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) {
39
    return new Cap(this.id, tag)
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()
72
        if (!message) break
73
74
        // if the message we recived had more ticks then we currently have then
75
        // update it
76
        if (message._fromTicks > this.ticks) {
77
          this.ticks = message._fromTicks
78
          this.hypervisor.scheduler.update(this)
79
        }
80
        // run the next message
81
        await this.runMessage(message)
82
        // wait for state ops to finish
83
        await this.state.done()
84
      }
85
86
      this.running = false
87
      this.container.onIdle()
88
    }
89
  }
90
91
  serializeMetaData () {
92
    return Actor.serializeMetaData(this.type, this.transparent, this.nonce)
93
  }
94
95
  static serializeMetaData (type, transparent = 0, nonce = 0) {
96
    const p = new Pipe()
97
    leb128.write(type, p)
98
    p.write(Buffer.from([transparent]))
99
    leb128.write(nonce, p)
100
    return p.buffer
101
  }
102
103
  static deserializeMetaData (buffer) {
104
    const pipe = new Pipe(buffer)
105
    return {
106
      type: leb128.read(pipe),
107
      nonce: leb128.read(pipe),
108
      transparent: pipe.read(1)[0]
109
    }
110
  }
111
112
  /**
113
   * Runs the shutdown routine for the actor
114
   */
115
  shutdown () {
116
    this.state.root['/'][3] = this.serializeMetaData()
117
    this.hypervisor.scheduler.done(this.id)
118
  }
119
120
  /**
121
   * Runs the startup routine for the actor
122
   */
123
  startup () {
124
    return this.container.onStartup()
125
  }
126
127
  /**
128
   * run the Actor with a given message
129
   * @param {object} message - the message to run
130
   * @param {String} method - which method to run
131
   * @returns {Promise}
132
   */
133
  async runMessage (message, method = 'onMessage') {
134
    const responseCap = message.responseCap
135
    delete message.responseCap
136
137
    let result
138
    try {
139
      result = await this.container[method](message)
140
    } catch (e) {
141
      message.emit('execution:error', e)
142
      result = {
143
        exception: true,
144
        exceptionError: e
145
      }
146
    }
147
148
    if (responseCap) {
149
      this.send(responseCap, new Message({
150
        data: result
151
      }))
152
    }
153
  }
154
155
  /**
156
   * updates the number of ticks that the actor has run
157
   * @param {Number} count - the number of ticks to add
158
   */
159
  incrementTicks (count) {
160
    this.ticks += count
161
    this.hypervisor.scheduler.update(this)
162
  }
163
164
  /**
165
   * creates an actor
166
   * @param {Integer} type - the type id for the container
167
   * @param {Object} message - an intial [message](https://github.com/primea/js-primea-message) to send newly created actor
168
   */
169
  createActor (type, message) {
170
    const id = this._generateNextId()
171
    return this.hypervisor.createActor(type, message, id)
172
  }
173
174
  _generateNextId () {
175
    const id = {
176
      nonce: this.nonce,
177
      parent: this.id
178
    }
179
180
    this.nonce++
181
    return id
182
  }
183
184
  /**
185
   * sends a message to a given port
186
   * @param {Object} portRef - the port
187
   * @param {Message} message - the message
188
   */
189
  send (cap, message) {
190
    const resolve = this._sending.lock(cap)
191
    message._fromTicks = this.ticks
192
    message._fromId = this.id
193
    message.tag = cap.tag
194
195
    return this.hypervisor.send(cap, message).then(() => resolve(cap))
196
  }
197
}
198