src/pools/abstract-pool.ts

   1 import crypto from 'node:crypto'
   2 import type { MessageValue, PromiseResponseWrapper } from '../utility-types'
   3 import {
   4   DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS,
   5   EMPTY_FUNCTION,
   6   median
   7 } from '../utils'
   8 import { KillBehaviors, isKillBehavior } from '../worker/worker-options'
   9 import { CircularArray } from '../circular-array'
  10 import { Queue } from '../queue'
  11 import {
  12   type IPool,
  13   PoolEmitter,
  14   PoolEvents,
  15   type PoolOptions,
  16   PoolType,
  17   type TasksQueueOptions
  18 } from './pool'
  19 import type { IWorker, Task, TasksUsage, WorkerNode } from './worker'
  20 import {
  21   WorkerChoiceStrategies,
  22   type WorkerChoiceStrategy,
  23   type WorkerChoiceStrategyOptions
  24 } from './selection-strategies/selection-strategies-types'
  25 import { WorkerChoiceStrategyContext } from './selection-strategies/worker-choice-strategy-context'
  26
  27 /**
  28  * Base class that implements some shared logic for all poolifier pools.
  29  *
  30  * @typeParam Worker - Type of worker which manages this pool.
  31  * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
  32  * @typeParam Response - Type of execution response. This can only be serializable data.
  33  */
  34 export abstract class AbstractPool<
  35   Worker extends IWorker,
  36   Data = unknown,
  37   Response = unknown
  38 > implements IPool<Worker, Data, Response> {
  39   /** @inheritDoc */
  40   public readonly workerNodes: Array<WorkerNode<Worker, Data>> = []
  41
  42   /** @inheritDoc */
  43   public readonly emitter?: PoolEmitter
  44
  45   /**
  46    * The execution response promise map.
  47    *
  48    * - `key`: The message id of each submitted task.
  49    * - `value`: An object that contains the worker, the execution response promise resolve and reject callbacks.
  50    *
  51    * When we receive a message from the worker, we get a map entry with the promise resolve/reject bound to the message id.
  52    */
  53   protected promiseResponseMap: Map<
  54   string,
  55   PromiseResponseWrapper<Worker, Response>
  56   > = new Map<string, PromiseResponseWrapper<Worker, Response>>()
  57
  58   /**
  59    * Worker choice strategy context referencing a worker choice algorithm implementation.
  60    *
  61    * Default to a round robin algorithm.
  62    */
  63   protected workerChoiceStrategyContext: WorkerChoiceStrategyContext<
  64   Worker,
  65   Data,
  66   Response
  67   >
  68
  69   /**
  70    * Constructs a new poolifier pool.
  71    *
  72    * @param numberOfWorkers - Number of workers that this pool should manage.
  73    * @param filePath - Path to the worker file.
  74    * @param opts - Options for the pool.
  75    */
  76   public constructor (
  77     public readonly numberOfWorkers: number,
  78     public readonly filePath: string,
  79     public readonly opts: PoolOptions<Worker>
  80   ) {
  81     if (!this.isMain()) {
  82       throw new Error('Cannot start a pool from a worker!')
  83     }
  84     this.checkNumberOfWorkers(this.numberOfWorkers)
  85     this.checkFilePath(this.filePath)
  86     this.checkPoolOptions(this.opts)
  87
  88     this.chooseWorkerNode = this.chooseWorkerNode.bind(this)
  89     this.executeTask = this.executeTask.bind(this)
  90     this.enqueueTask = this.enqueueTask.bind(this)
  91     this.checkAndEmitEvents = this.checkAndEmitEvents.bind(this)
  92
  93     this.setupHook()
  94
  95     for (let i = 1; i <= this.numberOfWorkers; i++) {
  96       this.createAndSetupWorker()
  97     }
  98
  99     if (this.opts.enableEvents === true) {
 100       this.emitter = new PoolEmitter()
 101     }
 102     this.workerChoiceStrategyContext = new WorkerChoiceStrategyContext<
 103     Worker,
 104     Data,
 105     Response
 106     >(
 107       this,
 108       this.opts.workerChoiceStrategy,
 109       this.opts.workerChoiceStrategyOptions
 110     )
 111   }
 112
 113   private checkFilePath (filePath: string): void {
 114     if (
 115       filePath == null ||
 116       (typeof filePath === 'string' && filePath.trim().length === 0)
 117     ) {
 118       throw new Error('Please specify a file with a worker implementation')
 119     }
 120   }
 121
 122   private checkNumberOfWorkers (numberOfWorkers: number): void {
 123     if (numberOfWorkers == null) {
 124       throw new Error(
 125         'Cannot instantiate a pool without specifying the number of workers'
 126       )
 127     } else if (!Number.isSafeInteger(numberOfWorkers)) {
 128       throw new TypeError(
 129         'Cannot instantiate a pool with a non integer number of workers'
 130       )
 131     } else if (numberOfWorkers < 0) {
 132       throw new RangeError(
 133         'Cannot instantiate a pool with a negative number of workers'
 134       )
 135     } else if (this.type === PoolType.FIXED && numberOfWorkers === 0) {
 136       throw new Error('Cannot instantiate a fixed pool with no worker')
 137     }
 138   }
 139
 140   private checkPoolOptions (opts: PoolOptions<Worker>): void {
 141     this.opts.workerChoiceStrategy =
 142       opts.workerChoiceStrategy ?? WorkerChoiceStrategies.ROUND_ROBIN
 143     this.checkValidWorkerChoiceStrategy(this.opts.workerChoiceStrategy)
 144     this.opts.workerChoiceStrategyOptions =
 145       opts.workerChoiceStrategyOptions ?? DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
 146     this.opts.enableEvents = opts.enableEvents ?? true
 147     this.opts.enableTasksQueue = opts.enableTasksQueue ?? false
 148     if (this.opts.enableTasksQueue) {
 149       this.checkValidTasksQueueOptions(
 150         opts.tasksQueueOptions as TasksQueueOptions
 151       )
 152       this.opts.tasksQueueOptions = this.buildTasksQueueOptions(
 153         opts.tasksQueueOptions as TasksQueueOptions
 154       )
 155     }
 156   }
 157
 158   private checkValidWorkerChoiceStrategy (
 159     workerChoiceStrategy: WorkerChoiceStrategy
 160   ): void {
 161     if (!Object.values(WorkerChoiceStrategies).includes(workerChoiceStrategy)) {
 162       throw new Error(
 163         `Invalid worker choice strategy '${workerChoiceStrategy}'`
 164       )
 165     }
 166   }
 167
 168   private checkValidTasksQueueOptions (
 169     tasksQueueOptions: TasksQueueOptions
 170   ): void {
 171     if ((tasksQueueOptions?.concurrency as number) <= 0) {
 172       throw new Error(
 173         `Invalid worker tasks concurrency '${
 174           tasksQueueOptions.concurrency as number
 175         }'`
 176       )
 177     }
 178   }
 179
 180   /** @inheritDoc */
 181   public abstract get type (): PoolType
 182
 183   /** @inheritDoc */
 184   public abstract get size (): number
 185
 186   /**
 187    * Number of tasks running in the pool.
 188    */
 189   private get numberOfRunningTasks (): number {
 190     return this.workerNodes.reduce(
 191       (accumulator, workerNode) => accumulator + workerNode.tasksUsage.running,
 192       0
 193     )
 194   }
 195
 196   /**
 197    * Number of tasks queued in the pool.
 198    */
 199   private get numberOfQueuedTasks (): number {
 200     if (this.opts.enableTasksQueue === false) {
 201       return 0
 202     }
 203     return this.workerNodes.reduce(
 204       (accumulator, workerNode) => accumulator + workerNode.tasksQueue.size,
 205       0
 206     )
 207   }
 208
 209   /**
 210    * Gets the given worker its worker node key.
 211    *
 212    * @param worker - The worker.
 213    * @returns The worker node key if the worker is found in the pool worker nodes, `-1` otherwise.
 214    */
 215   private getWorkerNodeKey (worker: Worker): number {
 216     return this.workerNodes.findIndex(
 217       workerNode => workerNode.worker === worker
 218     )
 219   }
 220
 221   /** @inheritDoc */
 222   public setWorkerChoiceStrategy (
 223     workerChoiceStrategy: WorkerChoiceStrategy,
 224     workerChoiceStrategyOptions?: WorkerChoiceStrategyOptions
 225   ): void {
 226     this.checkValidWorkerChoiceStrategy(workerChoiceStrategy)
 227     this.opts.workerChoiceStrategy = workerChoiceStrategy
 228     for (const workerNode of this.workerNodes) {
 229       this.setWorkerNodeTasksUsage(workerNode, {
 230         run: 0,
 231         running: 0,
 232         runTime: 0,
 233         runTimeHistory: new CircularArray(),
 234         avgRunTime: 0,
 235         medRunTime: 0,
 236         error: 0
 237       })
 238     }
 239     this.workerChoiceStrategyContext.setWorkerChoiceStrategy(
 240       this.opts.workerChoiceStrategy
 241     )
 242     if (workerChoiceStrategyOptions != null) {
 243       this.setWorkerChoiceStrategyOptions(workerChoiceStrategyOptions)
 244     }
 245   }
 246
 247   /** @inheritDoc */
 248   public setWorkerChoiceStrategyOptions (
 249     workerChoiceStrategyOptions: WorkerChoiceStrategyOptions
 250   ): void {
 251     this.opts.workerChoiceStrategyOptions = workerChoiceStrategyOptions
 252     this.workerChoiceStrategyContext.setOptions(
 253       this.opts.workerChoiceStrategyOptions
 254     )
 255   }
 256
 257   /** @inheritDoc */
 258   public enableTasksQueue (
 259     enable: boolean,
 260     tasksQueueOptions?: TasksQueueOptions
 261   ): void {
 262     if (this.opts.enableTasksQueue === true && !enable) {
 263       this.flushTasksQueues()
 264     }
 265     this.opts.enableTasksQueue = enable
 266     this.setTasksQueueOptions(tasksQueueOptions as TasksQueueOptions)
 267   }
 268
 269   /** @inheritDoc */
 270   public setTasksQueueOptions (tasksQueueOptions: TasksQueueOptions): void {
 271     if (this.opts.enableTasksQueue === true) {
 272       this.checkValidTasksQueueOptions(tasksQueueOptions)
 273       this.opts.tasksQueueOptions =
 274         this.buildTasksQueueOptions(tasksQueueOptions)
 275     } else {
 276       delete this.opts.tasksQueueOptions
 277     }
 278   }
 279
 280   private buildTasksQueueOptions (
 281     tasksQueueOptions: TasksQueueOptions
 282   ): TasksQueueOptions {
 283     return {
 284       concurrency: tasksQueueOptions?.concurrency ?? 1
 285     }
 286   }
 287
 288   /**
 289    * Whether the pool is full or not.
 290    *
 291    * The pool filling boolean status.
 292    */
 293   protected abstract get full (): boolean
 294
 295   /**
 296    * Whether the pool is busy or not.
 297    *
 298    * The pool busyness boolean status.
 299    */
 300   protected abstract get busy (): boolean
 301
 302   protected internalBusy (): boolean {
 303     return (
 304       this.workerNodes.findIndex(workerNode => {
 305         return workerNode.tasksUsage?.running === 0
 306       }) === -1
 307     )
 308   }
 309
 310   /** @inheritDoc */
 311   public async execute (data?: Data, name?: string): Promise<Response> {
 312     const [workerNodeKey, workerNode] = this.chooseWorkerNode()
 313     const submittedTask: Task<Data> = {
 314       name,
 315       // eslint-disable-next-line @typescript-eslint/consistent-type-assertions
 316       data: data ?? ({} as Data),
 317       id: crypto.randomUUID()
 318     }
 319     const res = new Promise<Response>((resolve, reject) => {
 320       this.promiseResponseMap.set(submittedTask.id as string, {
 321         resolve,
 322         reject,
 323         worker: workerNode.worker
 324       })
 325     })
 326     if (
 327       this.opts.enableTasksQueue === true &&
 328       (this.busy ||
 329         this.workerNodes[workerNodeKey].tasksUsage.running >=
 330           ((this.opts.tasksQueueOptions as TasksQueueOptions)
 331             .concurrency as number))
 332     ) {
 333       this.enqueueTask(workerNodeKey, submittedTask)
 334     } else {
 335       this.executeTask(workerNodeKey, submittedTask)
 336     }
 337     this.checkAndEmitEvents()
 338     // eslint-disable-next-line @typescript-eslint/return-await
 339     return res
 340   }
 341
 342   /** @inheritDoc */
 343   public async destroy (): Promise<void> {
 344     await Promise.all(
 345       this.workerNodes.map(async (workerNode, workerNodeKey) => {
 346         this.flushTasksQueue(workerNodeKey)
 347         await this.destroyWorker(workerNode.worker)
 348       })
 349     )
 350   }
 351
 352   /**
 353    * Shutdowns the given worker.
 354    *
 355    * @param worker - A worker within `workerNodes`.
 356    */
 357   protected abstract destroyWorker (worker: Worker): void | Promise<void>
 358
 359   /**
 360    * Setup hook to execute code before worker node are created in the abstract constructor.
 361    * Can be overridden
 362    *
 363    * @virtual
 364    */
 365   protected setupHook (): void {
 366     // Intentionally empty
 367   }
 368
 369   /**
 370    * Should return whether the worker is the main worker or not.
 371    */
 372   protected abstract isMain (): boolean
 373
 374   /**
 375    * Hook executed before the worker task execution.
 376    * Can be overridden.
 377    *
 378    * @param workerNodeKey - The worker node key.
 379    */
 380   protected beforeTaskExecutionHook (workerNodeKey: number): void {
 381     ++this.workerNodes[workerNodeKey].tasksUsage.running
 382   }
 383
 384   /**
 385    * Hook executed after the worker task execution.
 386    * Can be overridden.
 387    *
 388    * @param worker - The worker.
 389    * @param message - The received message.
 390    */
 391   protected afterTaskExecutionHook (
 392     worker: Worker,
 393     message: MessageValue<Response>
 394   ): void {
 395     const workerTasksUsage = this.getWorkerTasksUsage(worker)
 396     --workerTasksUsage.running
 397     ++workerTasksUsage.run
 398     if (message.error != null) {
 399       ++workerTasksUsage.error
 400     }
 401     if (this.workerChoiceStrategyContext.getRequiredStatistics().runTime) {
 402       workerTasksUsage.runTime += message.runTime ?? 0
 403       if (
 404         this.workerChoiceStrategyContext.getRequiredStatistics().avgRunTime &&
 405         workerTasksUsage.run !== 0
 406       ) {
 407         workerTasksUsage.avgRunTime =
 408           workerTasksUsage.runTime / workerTasksUsage.run
 409       }
 410       if (this.workerChoiceStrategyContext.getRequiredStatistics().medRunTime) {
 411         workerTasksUsage.runTimeHistory.push(message.runTime ?? 0)
 412         workerTasksUsage.medRunTime = median(workerTasksUsage.runTimeHistory)
 413       }
 414     }
 415   }
 416
 417   /**
 418    * Chooses a worker node for the next task.
 419    *
 420    * The default uses a round robin algorithm to distribute the load.
 421    *
 422    * @returns [worker node key, worker node].
 423    */
 424   protected chooseWorkerNode (): [number, WorkerNode<Worker, Data>] {
 425     let workerNodeKey: number
 426     if (this.type === PoolType.DYNAMIC && !this.full && this.internalBusy()) {
 427       const workerCreated = this.createAndSetupWorker()
 428       this.registerWorkerMessageListener(workerCreated, message => {
 429         if (
 430           isKillBehavior(KillBehaviors.HARD, message.kill) ||
 431           (message.kill != null &&
 432             this.getWorkerTasksUsage(workerCreated)?.running === 0)
 433         ) {
 434           // Kill message received from the worker: no new tasks are submitted to that worker for a while ( > maxInactiveTime)
 435           this.flushTasksQueueByWorker(workerCreated)
 436           void (this.destroyWorker(workerCreated) as Promise<void>)
 437         }
 438       })
 439       workerNodeKey = this.getWorkerNodeKey(workerCreated)
 440     } else {
 441       workerNodeKey = this.workerChoiceStrategyContext.execute()
 442     }
 443     return [workerNodeKey, this.workerNodes[workerNodeKey]]
 444   }
 445
 446   /**
 447    * Sends a message to the given worker.
 448    *
 449    * @param worker - The worker which should receive the message.
 450    * @param message - The message.
 451    */
 452   protected abstract sendToWorker (
 453     worker: Worker,
 454     message: MessageValue<Data>
 455   ): void
 456
 457   /**
 458    * Registers a listener callback on the given worker.
 459    *
 460    * @param worker - The worker which should register a listener.
 461    * @param listener - The message listener callback.
 462    */
 463   protected abstract registerWorkerMessageListener<
 464     Message extends Data | Response
 465   >(worker: Worker, listener: (message: MessageValue<Message>) => void): void
 466
 467   /**
 468    * Returns a newly created worker.
 469    */
 470   protected abstract createWorker (): Worker
 471
 472   /**
 473    * Function that can be hooked up when a worker has been newly created and moved to the pool worker nodes.
 474    *
 475    * Can be used to update the `maxListeners` or binding the `main-worker`\<-\>`worker` connection if not bind by default.
 476    *
 477    * @param worker - The newly created worker.
 478    */
 479   protected abstract afterWorkerSetup (worker: Worker): void
 480
 481   /**
 482    * Creates a new worker and sets it up completely in the pool worker nodes.
 483    *
 484    * @returns New, completely set up worker.
 485    */
 486   protected createAndSetupWorker (): Worker {
 487     const worker = this.createWorker()
 488
 489     worker.on('message', this.opts.messageHandler ?? EMPTY_FUNCTION)
 490     worker.on('error', this.opts.errorHandler ?? EMPTY_FUNCTION)
 491     worker.on('online', this.opts.onlineHandler ?? EMPTY_FUNCTION)
 492     worker.on('exit', this.opts.exitHandler ?? EMPTY_FUNCTION)
 493     worker.once('exit', () => {
 494       this.removeWorkerNode(worker)
 495     })
 496
 497     this.pushWorkerNode(worker)
 498
 499     this.afterWorkerSetup(worker)
 500
 501     return worker
 502   }
 503
 504   /**
 505    * This function is the listener registered for each worker message.
 506    *
 507    * @returns The listener function to execute when a message is received from a worker.
 508    */
 509   protected workerListener (): (message: MessageValue<Response>) => void {
 510     return message => {
 511       if (message.id != null) {
 512         // Task execution response received
 513         const promiseResponse = this.promiseResponseMap.get(message.id)
 514         if (promiseResponse != null) {
 515           if (message.error != null) {
 516             promiseResponse.reject(message.error)
 517           } else {
 518             promiseResponse.resolve(message.data as Response)
 519           }
 520           this.afterTaskExecutionHook(promiseResponse.worker, message)
 521           this.promiseResponseMap.delete(message.id)
 522           const workerNodeKey = this.getWorkerNodeKey(promiseResponse.worker)
 523           if (
 524             this.opts.enableTasksQueue === true &&
 525             this.tasksQueueSize(workerNodeKey) > 0
 526           ) {
 527             this.executeTask(
 528               workerNodeKey,
 529               this.dequeueTask(workerNodeKey) as Task<Data>
 530             )
 531           }
 532         }
 533       }
 534     }
 535   }
 536
 537   private checkAndEmitEvents (): void {
 538     if (this.opts.enableEvents === true) {
 539       if (this.busy) {
 540         this.emitter?.emit(PoolEvents.busy)
 541       }
 542       if (this.type === PoolType.DYNAMIC && this.full) {
 543         this.emitter?.emit(PoolEvents.full)
 544       }
 545     }
 546   }
 547
 548   /**
 549    * Sets the given worker node its tasks usage in the pool.
 550    *
 551    * @param workerNode - The worker node.
 552    * @param tasksUsage - The worker node tasks usage.
 553    */
 554   private setWorkerNodeTasksUsage (
 555     workerNode: WorkerNode<Worker, Data>,
 556     tasksUsage: TasksUsage
 557   ): void {
 558     workerNode.tasksUsage = tasksUsage
 559   }
 560
 561   /**
 562    * Gets the given worker its tasks usage in the pool.
 563    *
 564    * @param worker - The worker.
 565    * @throws Error if the worker is not found in the pool worker nodes.
 566    * @returns The worker tasks usage.
 567    */
 568   private getWorkerTasksUsage (worker: Worker): TasksUsage {
 569     const workerNodeKey = this.getWorkerNodeKey(worker)
 570     if (workerNodeKey !== -1) {
 571       return this.workerNodes[workerNodeKey].tasksUsage
 572     }
 573     throw new Error('Worker could not be found in the pool worker nodes')
 574   }
 575
 576   /**
 577    * Pushes the given worker in the pool worker nodes.
 578    *
 579    * @param worker - The worker.
 580    * @returns The worker nodes length.
 581    */
 582   private pushWorkerNode (worker: Worker): number {
 583     return this.workerNodes.push({
 584       worker,
 585       tasksUsage: {
 586         run: 0,
 587         running: 0,
 588         runTime: 0,
 589         runTimeHistory: new CircularArray(),
 590         avgRunTime: 0,
 591         medRunTime: 0,
 592         error: 0
 593       },
 594       tasksQueue: new Queue<Task<Data>>()
 595     })
 596   }
 597
 598   /**
 599    * Sets the given worker in the pool worker nodes.
 600    *
 601    * @param workerNodeKey - The worker node key.
 602    * @param worker - The worker.
 603    * @param tasksUsage - The worker tasks usage.
 604    * @param tasksQueue - The worker task queue.
 605    */
 606   private setWorkerNode (
 607     workerNodeKey: number,
 608     worker: Worker,
 609     tasksUsage: TasksUsage,
 610     tasksQueue: Queue<Task<Data>>
 611   ): void {
 612     this.workerNodes[workerNodeKey] = {
 613       worker,
 614       tasksUsage,
 615       tasksQueue
 616     }
 617   }
 618
 619   /**
 620    * Removes the given worker from the pool worker nodes.
 621    *
 622    * @param worker - The worker.
 623    */
 624   private removeWorkerNode (worker: Worker): void {
 625     const workerNodeKey = this.getWorkerNodeKey(worker)
 626     this.workerNodes.splice(workerNodeKey, 1)
 627     this.workerChoiceStrategyContext.remove(workerNodeKey)
 628   }
 629
 630   private executeTask (workerNodeKey: number, task: Task<Data>): void {
 631     this.beforeTaskExecutionHook(workerNodeKey)
 632     this.sendToWorker(this.workerNodes[workerNodeKey].worker, task)
 633   }
 634
 635   private enqueueTask (workerNodeKey: number, task: Task<Data>): number {
 636     return this.workerNodes[workerNodeKey].tasksQueue.enqueue(task)
 637   }
 638
 639   private dequeueTask (workerNodeKey: number): Task<Data> | undefined {
 640     return this.workerNodes[workerNodeKey].tasksQueue.dequeue()
 641   }
 642
 643   private tasksQueueSize (workerNodeKey: number): number {
 644     return this.workerNodes[workerNodeKey].tasksQueue.size
 645   }
 646
 647   private flushTasksQueue (workerNodeKey: number): void {
 648     if (this.tasksQueueSize(workerNodeKey) > 0) {
 649       for (let i = 0; i < this.tasksQueueSize(workerNodeKey); i++) {
 650         this.executeTask(
 651           workerNodeKey,
 652           this.dequeueTask(workerNodeKey) as Task<Data>
 653         )
 654       }
 655     }
 656   }
 657
 658   private flushTasksQueueByWorker (worker: Worker): void {
 659     const workerNodeKey = this.getWorkerNodeKey(worker)
 660     this.flushTasksQueue(workerNodeKey)
 661   }
 662
 663   private flushTasksQueues (): void {
 664     for (const [workerNodeKey] of this.workerNodes.entries()) {
 665       this.flushTasksQueue(workerNodeKey)
 666     }
 667   }
 668 }