git ssb

1
const Actor = require('./actor.js')
2
const Scheduler = require('./scheduler.js')
3
4
module.exports = class Hypervisor {
5
  /**
6
   * The Hypervisor manages the container instances by instantiating them and
7
   * destorying them when possible. It also facilitates localating Containers
8
   * @param {Tree} tree - a [radix tree](https://github.com/dfinity/js-dfinity-radix-tree) to store the state
9
   */
10
  constructor (tree, nonce = 0) {
11
    this.tree = tree
12
    this.scheduler = new Scheduler()
13
    this._containerTypes = {}
14
    this.nonce = nonce
15
  }
16
17
  /**
18
   * sends a message
19
   * @param {Object} cap - the capabilitly used to send the message
20
   * @param {Object} message - the [message](https://github.com/primea/js-primea-message) to send
21
   * @returns {Promise} a promise that resolves once the receiving container is loaded
22
   */
23
  async send (message) {
24
    const id = message.funcRef.destId
25
    const instance = await this.getActor(id)
26
    instance.queue(message)
27
  }
28
29
  // loads an instance of a container from the state
30
  async _loadActor (id) {
31
    const state = await this.tree.getSubTree(id)
32
    const {type, nonce} = Actor.deserializeMetaData(state.root['/'][3])
33
    const container = this._containerTypes[type]
34
35
    // create a new actor instance
36
    const actor = new Actor({
37
      hypervisor: this,
38
      state,
39
      container,
40
      id,
41
      nonce,
42
      type
43
    })
44
45
    await actor.startup()
46
    this.scheduler.update(actor)
47
    return actor
48
  }
49
50
  /**
51
   * gets an existsing actor
52
   * @param {string} id - the actor's ID
53
   * @returns {Promise}
54
   */
55
  async getActor (id) {
56
    let actor = this.scheduler.getInstance(id)
57
    if (!actor) {
58
      const resolve = this.scheduler.lock(id)
59
      actor = await this._loadActor(id)
60
      resolve(actor)
61
    }
62
    return actor
63
  }
64
65
  /**
66
   * creates an instance of an Actor
67
   * @param {Integer} type - the type id for the container
68
   * @param {Object} message - an intial [message](https://github.com/primea/js-primea-message) to send newly created actor
69
   * @param {Object} id - the id for the actor
70
   */
71
  async createActor (type, code, id = {nonce: this.nonce++, parent: null}) {
72
    const encoded = encodedID(id)
73
    const idHash = await this._getHashFromObj(encoded)
74
    const metaData = Actor.serializeMetaData(type)
75
76
    // save the container in the state
77
    this.tree.set(idHash, metaData)
78
    const Container = this._containerTypes[type]
79
    await Container.validate(code)
80
    const module = await Container.compile(code)
81
    return {
82
      id: idHash,
83
      exports: Container.exports(module, idHash)
84
    }
85
  }
86
87
  // get a hash from a POJO
88
  _getHashFromObj (obj) {
89
    return this.tree.constructor.getMerkleLink(obj)
90
  }
91
92
  /**
93
   * creates a state root starting from a given container and a given number of
94
   * ticks
95
   * @param {Number} ticks the number of ticks at which to create the state root
96
   * @returns {Promise}
97
   */
98
  async createStateRoot (ticks = Infinity) {
99
    await this.scheduler.wait(ticks)
100
    return this.tree.flush()
101
  }
102
103
  /**
104
   * regirsters a container with the hypervisor
105
   * @param {Class} Constructor - a Class for instantiating the container
106
   * @param {*} args - any args that the contructor takes
107
   * @param {Integer} typeId - the container's type identification ID
108
   */
109
  registerContainer (Constructor) {
110
    this._containerTypes[Constructor.typeId] = Constructor
111
  }
112
}
113
114
function encodedID (id) {
115
  const nonce = Buffer.from([id.nonce])
116
  if (id.parent) {
117
    return Buffer.concat([nonce, id.parent])
118
  } else {
119
    return nonce
120
  }
121
}
122