src/worker/WorkerSet.ts

   1 // Partial Copyright Jerome Benoit. 2021-2023. All Rights Reserved.
   2
   3 import { EventEmitter } from 'node:events';
   4 import { SHARE_ENV, Worker } from 'node:worker_threads';
   5
   6 import { WorkerAbstract } from './WorkerAbstract';
   7 import { EMPTY_FUNCTION, workerSetVersion } from './WorkerConstants';
   8 import {
   9   type SetInfo,
  10   type WorkerData,
  11   type WorkerMessage,
  12   WorkerMessageEvents,
  13   type WorkerOptions,
  14   type WorkerSetElement,
  15   WorkerSetEvents,
  16 } from './WorkerTypes';
  17 import { sleep } from './WorkerUtils';
  18
  19 export class WorkerSet extends WorkerAbstract<WorkerData> {
  20   public readonly emitter!: EventEmitter;
  21   private readonly workerSet: Set<WorkerSetElement>;
  22   private started: boolean;
  23   private workerStartup: boolean;
  24
  25   /**
  26    * Creates a new `WorkerSet`.
  27    *
  28    * @param workerScript -
  29    * @param workerOptions -
  30    */
  31   constructor(workerScript: string, workerOptions: WorkerOptions) {
  32     super(workerScript, workerOptions);
  33     if (
  34       this.workerOptions.elementsPerWorker === null ||
  35       this.workerOptions.elementsPerWorker === undefined
  36     ) {
  37       throw new TypeError('Elements per worker is not defined');
  38     }
  39     if (!Number.isSafeInteger(this.workerOptions.elementsPerWorker)) {
  40       throw new TypeError('Elements per worker must be an integer');
  41     }
  42     if (this.workerOptions.elementsPerWorker <= 0) {
  43       throw new RangeError('Elements per worker must be greater than zero');
  44     }
  45     this.workerSet = new Set<WorkerSetElement>();
  46     if (this.workerOptions.poolOptions?.enableEvents) {
  47       this.emitter = new EventEmitter();
  48     }
  49     this.started = false;
  50     this.workerStartup = false;
  51   }
  52
  53   get info(): SetInfo {
  54     return {
  55       version: workerSetVersion,
  56       type: 'set',
  57       worker: 'thread',
  58       size: this.size,
  59       elementsExecuting: [...this.workerSet].reduce(
  60         (accumulator, workerSetElement) => accumulator + workerSetElement.numberOfWorkerElements,
  61         0,
  62       ),
  63       elementsPerWorker: this.maxElementsPerWorker!,
  64     };
  65   }
  66
  67   get size(): number {
  68     return this.workerSet.size;
  69   }
  70
  71   get maxElementsPerWorker(): number | undefined {
  72     return this.workerOptions.elementsPerWorker;
  73   }
  74
  75   /** @inheritDoc */
  76   public async start(): Promise<void> {
  77     this.addWorkerSetElement();
  78     // Add worker set element sequentially to optimize memory at startup
  79     this.workerOptions.workerStartDelay! > 0 && (await sleep(this.workerOptions.workerStartDelay!));
  80     this.started = true;
  81   }
  82
  83   /** @inheritDoc */
  84   public async stop(): Promise<void> {
  85     for (const workerSetElement of this.workerSet) {
  86       const worker = workerSetElement.worker;
  87       const waitWorkerExit = new Promise<void>((resolve) => {
  88         worker.on('exit', () => {
  89           resolve();
  90         });
  91       });
  92       await worker.terminate();
  93       await waitWorkerExit;
  94       this.started = false;
  95     }
  96   }
  97
  98   /** @inheritDoc */
  99   public async addElement(elementData: WorkerData): Promise<void> {
 100     if (!this.started) {
 101       throw new Error('Cannot add a WorkerSet element: not started');
 102     }
 103     if (!this.workerSet) {
 104       throw new Error("Cannot add a WorkerSet element: 'workerSet' property does not exist");
 105     }
 106     const workerSetElement = await this.getWorkerSetElement();
 107     workerSetElement.worker.postMessage({
 108       event: WorkerMessageEvents.startWorkerElement,
 109       data: elementData,
 110     });
 111     ++workerSetElement.numberOfWorkerElements;
 112     // Add element sequentially to optimize memory at startup
 113     if (this.workerOptions.elementStartDelay! > 0) {
 114       await sleep(this.workerOptions.elementStartDelay!);
 115     }
 116   }
 117
 118   /**
 119    * Adds a new `WorkerSetElement`.
 120    */
 121   private addWorkerSetElement(): WorkerSetElement {
 122     this.workerStartup = true;
 123     const worker = new Worker(this.workerScript, {
 124       env: SHARE_ENV,
 125       ...this.workerOptions.poolOptions?.workerOptions,
 126     });
 127     worker.on('message', this.workerOptions.poolOptions?.messageHandler ?? EMPTY_FUNCTION);
 128     worker.on('message', (message: WorkerMessage<WorkerData>) => {
 129       if (message.event === WorkerMessageEvents.startedWorkerElement) {
 130         this.emitter?.emit(WorkerSetEvents.elementStarted, this.info);
 131       } else if (message.event === WorkerMessageEvents.startWorkerElementError) {
 132         this.emitter?.emit(WorkerSetEvents.elementError, message.data);
 133       }
 134     });
 135     worker.on('error', this.workerOptions.poolOptions?.errorHandler ?? EMPTY_FUNCTION);
 136     worker.on('error', (error) => {
 137       this.emitter?.emit(WorkerSetEvents.error, error);
 138       if (
 139         this.workerOptions.poolOptions?.restartWorkerOnError &&
 140         this.started &&
 141         !this.workerStartup
 142       ) {
 143         this.addWorkerSetElement();
 144       }
 145     });
 146     worker.on('online', this.workerOptions.poolOptions?.onlineHandler ?? EMPTY_FUNCTION);
 147     worker.on('exit', this.workerOptions.poolOptions?.exitHandler ?? EMPTY_FUNCTION);
 148     worker.once('exit', () =>
 149       this.removeWorkerSetElement(this.getWorkerSetElementByWorker(worker)!),
 150     );
 151     const workerSetElement: WorkerSetElement = { worker, numberOfWorkerElements: 0 };
 152     this.workerSet.add(workerSetElement);
 153     this.workerStartup = false;
 154     return workerSetElement;
 155   }
 156
 157   private removeWorkerSetElement(workerSetElement: WorkerSetElement): void {
 158     this.workerSet.delete(workerSetElement);
 159   }
 160
 161   private async getWorkerSetElement(): Promise<WorkerSetElement> {
 162     let chosenWorkerSetElement: WorkerSetElement | undefined;
 163     for (const workerSetElement of this.workerSet) {
 164       if (workerSetElement.numberOfWorkerElements < this.workerOptions.elementsPerWorker!) {
 165         chosenWorkerSetElement = workerSetElement;
 166         break;
 167       }
 168     }
 169     if (!chosenWorkerSetElement) {
 170       chosenWorkerSetElement = this.addWorkerSetElement();
 171       // Add worker set element sequentially to optimize memory at startup
 172       this.workerOptions.workerStartDelay! > 0 &&
 173         (await sleep(this.workerOptions.workerStartDelay!));
 174     }
 175     return chosenWorkerSetElement;
 176   }
 177
 178   private getWorkerSetElementByWorker(worker: Worker): WorkerSetElement | undefined {
 179     let workerSetElt: WorkerSetElement | undefined;
 180     for (const workerSetElement of this.workerSet) {
 181       if (workerSetElement.worker.threadId === worker.threadId) {
 182         workerSetElt = workerSetElement;
 183         break;
 184       }
 185     }
 186     return workerSetElt;
 187   }
 188 }