const EthQuery = require('ethjs-query') const Transaction = require('ethereumjs-tx') const normalize = require('eth-sig-util').normalize const { hexToBn, BnMultiplyByFraction, bnToHex, } = require('./util') /* tx-utils are utility methods for Transaction manager its passed ethquery and used to do things like calculate gas of a tx. */ module.exports = class txProvideUtil { constructor (provider) { this.query = new EthQuery(provider) } async analyzeGasUsage (txMeta) { const block = await this.query.getBlockByNumber('latest', true) const estimatedGasHex = await this.estimateTxGas(txMeta, block.gasLimit) this.setTxGas(txMeta, block.gasLimit, estimatedGasHex) return txMeta } async estimateTxGas (txMeta, blockGasLimitHex) { const txParams = txMeta.txParams // check if gasLimit is already specified txMeta.gasLimitSpecified = Boolean(txParams.gas) // if not, fallback to block gasLimit if (!txMeta.gasLimitSpecified) { const blockGasLimitBN = hexToBn(blockGasLimitHex) const saferGasLimitBN = BnMultiplyByFraction(blockGasLimitBN, 19, 20) txParams.gas = bnToHex(saferGasLimitBN) } // run tx, see if it will OOG return this.query.estimateGas(txParams) } setTxGas (txMeta, blockGasLimitHex, estimatedGasHex) { txMeta.estimatedGas = estimatedGasHex const txParams = txMeta.txParams // if gasLimit was specified and doesnt OOG, // use original specified amount if (txMeta.gasLimitSpecified) { txMeta.estimatedGas = txParams.gas return } // if gasLimit not originally specified, // try adding an additional gas buffer to our estimation for safety const recommendedGasHex = this.addGasBuffer(txMeta.estimatedGas, blockGasLimitHex) txParams.gas = recommendedGasHex return } addGasBuffer (initialGasLimitHex, blockGasLimitHex) { const initialGasLimitBn = hexToBn(initialGasLimitHex) const blockGasLimitBn = hexToBn(blockGasLimitHex) const upperGasLimitBn = blockGasLimitBn.muln(0.9) const bufferedGasLimitBn = initialGasLimitBn.muln(1.5) // if initialGasLimit is above blockGasLimit, dont modify it if (initialGasLimitBn.gt(upperGasLimitBn)) return bnToHex(initialGasLimitBn) // if bufferedGasLimit is below blockGasLimit, use bufferedGasLimit if (bufferedGasLimitBn.lt(upperGasLimitBn)) return bnToHex(bufferedGasLimitBn) // otherwise use blockGasLimit return bnToHex(upperGasLimitBn) } // builds ethTx from txParams object buildEthTxFromParams (txParams) { // normalize values txParams.to = normalize(txParams.to) txParams.from = normalize(txParams.from) txParams.value = normalize(txParams.value) txParams.data = normalize(txParams.data) txParams.gas = normalize(txParams.gas || txParams.gasLimit) txParams.gasPrice = normalize(txParams.gasPrice) txParams.nonce = normalize(txParams.nonce) // build ethTx log.info(`Prepared tx for signing: ${JSON.stringify(txParams)}`) const ethTx = new Transaction(txParams) return ethTx } async publishTransaction (rawTx) { return await this.query.sendRawTransaction(rawTx) } async validateTxParams (txParams) { if (('value' in txParams) && txParams.value.indexOf('-') === 0) { throw new Error(`Invalid transaction value of ${txParams.value} not a positive number.`) } } }