tornado-relayer/src/worker.js

const Web3 = require('web3')
const { GasPriceOracle } = require('gas-price-oracle')
const { toBN, toWei, fromWei, toHex } = require('web3-utils')

const proxyLightABI = require('../abis/proxyLightABI.json')
const { queue } = require('./queue')
const { getInstance, fromDecimals } = require('./utils')
const { jobType, status } = require('./constants')
const {
  netId,
  gasPrices: GAS_PRICES,
  gasLimits,
  instances,
  privateKey,
  proxyLight,
  httpRpcUrl,
  tornadoServiceFee,
} = require('./config')
const { TxManager } = require('tx-manager')

let web3
let currentTx
let currentJob
let txManager
let gasPriceOracle

function start() {
  try {
    web3 = new Web3(httpRpcUrl)
    const { CONFIRMATIONS, MAX_GAS_PRICE } = process.env
    const gasPriceOracleConfig = {
      chainId: netId,
      defaultFallbackGasPrices: GAS_PRICES,
    }

    gasPriceOracle = new GasPriceOracle(gasPriceOracleConfig)

    txManager = new TxManager({
      privateKey,
      rpcUrl: httpRpcUrl,
      config: { CONFIRMATIONS, MAX_GAS_PRICE, THROW_ON_REVERT: false },
      gasPriceOracleConfig,
    })

    queue.process(processJob)
    console.log('Worker started')
  } catch (e) {
    console.error('error on start worker', e.message)
  }
}

async function getGasPrices() {
  const networksWithOracle = [56, 137]
  if (networksWithOracle.includes(netId)) {
    return await gasPriceOracle.gasPrices()
  }

  return GAS_PRICES
}

async function checkTornadoFee({ args, contract }) {
  const { currency, amount } = getInstance(contract)
  const { decimals } = instances[currency]
  const fee = toBN(args[4])

  const { fast } = await getGasPrices()

  const expense = toBN(toWei(fast.toString(), 'gwei')).mul(toBN(gasLimits[jobType.TORNADO_WITHDRAW]))
  const feePercent = toBN(fromDecimals(amount, decimals))
    .mul(toBN(parseInt(tornadoServiceFee * 1e10)))
    .div(toBN(1e10 * 100))
  const desiredFee = expense.add(feePercent)

  console.log(
    'sent fee, desired fee, feePercent',
    fromWei(fee.toString()),
    fromWei(desiredFee.toString()),
    fromWei(feePercent.toString()),
  )
  if (fee.lt(desiredFee)) {
    throw new Error('Provided fee is not enough. Probably it is a Gas Price spike, try to resubmit.')
  }
}

async function getTxObject({ data }) {
  const contract = new web3.eth.Contract(proxyLightABI, proxyLight)

  const calldata = contract.methods.withdraw(data.contract, data.proof, ...data.args).encodeABI()

  const { fast } = await getGasPrices()

  return {
    value: data.args[5],
    to: contract._address,
    data: calldata,
    gasLimit: gasLimits[jobType.TORNADO_WITHDRAW],
    gasPrice: toHex(toWei(fast.toString(), 'gwei')),
  }
}

async function processJob(job) {
  try {
    if (!jobType[job.data.type]) {
      throw new Error(`Unknown job type: ${job.data.type}`)
    }
    currentJob = job
    await updateStatus(status.ACCEPTED)
    console.log(`Start processing a new ${job.data.type} job #${job.id}`)
    await submitTx(job)
  } catch (e) {
    console.error('processJob', e.message)
    await updateStatus(status.FAILED)
    throw e
  }
}

async function submitTx(job) {
  await checkTornadoFee(job.data)
  currentTx = await txManager.createTx(await getTxObject(job))

  try {
    const receipt = await currentTx
      .send()
      .on('transactionHash', txHash => {
        updateTxHash(txHash)
        updateStatus(status.SENT)
      })
      .on('mined', receipt => {
        console.log('Mined in block', receipt.blockNumber)
        updateStatus(status.MINED)
      })
      .on('confirmations', updateConfirmations)

    if (receipt.status === 1) {
      await updateStatus(status.CONFIRMED)
    } else {
      throw new Error('Submitted transaction failed')
    }
  } catch (e) {
    // todo this could result in duplicated error logs
    // todo handle a case where account tree is still not up to date (wait and retry)?
    throw new Error(`Revert by smart contract ${e.message}`)
  }
}

async function updateTxHash(txHash) {
  console.log(`A new successfully sent tx ${txHash}`)
  currentJob.data.txHash = txHash
  await currentJob.update(currentJob.data)
}

async function updateConfirmations(confirmations) {
  console.log(`Confirmations count ${confirmations}`)
  currentJob.data.confirmations = confirmations
  await currentJob.update(currentJob.data)
}

async function updateStatus(status) {
  console.log(`Job status updated ${status}`)
  currentJob.data.status = status
  await currentJob.update(currentJob.data)
}

start()