git ssb

1
const Buffer = require('safe-buffer').Buffer
2
const Actor = require('./actor.js')
3
const Scheduler = require('./scheduler.js')
4
const {decoder, generateId, ModuleRef, ActorRef} = require('primea-objects')
5
6
module.exports = class Hypervisor {
7
  /**
8
   * The Hypervisor manages module instances by instantiating them and
9
   * destroying them when possible. It also facilitates locating Containers
10
   * @param {Object} opts
11
   * @param {Object} opts.tree - a [radix tree](https://github.com/dfinity/js-dfinity-radix-tree) to store the state
12
   * @param {Array} opts.modules - an array of modules to register
13
   * @param {Array} opts.drivers - an array of drivers to install
14
   * @param {boolean} [opts.meter=true] - whether to meter gas or not
15
   */
16
  constructor (opts) {
17
    opts.tree.dag.decoder = decoder
18
    this.tree = opts.tree
19
    this.scheduler = new Scheduler(this)
20
    this._modules = {}
21
    this.nonce = opts.nonce || 0
22
    this.meter = opts.meter !== undefined ? opts.meter : true;
23
    (opts.modules || []).forEach(mod => this.registerModule(mod));
24
    (opts.drivers || []).forEach(driver => this.registerDriver(driver))
25
  }
26
27
  /**
28
   * sends a message(s). If an array of message is given the all the messages will be sent at once
29
   * @param {Object} message - the [message](https://github.com/primea/js-primea-message) to send
30
   * @returns {Promise} a promise that resolves once the receiving module is loaded
31
   */
32
  send (messages) {
33
    if (!Array.isArray(messages)) {
34
      messages = [messages]
35
    }
36
    this.scheduler.queue(messages)
37
  }
38
39
  /**
40
   * loads an actor from the tree given its id
41
   * @param {ID} id
42
   * @returns {Promise<Actor>}
43
   */
44
  async loadActor (id) {
45
    const state = await this.tree.get(id.id)
46
    const [module, storage] = await Promise.all([
47
      this.tree.graph.tree(state.node, '1'),
48
      this.tree.graph.get(state.node, '2')
49
    ])
50
    await this.tree.graph.get(module[1][1], '')
51
    const [type, nonce] = state.value
52
    const Container = this._modules[type]
53
54
    // create a new actor instance
55
    const actor = new Actor({
56
      hypervisor: this,
57
      state,
58
      Container,
59
      id,
60
      nonce,
61
      module,
62
      storage,
63
      tree: this.tree
64
    })
65
66
    await actor.startup()
67
    return actor
68
  }
69
70
  /**
71
   * creates an actor from a module and code
72
   * @param {Module} mod - the module
73
   * @param {Buffer} code - the code
74
   * @return {ActorRef}
75
   */
76
  newActor (mod, code) {
77
    const modRef = this.createModule(mod, code)
78
    return this.createActor(modRef)
79
  }
80
81
  /**
82
   * creates a modref from a module and code
83
   * @param {Module} mod - the module
84
   * @param {Buffer} code - the code
85
   * @param {id} id - the id for the module
86
   * @return {ModuleRef}
87
   */
88
  createModule (mod, code, id = {nonce: this.nonce++, parent: null}) {
89
    const moduleID = generateId(id)
90
    const Module = this._modules[mod.typeId]
91
    const {exports, state} = Module.onCreation(code)
92
    return new ModuleRef(moduleID, mod.typeId, exports, state, code)
93
  }
94
95
  /**
96
   * creates an instance of an Actor
97
   * @param {ModuleRef} type - the modref
98
   * @param {Object} id - the id for the actor
99
   * @return {ActorRef}
100
   */
101
  createActor (modRef, id = {nonce: this.nonce++, parent: null}) {
102
    const actorId = generateId(id)
103
    const metaData = [modRef.type, 0]
104
105
    // save the container in the state
106
    this.tree.set(actorId.id, metaData).then(node => {
107
      // save the code
108
      node[1] = [modRef.id.id, {
109
        '/': modRef.code['/']
110
      }]
111
      // save the storage
112
      node[2] = {
113
        '/': modRef.state
114
      }
115
    })
116
117
    return new ActorRef(actorId, modRef)
118
  }
119
120
  /**
121
   * creates a state root when scheduler is idle
122
   * @returns {Promise}
123
   */
124
  async createStateRoot () {
125
    if (this.scheduler._running) {
126
      await new Promise((resolve, reject) => {
127
        this.scheduler.once('idle', resolve)
128
      })
129
    }
130
131
    await this.tree.set(Buffer.from([0]), this.nonce)
132
    return this.tree.flush()
133
  }
134
135
  /**
136
   * set the state root. The promise must resolve before creating or sending any more messages to the hypervisor
137
   * @param {Buffer} stateRoot
138
   * @return {Promise}
139
   */
140
  async setStateRoot (stateRoot) {
141
    this.tree.root = stateRoot
142
    const node = await this.tree.get(Buffer.from([0]))
143
    this.nonce = node.value
144
  }
145
146
  /**
147
   * registers a module with the hypervisor
148
   * @param {Function} Constructor - the module's constructor
149
   */
150
  registerModule (Constructor) {
151
    this._modules[Constructor.typeId] = Constructor
152
  }
153
154
  /**
155
   * register a driver with the hypervisor
156
   * @param {Driver} driver
157
   */
158
  registerDriver (driver) {
159
    driver.startup(this)
160
    this.scheduler.drivers.set(driver.id.toString(), driver)
161
  }
162
}
163