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 (cap, message) {
24
    message.tag = cap.tag
25
    const id = cap.destId
26
    const instance = await this.getActor(id)
27
    instance.queue(message)
28
  }
29
30
  // loads an instance of a container from the state
31
  async _loadActor (id) {
32
    const state = await this.tree.getSubTree(id)
33
    const {type, nonce} = Actor.deserializeMetaData(state.root['/'][3])
34
    const container = this._containerTypes[type]
35
36
    // create a new actor instance
37
    const actor = new Actor({
38
      hypervisor: this,
39
      state,
40
      container,
41
      id,
42
      nonce,
43
      type
44
    })
45
46
    // save the newly created instance
47
    this.scheduler.update(actor)
48
    return actor
49
  }
50
51
  /**
52
   * gets an existsing actor
53
   * @param {string} id - the actor's ID
54
   * @returns {Promise}
55
   */
56
  async getActor (id) {
57
    let actor = this.scheduler.getInstance(id)
58
    if (!actor) {
59
      const resolve = this.scheduler.lock(id)
60
      actor = await this._loadActor(id)
61
      await actor.startup()
62
      resolve(actor)
63
    }
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
  async createActor (type, message, id = {nonce: this.nonce++, parent: null}) {
74
    const encoded = encodedID(id)
75
    const idHash = await this._getHashFromObj(encoded)
76
    const metaData = Actor.serializeMetaData(type)
77
78
    // save the container in the state
79
    this.tree.set(idHash, metaData)
80
81
    // create the container instance
82
    const instance = await this._loadActor(idHash)
83
84
    // send the intialization message
85
    instance.create(message)
86
    return instance.mintCap()
87
  }
88
89
  // get a hash from a POJO
90
  _getHashFromObj (obj) {
91
    return this.tree.constructor.getMerkleLink(obj)
92
  }
93
94
  /**
95
   * creates a state root starting from a given container and a given number of
96
   * ticks
97
   * @param {Number} ticks the number of ticks at which to create the state root
98
   * @returns {Promise}
99
   */
100
  async createStateRoot (ticks = Infinity) {
101
    await this.scheduler.wait(ticks)
102
    return this.tree.flush()
103
  }
104
105
  /**
106
   * regirsters a container with the hypervisor
107
   * @param {Class} Constructor - a Class for instantiating the container
108
   * @param {*} args - any args that the contructor takes
109
   * @param {Integer} typeId - the container's type identification ID
110
   */
111
  registerContainer (Constructor, args, typeId = Constructor.typeId) {
112
    this._containerTypes[typeId] = {
113
      Constructor,
114
      args
115
    }
116
  }
117
}
118
119
function encodedID (id) {
120
  const nonce = Buffer.from([id.nonce])
121
  if (id.parent) {
122
    return Buffer.concat([nonce, id.parent])
123
  } else {
124
    return nonce
125
  }
126
}
127