src/worker/WorkerSet.ts

   1 import { WorkerEvents, WorkerSetElement } from '../types/Worker';
   2
   3 import Constants from '../utils/Constants';
   4 import Utils from '../utils/Utils';
   5 import { Worker } from 'worker_threads';
   6 import Wrk from './Wrk';
   7
   8 export default class WorkerSet<T> extends Wrk {
   9   public maxElementsPerWorker: number;
  10   private workerSet: Set<WorkerSetElement>;
  11
  12   /**
  13    * Create a new `WorkerSet`.
  14    *
  15    * @param {string} workerScript
  16    * @param {number} maxElementsPerWorker
  17    */
  18   constructor(workerScript: string, maxElementsPerWorker = 1) {
  19     super(workerScript);
  20     this.workerSet = new Set<WorkerSetElement>();
  21     this.maxElementsPerWorker = maxElementsPerWorker;
  22   }
  23
  24   get size(): number {
  25     return this.workerSet.size;
  26   }
  27
  28   /**
  29    *
  30    * @return {Promise<void>}
  31    * @public
  32    */
  33   public async addElement(elementData: T): Promise<void> {
  34     if (!this.workerSet) {
  35       throw Error('Cannot add a WorkerSet element: workers\' set does not exist');
  36     }
  37     if (this.getLastWorkerSetElement().numberOfWorkerElements >= this.maxElementsPerWorker) {
  38       this.startWorker();
  39       // Start worker sequentially to optimize memory at startup
  40       await Utils.sleep(Constants.START_WORKER_DELAY);
  41     }
  42     this.getLastWorker().postMessage({ id: WorkerEvents.START_WORKER_ELEMENT, workerData: elementData });
  43     this.getLastWorkerSetElement().numberOfWorkerElements++;
  44   }
  45
  46   /**
  47    *
  48    * @return {Promise<void>}
  49    * @public
  50    */
  51   public async start(): Promise<void> {
  52     this.startWorker();
  53     // Start worker sequentially to optimize memory at startup
  54     await Utils.sleep(Constants.START_WORKER_DELAY);
  55   }
  56
  57   /**
  58    *
  59    * @return {Promise<void>}
  60    * @public
  61    */
  62   public async stop(): Promise<void> {
  63     for (const workerSetElement of this.workerSet) {
  64       await workerSetElement.worker.terminate();
  65     }
  66     this.workerSet.clear();
  67   }
  68
  69   /**
  70    *
  71    * @return {Promise}
  72    * @private
  73    */
  74   private startWorker(): void {
  75     const worker = new Worker(this.workerScript);
  76     worker.on('message', () => { });
  77     worker.on('error', () => { });
  78     worker.on('exit', (code) => {
  79       if (code !== 0) {
  80         console.error(`Worker stopped with exit code ${code}`);
  81       }
  82       // FIXME: remove matching worker set element
  83     });
  84     this.workerSet.add({ worker, numberOfWorkerElements: 0 });
  85   }
  86
  87   private getLastWorkerSetElement(): WorkerSetElement {
  88     let workerSetElement: WorkerSetElement;
  89     // eslint-disable-next-line no-empty
  90     for (workerSetElement of this.workerSet) { }
  91     return workerSetElement;
  92   }
  93
  94   private getLastWorker(): Worker {
  95     return this.getLastWorkerSetElement().worker;
  96   }
  97
  98   private getWorkerSetElementByWorker(worker: Worker): WorkerSetElement {
  99     let workerSetElt: WorkerSetElement;
 100     this.workerSet.forEach((workerSetElement) => {
 101       if (JSON.stringify(workerSetElement.worker) === JSON.stringify(worker)) {
 102         workerSetElt = workerSetElement;
 103       }
 104     });
 105     return workerSetElt;
 106   }
 107 }