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 { randomizeDelay, 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 &&
  80       (await sleep(randomizeDelay(this.workerOptions.workerStartDelay!)));
  81     this.started = true;
  82   }
  83
  84   /** @inheritDoc */
  85   public async stop(): Promise<void> {
  86     for (const workerSetElement of this.workerSet) {
  87       const worker = workerSetElement.worker;
  88       const waitWorkerExit = new Promise<void>((resolve) => {
  89         worker.on('exit', () => {
  90           resolve();
  91         });
  92       });
  93       await worker.terminate();
  94       await waitWorkerExit;
  95       this.started = false;
  96     }
  97   }
  98
  99   /** @inheritDoc */
 100   public async addElement(elementData: WorkerData): Promise<void> {
 101     if (!this.started) {
 102       throw new Error('Cannot add a WorkerSet element: not started');
 103     }
 104     if (!this.workerSet) {
 105       throw new Error("Cannot add a WorkerSet element: 'workerSet' property does not exist");
 106     }
 107     const workerSetElement = await this.getWorkerSetElement();
 108     workerSetElement.worker.postMessage({
 109       event: WorkerMessageEvents.startWorkerElement,
 110       data: elementData,
 111     });
 112     ++workerSetElement.numberOfWorkerElements;
 113     // Add element sequentially to optimize memory at startup
 114     if (this.workerOptions.elementStartDelay! > 0) {
 115       await sleep(randomizeDelay(this.workerOptions.elementStartDelay!));
 116     }
 117   }
 118
 119   /**
 120    * Adds a new `WorkerSetElement`.
 121    */
 122   private addWorkerSetElement(): WorkerSetElement {
 123     this.workerStartup = true;
 124     const worker = new Worker(this.workerScript, {
 125       env: SHARE_ENV,
 126       ...this.workerOptions.poolOptions?.workerOptions,
 127     });
 128     worker.on('message', this.workerOptions.poolOptions?.messageHandler ?? EMPTY_FUNCTION);
 129     worker.on('message', (message: WorkerMessage<WorkerData>) => {
 130       if (message.event === WorkerMessageEvents.startedWorkerElement) {
 131         this.emitter?.emit(WorkerSetEvents.elementStarted, this.info);
 132       } else if (message.event === WorkerMessageEvents.startWorkerElementError) {
 133         this.emitter?.emit(WorkerSetEvents.elementError, message.data);
 134       }
 135     });
 136     worker.on('error', this.workerOptions.poolOptions?.errorHandler ?? EMPTY_FUNCTION);
 137     worker.on('error', (error) => {
 138       this.emitter?.emit(WorkerSetEvents.error, error);
 139       if (
 140         this.workerOptions.poolOptions?.restartWorkerOnError &&
 141         this.started &&
 142         !this.workerStartup
 143       ) {
 144         this.addWorkerSetElement();
 145       }
 146     });
 147     worker.on('online', this.workerOptions.poolOptions?.onlineHandler ?? EMPTY_FUNCTION);
 148     worker.on('exit', this.workerOptions.poolOptions?.exitHandler ?? EMPTY_FUNCTION);
 149     worker.once('exit', () =>
 150       this.removeWorkerSetElement(this.getWorkerSetElementByWorker(worker)!),
 151     );
 152     const workerSetElement: WorkerSetElement = { worker, numberOfWorkerElements: 0 };
 153     this.workerSet.add(workerSetElement);
 154     this.workerStartup = false;
 155     return workerSetElement;
 156   }
 157
 158   private removeWorkerSetElement(workerSetElement: WorkerSetElement): void {
 159     this.workerSet.delete(workerSetElement);
 160   }
 161
 162   private async getWorkerSetElement(): Promise<WorkerSetElement> {
 163     let chosenWorkerSetElement: WorkerSetElement | undefined;
 164     for (const workerSetElement of this.workerSet) {
 165       if (workerSetElement.numberOfWorkerElements < this.workerOptions.elementsPerWorker!) {
 166         chosenWorkerSetElement = workerSetElement;
 167         break;
 168       }
 169     }
 170     if (!chosenWorkerSetElement) {
 171       chosenWorkerSetElement = this.addWorkerSetElement();
 172       // Add worker set element sequentially to optimize memory at startup
 173       this.workerOptions.workerStartDelay! > 0 &&
 174         (await sleep(randomizeDelay(this.workerOptions.workerStartDelay!)));
 175     }
 176     return chosenWorkerSetElement;
 177   }
 178
 179   private getWorkerSetElementByWorker(worker: Worker): WorkerSetElement | undefined {
 180     let workerSetElt: WorkerSetElement | undefined;
 181     for (const workerSetElement of this.workerSet) {
 182       if (workerSetElement.worker.threadId === worker.threadId) {
 183         workerSetElt = workerSetElement;
 184         break;
 185       }
 186     }
 187     return workerSetElt;
 188   }
 189 }