git ssb

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const Buffer = require('safe-buffer').Buffer
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const Pipe = require('buffer-pipe')
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const Cap = require('primea-capability')
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const Message = require('primea-message')
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const leb128 = require('leb128').unsigned
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const Inbox = require('./inbox.js')
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module.exports = class Actor {
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  /**
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   * the Actor manages the varous message passing functions and provides
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   * an interface for the containers to use
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   * @param {Object} opts
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   * @param {Object} opts.id - the UUID of the Actor
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   * @param {Object} opts.state - the state of the container
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   * @param {Object} opts.hypervisor - the instance of the hypervisor
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   * @param {Object} opts.container - the container constuctor and argments
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   */
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  constructor (opts) {
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    Object.assign(this, opts)
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    this.container = new opts.container.Constructor(this, opts.container.args)
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    this.inbox = new Inbox({
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      actor: this,
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      hypervisor: opts.hypervisor
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    })
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    this.ticks = 0
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    this.running = false
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  }
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  /**
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   * Mints a new capabilitly with a given tag
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   * @param {*} tag - a tag which can be used to identify caps
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   * @return {Object}
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   */
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  mintCap (tag = 0, funcIndex = 0) {
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    return new Cap(this.id, tag, funcIndex)
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  }
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  /**
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   * adds a message to this actor's message queue
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   * @param {string} portName
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   * @param {object} message
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   */
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  queue (message) {
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    this.inbox.queue(message)
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    this._startMessageLoop()
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  }
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  /**
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   * runs the creation routine for the actor
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   * @param {object} message
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   * @returns {Promise}
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   */
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  create (message) {
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    this.running = true
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    return this.runMessage(message, 'onCreation').then(() => {
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      this.running = false
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      this._startMessageLoop()
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    })
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  }
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  // waits for the next message
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  async _startMessageLoop () {
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    // this ensure we only every have one loop running at a time
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    if (!this.running) {
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      this.running = true
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      while (1) {
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        const message = await this.inbox.nextMessage(0, true)
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        if (!message) break
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        // run the next message
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        await this.runMessage(message)
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        // wait for state ops to finish
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        await this.state.done()
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      }
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      this.running = false
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      this.container.onIdle()
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    }
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  }
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  serializeMetaData () {
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    return Actor.serializeMetaData(this.type, this.transparent, this.nonce)
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  }
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  static serializeMetaData (type, transparent = 0, nonce = 0) {
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    const p = new Pipe()
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    leb128.write(type, p)
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    p.write(Buffer.from([0]))
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    leb128.write(nonce, p)
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    return p.buffer
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  }
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  static deserializeMetaData (buffer) {
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    const pipe = new Pipe(buffer)
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    const type = leb128.read(pipe)
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    pipe.read(1)
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    const nonce = leb128.read(pipe)
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    return {
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      nonce,
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      type
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    }
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  }
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  /**
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   * Runs the shutdown routine for the actor
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   */
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  shutdown () {
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    this.state.root['/'][3] = this.serializeMetaData()
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    this.hypervisor.scheduler.done(this.id)
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  }
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  /**
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   * Runs the startup routine for the actor
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   */
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  startup () {
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    return this.container.onStartup()
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  }
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  /**
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   * run the Actor with a given message
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   * @param {object} message - the message to run
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   * @param {String} method - which method to run
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   * @returns {Promise}
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   */
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  async runMessage (message, method = 'onMessage') {
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    let result
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    try {
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      result = await this.container[method](message)
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    } catch (e) {
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      message.emit('execution:error', e)
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      result = {
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        exception: true,
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        exceptionError: e
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      }
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    }
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    if (message.responseCap) {
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      this.send(message.responseCap, new Message({
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        data: result
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      }))
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    }
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  }
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  /**
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   * updates the number of ticks that the actor has run
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   * @param {Number} count - the number of ticks to add
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   */
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  incrementTicks (count) {
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    this.ticks += count
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    this.hypervisor.scheduler.update(this)
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  }
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  /**
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   * creates an actor
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   * @param {Integer} type - the type id for the container
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   * @param {Object} message - an intial [message](https://github.com/primea/js-primea-message) to send newly created actor
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   */
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  createActor (type, message) {
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    const id = this._generateNextId()
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    return this.hypervisor.createActor(type, message, id)
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  }
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  _generateNextId () {
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    const id = {
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      nonce: this.nonce,
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      parent: this.id
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    }
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    this.nonce++
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    return id
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  }
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  /**
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   * sends a message to a given port
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   * @param {Object} portRef - the port
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   * @param {Message} message - the message
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   */
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  send (cap, message) {
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    message._fromTicks = this.ticks
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    message._fromId = this.id
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    message.tag = cap.tag
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    return this.hypervisor.send(cap, message)
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  }
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}
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