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|
/* Account Tracker
*
* This module is responsible for tracking any number of accounts
* and caching their current balances & transaction counts.
*
* It also tracks transaction hashes, and checks their inclusion status
* on each new block.
*/
const async = require('async')
const EthQuery = require('eth-query')
const ObservableStore = require('obs-store')
const EventEmitter = require('events').EventEmitter
function noop () {}
class AccountTracker extends EventEmitter {
constructor (opts = {}) {
super()
const initState = {
accounts: {},
currentBlockGasLimit: '',
}
this.store = new ObservableStore(initState)
this._provider = opts.provider
this._query = new EthQuery(this._provider)
this._blockTracker = opts.blockTracker
// subscribe to latest block
this._blockTracker.on('block', this._updateForBlock.bind(this))
// blockTracker.currentBlock may be null
this._currentBlockNumber = this._blockTracker.currentBlock
}
//
// public
//
syncWithAddresses (addresses) {
const accounts = this.store.getState().accounts
const locals = Object.keys(accounts)
const toAdd = []
addresses.forEach((upstream) => {
if (!locals.includes(upstream)) {
toAdd.push(upstream)
}
})
const toRemove = []
locals.forEach((local) => {
if (!addresses.includes(local)) {
toRemove.push(local)
}
})
toAdd.forEach(upstream => this.addAccount(upstream))
toRemove.forEach(local => this.removeAccount(local))
this._updateAccounts()
}
addAccount (address) {
const accounts = this.store.getState().accounts
accounts[address] = {}
this.store.updateState({ accounts })
if (!this._currentBlockNumber) return
this._updateAccount(address)
}
removeAccount (address) {
const accounts = this.store.getState().accounts
delete accounts[address]
this.store.updateState({ accounts })
}
//
// private
//
_updateForBlock (block) {
this._currentBlockNumber = block.number
const currentBlockGasLimit = block.gasLimit
this.store.updateState({ currentBlockGasLimit })
async.parallel([
this._updateAccounts.bind(this),
], (err) => {
if (err) return console.error(err)
this.emit('block', this.store.getState())
})
}
_updateAccounts (cb = noop) {
const accounts = this.store.getState().accounts
const addresses = Object.keys(accounts)
async.each(addresses, this._updateAccount.bind(this), cb)
}
_updateAccount (address, cb = noop) {
this._getAccount(address, (err, result) => {
if (err) return cb(err)
result.address = address
const accounts = this.store.getState().accounts
// only populate if the entry is still present
if (accounts[address]) {
accounts[address] = result
this.store.updateState({ accounts })
}
cb(null, result)
})
}
_getAccount (address, cb = noop) {
const query = this._query
async.parallel({
balance: query.getBalance.bind(query, address),
nonce: query.getTransactionCount.bind(query, address),
code: query.getCode.bind(query, address),
}, cb)
}
}
module.exports = AccountTracker
|
