git ssb

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const Pipe = require('buffer-pipe')
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const leb128 = require('leb128').unsigned
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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.inbox = []
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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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   * 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.push(message)
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    if (!this.running) {
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      this.running = true
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      return 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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    while (this.inbox.length) {
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      const message = this.inbox.shift()
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      if (message._fromTicks > this.ticks) {
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        this.hypervisor.scheduler.update(this.ticks, message._fromTicks)
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        this.ticks = message._fromTicks
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      }
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      await this.runMessage(message)
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    }
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    this.running = false
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  }
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  serializeMetaData () {
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    return Actor.serializeMetaData(this.type, this.nonce)
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  }
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  getFuncRef (name) {
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    return {
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      name,
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      destId: this.id
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    }
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  }
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  static serializeMetaData (type, nonce = 0) {
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    const p = new Pipe()
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    leb128.write(type, p)
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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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    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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  async shutdown () {
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    await this.state.done()
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    this.state.root['/'][3] = this.serializeMetaData()
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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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  async startup () {
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    this.instance = await this.container.instance(this)
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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) {
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    try {
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      this.currentMessage = message
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      await this.instance.exports[message.funcRef.name](...message.funcArguments)
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    } catch (e) {
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      message.emit('execution:error', e)
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    }
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    message.emit('done')
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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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    const oldValue = this.ticks
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    this.ticks += count
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    this.hypervisor.scheduler.update(oldValue, this.ticks)
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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, code) {
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    const id = this._generateNextId()
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    return this.hypervisor.createActor(type, code, 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 (message) {
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    message._fromTicks = this.ticks
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    message._fromId = this.id
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    this.hypervisor.scheduler.queue([message])
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  }
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}
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