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 {Tree} tree - a [radix tree](https://github.com/dfinity/js-dfinity-radix-tree) to store the state
13
   */
14
  constructor (tree, containers = [], drivers = [], nonce = 0) {
15
    tree.dag.decoder = decoder
16
    this.tree = tree
17
    this.scheduler = new Scheduler(this)
18
    this._containerTypes = {}
19
    this.nonce = nonce
20
    containers.forEach(container => this.registerContainer(container))
21
    drivers.forEach(driver => this.registerDriver(driver))
22
  }
23
24
  /**
25
   * sends a message
26
   * @param {Object} message - the [message](https://github.com/primea/js-primea-message) to send
27
   * @returns {Promise} a promise that resolves once the receiving container is loaded
28
   */
29
  send (messages) {
30
    if (!Array.isArray(messages)) {
31
      messages = [messages]
32
    }
33
    this.scheduler.queue(messages)
34
  }
35
36
  /**
37
   * loads an actor from the tree given its id
38
   * @param {ID} id
39
   * @returns {Promise<Actor>}
40
   */
41
  async loadActor (id) {
42
    const state = await this.tree.get(id.id, true)
43
    const [code, storage] = await Promise.all([
44
      this.tree.graph.get(state.node, '1'),
45
      this.tree.graph.get(state.node, '2')
46
    ])
47
    const [type, nonce] = state.value
48
    const Container = this._containerTypes[type]
49
50
    // create a new actor instance
51
    const actor = new Actor({
52
      hypervisor: this,
53
      state,
54
      Container,
55
      id,
56
      nonce,
57
      type,
58
      code,
59
      storage,
60
      tree: this.tree
61
    })
62
63
    await actor.startup()
64
    return actor
65
  }
66
67
  /**
68
   * creates an instance of an Actor
69
   * @param {Integer} type - the type id for the container
70
   * @param {Object} message - an intial [message](https://github.com/primea/js-primea-message) to send newly created actor
71
   * @param {Object} id - the id for the actor
72
   */
73
  createActor (type, code, id = {nonce: this.nonce++, parent: null}) {
74
    const Container = this._containerTypes[type]
75
    const encoded = encodedID(id)
76
    id = this._hash(encoded)
77
    id = new ID(id)
78
    const module = Container.onCreation(code, id, this.tree)
79
    const metaData = [type, 0]
80
81
    // save the container in the state
82
    this.tree.set(id.id, metaData).then(node => {
83
      // save the code
84
      node[1] = {
85
        '/': code
86
      }
87
      // save the storage
88
      node[2] = {
89
        '/': []
90
      }
91
    })
92
93
    return {
94
      id,
95
      module
96
    }
97
  }
98
99
  _hash (buf) {
100
    const hash = crypto.createHash('sha256')
101
    hash.update(buf)
102
    return hash.digest().slice(0, 20)
103
  }
104
105
  /**
106
   * creates a state root starting from a given container and a given number of
107
   * ticks
108
   * @param {Number} ticks the number of ticks at which to create the state root
109
   * @returns {Promise}
110
   */
111
  async createStateRoot () {
112
    if (this.scheduler._running) {
113
      await new Promise((resolve, reject) => {
114
        this.scheduler.once('idle', resolve)
115
      })
116
    }
117
    await this.tree.set(Buffer.from([0]), this.nonce)
118
    return this.tree.flush()
119
  }
120
121
  /**
122
   * set the state root
123
   */
124
  async setStateRoot (stateRoot) {
125
    this.tree.root = stateRoot
126
    const node = await this.tree.get(Buffer.from([0]))
127
    this.nonce = node.value
128
  }
129
130
  /**
131
   * regirsters a container with the hypervisor
132
   * @param {Class} Constructor - a Class for instantiating the container
133
   * @param {*} args - any args that the contructor takes
134
   * @param {Integer} typeId - the container's type identification ID
135
   */
136
  registerContainer (Constructor) {
137
    this._containerTypes[Constructor.typeId] = Constructor
138
  }
139
140
  registerDriver (driver) {
141
    this.scheduler.drivers.set(driver.id.toString(), driver)
142
  }
143
}
144
145
function encodedID (id) {
146
  if (id.parent) {
147
    return cbor.encode([id.nonce, id.parent.id])
148
  } else {
149
    return cbor.encode([id.nonce, null])
150
  }
151
}
152