const Tree = require('merkle-radix-tree') const Graph = require('ipld-graph-builder') const chunk = require('chunk') const Message = require('primea-message') const Kernel = require('./kernel.js') const Scheduler = require('./scheduler.js') const DFSchecker = require('./dfsChecker.js') module.exports = class Hypervisor { /** * The Hypervisor manages the container instances by instantiating them and * destorying them when possible. It also facilitates localating Containers * @param {Graph} dag an instance of [ipfs.dag](https://github.com/ipfs/interface-ipfs-core/tree/master/API/dag#dag-api) * @param {object} state - the starting state */ constructor (dag, state = {'/': Tree.emptyTreeState}) { this.graph = new Graph(dag) this.tree = new Tree({ graph: this.graph, root: state }) this.scheduler = new Scheduler() this.state = state this._containerTypes = {} this._nodesToCheck = new Set() this.ROOT_ID = 'zdpuAm6aTdLVMUuiZypxkwtA7sKm7BWERy8MPbaCrFsmiyzxr' this.MAX_DATA_BYTES = 65533 } /** * add a potaintail node in the state graph to check for garbage collection * @param {string} id */ addNodeToCheck (id) { this._nodesToCheck.add(id) } /** * given a port, this finds the corridsponeding endpoint port of the channel * @param {object} port * @returns {Promise} */ async getDestPort (port) { if (port.destPort) { return port.destPort } else { const containerState = await this.tree.get(port.destId) return this.graph.get(containerState, `ports/${port.destName}`) } } async send (port, message) { if (port.destId) { const id = port.destId const instance = await this.getInstance(id) return instance.queue(port.destName, message) } else { // port is unbound port.destPort.messages.push(message) } } // loads an instance of a container from the state async _loadInstance (id) { const state = await this.tree.get(id) const container = this._containerTypes[state.type] let code // checks if the code stored in the state is an array and that the elements // are merkle link if (state.code && state.code[0]['/']) { await this.graph.tree(state.code, 1) code = state.code.map(a => a['/']).reduce((a, b) => a + b) } else { code = state.code } // create a new kernel instance const kernel = new Kernel({ hypervisor: this, state: state, code: code, container: container, id: id }) // save the newly created instance this.scheduler.update(kernel) return kernel } // get a hash from a POJO _getHashFromObj (obj) { return this.graph.flush(obj).then(obj => obj['/']) } /** * gets an existsing container instances * @param {string} id - the containers ID * @returns {Promise} */ async getInstance (id) { let instance = this.scheduler.getInstance(id) if (instance) { return instance } else { const resolve = this.scheduler.getLock(id) const instance = await this._loadInstance(id) await instance.startup() resolve(instance) return instance } } /** * creates an new container instances and save it in the state * @param {string} type - the type of container to create * @param {*} code * @param {array} entryPorts * @param {object} id * @param {object} id.nonce * @param {object} id.parent * @returns {Promise} */ async createInstance (type, message = new Message(), id = {nonce: 0, parent: null}) { // create a lock to prevent the scheduler from reloving waits before the // new container is loaded const resolve = this.scheduler.getLock(id) const idHash = await this._getHashFromObj(id) // const code = message.data.byteLength ? message.data : undefined const state = { nonce: [0], ports: {}, type: type } if (message.data.length) { state.code = message.data } // save the container in the state await this.tree.set(idHash, state) // create the container instance const instance = await this._loadInstance(idHash) resolve(instance) // send the intialization message await instance.create(message) if (state.code && state.code.length > this.MAX_DATA_BYTES) { state.code = chunk(state.code, this.MAX_DATA_BYTES).map(chk => { return { '/': chk } }) } return instance } /** * creates a state root starting from a given container and a given number of * ticks * @param {Number} ticks the number of ticks at which to create the state root * @returns {Promise} */ async createStateRoot (ticks) { await this.scheduler.wait(ticks) const unlinked = await DFSchecker(this.tree, this.ROOT_ID, this._nodesToCheck) unlinked.forEach(id => { this.tree.delete(id) }) return this.graph.flush(this.state) } /** * regirsters a container with the hypervisor * @param {Class} Constructor - a Class for instantiating the container * @param {*} args - any args that the contructor takes * @param {interger} typeId - the container's type identification ID */ registerContainer (Constructor, args, typeId = Constructor.typeId) { this._containerTypes[typeId] = { Constructor: Constructor, args: args } } }