111 lines
2.6 KiB
JavaScript
111 lines
2.6 KiB
JavaScript
const ObservableStore = require('obs-store')
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const extend = require('xtend')
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const BN = require('ethereumjs-util').BN
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const EthQuery = require('eth-query')
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class RecentBlocksController {
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constructor (opts = {}) {
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const { blockTracker, provider } = opts
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this.blockTracker = blockTracker
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this.ethQuery = new EthQuery(provider)
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this.historyLength = opts.historyLength || 40
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const initState = extend({
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recentBlocks: [],
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}, opts.initState)
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this.store = new ObservableStore(initState)
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this.blockTracker.on('block', this.processBlock.bind(this))
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this.backfill()
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}
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resetState () {
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this.store.updateState({
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recentBlocks: [],
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})
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}
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processBlock (newBlock) {
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const block = this.mapTransactionsToPrices(newBlock)
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const state = this.store.getState()
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state.recentBlocks.push(block)
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while (state.recentBlocks.length > this.historyLength) {
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state.recentBlocks.shift()
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}
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this.store.updateState(state)
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}
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backfillBlock (newBlock) {
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const block = this.mapTransactionsToPrices(newBlock)
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const state = this.store.getState()
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if (state.recentBlocks.length < this.historyLength) {
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state.recentBlocks.unshift(block)
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}
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this.store.updateState(state)
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}
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mapTransactionsToPrices (newBlock) {
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const block = extend(newBlock, {
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gasPrices: newBlock.transactions.map((tx) => {
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return tx.gasPrice
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}),
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})
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delete block.transactions
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return block
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}
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async backfill() {
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this.blockTracker.once('block', async (block) => {
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let blockNum = block.number
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let recentBlocks
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let state = this.store.getState()
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recentBlocks = state.recentBlocks
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while (recentBlocks.length < this.historyLength) {
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try {
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let blockNumBn = new BN(blockNum.substr(2), 16)
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const newNum = blockNumBn.subn(1).toString(10)
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const newBlock = await this.getBlockByNumber(newNum)
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if (newBlock) {
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this.backfillBlock(newBlock)
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blockNum = newBlock.number
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}
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state = this.store.getState()
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recentBlocks = state.recentBlocks
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} catch (e) {
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log.error(e)
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}
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await this.wait()
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}
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})
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}
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async wait () {
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return new Promise((resolve) => {
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setTimeout(resolve, 100)
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})
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}
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async getBlockByNumber (number) {
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const bn = new BN(number)
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return new Promise((resolve, reject) => {
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this.ethQuery.getBlockByNumber('0x' + bn.toString(16), true, (err, block) => {
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if (err) reject(err)
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resolve(block)
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})
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})
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}
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}
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module.exports = RecentBlocksController
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