git ssb

1
const Buffer = require('safe-buffer').Buffer
2
const crypto = require('crypto')
3
const Actor = require('./actor.js')
4
const Scheduler = require('./scheduler.js')
5
const {ID, decoder} = require('primea-objects')
6
const cbor = require('borc')
7
8
module.exports = class Hypervisor {
9
  /**
10
   * The Hypervisor manages the container instances by instantiating them and
11
   * destorying them when possible. It also facilitates localating Containers
12
   * @param {Object} opts
13
   * @param {Object} opts.tree - a [radix tree](https://github.com/dfinity/js-dfinity-radix-tree) to store the state
14
   * @param {Array} opts.container - an array of containers to regester
15
   * @param {Array} opts.drivers - an array of drivers to install
16
   * @param {boolean} [opts.meter=true] - whether to meter gas or not
17
   */
18
  constructor (opts) {
19
    opts.tree.dag.decoder = decoder
20
    this.tree = opts.tree
21
    this.scheduler = new Scheduler(this)
22
    this._containerTypes = {}
23
    this.nonce = opts.nonce || 0
24
    this.meter = opts.meter !== undefined ? opts.meter : true;
25
    (opts.containers || []).forEach(container => this.registerContainer(container));
26
    (opts.drivers || []).forEach(driver => this.registerDriver(driver))
27
  }
28
29
  /**
30
   * sends a message(s). If an array of message is given the all the messages will be sent at once
31
   * @param {Object} message - the [message](https://github.com/primea/js-primea-message) to send
32
   * @returns {Promise} a promise that resolves once the receiving container is loaded
33
   */
34
  send (messages) {
35
    if (!Array.isArray(messages)) {
36
      messages = [messages]
37
    }
38
    this.scheduler.queue(messages)
39
  }
40
41
  /**
42
   * loads an actor from the tree given its id
43
   * @param {ID} id
44
   * @returns {Promise<Actor>}
45
   */
46
  async loadActor (id) {
47
    const state = await this.tree.get(id.id, true)
48
    const [code, storage] = await Promise.all([
49
      this.tree.graph.get(state.node, '1'),
50
      this.tree.graph.get(state.node, '2')
51
    ])
52
    const [type, nonce] = state.value
53
    const Container = this._containerTypes[type]
54
55
    // create a new actor instance
56
    const actor = new Actor({
57
      hypervisor: this,
58
      state,
59
      Container,
60
      id,
61
      nonce,
62
      type,
63
      code,
64
      storage,
65
      tree: this.tree
66
    })
67
68
    await actor.startup()
69
    return actor
70
  }
71
72
  /**
73
   * creates an instance of an Actor
74
   * @param {Integer} type - the type id for the container
75
   * @param {Object} message - an intial [message](https://github.com/primea/js-primea-message) to send newly created actor
76
   * @param {Object} id - the id for the actor
77
   */
78
  createActor (type, code, id = {nonce: this.nonce++, parent: null}) {
79
    const Container = this._containerTypes[type]
80
    const encoded = encodedID(id)
81
    id = this._hash(encoded)
82
    id = new ID(id)
83
    const module = Container.onCreation(code, id)
84
    const metaData = [type, 0]
85
86
    // save the container in the state
87
    this.tree.set(id.id, metaData).then(node => {
88
      // save the code
89
      node[1] = {
90
        '/': code
91
      }
92
      // save the storage
93
      node[2] = {
94
        '/': []
95
      }
96
    })
97
98
    return {
99
      id,
100
      module
101
    }
102
  }
103
104
  _hash (buf) {
105
    const hash = crypto.createHash('sha256')
106
    hash.update(buf)
107
    return hash.digest().slice(0, 20)
108
  }
109
110
  /**
111
   * creates a state root starting from a given container and a given number of
112
   * ticks
113
   * @param {Number} ticks the number of ticks at which to create the state root
114
   * @returns {Promise}
115
   */
116
  async createStateRoot () {
117
    if (this.scheduler._running) {
118
      await new Promise((resolve, reject) => {
119
        this.scheduler.once('idle', resolve)
120
      })
121
    }
122
    await this.tree.set(Buffer.from([0]), this.nonce)
123
    return this.tree.flush()
124
  }
125
126
  /**
127
   * set the state root. The promise must resolve before creating or sending any more messages to the hypervisor
128
   * @param {Buffer} stateRoot
129
   * @return {Promise}
130
   */
131
  async setStateRoot (stateRoot) {
132
    this.tree.root = stateRoot
133
    const node = await this.tree.get(Buffer.from([0]))
134
    this.nonce = node.value
135
  }
136
137
  /**
138
   * regesters a container with the hypervisor
139
   * @param {Function} Constructor - the container's constuctor
140
   */
141
  registerContainer (Constructor) {
142
    this._containerTypes[Constructor.typeId] = Constructor
143
  }
144
145
  /**
146
   * register a driver with the hypervisor
147
   * @param {driver} driver
148
   */
149
  registerDriver (driver) {
150
    this.scheduler.drivers.set(driver.id.toString(), driver)
151
  }
152
}
153
154
function encodedID (id) {
155
  if (id.parent) {
156
    return cbor.encode([id.nonce, id.parent.id])
157
  } else {
158
    return cbor.encode([id.nonce, null])
159
  }
160
}
161