'use strict';
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var Promise = require('./Promise');
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var environment = require('./environment');
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var requireFoolWebpack = require('./requireFoolWebpack');
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/**
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* Special message sent by parent which causes a child process worker to terminate itself.
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* Not a "message object"; this string is the entire message.
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*/
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var TERMINATE_METHOD_ID = '__workerpool-terminate__';
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/**
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* If sending `TERMINATE_METHOD_ID` does not cause the child process to exit in this many milliseconds,
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* force-kill the child process.
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*/
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var CHILD_PROCESS_EXIT_TIMEOUT = 1000;
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function ensureWorkerThreads() {
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var WorkerThreads = tryRequireWorkerThreads()
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if (!WorkerThreads) {
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throw new Error('WorkerPool: workerType = \'thread\' is not supported, Node >= 11.7.0 required')
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}
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return WorkerThreads;
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}
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// check whether Worker is supported by the browser
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function ensureWebWorker() {
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// Workaround for a bug in PhantomJS (Or QtWebkit): https://github.com/ariya/phantomjs/issues/14534
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if (typeof Worker !== 'function' && (typeof Worker !== 'object' || typeof Worker.prototype.constructor !== 'function')) {
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throw new Error('WorkerPool: Web Workers not supported');
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}
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}
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function tryRequireWorkerThreads() {
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try {
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return requireFoolWebpack('worker_threads');
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} catch(error) {
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if (typeof error === 'object' && error !== null && error.code === 'MODULE_NOT_FOUND') {
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// no worker_threads available (old version of node.js)
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return null;
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} else {
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throw error;
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}
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}
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}
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// get the default worker script
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function getDefaultWorker() {
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if (environment.platform === 'browser') {
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// test whether the browser supports all features that we need
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if (typeof Blob === 'undefined') {
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throw new Error('Blob not supported by the browser');
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}
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if (!window.URL || typeof window.URL.createObjectURL !== 'function') {
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throw new Error('URL.createObjectURL not supported by the browser');
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}
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// use embedded worker.js
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var blob = new Blob([require('./generated/embeddedWorker')], {type: 'text/javascript'});
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return window.URL.createObjectURL(blob);
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}
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else {
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// use external worker.js in current directory
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return __dirname + '/worker.js';
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}
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}
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function setupWorker(script, options) {
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if (options.workerType === 'web') { // browser only
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ensureWebWorker();
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return setupBrowserWorker(script, Worker);
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} else if (options.workerType === 'thread') { // node.js only
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WorkerThreads = ensureWorkerThreads();
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return setupWorkerThreadWorker(script, WorkerThreads);
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} else if (options.workerType === 'process' || !options.workerType) { // node.js only
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return setupProcessWorker(script, resolveForkOptions(options), requireFoolWebpack('child_process'));
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} else { // options.workerType === 'auto' or undefined
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if (environment.platform === 'browser') {
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ensureWebWorker();
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return setupBrowserWorker(script, Worker);
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}
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else { // environment.platform === 'node'
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var WorkerThreads = tryRequireWorkerThreads();
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if (WorkerThreads) {
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return setupWorkerThreadWorker(script, WorkerThreads);
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} else {
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return setupProcessWorker(script, resolveForkOptions(options), requireFoolWebpack('child_process'));
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}
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}
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}
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}
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function setupBrowserWorker(script, Worker) {
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// create the web worker
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var worker = new Worker(script);
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worker.isBrowserWorker = true;
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// add node.js API to the web worker
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worker.on = function (event, callback) {
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this.addEventListener(event, function (message) {
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callback(message.data);
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});
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};
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worker.send = function (message) {
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this.postMessage(message);
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};
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return worker;
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}
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function setupWorkerThreadWorker(script, WorkerThreads) {
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var worker = new WorkerThreads.Worker(script, {
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stdout: false, // automatically pipe worker.STDOUT to process.STDOUT
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stderr: false // automatically pipe worker.STDERR to process.STDERR
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});
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worker.isWorkerThread = true;
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// make the worker mimic a child_process
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worker.send = function(message) {
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this.postMessage(message);
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};
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worker.kill = function() {
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this.terminate();
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return true;
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};
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worker.disconnect = function() {
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this.terminate();
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};
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return worker;
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}
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function setupProcessWorker(script, options, child_process) {
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// no WorkerThreads, fallback to sub-process based workers
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var worker = child_process.fork(
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script,
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options.forkArgs,
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options.forkOpts
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);
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worker.isChildProcess = true;
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return worker;
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}
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// add debug flags to child processes if the node inspector is active
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function resolveForkOptions(opts) {
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opts = opts || {};
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var processExecArgv = process.execArgv.join(' ');
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var inspectorActive = processExecArgv.indexOf('--inspect') !== -1;
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var debugBrk = processExecArgv.indexOf('--debug-brk') !== -1;
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var execArgv = [];
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if (inspectorActive) {
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execArgv.push('--inspect=' + opts.debugPort);
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if (debugBrk) {
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execArgv.push('--debug-brk');
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}
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}
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process.execArgv.forEach(function(arg) {
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if (arg.indexOf('--max-old-space-size') > -1) {
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execArgv.push(arg)
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}
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})
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return Object.assign({}, opts, {
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forkArgs: opts.forkArgs,
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forkOpts: Object.assign({}, opts.forkOpts, {
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execArgv: (opts.forkOpts && opts.forkOpts.execArgv || [])
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.concat(execArgv)
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})
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});
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}
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/**
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* Converts a serialized error to Error
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* @param {Object} obj Error that has been serialized and parsed to object
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* @return {Error} The equivalent Error.
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*/
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function objectToError (obj) {
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var temp = new Error('')
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var props = Object.keys(obj)
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for (var i = 0; i < props.length; i++) {
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temp[props[i]] = obj[props[i]]
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}
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return temp
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}
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/**
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* A WorkerHandler controls a single worker. This worker can be a child process
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* on node.js or a WebWorker in a browser environment.
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* @param {String} [script] If no script is provided, a default worker with a
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* function run will be created.
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* @param {WorkerPoolOptions} _options See docs
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* @constructor
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*/
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function WorkerHandler(script, _options) {
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var me = this;
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var options = _options || {};
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this.script = script || getDefaultWorker();
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this.worker = setupWorker(this.script, options);
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this.debugPort = options.debugPort;
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this.forkOpts = options.forkOpts;
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this.forkArgs = options.forkArgs;
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// The ready message is only sent if the worker.add method is called (And the default script is not used)
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if (!script) {
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this.worker.ready = true;
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}
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// queue for requests that are received before the worker is ready
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this.requestQueue = [];
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this.worker.on('message', function (response) {
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if (me.terminated) {
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return;
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}
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if (typeof response === 'string' && response === 'ready') {
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me.worker.ready = true;
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dispatchQueuedRequests();
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} else {
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// find the task from the processing queue, and run the tasks callback
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var id = response.id;
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var task = me.processing[id];
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if (task !== undefined) {
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if (response.isEvent) {
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if (task.options && typeof task.options.on === 'function') {
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task.options.on(response.payload);
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}
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} else {
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// remove the task from the queue
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delete me.processing[id];
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// test if we need to terminate
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if (me.terminating === true) {
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// complete worker termination if all tasks are finished
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me.terminate();
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}
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// resolve the task's promise
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if (response.error) {
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task.resolver.reject(objectToError(response.error));
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}
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else {
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task.resolver.resolve(response.result);
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}
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}
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}
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}
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});
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// reject all running tasks on worker error
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function onError(error) {
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me.terminated = true;
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for (var id in me.processing) {
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if (me.processing[id] !== undefined) {
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me.processing[id].resolver.reject(error);
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}
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}
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me.processing = Object.create(null);
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}
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// send all queued requests to worker
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function dispatchQueuedRequests()
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{
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for(const request of me.requestQueue.splice(0)) {
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me.worker.send(request);
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}
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}
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var worker = this.worker;
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// listen for worker messages error and exit
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this.worker.on('error', onError);
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this.worker.on('exit', function (exitCode, signalCode) {
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var message = 'Workerpool Worker terminated Unexpectedly\n';
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message += ' exitCode: `' + exitCode + '`\n';
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message += ' signalCode: `' + signalCode + '`\n';
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message += ' workerpool.script: `' + me.script + '`\n';
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message += ' spawnArgs: `' + worker.spawnargs + '`\n';
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message += ' spawnfile: `' + worker.spawnfile + '`\n'
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message += ' stdout: `' + worker.stdout + '`\n'
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message += ' stderr: `' + worker.stderr + '`\n'
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onError(new Error(message));
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});
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this.processing = Object.create(null); // queue with tasks currently in progress
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this.terminating = false;
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this.terminated = false;
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this.terminationHandler = null;
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this.lastId = 0;
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}
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/**
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* Get a list with methods available on the worker.
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* @return {Promise.<String[], Error>} methods
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*/
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WorkerHandler.prototype.methods = function () {
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return this.exec('methods');
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};
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/**
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* Execute a method with given parameters on the worker
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* @param {String} method
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* @param {Array} [params]
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* @param {{resolve: Function, reject: Function}} [resolver]
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* @param {ExecOptions} [options]
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* @return {Promise.<*, Error>} result
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*/
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WorkerHandler.prototype.exec = function(method, params, resolver, options) {
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if (!resolver) {
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resolver = Promise.defer();
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}
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// generate a unique id for the task
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var id = ++this.lastId;
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// register a new task as being in progress
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this.processing[id] = {
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id: id,
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resolver: resolver,
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options: options
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};
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// build a JSON-RPC request
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var request = {
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id: id,
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method: method,
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params: params
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};
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if (this.terminated) {
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resolver.reject(new Error('Worker is terminated'));
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} else if (this.worker.ready) {
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// send the request to the worker
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this.worker.send(request);
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} else {
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this.requestQueue.push(request);
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}
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// on cancellation, force the worker to terminate
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var me = this;
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return resolver.promise.catch(function (error) {
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if (error instanceof Promise.CancellationError || error instanceof Promise.TimeoutError) {
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// remove this task from the queue. It is already rejected (hence this
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// catch event), and else it will be rejected again when terminating
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delete me.processing[id];
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// terminate worker
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return me.terminateAndNotify(true)
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.then(function() {
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throw error;
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}, function(err) {
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throw err;
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});
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} else {
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throw error;
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}
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})
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};
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/**
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* Test whether the worker is working or not
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* @return {boolean} Returns true if the worker is busy
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*/
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WorkerHandler.prototype.busy = function () {
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return Object.keys(this.processing).length > 0;
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};
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/**
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* Terminate the worker.
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* @param {boolean} [force=false] If false (default), the worker is terminated
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* after finishing all tasks currently in
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* progress. If true, the worker will be
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* terminated immediately.
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* @param {function} [callback=null] If provided, will be called when process terminates.
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*/
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WorkerHandler.prototype.terminate = function (force, callback) {
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var me = this;
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if (force) {
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// cancel all tasks in progress
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for (var id in this.processing) {
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if (this.processing[id] !== undefined) {
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this.processing[id].resolver.reject(new Error('Worker terminated'));
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}
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}
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this.processing = Object.create(null);
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}
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if (typeof callback === 'function') {
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this.terminationHandler = callback;
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}
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if (!this.busy()) {
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// all tasks are finished. kill the worker
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var cleanup = function(err) {
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me.terminated = true;
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if (me.worker != null && me.worker.removeAllListeners) {
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// removeAllListeners is only available for child_process
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me.worker.removeAllListeners('message');
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}
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me.worker = null;
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me.terminating = false;
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if (me.terminationHandler) {
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me.terminationHandler(err, me);
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} else if (err) {
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throw err;
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}
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}
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if (this.worker) {
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if (typeof this.worker.kill === 'function') {
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if (this.worker.killed) {
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cleanup(new Error('worker already killed!'));
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return;
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}
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if (this.worker.isChildProcess) {
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var cleanExitTimeout = setTimeout(function() {
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if (me.worker) {
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me.worker.kill();
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}
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}, CHILD_PROCESS_EXIT_TIMEOUT);
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this.worker.once('exit', function() {
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clearTimeout(cleanExitTimeout);
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if (me.worker) {
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me.worker.killed = true;
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}
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cleanup();
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});
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if (this.worker.ready) {
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this.worker.send(TERMINATE_METHOD_ID);
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} else {
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this.worker.requestQueue.push(TERMINATE_METHOD_ID)
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}
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} else {
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// worker_thread
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this.worker.kill();
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this.worker.killed = true;
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cleanup();
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}
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return;
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}
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else if (typeof this.worker.terminate === 'function') {
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this.worker.terminate(); // web worker
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this.worker.killed = true;
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}
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else {
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throw new Error('Failed to terminate worker');
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}
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}
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cleanup();
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}
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else {
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// we can't terminate immediately, there are still tasks being executed
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this.terminating = true;
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}
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};
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/**
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* Terminate the worker, returning a Promise that resolves when the termination has been done.
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* @param {boolean} [force=false] If false (default), the worker is terminated
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* after finishing all tasks currently in
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* progress. If true, the worker will be
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* terminated immediately.
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* @param {number} [timeout] If provided and non-zero, worker termination promise will be rejected
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* after timeout if worker process has not been terminated.
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* @return {Promise.<WorkerHandler, Error>}
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*/
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WorkerHandler.prototype.terminateAndNotify = function (force, timeout) {
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var resolver = Promise.defer();
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if (timeout) {
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resolver.promise.timeout = timeout;
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}
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this.terminate(force, function(err, worker) {
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if (err) {
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resolver.reject(err);
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} else {
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resolver.resolve(worker);
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}
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});
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return resolver.promise;
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};
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module.exports = WorkerHandler;
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module.exports._tryRequireWorkerThreads = tryRequireWorkerThreads;
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module.exports._setupProcessWorker = setupProcessWorker;
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module.exports._setupBrowserWorker = setupBrowserWorker;
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module.exports._setupWorkerThreadWorker = setupWorkerThreadWorker;
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module.exports.ensureWorkerThreads = ensureWorkerThreads;
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