git ssb

1
const Buffer = require('safe-buffer').Buffer
2
const Pipe = require('buffer-pipe')
3
const Cap = require('primea-capability')
4
const Message = require('primea-message')
5
const leb128 = require('leb128').unsigned
6
const LockMap = require('lockmap')
7
const Inbox = require('./inbox.js')
8
9
module.exports = class Actor {
10
  /**
11
   * the Actor manages the varous message passing functions and provides
12
   * an interface for the containers to use
13
   * @param {Object} opts
14
   * @param {Object} opts.id - the UUID of the Actor
15
   * @param {Object} opts.state - the state of the container
16
   * @param {Object} opts.hypervisor - the instance of the hypervisor
17
   * @param {Object} opts.container - the container constuctor and argments
18
   */
19
  constructor (opts) {
20
    Object.assign(this, opts)
21
22
    this.container = new opts.container.Constructor(this, opts.container.args)
23
    this.inbox = new Inbox({
24
      actor: this,
25
      hypervisor: opts.hypervisor
26
    })
27
28
    this.ticks = 0
29
    this.running = false
30
    this._sending = new LockMap()
31
  }
32
33
  /**
34
   * Mints a new capabilitly with a given tag
35
   * @param {*} tag - a tag which can be used to identify caps
36
   * @return {Object}
37
   */
38
  mintCap (tag = 0, funcIndex = 0) {
39
    return new Cap(this.id, tag, funcIndex)
40
  }
41
42
  /**
43
   * adds a message to this actor's message queue
44
   * @param {string} portName
45
   * @param {object} message
46
   */
47
  queue (message) {
48
    this.inbox.queue(message)
49
    this._startMessageLoop()
50
  }
51
52
  /**
53
   * runs the creation routine for the actor
54
   * @param {object} message
55
   * @returns {Promise}
56
   */
57
  create (message) {
58
    // start loop before running intializtion message so the the container state
59
    // will be "running" incase the actor recievse a message will running
60
    // creation code
61
    this._startMessageLoop()
62
    return this.runMessage(message, 'onCreation')
63
  }
64
65
  // waits for the next message
66
  async _startMessageLoop () {
67
    // this ensure we only every have one loop running at a time
68
    if (!this.running) {
69
      this.running = true
70
      while (1) {
71
        const message = await this.inbox.nextMessage(0, true)
72
        if (!message) break
73
74
        // run the next message
75
        await this.runMessage(message)
76
        // wait for state ops to finish
77
        await this.state.done()
78
      }
79
80
      this.running = false
81
      this.container.onIdle()
82
    }
83
  }
84
85
  serializeMetaData () {
86
    return Actor.serializeMetaData(this.type, this.transparent, this.nonce)
87
  }
88
89
  static serializeMetaData (type, transparent = 0, nonce = 0) {
90
    const p = new Pipe()
91
    leb128.write(type, p)
92
    p.write(Buffer.from([0]))
93
    leb128.write(nonce, p)
94
    return p.buffer
95
  }
96
97
  static deserializeMetaData (buffer) {
98
    const pipe = new Pipe(buffer)
99
    return {
100
      type: leb128.read(pipe),
101
      nonce: leb128.read(pipe)
102
    }
103
  }
104
105
  /**
106
   * Runs the shutdown routine for the actor
107
   */
108
  shutdown () {
109
    this.state.root['/'][3] = this.serializeMetaData()
110
    this.hypervisor.scheduler.done(this.id)
111
  }
112
113
  /**
114
   * Runs the startup routine for the actor
115
   */
116
  startup () {
117
    return this.container.onStartup()
118
  }
119
120
  /**
121
   * run the Actor with a given message
122
   * @param {object} message - the message to run
123
   * @param {String} method - which method to run
124
   * @returns {Promise}
125
   */
126
  async runMessage (message, method = 'onMessage') {
127
    let result
128
    try {
129
      result = await this.container[method](message)
130
    } catch (e) {
131
      message.emit('execution:error', e)
132
      result = {
133
        exception: true,
134
        exceptionError: e
135
      }
136
    }
137
138
    if (message.responseCap) {
139
      this.send(message.responseCap, new Message({
140
        data: result
141
      }))
142
    }
143
  }
144
145
  /**
146
   * updates the number of ticks that the actor has run
147
   * @param {Number} count - the number of ticks to add
148
   */
149
  incrementTicks (count) {
150
    this.ticks += count
151
    this.hypervisor.scheduler.update(this)
152
  }
153
154
  /**
155
   * creates an actor
156
   * @param {Integer} type - the type id for the container
157
   * @param {Object} message - an intial [message](https://github.com/primea/js-primea-message) to send newly created actor
158
   */
159
  createActor (type, message) {
160
    const id = this._generateNextId()
161
    return this.hypervisor.createActor(type, message, id)
162
  }
163
164
  _generateNextId () {
165
    const id = {
166
      nonce: this.nonce,
167
      parent: this.id
168
    }
169
170
    this.nonce++
171
    return id
172
  }
173
174
  /**
175
   * sends a message to a given port
176
   * @param {Object} portRef - the port
177
   * @param {Message} message - the message
178
   */
179
  send (cap, message) {
180
    const resolve = this._sending.lock(cap)
181
    message._fromTicks = this.ticks
182
    message._fromId = this.id
183
    message.tag = cap.tag
184
185
    return this.hypervisor.send(cap, message).then(() => resolve(cap))
186
  }
187
}
188