import std/[deques, tables, hashes, options, strformat, strutils], chronos, web3, web3/ethtypes as web3Types, json, chronicles, eth/common/eth_types, eth/async_utils, spec/[datatypes, digest, crypto, beaconstate, helpers], ssz, beacon_chain_db, network_metadata, merkle_minimal, beacon_node_status export web3Types contract(DepositContract): proc deposit(pubkey: Bytes48, withdrawalCredentials: Bytes32, signature: Bytes96, deposit_data_root: FixedBytes[32]) proc get_deposit_root(): FixedBytes[32] proc get_deposit_count(): Bytes8 proc DepositEvent(pubkey: Bytes48, withdrawalCredentials: Bytes32, amount: Bytes8, signature: Bytes96, index: Bytes8) {.event.} # TODO # The raises list of this module are still not usable due to general # Exceptions being reported from Chronos's asyncfutures2. type Eth1BlockNumber* = uint64 Eth1BlockTimestamp* = uint64 Eth1BlockHeader = web3Types.BlockHeader Database* = object Eth1Block* = ref object number*: Eth1BlockNumber timestamp*: Eth1BlockTimestamp deposits*: seq[Deposit] voteData*: Eth1Data activeValidatorsCount*: uint64 Eth1Chain* = object knownStart: Eth1Data blocks: Deque[Eth1Block] blocksByHash: Table[BlockHash, Eth1Block] Eth1Monitor* = ref object db: BeaconChainDB preset: RuntimePreset dataProvider: Web3DataProviderRef latestEth1BlockNumber: Eth1BlockNumber eth1Progress: AsyncEvent eth1Chain: Eth1Chain genesisState: NilableBeaconStateRef genesisStateFut: Future[void] runFut: Future[void] Web3DataProvider* = object url: string web3: Web3 ns: Sender[DepositContract] blockHeadersSubscription: Subscription Web3DataProviderRef* = ref Web3DataProvider ReorgDepthLimitExceeded = object of CatchableError CorruptDataProvider = object of CatchableError DisconnectHandler* = proc () {.gcsafe, raises: [Defect].} DepositEventHandler* = proc ( pubkey: Bytes48, withdrawalCredentials: Bytes32, amount: Bytes8, signature: Bytes96, merkleTreeIndex: Bytes8, j: JsonNode) {.raises: [Defect], gcsafe.} const web3Timeouts = 5.seconds hasDepositRootChecks = defined(with_deposit_root_checks) template depositContractAddress(m: Eth1Monitor): Eth1Address = m.dataProvider.ns.contractAddress template web3Url(m: Eth1Monitor): string = m.dataProvider.url proc fixupInfuraUrls*(web3Url: var string) = ## Converts HTTP and HTTPS Infura URLs to their WebSocket equivalents ## because we are missing a functional HTTPS client. let normalizedUrl = toLowerAscii(web3Url) var pos = 0 template skip(x: string): bool = if normalizedUrl.len - pos >= x.len and normalizedUrl.toOpenArray(pos, pos + x.len - 1) == x: pos += x.len true else: false if not (skip("https://") or skip("http://")): return let isMainnet = skip("mainnet") isGoerli = skip("goerli") if not (isMainnet or isGoerli): return if not skip(".infura.io/v3/"): return template infuraKey: string = normalizedUrl.substr(pos) web3Url = "wss://" & (if isMainnet: "mainnet" else: "goerli") & ".infura.io/ws/v3/" & infuraKey # TODO: Add preset validation # MIN_GENESIS_ACTIVE_VALIDATOR_COUNT should be larger than SLOTS_PER_EPOCH # doAssert SECONDS_PER_ETH1_BLOCK * preset.ETH1_FOLLOW_DISTANCE < GENESIS_DELAY, # "Invalid configuration: GENESIS_DELAY is set too low" # https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/validator.md#get_eth1_data func compute_time_at_slot(state: BeaconState, slot: Slot): uint64 = state.genesis_time + slot * SECONDS_PER_SLOT # https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/validator.md#get_eth1_data func voting_period_start_time*(state: BeaconState): uint64 = let eth1_voting_period_start_slot = state.slot - state.slot mod SLOTS_PER_ETH1_VOTING_PERIOD.uint64 compute_time_at_slot(state, eth1_voting_period_start_slot) # https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/validator.md#get_eth1_data func is_candidate_block(preset: RuntimePreset, blk: Eth1Block, period_start: uint64): bool = (blk.timestamp + SECONDS_PER_ETH1_BLOCK.uint64 * preset.ETH1_FOLLOW_DISTANCE <= period_start) and (blk.timestamp + SECONDS_PER_ETH1_BLOCK.uint64 * preset.ETH1_FOLLOW_DISTANCE * 2 >= period_start) func asEth2Digest*(x: BlockHash): Eth2Digest = Eth2Digest(data: array[32, byte](x)) template asBlockHash(x: Eth2Digest): BlockHash = BlockHash(x.data) func shortLog*(b: Eth1Block): string = &"{b.number}:{shortLog b.voteData.block_hash}" template findBlock*(eth1Chain: Eth1Chain, hash: BlockHash): Eth1Block = eth1Chain.blocksByHash.getOrDefault(hash, nil) template findBlock*(eth1Chain: Eth1Chain, eth1Data: Eth1Data): Eth1Block = getOrDefault(eth1Chain.blocksByHash, asBlockHash(eth1Data.block_hash), nil) func latestCandidateBlock(eth1Chain: Eth1Chain, preset: RuntimePreset, periodStart: uint64): Eth1Block = for i in countdown(eth1Chain.blocks.len - 1, 0): let blk = eth1Chain.blocks[i] if is_candidate_block(preset, blk, periodStart): return blk func popFirst(eth1Chain: var Eth1Chain) = let removed = eth1Chain.blocks.popFirst eth1Chain.blocksByHash.del removed.voteData.block_hash.asBlockHash func addBlock(eth1Chain: var Eth1Chain, newBlock: Eth1Block) = eth1Chain.blocks.addLast newBlock eth1Chain.blocksByHash[newBlock.voteData.block_hash.asBlockHash] = newBlock template hash*(x: Eth1Block): Hash = hash(x.voteData.block_hash.data) proc close*(p: Web3DataProviderRef): Future[void] {.async.} = if p.blockHeadersSubscription != nil: await p.blockHeadersSubscription.unsubscribe() await p.web3.close() proc getBlockByHash*(p: Web3DataProviderRef, hash: BlockHash): Future[BlockObject] = return p.web3.provider.eth_getBlockByHash(hash, false) proc getBlockByNumber*(p: Web3DataProviderRef, number: Eth1BlockNumber): Future[BlockObject] = return p.web3.provider.eth_getBlockByNumber(&"0x{number:X}", false) proc getBlockNumber(p: Web3DataProviderRef, hash: BlockHash): Future[Eth1BlockNumber] {.async.} = try: let blk = awaitWithTimeout(p.getBlockByHash(hash), web3Timeouts): return 0 return Eth1BlockNumber(blk.number) except CatchableError as exc: debug "Failed to get Eth1 block number from hash", hash = $hash, err = exc.msg raise exc template readJsonField(j: JsonNode, fieldName: string, ValueType: type): untyped = var res: ValueType fromJson(j[fieldName], fieldName, res) res proc depositEventsToBlocks(depositsList: JsonNode): seq[Eth1Block] = if depositsList.kind != JArray: raise newException(CatchableError, "Web3 provider didn't return a list of deposit events") var lastEth1Block: Eth1Block for logEvent in depositsList: let blockNumber = Eth1BlockNumber readJsonField(logEvent, "blockNumber", Quantity) blockHash = readJsonField(logEvent, "blockHash", BlockHash) logData = strip0xPrefix(logEvent["data"].getStr) if lastEth1Block == nil or lastEth1Block.number != blockNumber: lastEth1Block = Eth1Block( number: blockNumber, voteData: Eth1Data(block_hash: blockHash.asEth2Digest)) result.add lastEth1Block var pubkey: Bytes48 withdrawalCredentials: Bytes32 amount: Bytes8 signature: Bytes96 index: Bytes8 var offset = 0 offset += decode(logData, offset, pubkey) offset += decode(logData, offset, withdrawalCredentials) offset += decode(logData, offset, amount) offset += decode(logData, offset, signature) offset += decode(logData, offset, index) lastEth1Block.deposits.add Deposit( data: DepositData( pubkey: ValidatorPubKey.init(array[48, byte](pubkey)), withdrawal_credentials: Eth2Digest(data: array[32, byte](withdrawalCredentials)), amount: bytes_to_uint64(array[8, byte](amount)), signature: ValidatorSig.init(array[96, byte](signature)))) proc fetchTimestamp(p: Web3DataProviderRef, blk: Eth1Block) {.async.} = let web3block = await p.getBlockByHash(blk.voteData.block_hash.asBlockHash) blk.timestamp = Eth1BlockTimestamp web3block.timestamp when hasDepositRootChecks: type DepositContractDataStatus = enum Fetched VerifiedCorrect DepositRootIncorrect DepositRootUnavailable DepositCountIncorrect DepositCountUnavailable proc fetchDepositContractData(p: Web3DataProviderRef, blk: Eth1Block): Future[DepositContractDataStatus] {.async.} = let depositRoot = p.ns.get_deposit_root.call(blockNumber = blk.number) rawCount = p.ns.get_deposit_count.call(blockNumber = blk.number) try: let fetchedRoot = asEth2Digest(await depositRoot) if blk.voteData.deposit_root == default(Eth2Digest): blk.voteData.deposit_root = fetchedRoot result = Fetched elif blk.voteData.deposit_root == fetchedRoot: result = VerifiedCorrect else: result = DepositRootIncorrect except CatchableError as err: debug "Failed to fetch deposits root", blockNumber = blk.number, err = err.msg result = DepositRootUnavailable try: let fetchedCount = bytes_to_uint64(array[8, byte](await rawCount)) if blk.voteData.deposit_count == 0: blk.voteData.deposit_count = fetchedCount elif blk.voteData.deposit_count != fetchedCount: result = DepositCountIncorrect except CatchableError as err: debug "Failed to fetch deposits count", blockNumber = blk.number, err = err.msg result = DepositCountUnavailable proc onBlockHeaders*(p: Web3DataProviderRef, blockHeaderHandler: BlockHeaderHandler, errorHandler: SubscriptionErrorHandler) {.async.} = if p.blockHeadersSubscription != nil: await p.blockHeadersSubscription.unsubscribe() info "Waiting for new Eth1 block headers" p.blockHeadersSubscription = await p.web3.subscribeForBlockHeaders( blockHeaderHandler, errorHandler) func getDepositsRoot(m: DepositsMerkleizer): Eth2Digest = mixInLength(m.getFinalHash, int m.totalChunks) # https://github.com/ethereum/eth2.0-specs/blob/v1.0.0-rc.0/specs/phase0/validator.md#get_eth1_data proc getBlockProposalData*(m: Eth1Monitor, state: BeaconState, finalizedEth1Data: Eth1Data): (Eth1Data, seq[Deposit]) = var pendingDepositsCount = state.eth1_data.deposit_count - state.eth1_deposit_index # TODO To make block proposal cheaper, we can perform this action more regularly # (e.g. in BeaconNode.onSlot). But keep in mind that this action needs to be # performed only when there are validators attached to the node. let ourDepositsCount = m.db.deposits.len let targetDepositsCount = finalizedEth1Data.deposit_count let hasLatestDeposits = if ourDepositsCount >= targetDepositsCount: m.db.finalizedEth2DepositsMerkleizer.advanceTo(m.db, targetDepositsCount) let ourDepositsRoot = m.db.finalizedEth2DepositsMerkleizer.getDepositsRoot if (ourDepositsRoot != finalizedEth1Data.deposit_root): error "Corrupted deposits history. Producing block without deposits", ourDepositsRoot, targetDepositsRoot = finalizedEth1Data.deposit_root, depositsCount = ourDepositsCount false else: true else: warn "ETH1 deposits not fully synced. Producing block without deposits", targetDepositsCount, ourDepositsCount false let periodStart = voting_period_start_time(state) var otherVotesCountTable = initCountTable[Eth1Block]() for vote in state.eth1_data_votes: let eth1Block = m.eth1Chain.findBlock(vote) if eth1Block != nil and is_candidate_block(m.preset, eth1Block, periodStart) and eth1Block.voteData.deposit_count > state.eth1_data.deposit_count: otherVotesCountTable.inc eth1Block if otherVotesCountTable.len > 0: let (winningBlock, votes) = otherVotesCountTable.largest result[0] = winningBlock.voteData if uint64((votes + 1) * 2) > SLOTS_PER_ETH1_VOTING_PERIOD: pendingDepositsCount = winningBlock.voteData.deposit_count - state.eth1_deposit_index else: let latestBlock = m.eth1Chain.latestCandidateBlock(m.preset, periodStart) if latestBlock == nil: result[0] = state.eth1_data else: result[0] = latestBlock.voteData if pendingDepositsCount > 0 and hasLatestDeposits: let totalDepositsInNewBlock = min(MAX_DEPOSITS, pendingDepositsCount) var deposits = newSeq[Deposit](pendingDepositsCount) depositRoots = newSeq[Eth2Digest](pendingDepositsCount) depositsMerkleizerClone = clone m.db.finalizedEth2DepositsMerkleizer depositsMerkleizerClone.advanceTo(m.db, state.eth1_deposit_index) for i in 0 ..< totalDepositsInNewBlock: deposits[i].data = m.db.deposits.get(state.eth1_deposit_index + i) depositRoots[i] = hash_tree_root(deposits[i].data) let proofs = depositsMerkleizerClone.addChunksAndGenMerkleProofs(depositRoots) for i in 0 ..< totalDepositsInNewBlock: deposits[i].proof[0..31] = proofs.getProof(i.int) deposits[i].proof[32].data[0..7] = toBytesLE uint64(state.eth1_deposit_index + i + 1) swap(result[1], deposits) proc init*(T: type Eth1Monitor, db: BeaconChainDB, preset: RuntimePreset, web3Url: string, depositContractAddress: Eth1Address, depositContractDeployedAt: string, eth1Network: Option[Eth1Network]): Future[Result[T, string]] {.async.} = var web3Url = web3Url fixupInfuraUrls web3Url let web3 = try: await newWeb3(web3Url) except CatchableError as err: return err "Failed to setup web3 connection" let ns = web3.contractSender(DepositContract, depositContractAddress) dataProvider = Web3DataProviderRef(url: web3Url, web3: web3, ns: ns) if eth1Network.isSome: let providerNetwork = await web3.provider.net_version() expectedNetwork = case eth1Network.get of mainnet: "1" of rinkeby: "4" of goerli: "5" if expectedNetwork != providerNetwork: return err("The specified we3 provider is not attached to the " & $eth1Network.get & " network") let previouslyPersistedTo = db.getEth1PersistedTo() knownStart = previouslyPersistedTo.get: # `previouslyPersistedTo` wall null, we start from scratch let deployedAtHash = if depositContractDeployedAt.startsWith "0x": try: BlockHash.fromHex depositContractDeployedAt except ValueError: return err "Invalid hex value specified for deposit-contract-block" else: let blockNum = try: parseBiggestUInt depositContractDeployedAt except ValueError: return err "Invalid nummeric value for deposit-contract-block" try: let blk = await dataProvider.getBlockByNumber(blockNum) blk.hash except CatchableError: return err("Failed to obtain block hash for block number " & $blockNum) Eth1Data(block_hash: deployedAtHash.asEth2Digest, deposit_count: 0) return ok T( db: db, preset: preset, dataProvider: dataProvider, eth1Progress: newAsyncEvent(), eth1Chain: Eth1Chain(knownStart: knownStart)) proc allDepositsUpTo(m: Eth1Monitor, totalDeposits: uint64): seq[Deposit] = for i in 0'u64 ..< totalDeposits: result.add Deposit(data: m.db.deposits.get(i)) proc createGenesisState(m: Eth1Monitor, eth1Block: Eth1Block): BeaconStateRef = notice "Generating genesis state", blockNum = eth1Block.number, blockHash = eth1Block.voteData.block_hash, blockTimestamp = eth1Block.timestamp, totalDeposits = eth1Block.voteData.deposit_count, activeValidators = eth1Block.activeValidatorsCount var deposits = m.allDepositsUpTo(eth1Block.voteData.deposit_count) attachMerkleProofs deposits result = initialize_beacon_state_from_eth1( m.preset, eth1Block.voteData.block_hash, eth1Block.timestamp.uint64, deposits, {}) doAssert result.validators.lenu64 == eth1Block.activeValidatorsCount proc signalGenesis(m: Eth1Monitor, genesisState: BeaconStateRef) = m.genesisState = genesisState if not m.genesisStateFut.isNil: m.genesisStateFut.complete() m.genesisStateFut = nil template hasEnoughValidators(m: Eth1Monitor, blk: Eth1Block): bool = blk.activeValidatorsCount >= m.preset.MIN_GENESIS_ACTIVE_VALIDATOR_COUNT func isAfterMinGenesisTime(m: Eth1Monitor, blk: Eth1Block): bool = doAssert blk.timestamp != 0 let t = genesis_time_from_eth1_timestamp(m.preset, uint64 blk.timestamp) t >= m.preset.MIN_GENESIS_TIME func isGenesisCandidate(m: Eth1Monitor, blk: Eth1Block): bool = m.hasEnoughValidators(blk) and m.isAfterMinGenesisTime(blk) proc findGenesisBlockInRange(m: Eth1Monitor, startBlock, endBlock: Eth1Block): Future[Eth1Block] {.async.} = doAssert startBlock.timestamp != 0 and not m.isAfterMinGenesisTime(startBlock) doAssert endBlock.timestamp != 0 and m.isAfterMinGenesisTime(endBlock) doAssert m.hasEnoughValidators(startBlock) doAssert m.hasEnoughValidators(endBlock) var startBlock = startBlock endBlock = endBlock depositData = startBlock.voteData activeValidatorsCountDuringRange = startBlock.activeValidatorsCount while startBlock.number + 1 < endBlock.number: let MIN_GENESIS_TIME = m.preset.MIN_GENESIS_TIME startBlockTime = genesis_time_from_eth1_timestamp(m.preset, startBlock.timestamp) secondsPerBlock = float(endBlock.timestamp - startBlock.timestamp) / float(endBlock.number - startBlock.number) blocksToJump = max(float(MIN_GENESIS_TIME - startBlockTime) / secondsPerBlock, 1.0) candidateNumber = min(endBlock.number - 1, startBlock.number + blocksToJump.uint64) candidateBlock = await m.dataProvider.getBlockByNumber(candidateNumber) var candidateAsEth1Block = Eth1Block(number: candidateBlock.number.uint64, timestamp: candidateBlock.timestamp.uint64, voteData: depositData) candidateAsEth1Block.voteData.block_hash = candidateBlock.hash.asEth2Digest let candidateGenesisTime = genesis_time_from_eth1_timestamp( m.preset, candidateBlock.timestamp.uint64) notice "Probing possible genesis block", `block` = candidateBlock.number.uint64, candidateGenesisTime if candidateGenesisTime < MIN_GENESIS_TIME: startBlock = candidateAsEth1Block else: endBlock = candidateAsEth1Block if endBlock.activeValidatorsCount == 0: endBlock.activeValidatorsCount = activeValidatorsCountDuringRange return endBlock proc safeCancel(fut: var Future[void]) = if not fut.isNil and not fut.finished: fut.cancel() fut = nil proc stop*(m: Eth1Monitor) = safeCancel m.runFut proc waitGenesis*(m: Eth1Monitor): Future[BeaconStateRef] {.async.} = if m.genesisState.isNil: if m.genesisStateFut.isNil: m.genesisStateFut = newFuture[void]("waitGenesis") info "Awaiting genesis event" await m.genesisStateFut m.genesisStateFut = nil if m.genesisState != nil: return m.genesisState else: doAssert bnStatus == BeaconNodeStatus.Stopping return new BeaconStateRef # cannot return nil... proc syncBlockRange(m: Eth1Monitor, fromBlock, toBlock: Eth1BlockNumber) {.async.} = var currentBlock = fromBlock while currentBlock <= toBlock: var depositLogs: JsonNode = nil var blocksPerRequest = 5000'u64 # This is roughly a day of Eth1 blocks while true: let requestToBlock = min(toBlock, currentBlock + blocksPerRequest - 1) debug "Obtaining deposit log events", fromBlock = currentBlock, toBlock = requestToBlock try: depositLogs = await m.dataProvider.ns.getJsonLogs( DepositEvent, fromBlock = some blockId(currentBlock), toBlock = some blockId(requestToBlock)) currentBlock = requestToBlock + 1 break except CatchableError as err: blocksPerRequest = blocksPerRequest div 2 if blocksPerRequest == 0: raise err let eth1Blocks = depositEventsToBlocks(depositLogs) for i in 0 ..< eth1Blocks.len: # TODO: The DB operations should be executed as a transaction here let blk = eth1Blocks[i] for deposit in blk.deposits: m.db.processDeposit(deposit.data) blk.voteData.deposit_count = m.db.finalizedEth1DepositsMerkleizer.totalChunks blk.voteData.deposit_root = m.db.finalizedEth1DepositsMerkleizer.getDepositsRoot blk.activeValidatorsCount = m.db.immutableValidatorData.lenu64 m.eth1Chain.addBlock blk if eth1Blocks.len > 0: let lastBlock = eth1Blocks[^1] when hasDepositRootChecks: let status = await m.dataProvider.fetchDepositContractData(lastBlock) debug "Deposit root checks", status, ourCount = lastBlock.voteData.deposit_count, ourRoot = lastBlock.voteData.deposit_root m.db.putEth1PersistedTo lastBlock.voteData notice "Eth1 sync progress", blockNumber = lastBlock.number, depositsProcessed = lastBlock.voteData.deposit_count if m.genesisStateFut != nil and m.hasEnoughValidators(lastBlock): await m.dataProvider.fetchTimestamp(lastBlock) if m.isAfterMinGenesisTime(lastBlock): var genesisBlockIdx = m.eth1Chain.blocks.len - 1 for i in 1 ..< eth1Blocks.len: let idx = (m.eth1Chain.blocks.len - 1) - i let blk = m.eth1Chain.blocks[idx] await m.dataProvider.fetchTimestamp(blk) if m.isGenesisCandidate(blk): genesisBlockIdx = idx else: break # We have a candidate state on our hands, but our current Eth1Chain # may consist only of blocks that have deposits attached to them # while the real genesis may have happened in a block without any # deposits (triggered by MIN_GENESIS_TIME). # # This can happen when the beacon node is launched after the genesis # event. We take a short cut when constructing the initial Eth1Chain # by downloading only deposit log entries. Thus, we'll see all the # blocks with deposits, but not the regular blocks in between. # # We'll handle this special case below by examing whether we are in # this potential scenario and we'll use a fast guessing algorith to # discover the ETh1 block with minimal valid genesis time. var genesisBlock = m.eth1Chain.blocks[genesisBlockIdx] if genesisBlockIdx > 0: let genesisParent = m.eth1Chain.blocks[genesisBlockIdx - 1] if genesisParent.timestamp == 0: await m.dataProvider.fetchTimestamp(genesisParent) if m.hasEnoughValidators(genesisParent) and genesisBlock.number - genesisParent.number > 1: genesisBlock = await m.findGenesisBlockInRange(genesisParent, genesisBlock) m.signalGenesis m.createGenesisState(genesisBlock) proc handleEth1Progress(m: Eth1Monitor) {.async.} = # ATTENTION! # Please note that this code is using an async event in order # to guarantee the strict serial order of processing of deposits. # If we had the same code embedded in the new block headers event, # it could easily re-order the steps due to the interruptible # interleaved execution of async code. var eth1SyncedTo = await m.dataProvider.getBlockNumber( m.eth1Chain.knownStart.block_hash.asBlockHash) while true: if bnStatus == BeaconNodeStatus.Stopping: if not m.genesisStateFut.isNil: m.genesisStateFut.complete() m.genesisStateFut = nil m.stop() return await m.eth1Progress.wait() m.eth1Progress.clear() if m.latestEth1BlockNumber <= m.preset.ETH1_FOLLOW_DISTANCE: continue let targetBlock = m.latestEth1BlockNumber - m.preset.ETH1_FOLLOW_DISTANCE if targetBlock <= eth1SyncedTo: continue await m.syncBlockRange(eth1SyncedTo + 1, targetBlock) eth1SyncedTo = targetBlock while m.eth1Chain.blocks.len > 0: # We'll clean old blocks that can no longer be voting candidates. # Technically, we should check that the block is outside of the current # voting period as determined by its timestamp, but we'll approximate # this by requiring a much larger difference in block numbers. # (i.e. twice the follow distance). let earliestBlock = m.eth1Chain.blocks.peekFirst if earliestBlock.number < targetBlock and targetBlock - earliestBlock.number < m.preset.ETH1_FOLLOW_DISTANCE * 2: break m.eth1Chain.popFirst() proc run(m: Eth1Monitor, delayBeforeStart: Duration) {.async.} = if delayBeforeStart != ZeroDuration: await sleepAsync(delayBeforeStart) info "Starting Eth1 deposit contract monitoring", contract = $m.depositContractAddress, url = m.web3Url await m.dataProvider.onBlockHeaders do (blk: Eth1BlockHeader) {.raises: [Defect], gcsafe.}: try: if blk.number.uint64 > m.latestEth1BlockNumber: m.latestEth1BlockNumber = blk.number.uint64 m.eth1Progress.fire() except Exception: # TODO Investigate why this exception is being raised raiseAssert "AsyncEvent.fire should not raise exceptions" do (err: CatchableError): debug "Error while processing Eth1 block headers subscription", err = err.msg await m.handleEth1Progress() proc start(m: Eth1Monitor, delayBeforeStart: Duration) = if m.runFut.isNil: let runFut = m.run(delayBeforeStart) m.runFut = runFut runFut.addCallback do (p: pointer): if runFut.failed: if runFut.error[] of CatchableError: if runFut == m.runFut: error "Eth1 chain monitoring failure, restarting", err = runFut.error.msg m.stop() m.start(5.seconds) else: fatal "Fatal exception reached", err = runFut.error.msg quit 1 proc start*(m: Eth1Monitor) {.inline.} = m.start(0.seconds) proc getEth1BlockHash*(url: string, blockId: RtBlockIdentifier): Future[BlockHash] {.async.} = let web3 = await newWeb3(url) try: let blk = await web3.provider.eth_getBlockByNumber(blockId, false) return blk.hash finally: await web3.close()