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57 lines
1.8 KiB
57 lines
1.8 KiB
const EthQuery = require('eth-query')
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class NonceTracker {
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constructor ({ blockTracker, provider, getPendingTransactions }) {
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this.blockTracker = blockTracker
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this.ethQuery = new EthQuery(provider)
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this.getPendingTransactions = getPendingTransactions
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this.lockMap = {}
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}
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// releaseLock must be called
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// releaseLock must be called after adding signed tx to pending transactions (or discarding)
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async getNonceLock (address) {
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// await lock free
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await this.lockMap[address]
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// take lock
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const releaseLock = this._takeLock(address)
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// calculate next nonce
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const currentBlock = await this._getCurrentBlock()
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const blockNumber = currentBlock.number
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const pendingTransactions = this.getPendingTransactions(address)
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const baseCount = await this._getTxCount(address, blockNumber)
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const nextNonce = parseInt(baseCount) + pendingTransactions.length
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// return next nonce and release cb
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return { nextNonce: nextNonce.toString(16), releaseLock }
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}
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async _getCurrentBlock () {
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const currentBlock = this.blockTracker.getCurrentBlock()
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if (currentBlock) return currentBlock
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return await Promise((reject, resolve) => {
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this.blockTracker.once('latest', resolve)
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})
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}
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_takeLock (lockId) {
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let releaseLock = null
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// create and store lock
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const lock = new Promise((resolve, reject) => { releaseLock = resolve })
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this.lockMap[lockId] = lock
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// setup lock teardown
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lock.then(() => delete this.lockMap[lockId])
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return releaseLock
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}
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_getTxCount (address, blockNumber) {
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return new Promise((resolve, reject) => {
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this.ethQuery.getTransactionCount(address, blockNumber, (err, result) => {
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err ? reject(err) : resolve(result)
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})
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})
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}
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}
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module.exports = NonceTracker
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