureBid.slot)
return err()
dag.withUpdatedExistingState(tmpState[], attestedBid.atSlot) do:
let bdata = dag.getExistingForkedBlock(bid).valueOr:
dag.handleUnexpectedLightClientError(bid.slot)
return err()
withStateAndBlck(state, bdata):
when stateFork >= BeaconStateFork.Altair:
update.attested_header = blck.toBeaconBlockHeader()
update.next_sync_committee = state.data.next_sync_committee
update.next_sync_committee_branch =
state.data.build_proof(altair.NEXT_SYNC_COMMITTEE_INDEX).get
if finalizedBid.slot == FAR_FUTURE_SLOT:
update.finality_branch.reset()
else:
update.finality_branch =
state.data.build_proof(altair.FINALIZED_ROOT_INDEX).get
else: raiseAssert "Unreachable"
do:
dag.handleUnexpectedLightClientError(attestedBid.slot)
return err()
if finalizedBid.slot == FAR_FUTURE_SLOT or finalizedBid.slot == GENESIS_SLOT:
update.finalized_header.reset()
else:
let bdata = dag.getExistingForkedBlock(finalizedBid).valueOr:
dag.handleUnexpectedLightClientError(finalizedBid.slot)
return err()
withBlck(bdata):
update.finalized_header = blck.toBeaconBlockHeader()
let bdata = dag.getExistingForkedBlock(signatureBid).valueOr:
dag.handleUnexpectedLightClientError(signatureBid.slot)
return err()
withBlck(bdata):
when stateFork >= BeaconStateFork.Altair:
update.sync_aggregate = blck.asSigned().message.body.sync_aggregate
else: raiseAssert "Unreachable"
update.signature_slot = signatureBid.slot
if fullPeriodCovered and res.isOk:
dag.lcDataStore.db.putBestUpdate(period, update)
else:
dag.lcDataStore.db.putUpdateIfBetter(period, update)
res
proc initLightClientDataForPeriod(
dag: ChainDAGRef, period: SyncCommitteePeriod): Opt[void] =
## Import light client data for a given sync committee period.
if dag.lcDataStore.db.isPeriodSealed(period):
return ok()
let
fullPeriodCovered = (dag.finalizedHead.slot >= (period + 1).start_slot)
res1 = dag.initLightClientBootstrapForPeriod(period)
res2 = dag.initLightClientUpdateForPeriod(period)
if res1.isErr or res2.isErr:
return err()
if fullPeriodCovered:
dag.lcDataStore.db.sealPeriod(period)
ok()
proc getLightClientData(
dag: ChainDAGRef,
bid: BlockId): CachedLightClientData =
## Fetch cached light client data about a given block.
## Data must be cached (`cacheLightClientData`) before calling this function.
try: dag.lcDataStore.cache.data[bid]
except KeyError: raiseAssert "Unreachable"
proc cacheLightClientData(
dag: ChainDAGRef, state: HashedBeaconStateWithSyncCommittee, bid: BlockId) =
## Cache data for a given block and its post-state to speed up creating future
## `LightClientUpdate` and `LightClientBootstrap` instances that refer to this
## block and state.
let cachedData = CachedLightClientData(
current_sync_committee_branch:
state.data.build_proof(altair.CURRENT_SYNC_COMMITTEE_INDEX).get,
next_sync_committee_branch:
state.data.build_proof(altair.NEXT_SYNC_COMMITTEE_INDEX).get,
finalized_slot:
state.data.finalized_checkpoint.epoch.start_slot,
finality_branch:
state.data.build_proof(altair.FINALIZED_ROOT_INDEX).get)
if dag.lcDataStore.cache.data.hasKeyOrPut(bid, cachedData):
doAssert false, "Redundant `cacheLightClientData` call"
proc deleteLightClientData*(dag: ChainDAGRef, bid: BlockId) =
## Delete cached light client data for a given block. This needs to be called
## when a block becomes unreachable due to finalization of a different fork.
if dag.lcDataStore.importMode == LightClientDataImportMode.None:
return
dag.lcDataStore.cache.data.del bid
template lazy_header(name: untyped): untyped {.dirty.} =
## `createLightClientUpdates` helper to lazily load a known block header.
var
`name _ ptr`: ptr[BeaconBlockHeader]
`name _ ok` = true
template `assign _ name`(target: var BeaconBlockHeader, bid: BlockId): bool =
if `name _ ptr` != nil:
target = `name _ ptr`[]
elif `name _ ok`:
let bdata = dag.getExistingForkedBlock(bid)
if bdata.isErr:
dag.handleUnexpectedLightClientError(bid.slot)
`name _ ok` = false
else:
target = bdata.get.toBeaconBlockHeader()
`name _ ptr` = addr target
`name _ ok`
template lazy_data(name: untyped): untyped {.dirty.} =
## `createLightClientUpdates` helper to lazily load cached light client state.
var `name` {.noinit.}: CachedLightClientData
`name`.finalized_slot = FAR_FUTURE_SLOT
template `load _ name`(bid: BlockId) =
if `name`.finalized_slot == FAR_FUTURE_SLOT:
`name` = dag.getLightClientData(bid)
template lazy_bid(name: untyped): untyped {.dirty.} =
## `createLightClientUpdates` helper to lazily load a known to exist block id.
var
`name` {.noinit.}: BlockId
`name _ ok` = true
`name`.slot = FAR_FUTURE_SLOT
template `load _ name`(slot: Slot): bool =
if `name _ ok` and `name`.slot == FAR_FUTURE_SLOT:
let bsi = dag.getExistingBlockIdAtSlot(slot)
if bsi.isErr:
dag.handleUnexpectedLightClientError(slot)
`name _ ok` = false
else:
`name` = bsi.get.bid
`name _ ok`
proc createLightClientUpdates(
dag: ChainDAGRef,
state: HashedBeaconStateWithSyncCommittee,
blck: TrustedSignedBeaconBlockWithSyncAggregate,
parent_bid: BlockId) =
## Create `LightClientUpdate` instances for a given block and its post-state,
## and keep track of best / latest ones. Data about the parent block's
## post-state must be cached (`cacheLightClientData`) before calling this.
# Verify sync committee has sufficient participants
template sync_aggregate(): auto = blck.asSigned().message.body.sync_aggregate
template sync_committee_bits(): auto = sync_aggregate.sync_committee_bits
let num_active_participants = countOnes(sync_committee_bits).uint64
if num_active_participants < MIN_SYNC_COMMITTEE_PARTICIPANTS:
return
# Verify attested block (parent) is recent enough and that state is available
template attested_bid(): auto = parent_bid
let attested_slot = attested_bid.slot
if attested_slot < dag.lcDataStore.cache.tailSlot:
return
# Lazy variables to hold historic data
lazy_header(attested_header)
lazy_data(attested_data)
lazy_bid(finalized_bid)
lazy_header(finalized_header)
# Update latest light client data
template latest(): auto = dag.lcDataStore.cache.latest
var
newFinality = false
newOptimistic = false
let
signature_slot = blck.message.slot
is_later =
if attested_slot != latest.attested_header.slot:
attested_slot > latest.attested_header.slot
else:
signature_slot > latest.signature_slot
if is_later and latest.attested_header.assign_attested_header(attested_bid):
load_attested_data(attested_bid)
let finalized_slot = attested_data.finalized_slot
if finalized_slot == latest.finalized_header.slot:
latest.finality_branch = attested_data.finality_branch
elif finalized_slot == GENESIS_SLOT:
latest.finalized_header.reset()
latest.finality_branch = attested_data.finality_branch
elif finalized_slot >= dag.tail.slot and
load_finalized_bid(finalized_slot) and
latest.finalized_header.assign_finalized_header(finalized_bid):
latest.finality_branch = attested_data.finality_branch
newFinality = true
else:
latest.finalized_header.reset()
latest.finality_branch.reset()
latest.sync_aggregate = sync_aggregate
latest.signature_slot = signature_slot
newOptimistic = true
# Track best light client data for current period
let
attested_period = attested_slot.sync_committee_period
signature_period = signature_slot.sync_committee_period
if attested_period == signature_period:
template next_sync_committee(): auto = state.data.next_sync_committee
let isCommitteeFinalized = dag.isNextSyncCommitteeFinalized(attested_period)
var best =
if isCommitteeFinalized:
dag.lcDataStore.db.getBestUpdate(attested_period)
else:
let key = (attested_period, state.syncCommitteeRoot)
dag.lcDataStore.cache.pendingBest.getOrDefault(key)
load_attested_data(attested_bid)
let
finalized_slot = attested_data.finalized_slot
has_finality =
finalized_slot >= dag.tail.slot and load_finalized_bid(finalized_slot)
meta = LightClientUpdateMetadata(
attested_slot: attested_slot,
finalized_slot: finalized_slot,
signature_slot: signature_slot,
has_sync_committee: true,
has_finality: has_finality,
num_active_participants: num_active_participants)
is_better = is_better_data(meta, best.toMeta)
if is_better and best.attested_header.assign_attested_header(attested_bid):
best.next_sync_committee = next_sync_committee
best.next_sync_committee_branch = attested_data.next_sync_committee_branch
if finalized_slot == best.finalized_header.slot:
best.finality_branch = attested_data.finality_branch
elif finalized_slot == GENESIS_SLOT:
best.finalized_header.reset()
best.finality_branch = attested_data.finality_branch
elif has_finality and
best.finalized_header.assign_finalized_header(finalized_bid):
best.finality_branch = attested_data.finality_branch
else:
best.finalized_header.reset()
best.finality_branch.reset()
best.sync_aggregate = sync_aggregate
best.signature_slot = signature_slot
if isCommitteeFinalized:
dag.lcDataStore.db.putBestUpdate(attested_period, best)
debug "Best LC update improved", period = attested_period, update = best
else:
let key = (attested_period, state.syncCommitteeRoot)
dag.lcDataStore.cache.pendingBest[key] = best
debug "Best LC update improved", period = key, update = best
if newFinality and dag.lcDataStore.onLightClientFinalityUpdate != nil:
dag.lcDataStore.onLightClientFinalityUpdate(latest)
if newOptimistic and dag.lcDataStore.onLightClientOptimisticUpdate != nil:
dag.lcDataStore.onLightClientOptimisticUpdate(latest.toOptimistic)
proc initLightClientDataCache*(dag: ChainDAGRef) =
## Initialize cached light client data
if dag.lcDataStore.importMode == LightClientDataImportMode.None:
return
# Prune non-finalized data
dag.lcDataStore.db.delPeriodsFrom(dag.firstNonFinalizedPeriod)
# Initialize tail slot
let targetTailSlot = dag.targetLightClientTailSlot
dag.lcDataStore.cache.tailSlot = max(dag.head.slot, targetTailSlot)
# Import head state
if dag.head.slot < dag.lcDataStore.cache.tailSlot:
return
withState(dag.headState):
when stateFork >= BeaconStateFork.Altair:
dag.cacheLightClientData(state, dag.head.bid)
else: raiseAssert "Unreachable" # `tailSlot` cannot be before Altair
if dag.lcDataStore.importMode == LightClientDataImportMode.OnlyNew:
return
# Import light client data for finalized period through finalized head
let finalizedSlot = max(dag.finalizedHead.blck.slot, targetTailSlot)
if finalizedSlot >= dag.lcDataStore.cache.tailSlot:
return
dag.lcDataStore.cache.tailSlot = finalizedSlot
let finalizedPeriod = finalizedSlot.sync_committee_period
var res = dag.initLightClientDataForPeriod(finalizedPeriod)
let lightClientStartTick = Moment.now()
logScope: lightClientDataMaxPeriods = dag.lcDataStore.maxPeriods
debug "Initializing cached LC data", res
# Build list of block to process.
# As it is slow to load states in descending order,
# build a reverse todo list to then process them in ascending order
var
blocks = newSeqOfCap[BlockId](dag.head.slot - finalizedSlot + 1)
bid = dag.head.bid
while bid.slot > finalizedSlot:
blocks.add bid
bid = dag.existingParent(bid).valueOr:
dag.handleUnexpectedLightClientError(bid.slot)
res.err()
break
if bid.slot == finalizedSlot:
blocks.add bid
# Process blocks (reuses `dag.headState`, but restores it to the current head)
var
tmpState = assignClone(dag.headState)
tmpCache, cache: StateCache
oldCheckpoint: Checkpoint
cpIndex = 0
for i in countdown(blocks.high, blocks.low):
bid = blocks[i]
if not dag.updateExistingState(
dag.headState, bid.atSlot, save = false, cache):
dag.handleUnexpectedLightClientError(bid.slot)
res.err()
continue
let bdata = dag.getExistingForkedBlock(bid).valueOr:
dag.handleUnexpectedLightClientError(bid.slot)
res.err()
continue
withStateAndBlck(dag.headState, bdata):
when stateFork >= BeaconStateFork.Altair:
# Cache light client data (non-finalized blocks may refer to this)
if i != blocks.low:
dag.cacheLightClientData(state, bid) # `dag.head` already cached
# Create `LightClientUpdate` instances
if i < blocks.high:
dag.createLightClientUpdates(state, blck, parentBid = blocks[i + 1])
else: raiseAssert "Unreachable"
let lightClientEndTick = Moment.now()
debug "Initialized cached LC data",
initDur = lightClientEndTick - lightClientStartTick, res
if res.isErr:
return
if dag.lcDataStore.importMode == LightClientDataImportMode.OnDemand:
return
# Import historic data
dag.lcDataStore.cache.tailSlot = targetTailSlot
let targetTailPeriod = targetTailSlot.sync_committee_period
if targetTailPeriod < finalizedPeriod:
# `countdown` through 0 fails on distinct `uint64`
# https://github.com/nim-lang/Nim/pull/19926
var period = finalizedPeriod - 1
while period >= targetTailPeriod:
if dag.initLightClientDataForPeriod(period).isErr:
res.err()
if period <= targetTailPeriod:
break
dec period
debug "Historic LC data imported", res
proc processNewBlockForLightClient*(
dag: ChainDAGRef,
state: ForkedHashedBeaconState,
signedBlock: ForkyTrustedSignedBeaconBlock,
parentBid: BlockId) =
## Update light client data with information from a new block.
if dag.lcDataStore.importMode == LightClientDataImportMode.None:
return
if signedBlock.message.slot < dag.lcDataStore.cache.tailSlot:
return
when signedBlock is bellatrix.TrustedSignedBeaconBlock:
dag.cacheLightClientData(state.bellatrixData, signedBlock.toBlockId())
dag.createLightClientUpdates(state.bellatrixData, signedBlock, parentBid)
elif signedBlock is altair.TrustedSignedBeaconBlock:
dag.cacheLightClientData(state.altairData, signedBlock.toBlockId())
dag.createLightClientUpdates(state.altairData, signedBlock, parentBid)
elif signedBlock is phase0.TrustedSignedBeaconBlock:
raiseAssert "Unreachable" # `tailSlot` cannot be before Altair
else:
{.error: "Unreachable".}
proc processHeadChangeForLightClient*(dag: ChainDAGRef) =
## Update light client data to account for a new head block.
## Note that `dag.finalizedHead` is not yet updated when this is called.
if dag.lcDataStore.importMode == LightClientDataImportMode.None:
return
if dag.head.slot < dag.lcDataStore.cache.tailSlot:
return
# Update `bestUpdates` from `pendingBest` to ensure light client data
# only refers to sync committees as selected by fork choice
let headPeriod = dag.head.slot.sync_committee_period
if not dag.isNextSyncCommitteeFinalized(headPeriod):
let
tailPeriod = dag.lcDataStore.cache.tailSlot.sync_committee_period
lowPeriod = max(dag.firstNonFinalizedPeriod, tailPeriod)
if headPeriod > lowPeriod:
var tmpState = assignClone(dag.headState)
for period in lowPeriod ..< headPeriod:
let
syncCommitteeRoot =
dag.syncCommitteeRootForPeriod(tmpState[], period).valueOr:
dag.handleUnexpectedLightClientError(period.start_slot)
continue
key = (period, syncCommitteeRoot)
dag.lcDataStore.db.putBestUpdate(
period, dag.lcDataStore.cache.pendingBest.getOrDefault(key))
withState(dag.headState): # Common case separate to avoid `tmpState` copy
when stateFork >= BeaconStateFork.Altair:
let key = (headPeriod, state.syncCommitteeRoot)
dag.lcDataStore.db.putBestUpdate(
headPeriod, dag.lcDataStore.cache.pendingBest.getOrDefault(key))
else: raiseAssert "Unreachable" # `tailSlot` cannot be before Altair
proc processFinalizationForLightClient*(
dag: ChainDAGRef, oldFinalizedHead: BlockSlot) =
## Prune cached data that is no longer useful for creating future
## `LightClientUpdate` and `LightClientBootstrap` instances.
## This needs to be called whenever `finalized_checkpoint` changes.
if dag.lcDataStore.importMode == LightClientDataImportMode.None:
return
let finalizedSlot = dag.finalizedHead.slot
if finalizedSlot < dag.lcDataStore.cache.tailSlot:
return
# Cache `LightClientBootstrap` for newly finalized epoch boundary blocks
let
firstNewSlot = oldFinalizedHead.slot + 1
lowSlot = max(firstNewSlot, dag.lcDataStore.cache.tailSlot)
var boundarySlot = finalizedSlot
while boundarySlot >= lowSlot:
let
bsi = dag.getExistingBlockIdAtSlot(boundarySlot).valueOr:
dag.handleUnexpectedLightClientError(boundarySlot)
break
bid = bsi.bid
if bid.slot >= lowSlot:
dag.lcDataStore.db.putCurrentSyncCommitteeBranch(
bid.slot, dag.getLightClientData(bid).current_sync_committee_branch)
boundarySlot = bid.slot.nextEpochBoundarySlot
if boundarySlot < SLOTS_PER_EPOCH:
break
boundarySlot -= SLOTS_PER_EPOCH
# Seal sync committee periods for which data can no longer improve further
let
oldFinalizedPeriod = oldFinalizedHead.slot.sync_committee_period
newFinalizedPeriod = dag.finalizedHead.slot.sync_committee_period
if newFinalizedPeriod > oldFinalizedPeriod:
for period in countdown(newFinalizedPeriod - 1, oldFinalizedPeriod):
if dag.lcDataStore.cache.tailSlot > period.start_slot:
break
debug "Best LC update sealed",
period, update = dag.lcDataStore.db.getBestUpdate(period)
dag.lcDataStore.db.sealPeriod(period)
# Prune light client data that is no longer referrable by future updates
var bidsToDelete: seq[BlockId]
for bid, data in dag.lcDataStore.cache.data:
if bid.slot >= dag.finalizedHead.blck.slot:
continue
bidsToDelete.add bid
for bid in bidsToDelete:
dag.lcDataStore.cache.data.del bid
# Prune seal tracking data that is no longer relevant
let targetTailPeriod = dag.targetLightClientTailSlot.sync_committee_period
dag.lcDataStore.db.keepPeriodsFrom(targetTailPeriod)
# Prune best `LightClientUpdate` referring to non-finalized sync committees
# that are no longer relevant, i.e., orphaned or too old
let firstNonFinalizedPeriod = dag.firstNonFinalizedPeriod
var keysToDelete: seq[(SyncCommitteePeriod, Eth2Digest)]
for (period, committeeRoot) in dag.lcDataStore.cache.pendingBest.keys:
if period < firstNonFinalizedPeriod:
keysToDelete.add (period, committeeRoot)
for key in keysToDelete:
dag.lcDataStore.cache.pendingBest.del key
proc getLightClientBootstrap*(
dag: ChainDAGRef,
blockRoot: Eth2Digest): Opt[altair.LightClientBootstrap] =
if not dag.lcDataStore.serve:
return err()
let bdata = dag.getForkedBlock(blockRoot).valueOr:
debug "LC bootstrap unavailable: Block not found", blockRoot
return err()
withBlck(bdata):
let slot = blck.message.slot
when stateFork >= BeaconStateFork.Altair:
if slot < dag.targetLightClientTailSlot:
debug "LC bootstrap unavailable: Block too old", slot
return err()
if slot > dag.finalizedHead.blck.slot:
debug "LC bootstrap unavailable: Not finalized", blockRoot
return err()
var branch = dag.lcDataStore.db.getCurrentSyncCommitteeBranch(slot)
if branch.isZeroMemory:
if dag.lcDataStore.importMode == LightClientDataImportMode.OnDemand:
let bsi = ? dag.getExistingBlockIdAtSlot(slot)
var tmpState = assignClone(dag.headState)
dag.withUpdatedExistingState(tmpState[], bsi) do:
branch = withState(state):
when stateFork >= BeaconStateFork.Altair:
state.data.build_proof(altair.CURRENT_SYNC_COMMITTEE_INDEX).get
else: raiseAssert "Unreachable"
do: return err()
dag.lcDataStore.db.putCurrentSyncCommitteeBranch(slot, branch)
else:
debug "LC bootstrap unavailable: Data not cached", slot
return err()
let period = slot.sync_committee_period
var tmpState = assignClone(dag.headState)
var bootstrap {.noinit.}: altair.LightClientBootstrap
bootstrap.header =
blck.toBeaconBlockHeader()
bootstrap.current_sync_committee =
? dag.existingCurrentSyncCommitteeForPeriod(tmpState[], period)
bootstrap.current_sync_committee_branch =
branch
return ok bootstrap
else:
debug "LC bootstrap unavailable: Block before Altair", slot
return err()
proc getLightClientUpdateForPeriod*(
dag: ChainDAGRef,
period: SyncCommitteePeriod): Option[altair.LightClientUpdate] =
if not dag.lcDataStore.serve:
return
if dag.lcDataStore.importMode == LightClientDataImportMode.OnDemand:
if dag.initLightClientUpdateForPeriod(period).isErr:
return
result = some(dag.lcDataStore.db.getBestUpdate(period))
let numParticipants = countOnes(result.get.sync_aggregate.sync_committee_bits)
if numParticipants < MIN_SYNC_COMMITTEE_PARTICIPANTS:
result.reset()
proc getLightClientFinalityUpdate*(
dag: ChainDAGRef): Option[altair.LightClientFinalityUpdate] =
if not dag.lcDataStore.serve:
return
result = some(dag.lcDataStore.cache.latest)
let numParticipants = countOnes(result.get.sync_aggregate.sync_committee_bits)
if numParticipants < MIN_SYNC_COMMITTEE_PARTICIPANTS:
result.reset()
proc getLightClientOptimisticUpdate*(
dag: ChainDAGRef): Option[altair.LightClientOptimisticUpdate] =
if not dag.lcDataStore.serve:
return
result = some(dag.lcDataStore.cache.latest.toOptimistic)
let numParticipants = countOnes(result.get.sync_aggregate.sync_committee_bits)
if numParticipants < MIN_SYNC_COMMITTEE_PARTICIPANTS:
result.reset()