mirror of
https://github.com/kremalicious/metamask-extension.git
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181 lines
5.8 KiB
JavaScript
181 lines
5.8 KiB
JavaScript
/* Account Tracker
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*
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* This module is responsible for tracking any number of accounts
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* and caching their current balances & transaction counts.
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*
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* It also tracks transaction hashes, and checks their inclusion status
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* on each new block.
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*/
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const EthQuery = require('eth-query')
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const ObservableStore = require('obs-store')
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const log = require('loglevel')
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const pify = require('pify')
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class AccountTracker {
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/**
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* This module is responsible for tracking any number of accounts and caching their current balances & transaction
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* counts.
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*
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* It also tracks transaction hashes, and checks their inclusion status on each new block.
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*
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* @typedef {Object} AccountTracker
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* @param {Object} opts Initialize various properties of the class.
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* @property {Object} store The stored object containing all accounts to track, as well as the current block's gas limit.
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* @property {Object} store.accounts The accounts currently stored in this AccountTracker
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* @property {string} store.currentBlockGasLimit A hex string indicating the gas limit of the current block
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* @property {Object} _provider A provider needed to create the EthQuery instance used within this AccountTracker.
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* @property {EthQuery} _query An EthQuery instance used to access account information from the blockchain
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* @property {BlockTracker} _blockTracker A BlockTracker instance. Needed to ensure that accounts and their info updates
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* when a new block is created.
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* @property {Object} _currentBlockNumber Reference to a property on the _blockTracker: the number (i.e. an id) of the the current block
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*
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*/
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constructor (opts = {}) {
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const initState = {
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accounts: {},
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currentBlockGasLimit: '',
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}
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this.store = new ObservableStore(initState)
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this._provider = opts.provider
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this._query = pify(new EthQuery(this._provider))
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this._blockTracker = opts.blockTracker
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// subscribe to latest block
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this._blockTracker.on('latest', this._updateForBlock.bind(this))
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// blockTracker.currentBlock may be null
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this._currentBlockNumber = this._blockTracker.getCurrentBlock()
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}
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/**
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* Ensures that the locally stored accounts are in sync with a set of accounts stored externally to this
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* AccountTracker.
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*
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* Once this AccountTracker's accounts are up to date with those referenced by the passed addresses, each
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* of these accounts are given an updated balance via EthQuery.
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*
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* @param {array} address The array of hex addresses for accounts with which this AccountTracker's accounts should be
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* in sync
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*
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*/
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syncWithAddresses (addresses) {
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const accounts = this.store.getState().accounts
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const locals = Object.keys(accounts)
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const accountsToAdd = []
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addresses.forEach((upstream) => {
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if (!locals.includes(upstream)) {
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accountsToAdd.push(upstream)
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}
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})
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const accountsToRemove = []
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locals.forEach((local) => {
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if (!addresses.includes(local)) {
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accountsToRemove.push(local)
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}
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})
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this.addAccounts(accountsToAdd)
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this.removeAccount(accountsToRemove)
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}
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/**
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* Adds new addresses to track the balances of
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* given a balance as long this._currentBlockNumber is defined.
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*
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* @param {array} addresses An array of hex addresses of new accounts to track
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*
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*/
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addAccounts (addresses) {
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const accounts = this.store.getState().accounts
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// add initial state for addresses
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addresses.forEach(address => {
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accounts[address] = {}
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})
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// save accounts state
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this.store.updateState({ accounts })
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// fetch balances for the accounts if there is block number ready
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if (!this._currentBlockNumber) return
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addresses.forEach(address => this._updateAccount(address))
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}
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/**
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* Removes accounts from being tracked
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*
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* @param {array} an array of hex addresses to stop tracking
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*
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*/
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removeAccount (addresses) {
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const accounts = this.store.getState().accounts
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// remove each state object
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addresses.forEach(address => {
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delete accounts[address]
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})
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// save accounts state
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this.store.updateState({ accounts })
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}
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/**
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* Given a block, updates this AccountTracker's currentBlockGasLimit, and then updates each local account's balance
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* via EthQuery
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*
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* @private
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* @param {number} blockNumber the block number to update to.
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* @fires 'block' The updated state, if all account updates are successful
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*
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*/
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async _updateForBlock (blockNumber) {
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this._currentBlockNumber = blockNumber
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// block gasLimit polling shouldn't be in account-tracker shouldn't be here...
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const currentBlock = await this._query.getBlockByNumber(blockNumber, false)
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if (!currentBlock) return
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const currentBlockGasLimit = currentBlock.gasLimit
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this.store.updateState({ currentBlockGasLimit })
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try {
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await this._updateAccounts()
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} catch (err) {
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log.error(err)
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}
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}
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/**
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* Calls this._updateAccount for each account in this.store
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*
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* @returns {Promise} after all account balances updated
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*
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*/
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async _updateAccounts () {
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const accounts = this.store.getState().accounts
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const addresses = Object.keys(accounts)
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await Promise.all(addresses.map(this._updateAccount.bind(this)))
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}
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/**
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* Updates the current balance of an account.
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*
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* @private
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* @param {string} address A hex address of a the account to be updated
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* @returns {Promise} after the account balance is updated
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*
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*/
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async _updateAccount (address) {
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// query balance
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const balance = await this._query.getBalance(address)
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const result = { address, balance }
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// update accounts state
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const { accounts } = this.store.getState()
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// only populate if the entry is still present
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if (!accounts[address]) return
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accounts[address] = result
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this.store.updateState({ accounts })
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}
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}
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module.exports = AccountTracker
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