source: trip-planner-front/node_modules/jest-worker/build/workers/processChild.js

Last change on this file was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago

initial commit

  • Property mode set to 100644
File size: 3.4 KB
Line 
1'use strict';
2
3var _types = require('../types');
4
5/**
6 * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
7 *
8 * This source code is licensed under the MIT license found in the
9 * LICENSE file in the root directory of this source tree.
10 */
11let file = null;
12let setupArgs = [];
13let initialized = false;
14/**
15 * This file is a small bootstrapper for workers. It sets up the communication
16 * between the worker and the parent process, interpreting parent messages and
17 * sending results back.
18 *
19 * The file loaded will be lazily initialized the first time any of the workers
20 * is called. This is done for optimal performance: if the farm is initialized,
21 * but no call is made to it, child Node processes will be consuming the least
22 * possible amount of memory.
23 *
24 * If an invalid message is detected, the child will exit (by throwing) with a
25 * non-zero exit code.
26 */
27
28const messageListener = request => {
29 switch (request[0]) {
30 case _types.CHILD_MESSAGE_INITIALIZE:
31 const init = request;
32 file = init[2];
33 setupArgs = request[3];
34 break;
35
36 case _types.CHILD_MESSAGE_CALL:
37 const call = request;
38 execMethod(call[2], call[3]);
39 break;
40
41 case _types.CHILD_MESSAGE_END:
42 end();
43 break;
44
45 default:
46 throw new TypeError(
47 'Unexpected request from parent process: ' + request[0]
48 );
49 }
50};
51
52process.on('message', messageListener);
53
54function reportSuccess(result) {
55 if (!process || !process.send) {
56 throw new Error('Child can only be used on a forked process');
57 }
58
59 process.send([_types.PARENT_MESSAGE_OK, result]);
60}
61
62function reportClientError(error) {
63 return reportError(error, _types.PARENT_MESSAGE_CLIENT_ERROR);
64}
65
66function reportInitializeError(error) {
67 return reportError(error, _types.PARENT_MESSAGE_SETUP_ERROR);
68}
69
70function reportError(error, type) {
71 if (!process || !process.send) {
72 throw new Error('Child can only be used on a forked process');
73 }
74
75 if (error == null) {
76 error = new Error('"null" or "undefined" thrown');
77 }
78
79 process.send([
80 type,
81 error.constructor && error.constructor.name,
82 error.message,
83 error.stack,
84 typeof error === 'object' ? {...error} : error
85 ]);
86}
87
88function end() {
89 const main = require(file);
90
91 if (!main.teardown) {
92 exitProcess();
93 return;
94 }
95
96 execFunction(main.teardown, main, [], exitProcess, exitProcess);
97}
98
99function exitProcess() {
100 // Clean up open handles so the process ideally exits gracefully
101 process.removeListener('message', messageListener);
102}
103
104function execMethod(method, args) {
105 const main = require(file);
106
107 let fn;
108
109 if (method === 'default') {
110 fn = main.__esModule ? main['default'] : main;
111 } else {
112 fn = main[method];
113 }
114
115 function execHelper() {
116 execFunction(fn, main, args, reportSuccess, reportClientError);
117 }
118
119 if (initialized || !main.setup) {
120 execHelper();
121 return;
122 }
123
124 initialized = true;
125 execFunction(main.setup, main, setupArgs, execHelper, reportInitializeError);
126}
127
128const isPromise = obj =>
129 !!obj &&
130 (typeof obj === 'object' || typeof obj === 'function') &&
131 typeof obj.then === 'function';
132
133function execFunction(fn, ctx, args, onResult, onError) {
134 let result;
135
136 try {
137 result = fn.apply(ctx, args);
138 } catch (err) {
139 onError(err);
140 return;
141 }
142
143 if (isPromise(result)) {
144 result.then(onResult, onError);
145 } else {
146 onResult(result);
147 }
148}
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