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74 lines
2.3 KiB
74 lines
2.3 KiB
const async = require('async')
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const EthQuery = require('eth-query')
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const ethUtil = require('ethereumjs-util')
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const BN = ethUtil.BN
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/*
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tx-utils are utility methods for Transaction manager
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its passed a provider and that is passed to ethquery
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and used to do things like calculate gas of a tx.
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*/
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module.exports = class txProviderUtils {
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constructor (provider) {
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this.provider = provider
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this.query = new EthQuery(provider)
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}
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analyzeGasUsage (txData, cb) {
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var self = this
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this.query.getBlockByNumber('latest', true, (err, block) => {
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if (err) return cb(err)
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async.waterfall([
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self.estimateTxGas.bind(self, txData, block.gasLimit),
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self.setTxGas.bind(self, txData, block.gasLimit),
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], cb)
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})
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}
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estimateTxGas (txData, blockGasLimitHex, cb) {
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const txParams = txData.txParams
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// check if gasLimit is already specified
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txData.gasLimitSpecified = Boolean(txParams.gas)
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// if not, fallback to block gasLimit
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if (!txData.gasLimitSpecified) {
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txParams.gas = blockGasLimitHex
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}
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// run tx, see if it will OOG
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this.query.estimateGas(txParams, cb)
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}
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setTxGas (txData, blockGasLimitHex, estimatedGasHex, cb) {
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txData.estimatedGas = estimatedGasHex
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const txParams = txData.txParams
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// if gasLimit was specified and doesnt OOG,
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// use original specified amount
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if (txData.gasLimitSpecified) {
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txData.estimatedGas = txParams.gas
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cb()
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return
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}
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// if gasLimit not originally specified,
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// try adding an additional gas buffer to our estimation for safety
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const estimatedGasBn = new BN(ethUtil.stripHexPrefix(txData.estimatedGas), 16)
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const blockGasLimitBn = new BN(ethUtil.stripHexPrefix(blockGasLimitHex), 16)
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const estimationWithBuffer = new BN(this.addGasBuffer(estimatedGasBn), 16)
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// added gas buffer is too high
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if (estimationWithBuffer.gt(blockGasLimitBn)) {
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txParams.gas = txData.estimatedGas
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// added gas buffer is safe
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} else {
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const gasWithBufferHex = ethUtil.intToHex(estimationWithBuffer)
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txParams.gas = gasWithBufferHex
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}
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cb()
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return
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}
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addGasBuffer (gas) {
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const gasBuffer = new BN('100000', 10)
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const bnGas = new BN(ethUtil.stripHexPrefix(gas), 16)
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const correct = bnGas.add(gasBuffer)
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return ethUtil.addHexPrefix(correct.toString(16))
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}
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}
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