const ReferanceMap = require('./referanceMap.js') module.exports = class WasmContainer { /** * The wasm container runs wasm code and provides a basic API for wasm * interfaces for interacting with the kernel * @param {object} kernel - the kernel instance * @param {object} interfaces - a map of interfaces to expose to the wasm binary */ constructor (kernel, interfaces) { this.kernel = kernel this.imports = interfaces this.referanceMap = new ReferanceMap() } async initialize (message) { let code = message.data if (!WebAssembly.validate(code)) { throw new Error('invalid wasm binary') } else { for (const name in this.imports) { const interf = this.imports[name] if (interf.initialize) { code = await interf.initialize(code) } } this.kernel.state.code = code } return this._run(message, 'init') } /** * Runs the wasm VM given a message * @param {object} message * @returns {Promise} a promise that resolves once the compuation is finished */ run (message) { return this._run(message, 'main') } async _run (message, method) { // Builds a import map with an array of given interfaces const importMap = {} for (const name in this.imports) { importMap[name] = {} const Import = this.imports[name] const newInterface = new Import(this) const props = Object.getOwnPropertyNames(Import.prototype) // bind the methods to the correct 'this' for (const prop of props) { if (prop !== 'constructor') { importMap[name][prop] = newInterface[prop].bind(newInterface) } } } const result = await WebAssembly.instantiate(this.kernel.state.code, importMap) this.instance = result.instance // runs the wasm code this.instance.exports[method]() return this.onDone() } /** * returns a promise that resolves when the wasm instance is done running * @returns {Promise} */ async onDone () { let prevOps while (prevOps !== this._opsQueue) { prevOps = this._opsQueue await prevOps } this.referanceMap.clear() } /** * Pushed an async operation to the a promise queue that * @returns {Promise} the returned promise resolves in the order the intail * operation was pushed to the queue */ pushOpsQueue (promise) { this._opsQueue = Promise.all([this._opsQueue, promise]) return this._opsQueue } /** * executes a callback given an index in the exported callback container * @param {integer} cb * @param {*} val - a value to return to the callback function */ execute (cb, val) { this.instance.exports.table.get(cb)(val) } /** * returns a section of memory from the wasm instance * @param {integer} offset * @param {integer} length * @returns {Uint8Array} */ getMemory (offset, length) { return new Uint8Array(this.instance.exports.memory.buffer, offset, length) } }