git ssb

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const Buffer = require('safe-buffer').Buffer
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const Actor = require('./actor.js')
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const Scheduler = require('./scheduler.js')
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const {decoder, generateId, ModuleRef, ActorRef} = require('primea-objects')
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const debug = require('debug')('lifecycle:createActor')
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module.exports = class Hypervisor {
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  /**
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   * The Hypervisor manages module instances by instantiating them and
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   * destroying them when possible. It also facilitates locating Containers
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   * @param {Object} opts
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   * @param {Object} opts.tree - a [radix tree](https://github.com/dfinity/js-dfinity-radix-tree) to store the state
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   * @param {Array} opts.modules - an array of modules to register
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   * @param {Array} opts.drivers - an array of drivers to install
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   * @param {boolean} [opts.meter=true] - whether to meter gas or not
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   */
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  constructor (opts) {
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    opts.tree.dag.decoder = decoder
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    this.tree = opts.tree
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    this.scheduler = new Scheduler(this)
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    this._modules = {}
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    this.nonce = opts.nonce || 0
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    this.meter = opts.meter !== undefined ? opts.meter : true;
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    (opts.modules || []).forEach(mod => this.registerModule(mod));
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    (opts.drivers || []).forEach(driver => this.registerDriver(driver))
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  }
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  /**
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   * sends a message(s). If an array of message is given the all the messages will be sent at once
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   * @param {Object} message - the [message](https://github.com/primea/js-primea-message) to send
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   * @returns {Promise} a promise that resolves once the receiving module is loaded
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   */
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  send (messages) {
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    if (!Array.isArray(messages)) {
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      messages = [messages]
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    }
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    this.scheduler.queue(messages)
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  }
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  /**
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   * loads an actor from the tree given its id
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   * @param {ID} id
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   * @returns {Promise<Actor>}
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   */
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  async loadActor (id) {
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    const state = await this.tree.get(id.id)
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    const [module, storage] = await Promise.all([
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      this.tree.graph.tree(state.node, '1'),
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      this.tree.graph.get(state.node, '2')
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    ])
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    await this.tree.graph.get(module[1][1], '')
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    const [type, nonce] = state.value
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    const Container = this._modules[type]
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    // create a new actor instance
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    const actor = new Actor({
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      hypervisor: this,
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      state,
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      Container,
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      id,
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      nonce,
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      module,
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      storage,
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      tree: this.tree
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    })
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    await actor.startup()
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    return actor
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  }
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  /**
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   * creates an actor from a module and code
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   * @param {Module} mod - the module
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   * @param {Buffer} code - the code
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   * @return {ActorRef}
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   */
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  newActor (mod, code) {
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    const modRef = this.createModule(mod, code)
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    return this.createActor(modRef)
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  }
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  /**
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   * creates a modref from a module and code
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   * @param {Module} mod - the module
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   * @param {Buffer} code - the code
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   * @param {id} id - the id for the module
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   * @return {ModuleRef}
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   */
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  createModule (mod, code, id = {nonce: this.nonce++, parent: null}) {
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    const moduleID = generateId(id)
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    const Module = this._modules[mod.typeId]
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    const {exports, state} = Module.onCreation(code)
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    return new ModuleRef(moduleID, mod.typeId, exports, state, code)
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  }
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  /**
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   * creates an instance of an Actor
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   * @param {ModuleRef} type - the modref
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   * @param {Object} id - the id for the actor
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   * @return {ActorRef}
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   */
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  createActor (modRef, id = {nonce: this.nonce++, parent: null}) {
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    const actorId = generateId(id)
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    const metaData = [modRef.type, 0]
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    debug('new id', actorId.toJSON())
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    debug(modRef.toJSON())
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    // save the container in the state
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    this.tree.set(actorId.id, metaData).then(node => {
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      // save the code
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      node[1] = [modRef.id.id, {
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        '/': modRef.code['/']
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      }]
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      // save the storage
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      node[2] = {
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        '/': modRef.persist
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      }
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    })
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    return new ActorRef(actorId, modRef)
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  }
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  /**
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   * creates a state root when scheduler is idle
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   * @returns {Promise}
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   */
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  async createStateRoot () {
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    if (this.scheduler._running) {
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      await new Promise((resolve, reject) => {
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        this.scheduler.once('idle', resolve)
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      })
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    }
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    await this.tree.set(Buffer.from([0]), this.nonce)
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    return this.tree.flush()
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  }
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  /**
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   * set the state root. The promise must resolve before creating or sending any more messages to the hypervisor
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   * @param {Buffer} stateRoot
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   * @return {Promise}
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   */
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  async setStateRoot (stateRoot) {
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    this.tree.root = stateRoot
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    const node = await this.tree.get(Buffer.from([0]))
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    this.nonce = node.value
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  }
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  /**
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   * registers a module with the hypervisor
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   * @param {Function} Constructor - the module's constructor
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   */
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  registerModule (Constructor) {
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    this._modules[Constructor.typeId] = Constructor
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  }
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  /**
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   * register a driver with the hypervisor
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   * @param {Driver} driver
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   */
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  registerDriver (driver) {
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    driver.startup(this)
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    this.scheduler.drivers.set(driver.id.toString(), driver)
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  }
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}
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