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Diffstat (limited to 'app/scripts/controllers/transactions/tx-gas-utils.js')
| -rw-r--r-- | app/scripts/controllers/transactions/tx-gas-utils.js | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/app/scripts/controllers/transactions/tx-gas-utils.js b/app/scripts/controllers/transactions/tx-gas-utils.js new file mode 100644 index 000000000..36b5cdbc9 --- /dev/null +++ b/app/scripts/controllers/transactions/tx-gas-utils.js @@ -0,0 +1,129 @@ +const EthQuery = require('ethjs-query') +const { + hexToBn, + BnMultiplyByFraction, + bnToHex, +} = require('../../lib/util') +const { addHexPrefix } = require('ethereumjs-util') +const SIMPLE_GAS_COST = '0x5208' // Hex for 21000, cost of a simple send. + +/** +tx-gas-utils are gas utility methods for Transaction manager +its passed ethquery +and used to do things like calculate gas of a tx. +@param {Object} provider - A network provider. +*/ + +class TxGasUtil { + + constructor (provider) { + this.query = new EthQuery(provider) + } + + /** + @param txMeta {Object} - the txMeta object + @returns {object} the txMeta object with the gas written to the txParams + */ + async analyzeGasUsage (txMeta) { + const block = await this.query.getBlockByNumber('latest', true) + let estimatedGasHex + try { + estimatedGasHex = await this.estimateTxGas(txMeta, block.gasLimit) + } catch (err) { + const simulationFailed = ( + err.message.includes('Transaction execution error.') || + err.message.includes('gas required exceeds allowance or always failing transaction') + ) + if (simulationFailed) { + txMeta.simulationFails = true + return txMeta + } + } + this.setTxGas(txMeta, block.gasLimit, estimatedGasHex) + return txMeta + } + + /** + Estimates the tx's gas usage + @param txMeta {Object} - the txMeta object + @param blockGasLimitHex {string} - hex string of the block's gas limit + @returns {string} the estimated gas limit as a hex string + */ + async estimateTxGas (txMeta, blockGasLimitHex) { + const txParams = txMeta.txParams + + // check if gasLimit is already specified + txMeta.gasLimitSpecified = Boolean(txParams.gas) + + // if it is, use that value + if (txMeta.gasLimitSpecified) { + return txParams.gas + } + + // if recipient has no code, gas is 21k max: + const recipient = txParams.to + const hasRecipient = Boolean(recipient) + let code + if (recipient) code = await this.query.getCode(recipient) + + if (hasRecipient && (!code || code === '0x')) { + txParams.gas = SIMPLE_GAS_COST + txMeta.simpleSend = true // Prevents buffer addition + return SIMPLE_GAS_COST + } + + // if not, fall back to block gasLimit + const blockGasLimitBN = hexToBn(blockGasLimitHex) + const saferGasLimitBN = BnMultiplyByFraction(blockGasLimitBN, 19, 20) + txParams.gas = bnToHex(saferGasLimitBN) + + // run tx + return await this.query.estimateGas(txParams) + } + + /** + Writes the gas on the txParams in the txMeta + @param txMeta {Object} - the txMeta object to write to + @param blockGasLimitHex {string} - the block gas limit hex + @param estimatedGasHex {string} - the estimated gas hex + */ + setTxGas (txMeta, blockGasLimitHex, estimatedGasHex) { + txMeta.estimatedGas = addHexPrefix(estimatedGasHex) + const txParams = txMeta.txParams + + // if gasLimit was specified and doesnt OOG, + // use original specified amount + if (txMeta.gasLimitSpecified || txMeta.simpleSend) { + 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 + } + + /** + Adds a gas buffer with out exceeding the block gas limit + + @param initialGasLimitHex {string} - the initial gas limit to add the buffer too + @param blockGasLimitHex {string} - the block gas limit + @returns {string} the buffered gas limit as a hex string + */ + 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) + } +} + +module.exports = TxGasUtil
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