const EventEmitter = require('safe-event-emitter') const log = require('loglevel') const EthQuery = require('ethjs-query') /** Event emitter utility class for tracking the transactions as they
go from a pending state to a confirmed (mined in a block) state

As well as continues broadcast while in the pending state
@param config {object} - non optional configuration object consists of: @param {Object} config.provider - A network provider. @param {Object} config.nonceTracker see nonce tracker @param {function} config.getPendingTransactions a function for getting an array of transactions, @param {function} config.publishTransaction a async function for publishing raw transactions, @class */ class PendingTransactionTracker extends EventEmitter { constructor (config) { super() this.droppedBuffer = {} this.query = new EthQuery(config.provider) this.nonceTracker = config.nonceTracker this.getPendingTransactions = config.getPendingTransactions this.getCompletedTransactions = config.getCompletedTransactions this.publishTransaction = config.publishTransaction this.approveTransaction = config.approveTransaction this.confirmTransaction = config.confirmTransaction } /** checks the network for signed txs and releases the nonce global lock if it is */ async updatePendingTxs () { // in order to keep the nonceTracker accurate we block it while updating pending transactions const nonceGlobalLock = await this.nonceTracker.getGlobalLock() try { const pendingTxs = this.getPendingTransactions() await Promise.all(pendingTxs.map((txMeta) => this._checkPendingTx(txMeta))) } catch (err) { log.error('PendingTransactionTracker - Error updating pending transactions') log.error(err) } nonceGlobalLock.releaseLock() } /** Will resubmit any transactions who have not been confirmed in a block @param block {object} - a block object @emits tx:warning */ resubmitPendingTxs (blockNumber) { const pending = this.getPendingTransactions() // only try resubmitting if their are transactions to resubmit if (!pending.length) return pending.forEach((txMeta) => this._resubmitTx(txMeta, blockNumber).catch((err) => { /* Dont marked as failed if the error is a "known" transaction warning "there is already a transaction with the same sender-nonce but higher/same gas price" Also don't mark as failed if it has ever been broadcast successfully. A successful broadcast means it may still be mined. */ const errorMessage = err.message.toLowerCase() const isKnownTx = ( // geth errorMessage.includes('replacement transaction underpriced') || errorMessage.includes('known transaction') || // parity errorMessage.includes('gas price too low to replace') || errorMessage.includes('transaction with the same hash was already imported') || // other errorMessage.includes('gateway timeout') || errorMessage.includes('nonce too low') ) // ignore resubmit warnings, return early if (isKnownTx) return // encountered real error - transition to error state txMeta.warning = { error: errorMessage, message: 'There was an error when resubmitting this transaction.', } this.emit('tx:warning', txMeta, err) })) } /** resubmits the individual txMeta used in resubmitPendingTxs @param txMeta {Object} - txMeta object @param latestBlockNumber {string} - hex string for the latest block number @emits tx:retry @returns txHash {string} */ async _resubmitTx (txMeta, latestBlockNumber) { if (!txMeta.firstRetryBlockNumber) { this.emit('tx:block-update', txMeta, latestBlockNumber) } const firstRetryBlockNumber = txMeta.firstRetryBlockNumber || latestBlockNumber const txBlockDistance = Number.parseInt(latestBlockNumber, 16) - Number.parseInt(firstRetryBlockNumber, 16) const retryCount = txMeta.retryCount || 0 // Exponential backoff to limit retries at publishing if (txBlockDistance <= Math.pow(2, retryCount) - 1) return // Only auto-submit already-signed txs: if (!('rawTx' in txMeta)) return this.approveTransaction(txMeta.id) const rawTx = txMeta.rawTx const txHash = await this.publishTransaction(rawTx) // Increment successful tries: this.emit('tx:retry', txMeta) return txHash } /** Ask the network for the transaction to see if it has been include in a block @param txMeta {Object} - the txMeta object @emits tx:failed @emits tx:confirmed @emits tx:warning */ async _checkPendingTx (txMeta) { const txHash = txMeta.hash const txId = txMeta.id // Only check submitted txs if (txMeta.status !== 'submitted') return // extra check in case there was an uncaught error during the // signature and submission process if (!txHash) { const noTxHashErr = new Error('We had an error while submitting this transaction, please try again.') noTxHashErr.name = 'NoTxHashError' this.emit('tx:failed', txId, noTxHashErr) return } // If another tx with the same nonce is mined, set as dropped. const taken = await this._checkIfNonceIsTaken(txMeta) let dropped try { // check the network if the nonce is ahead the tx // and the tx has not been mined into a block dropped = await this._checkIftxWasDropped(txMeta) // the dropped buffer is in case we ask a node for the tx // that is behind the node we asked for tx count // IS A SECURITY FOR HITTING NODES IN INFURA THAT COULD GO OUT // OF SYNC. // on the next block event it will return fire as dropped if (dropped && !this.droppedBuffer[txHash]) { this.droppedBuffer[txHash] = true dropped = false } else if (dropped && this.droppedBuffer[txHash]) { // clean up delete this.droppedBuffer[txHash] } } catch (e) { log.error(e) } if (taken || dropped) { return this.emit('tx:dropped', txId) } // get latest transaction status try { const { blockNumber } = await this.query.getTransactionByHash(txHash) || {} if (blockNumber) { this.emit('tx:confirmed', txId) } } catch (err) { txMeta.warning = { error: err.message, message: 'There was a problem loading this transaction.', } this.emit('tx:warning', txMeta, err) } } /** checks to see if if the tx's nonce has been used by another transaction @param txMeta {Object} - txMeta object @emits tx:dropped @returns {boolean} */ async _checkIftxWasDropped (txMeta) { const { txParams: { nonce, from }, hash } = txMeta const nextNonce = await this.query.getTransactionCount(from) const { blockNumber } = await this.query.getTransactionByHash(hash) || {} if (!blockNumber && parseInt(nextNonce) > parseInt(nonce)) { return true } return false } /** checks to see if a confirmed txMeta has the same nonce @param txMeta {Object} - txMeta object @returns {boolean} */ async _checkIfNonceIsTaken (txMeta) { const address = txMeta.txParams.from const completed = this.getCompletedTransactions(address) const sameNonce = completed.filter((otherMeta) => { return otherMeta.txParams.nonce === txMeta.txParams.nonce }) return sameNonce.length > 0 } } module.exports = PendingTransactionTracker