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- 'use strict';
- function _types() {
- const data = require('../types');
- _types = function () {
- return data;
- };
- return data;
- }
- /**
- * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
- let file = null;
- let setupArgs = [];
- let initialized = false;
- /**
- * This file is a small bootstrapper for workers. It sets up the communication
- * between the worker and the parent process, interpreting parent messages and
- * sending results back.
- *
- * The file loaded will be lazily initialized the first time any of the workers
- * is called. This is done for optimal performance: if the farm is initialized,
- * but no call is made to it, child Node processes will be consuming the least
- * possible amount of memory.
- *
- * If an invalid message is detected, the child will exit (by throwing) with a
- * non-zero exit code.
- */
- const messageListener = request => {
- switch (request[0]) {
- case _types().CHILD_MESSAGE_INITIALIZE:
- const init = request;
- file = init[2];
- setupArgs = request[3];
- break;
- case _types().CHILD_MESSAGE_CALL:
- const call = request;
- execMethod(call[2], call[3]);
- break;
- case _types().CHILD_MESSAGE_END:
- end();
- break;
- default:
- throw new TypeError(
- 'Unexpected request from parent process: ' + request[0]
- );
- }
- };
- process.on('message', messageListener);
- function reportSuccess(result) {
- if (!process || !process.send) {
- throw new Error('Child can only be used on a forked process');
- }
- process.send([_types().PARENT_MESSAGE_OK, result]);
- }
- function reportClientError(error) {
- return reportError(error, _types().PARENT_MESSAGE_CLIENT_ERROR);
- }
- function reportInitializeError(error) {
- return reportError(error, _types().PARENT_MESSAGE_SETUP_ERROR);
- }
- function reportError(error, type) {
- if (!process || !process.send) {
- throw new Error('Child can only be used on a forked process');
- }
- if (error == null) {
- error = new Error('"null" or "undefined" thrown');
- }
- process.send([
- type,
- error.constructor && error.constructor.name,
- error.message,
- error.stack,
- typeof error === 'object' ? {...error} : error
- ]);
- }
- function end() {
- const main = require(file);
- if (!main.teardown) {
- exitProcess();
- return;
- }
- execFunction(main.teardown, main, [], exitProcess, exitProcess);
- }
- function exitProcess() {
- // Clean up open handles so the process ideally exits gracefully
- process.removeListener('message', messageListener);
- }
- function execMethod(method, args) {
- const main = require(file);
- let fn;
- if (method === 'default') {
- fn = main.__esModule ? main['default'] : main;
- } else {
- fn = main[method];
- }
- function execHelper() {
- execFunction(fn, main, args, reportSuccess, reportClientError);
- }
- if (initialized || !main.setup) {
- execHelper();
- return;
- }
- initialized = true;
- execFunction(main.setup, main, setupArgs, execHelper, reportInitializeError);
- }
- const isPromise = obj =>
- !!obj &&
- (typeof obj === 'object' || typeof obj === 'function') &&
- typeof obj.then === 'function';
- function execFunction(fn, ctx, args, onResult, onError) {
- let result;
- try {
- result = fn.apply(ctx, args);
- } catch (err) {
- onError(err);
- return;
- }
- if (isPromise(result)) {
- result.then(onResult, onError);
- } else {
- onResult(result);
- }
- }
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