104 lines
2.8 KiB
JavaScript
104 lines
2.8 KiB
JavaScript
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/**
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* Copyright (c) 2017-present, Facebook, Inc. All rights reserved.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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*
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*/
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'use strict';var _types;
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function _load_types() {return _types = require('./types');}
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let file = null;
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/**
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* This file is a small bootstrapper for workers. It sets up the communication
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* between the worker and the parent process, interpreting parent messages and
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* sending results back.
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*
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* The file loaded will be lazily initialized the first time any of the workers
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* is called. This is done for optimal performance: if the farm is initialized,
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* but no call is made to it, child Node processes will be consuming the least
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* possible amount of memory.
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*
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* If an invalid message is detected, the child will exit (by throwing) with a
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* non-zero exit code.
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*/
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process.on('message', (request /* Should be ChildMessage */) => {
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switch (request[0]) {
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case (_types || _load_types()).CHILD_MESSAGE_INITIALIZE:
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file = request[2];
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break;
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case (_types || _load_types()).CHILD_MESSAGE_CALL:
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execMethod(request[2], request[3]);
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break;
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case (_types || _load_types()).CHILD_MESSAGE_END:
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process.exit(0);
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break;
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default:
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throw new TypeError(
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'Unexpected request from parent process: ' + request[0]);}
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});
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function reportSuccess(result) {
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if (!process || !process.send) {
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throw new Error('Child can only be used on a forked process');
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}
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process.send([(_types || _load_types()).PARENT_MESSAGE_OK, result]);
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}
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function reportError(error) {
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if (!process || !process.send) {
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throw new Error('Child can only be used on a forked process');
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}
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if (error == null) {
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error = new Error('"null" or "undefined" thrown');
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}
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process.send([(_types || _load_types()).PARENT_MESSAGE_ERROR,
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error.constructor && error.constructor.name,
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error.message,
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error.stack,
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// $FlowFixMe: this is safe to just inherit from Object.
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typeof error === 'object' ? Object.assign({}, error) : error]);
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}
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function execMethod(method, args) {
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// $FlowFixMe: This has to be a dynamic require.
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const main = require(file);
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let result;
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try {
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if (method === 'default') {
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result = (main.__esModule ? main['default'] : main).apply(global, args);
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} else {
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result = main[method].apply(main, args);
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}
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} catch (err) {
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reportError(err);
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return;
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}
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if (result && typeof result.then === 'function') {
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result.then(reportSuccess, reportError);
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} else {
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reportSuccess(result);
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}
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}
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