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) {
11
    this.tree = tree
12
    this.scheduler = new Scheduler()
13
    this._containerTypes = {}
14
    this.nonce = 0
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
    const id = cap.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.get(id, true)
32
    const container = this._containerTypes[state.value.type]
33
34
    // create a new actor instance
35
    const actor = new Actor({
36
      hypervisor: this,
37
      state: state,
38
      container: container,
39
      id: id
40
    })
41
42
    // save the newly created instance
43
    this.scheduler.update(actor)
44
    return actor
45
  }
46
47
  /**
48
   * gets an existsing actor
49
   * @param {string} id - the actor's ID
50
   * @returns {Promise}
51
   */
52
  async getActor (id) {
53
    let actor = this.scheduler.getInstance(id)
54
    if (actor) {
55
      return actor
56
    } else {
57
      const resolve = this.scheduler.lock(id)
58
      const actor = await this._loadActor(id)
59
      await actor.startup()
60
      resolve(actor)
61
      return actor
62
    }
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, message, id = {nonce: this.nonce, parent: null}) {
72
    const encoded = encodedID(id)
73
    this.nonce++
74
    const idHash = await this._getHashFromObj(encoded)
75
    const state = {
76
      nonce: 0,
77
      caps: {},
78
      type: type
79
    }
80
81
    const code = message.data
82
    if (code.length) {
83
      state.code = code
84
    }
85
86
    // save the container in the state
87
    await this.tree.set(idHash, state)
88
89
    // create the container instance
90
    const instance = await this._loadActor(idHash)
91
92
    // send the intialization message
93
    await instance.create(message)
94
    return instance.mintCap()
95
  }
96
97
  // get a hash from a POJO
98
  _getHashFromObj (obj) {
99
    return this.tree.constructor.getMerkleLink(obj)
100
  }
101
102
  /**
103
   * creates a state root starting from a given container and a given number of
104
   * ticks
105
   * @param {Number} ticks the number of ticks at which to create the state root
106
   * @returns {Promise}
107
   */
108
  async createStateRoot (ticks) {
109
    await this.scheduler.wait(ticks)
110
    return this.tree.flush()
111
  }
112
113
  /**
114
   * regirsters a container with the hypervisor
115
   * @param {Class} Constructor - a Class for instantiating the container
116
   * @param {*} args - any args that the contructor takes
117
   * @param {Integer} typeId - the container's type identification ID
118
   */
119
  registerContainer (Constructor, args, typeId = Constructor.typeId) {
120
    this._containerTypes[typeId] = {
121
      Constructor: Constructor,
122
      args: args
123
    }
124
  }
125
}
126
127
function encodedID (id) {
128
  const nonce = Buffer.from([id.nonce])
129
  if (id.parent) {
130
    return Buffer.concat([nonce, id.parent])
131
  } else {
132
    return nonce
133
  }
134
}
135