worker.js (2271B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2018 The Stdlib Authors. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 'use strict'; 20 21 // MODULES // 22 23 var logger = require( 'debug' ); 24 var proc = require( './process.js' ); 25 var db = require( './children.js' ); 26 var closeProcess = require( './close.js' ); 27 var exec = require( './exec.js' ); 28 var spawn = require( './spawn.js' ); 29 30 31 // VARIABLES // 32 33 var debug = logger( 'parallel:worker' ); 34 35 36 // FUNCTIONS // 37 38 /** 39 * Callback invoked upon receiving a message from a parent process. 40 * 41 * @private 42 * @param {string} message - message from parent 43 * @returns {void} 44 */ 45 function onMessage( message ) { 46 var child; 47 if ( message === 'close' ) { 48 debug( 'Received a message to close. Closing...' ); 49 return closeProcess(); 50 } 51 debug( 'Received a message to run a script: %s. pid: %s.', message, proc.pid ); 52 if ( proc.env.WORKER_ORDERED ) { 53 debug( 'Environment configuration specifies to preserve script output.' ); 54 child = exec( proc.env.WORKER_CMD, message, done ); 55 } else { 56 debug( 'Environment configuration allows interleaved script output.' ); 57 child = spawn( proc.env.WORKER_CMD, message, done ); 58 } 59 db[ child.pid ] = true; 60 } 61 62 /** 63 * Callback invoked once a child process finishes. 64 * 65 * @private 66 * @param {(Error|null)} error - error object 67 * @param {number} pid - child process id 68 * @param {string} script - script filepath (i.e., identifier) 69 * @returns {void} 70 */ 71 function done( error, pid, script ) { 72 delete db[ pid ]; 73 if ( error ) { 74 closeProcess(); 75 return proc.emit( 'error', error ); 76 } 77 // Inform the parent process that the script has finished: 78 proc.send( script ); 79 } 80 81 82 // MAIN // 83 84 /** 85 * Main script. 86 * 87 * @private 88 */ 89 function main() { 90 proc.on( 'message', onMessage ); 91 } 92 93 94 // EXPORTS // 95 96 module.exports = main;