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