eth-block-tracker/src/index.js at aegir · EvolutionOS/eth-block-tracker · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
'use strict'
const EthQuery = require('eth-query')
const AsyncEventEmitter = require('async-eventemitter')
const pify = require('pify')
const incrementHexNumber = require('./hexUtils').incrementHexNumber

class RpcBlockTracker extends AsyncEventEmitter {
  constructor (opts = {}) {
    super()
    if (!opts.provider) throw new Error('RpcBlockTracker - no provider specified.')
    this._query = new EthQuery(opts.provider)
    // config
    this._pollingInterval = opts.pollingInterval || 800
    // state
    this._trackingBlock = null
    this._currentBlock = null
    this._isRunning = false
    // bind methods for cleaner syntax later
    this.emit = this.emit.bind(this)
    this._performSync = this._performSync.bind(this)
  }

  getTrackingBlock () {
    return this._trackingBlock
  }

  getCurrentBlock () {
    return this._currentBlock
  }

  async start (opts = {}) {
    // abort if already started
    if (this._isRunning) return
    this._isRunning = true
    // if this._currentBlock
    if (opts.fromBlock) {
      // use specified start point
      await this._setTrackingBlock(await this._fetchBlockByNumber(opts.fromBlock))
    } else {
      // or query for latest
      await this._setTrackingBlock(await this._fetchLatestBlock())
    }
    this._performSync()
    .catch((err) => {
      if (err) console.error(err)
    })
  }

  stop () {
    this._isRunning = false
  }

  //
  // private
  //

  async _setTrackingBlock (newBlock) {
    if (this._trackingBlock && (this._trackingBlock.hash === newBlock.hash)) return
    this._trackingBlock = newBlock
    await pify(this.emit)('block', newBlock)
  }

  async _setCurrentBlock (newBlock) {
    if (this._currentBlock && (this._currentBlock.hash === newBlock.hash)) return
    this._currentBlock = newBlock
    await pify(this.emit)('latest', newBlock)
  }

  async _pollForNextBlock () {
    setTimeout(() => this._performSync(), this._pollingInterval)
  }

  async _performSync () {
    if (!this._isRunning) return
    const trackingBlock = this.getTrackingBlock()
    if (!trackingBlock) throw new Error('RpcBlockTracker - tracking block is missing')
    const nextNumber = incrementHexNumber(trackingBlock.number)
    try {
      const newBlock = await this._fetchBlockByNumber(nextNumber)
      if (newBlock) {
        // set as new tracking block
        await this._setTrackingBlock(newBlock)
        // ask for next block
        this._performSync()
      } else {
        // set tracking block as current block
        await this._setCurrentBlock(trackingBlock)
        // setup poll for next block
        this._pollForNextBlock()
      }
    } catch (err) {
      if (err) console.error(err)
    }
  }

  _fetchLatestBlock () {
    return pify(this._query.getBlockByNumber).call(this._query, 'latest', false)
  }

  _fetchBlockByNumber (hexNumber) {
    return pify(this._query.getBlockByNumber).call(this._query, hexNumber, false)
  }
}

module.exports = RpcBlockTracker

 // ├─ difficulty: 0x2892ddca
 // ├─ extraData: 0xd983010507846765746887676f312e372e348777696e646f7773
 // ├─ gasLimit: 0x47e7c4
 // ├─ gasUsed: 0x6384
 // ├─ hash: 0xf60903687b1559b9c80f2d935b4c4f468ad95c3076928c432ec34f2ef3d4eec9
 // ├─ logsBloom: 0x00000000000000000000000000000000000000000000000000000000000020000000000000000000000000040000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000000000000000000
 // ├─ miner: 0x01711853335f857442ef6f349b2467c531731318
 // ├─ mixHash: 0xf0d9bec999600eec92e8e4da8fc1182e357468c9ed2f849aa17e0e900412b352
 // ├─ nonce: 0xd556d5a5504198e4
 // ├─ number: 0x72ac8
 // ├─ parentHash: 0xf5239c3ce1085194521435a5052494c02bbb1002b019684dcf368490ea6208e5
 // ├─ receiptsRoot: 0x78c6f8236094b392bcc43b47b0dc1ce93ecd2875bfb5e4e4c3431e5af698ff99
 // ├─ sha3Uncles: 0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347
 // ├─ size: 0x2ad
 // ├─ stateRoot: 0x0554f145c481df2fa02ecd2da17071672740c3aa948c896f1465e6772f741ac6
 // ├─ timestamp: 0x58955844
 // ├─ totalDifficulty: 0x751d0dfa03c1
 // ├─ transactions
 // │  └─ 0
 // │     ├─ blockHash: 0xf60903687b1559b9c80f2d935b4c4f468ad95c3076928c432ec34f2ef3d4eec9
 // │     ├─ blockNumber: 0x72ac8
 // │     ├─ from: 0x201354729f8d0f8b64e9a0c353c672c6a66b3857
 // │     ├─ gas: 0x15f90
 // │     ├─ gasPrice: 0x4a817c800
 // │     ├─ hash: 0xd5a15d7c2449150db4f74f42a6ca0702150a24c46c5b406a7e1b3e44908ef44d
 // │     ├─ input: 0xe1fa8e849bc10d87fb03c6b0603b05a3e29043c7e0b7c927119576a4bec457e96c7d7cde
 // │     ├─ nonce: 0x323e
 // │     ├─ to: 0xd10e3be2bc8f959bc8c41cf65f60de721cf89adf
 // │     ├─ transactionIndex: 0x0
 // │     ├─ value: 0x0
 // │     ├─ v: 0x29
 // │     ├─ r: 0xf35f8ab241e6bb3ccaffd21b268dbfc7fcb5df1c1fb83ee5306207e4a1a3e954
 // │     └─ s: 0x1610cdac2782c91065fd43584cd8974f7f3b4e6d46a2aafe7b101788285bf3f2
 // ├─ transactionsRoot: 0xb090c32d840dec1e9752719f21bbae4a73e58333aecb89bc3b8ed559fb2712a3
 // └─ uncles