src/worker/abstract-worker.ts

   1 import { AsyncResource } from 'node:async_hooks'
   2 import type { Worker } from 'node:cluster'
   3 import type { MessagePort } from 'node:worker_threads'
   4 import { performance } from 'node:perf_hooks'
   5 import type {
   6   MessageValue,
   7   Task,
   8   TaskPerformance,
   9   WorkerStatistics
  10 } from '../utility-types'
  11 import {
  12   DEFAULT_TASK_NAME,
  13   EMPTY_FUNCTION,
  14   isAsyncFunction,
  15   isPlainObject
  16 } from '../utils'
  17 import { KillBehaviors, type WorkerOptions } from './worker-options'
  18 import type {
  19   TaskAsyncFunction,
  20   TaskFunction,
  21   TaskFunctions,
  22   TaskSyncFunction
  23 } from './task-functions'
  24
  25 const DEFAULT_MAX_INACTIVE_TIME = 60000
  26 const DEFAULT_WORKER_OPTIONS: WorkerOptions = {
  27   /**
  28    * The kill behavior option on this worker or its default value.
  29    */
  30   killBehavior: KillBehaviors.SOFT,
  31   /**
  32    * The maximum time to keep this worker active while idle.
  33    * The pool automatically checks and terminates this worker when the time expires.
  34    */
  35   maxInactiveTime: DEFAULT_MAX_INACTIVE_TIME,
  36   /**
  37    * The function to call when the worker is killed.
  38    */
  39   killHandler: EMPTY_FUNCTION
  40 }
  41
  42 /**
  43  * Base class that implements some shared logic for all poolifier workers.
  44  *
  45  * @typeParam MainWorker - Type of main worker.
  46  * @typeParam Data - Type of data this worker receives from pool's execution. This can only be structured-cloneable data.
  47  * @typeParam Response - Type of response the worker sends back to the main worker. This can only be structured-cloneable data.
  48  */
  49 export abstract class AbstractWorker<
  50   MainWorker extends Worker | MessagePort,
  51   Data = unknown,
  52   Response = unknown
  53 > extends AsyncResource {
  54   /**
  55    * Worker id.
  56    */
  57   protected abstract id: number
  58   /**
  59    * Task function(s) processed by the worker when the pool's `execution` function is invoked.
  60    */
  61   protected taskFunctions!: Map<string, TaskFunction<Data, Response>>
  62   /**
  63    * Timestamp of the last task processed by this worker.
  64    */
  65   protected lastTaskTimestamp!: number
  66   /**
  67    * Performance statistics computation requirements.
  68    */
  69   protected statistics!: WorkerStatistics
  70   /**
  71    * Handler id of the `activeInterval` worker activity check.
  72    */
  73   protected activeInterval?: NodeJS.Timeout
  74   /**
  75    * Constructs a new poolifier worker.
  76    *
  77    * @param type - The type of async event.
  78    * @param isMain - Whether this is the main worker or not.
  79    * @param mainWorker - Reference to main worker.
  80    * @param taskFunctions - Task function(s) processed by the worker when the pool's `execution` function is invoked. The first function is the default function.
  81    * @param opts - Options for the worker.
  82    */
  83   public constructor (
  84     type: string,
  85     protected readonly isMain: boolean,
  86     private readonly mainWorker: MainWorker,
  87     taskFunctions: TaskFunction<Data, Response> | TaskFunctions<Data, Response>,
  88     protected opts: WorkerOptions = DEFAULT_WORKER_OPTIONS
  89   ) {
  90     super(type)
  91     if (this.isMain == null) {
  92       throw new Error('isMain parameter is mandatory')
  93     }
  94     this.checkTaskFunctions(taskFunctions)
  95     this.checkWorkerOptions(this.opts)
  96     if (!this.isMain) {
  97       this.getMainWorker().on('message', this.handleReadyMessage.bind(this))
  98     }
  99   }
 100
 101   private checkWorkerOptions (opts: WorkerOptions): void {
 102     this.opts = { ...DEFAULT_WORKER_OPTIONS, ...opts }
 103     delete this.opts.async
 104   }
 105
 106   private checkValidTaskFunction (
 107     name: string,
 108     fn: TaskFunction<Data, Response>
 109   ): void {
 110     if (typeof name !== 'string') {
 111       throw new TypeError(
 112         'A taskFunctions parameter object key is not a string'
 113       )
 114     }
 115     if (typeof name === 'string' && name.trim().length === 0) {
 116       throw new TypeError(
 117         'A taskFunctions parameter object key is an empty string'
 118       )
 119     }
 120     if (typeof fn !== 'function') {
 121       throw new TypeError(
 122         'A taskFunctions parameter object value is not a function'
 123       )
 124     }
 125   }
 126
 127   /**
 128    * Checks if the `taskFunctions` parameter is passed to the constructor.
 129    *
 130    * @param taskFunctions - The task function(s) parameter that should be checked.
 131    */
 132   private checkTaskFunctions (
 133     taskFunctions: TaskFunction<Data, Response> | TaskFunctions<Data, Response>
 134   ): void {
 135     if (taskFunctions == null) {
 136       throw new Error('taskFunctions parameter is mandatory')
 137     }
 138     this.taskFunctions = new Map<string, TaskFunction<Data, Response>>()
 139     if (typeof taskFunctions === 'function') {
 140       const boundFn = taskFunctions.bind(this)
 141       this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 142       this.taskFunctions.set(
 143         typeof taskFunctions.name === 'string' &&
 144         taskFunctions.name.trim().length > 0
 145           ? taskFunctions.name
 146           : 'fn1',
 147         boundFn
 148       )
 149     } else if (isPlainObject(taskFunctions)) {
 150       let firstEntry = true
 151       for (const [name, fn] of Object.entries(taskFunctions)) {
 152         this.checkValidTaskFunction(name, fn)
 153         const boundFn = fn.bind(this)
 154         if (firstEntry) {
 155           this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 156           firstEntry = false
 157         }
 158         this.taskFunctions.set(name, boundFn)
 159       }
 160       if (firstEntry) {
 161         throw new Error('taskFunctions parameter object is empty')
 162       }
 163     } else {
 164       throw new TypeError(
 165         'taskFunctions parameter is not a function or a plain object'
 166       )
 167     }
 168   }
 169
 170   /**
 171    * Checks if the worker has a task function with the given name.
 172    *
 173    * @param name - The name of the task function to check.
 174    * @returns Whether the worker has a task function with the given name or not.
 175    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
 176    */
 177   public hasTaskFunction (name: string): boolean {
 178     this.checkTaskFunctionName(name)
 179     return this.taskFunctions.has(name)
 180   }
 181
 182   /**
 183    * Adds a task function to the worker.
 184    * If a task function with the same name already exists, it is replaced.
 185    *
 186    * @param name - The name of the task function to add.
 187    * @param fn - The task function to add.
 188    * @returns Whether the task function was added or not.
 189    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
 190    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 191    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `fn` parameter is not a function.
 192    */
 193   public addTaskFunction (
 194     name: string,
 195     fn: TaskFunction<Data, Response>
 196   ): boolean {
 197     this.checkTaskFunctionName(name)
 198     if (name === DEFAULT_TASK_NAME) {
 199       throw new Error(
 200         'Cannot add a task function with the default reserved name'
 201       )
 202     }
 203     if (typeof fn !== 'function') {
 204       throw new TypeError('fn parameter is not a function')
 205     }
 206     try {
 207       const boundFn = fn.bind(this)
 208       if (
 209         this.taskFunctions.get(name) ===
 210         this.taskFunctions.get(DEFAULT_TASK_NAME)
 211       ) {
 212         this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 213       }
 214       this.taskFunctions.set(name, boundFn)
 215       this.sendTaskFunctionsListToMainWorker()
 216       return true
 217     } catch {
 218       return false
 219     }
 220   }
 221
 222   /**
 223    * Removes a task function from the worker.
 224    *
 225    * @param name - The name of the task function to remove.
 226    * @returns Whether the task function existed and was removed or not.
 227    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
 228    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 229    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the task function used as default task function.
 230    */
 231   public removeTaskFunction (name: string): boolean {
 232     this.checkTaskFunctionName(name)
 233     if (name === DEFAULT_TASK_NAME) {
 234       throw new Error(
 235         'Cannot remove the task function with the default reserved name'
 236       )
 237     }
 238     if (
 239       this.taskFunctions.get(name) === this.taskFunctions.get(DEFAULT_TASK_NAME)
 240     ) {
 241       throw new Error(
 242         'Cannot remove the task function used as the default task function'
 243       )
 244     }
 245     const deleteStatus = this.taskFunctions.delete(name)
 246     this.sendTaskFunctionsListToMainWorker()
 247     return deleteStatus
 248   }
 249
 250   /**
 251    * Lists the names of the worker's task functions.
 252    *
 253    * @returns The names of the worker's task functions.
 254    */
 255   public listTaskFunctions (): string[] {
 256     const names: string[] = [...this.taskFunctions.keys()]
 257     let defaultTaskFunctionName: string = DEFAULT_TASK_NAME
 258     for (const [name, fn] of this.taskFunctions) {
 259       if (
 260         name !== DEFAULT_TASK_NAME &&
 261         fn === this.taskFunctions.get(DEFAULT_TASK_NAME)
 262       ) {
 263         defaultTaskFunctionName = name
 264         break
 265       }
 266     }
 267     return [
 268       names[names.indexOf(DEFAULT_TASK_NAME)],
 269       defaultTaskFunctionName,
 270       ...names.filter(
 271         name => name !== DEFAULT_TASK_NAME && name !== defaultTaskFunctionName
 272       )
 273     ]
 274   }
 275
 276   /**
 277    * Sets the default task function to use in the worker.
 278    *
 279    * @param name - The name of the task function to use as default task function.
 280    * @returns Whether the default task function was set or not.
 281    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
 282    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 283    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is a non-existing task function.
 284    */
 285   public setDefaultTaskFunction (name: string): boolean {
 286     this.checkTaskFunctionName(name)
 287     if (name === DEFAULT_TASK_NAME) {
 288       throw new Error(
 289         'Cannot set the default task function reserved name as the default task function'
 290       )
 291     }
 292     if (!this.taskFunctions.has(name)) {
 293       throw new Error(
 294         'Cannot set the default task function to a non-existing task function'
 295       )
 296     }
 297     try {
 298       this.taskFunctions.set(
 299         DEFAULT_TASK_NAME,
 300         this.taskFunctions.get(name) as TaskFunction<Data, Response>
 301       )
 302       return true
 303     } catch {
 304       return false
 305     }
 306   }
 307
 308   private checkTaskFunctionName (name: string): void {
 309     if (typeof name !== 'string') {
 310       throw new TypeError('name parameter is not a string')
 311     }
 312     if (typeof name === 'string' && name.trim().length === 0) {
 313       throw new TypeError('name parameter is an empty string')
 314     }
 315   }
 316
 317   /**
 318    * Handles the ready message sent by the main worker.
 319    *
 320    * @param message - The ready message.
 321    */
 322   protected abstract handleReadyMessage (message: MessageValue<Data>): void
 323
 324   /**
 325    * Worker message listener.
 326    *
 327    * @param message - The received message.
 328    */
 329   protected messageListener (message: MessageValue<Data>): void {
 330     this.checkMessageWorkerId(message)
 331     if (message.statistics != null) {
 332       // Statistics message received
 333       this.statistics = message.statistics
 334     } else if (message.checkActive != null) {
 335       // Check active message received
 336       message.checkActive ? this.startCheckActive() : this.stopCheckActive()
 337     } else if (message.taskId != null && message.data != null) {
 338       // Task message received
 339       this.run(message)
 340     } else if (message.kill === true) {
 341       // Kill message received
 342       this.handleKillMessage(message)
 343     }
 344   }
 345
 346   /**
 347    * Handles a kill message sent by the main worker.
 348    *
 349    * @param message - The kill message.
 350    */
 351   protected handleKillMessage (message: MessageValue<Data>): void {
 352     this.stopCheckActive()
 353     if (isAsyncFunction(this.opts.killHandler)) {
 354       (this.opts.killHandler?.() as Promise<void>)
 355         .then(() => {
 356           this.sendToMainWorker({ kill: 'success', workerId: this.id })
 357           return null
 358         })
 359         .catch(() => {
 360           this.sendToMainWorker({ kill: 'failure', workerId: this.id })
 361         })
 362         .finally(() => {
 363           this.emitDestroy()
 364         })
 365         .catch(EMPTY_FUNCTION)
 366     } else {
 367       try {
 368         // eslint-disable-next-line @typescript-eslint/no-invalid-void-type
 369         this.opts.killHandler?.() as void
 370         this.sendToMainWorker({ kill: 'success', workerId: this.id })
 371       } catch {
 372         this.sendToMainWorker({ kill: 'failure', workerId: this.id })
 373       } finally {
 374         this.emitDestroy()
 375       }
 376     }
 377   }
 378
 379   /**
 380    * Check if the message worker id is set and matches the worker id.
 381    *
 382    * @param message - The message to check.
 383    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the message worker id is not set or does not match the worker id.
 384    */
 385   private checkMessageWorkerId (message: MessageValue<Data>): void {
 386     if (message.workerId == null) {
 387       throw new Error('Message worker id is not set')
 388     } else if (message.workerId != null && message.workerId !== this.id) {
 389       throw new Error(
 390         `Message worker id ${message.workerId} does not match the worker id ${this.id}`
 391       )
 392     }
 393   }
 394
 395   /**
 396    * Starts the worker check active interval.
 397    */
 398   private startCheckActive (): void {
 399     this.lastTaskTimestamp = performance.now()
 400     this.activeInterval = setInterval(
 401       this.checkActive.bind(this),
 402       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
 403     )
 404   }
 405
 406   /**
 407    * Stops the worker check active interval.
 408    */
 409   private stopCheckActive (): void {
 410     if (this.activeInterval != null) {
 411       clearInterval(this.activeInterval)
 412       delete this.activeInterval
 413     }
 414   }
 415
 416   /**
 417    * Checks if the worker should be terminated, because its living too long.
 418    */
 419   private checkActive (): void {
 420     if (
 421       performance.now() - this.lastTaskTimestamp >
 422       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 423     ) {
 424       this.sendToMainWorker({ kill: this.opts.killBehavior, workerId: this.id })
 425     }
 426   }
 427
 428   /**
 429    * Returns the main worker.
 430    *
 431    * @returns Reference to the main worker.
 432    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the main worker is not set.
 433    */
 434   protected getMainWorker (): MainWorker {
 435     if (this.mainWorker == null) {
 436       throw new Error('Main worker not set')
 437     }
 438     return this.mainWorker
 439   }
 440
 441   /**
 442    * Sends a message to main worker.
 443    *
 444    * @param message - The response message.
 445    */
 446   protected abstract sendToMainWorker (
 447     message: MessageValue<Response, Data>
 448   ): void
 449
 450   /**
 451    * Sends the list of task function names to the main worker.
 452    */
 453   protected sendTaskFunctionsListToMainWorker (): void {
 454     this.sendToMainWorker({
 455       taskFunctions: this.listTaskFunctions(),
 456       workerId: this.id
 457     })
 458   }
 459
 460   /**
 461    * Handles an error and convert it to a string so it can be sent back to the main worker.
 462    *
 463    * @param e - The error raised by the worker.
 464    * @returns The error message.
 465    */
 466   protected handleError (e: Error | string): string {
 467     return e instanceof Error ? e.message : e
 468   }
 469
 470   /**
 471    * Runs the given task.
 472    *
 473    * @param task - The task to execute.
 474    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 475    */
 476   protected run (task: Task<Data>): void {
 477     const { name, taskId, data } = task
 478     const fn = this.taskFunctions.get(name ?? DEFAULT_TASK_NAME)
 479     if (fn == null) {
 480       this.sendToMainWorker({
 481         taskError: {
 482           name: name as string,
 483           message: `Task function '${name as string}' not found`,
 484           data
 485         },
 486         workerId: this.id,
 487         taskId
 488       })
 489       return
 490     }
 491     if (isAsyncFunction(fn)) {
 492       this.runInAsyncScope(this.runAsync.bind(this), this, fn, task)
 493     } else {
 494       this.runInAsyncScope(this.runSync.bind(this), this, fn, task)
 495     }
 496   }
 497
 498   /**
 499    * Runs the given task function synchronously.
 500    *
 501    * @param fn - Task function that will be executed.
 502    * @param task - Input data for the task function.
 503    */
 504   protected runSync (
 505     fn: TaskSyncFunction<Data, Response>,
 506     task: Task<Data>
 507   ): void {
 508     const { name, taskId, data } = task
 509     try {
 510       let taskPerformance = this.beginTaskPerformance(name)
 511       const res = fn(data)
 512       taskPerformance = this.endTaskPerformance(taskPerformance)
 513       this.sendToMainWorker({
 514         data: res,
 515         taskPerformance,
 516         workerId: this.id,
 517         taskId
 518       })
 519     } catch (e) {
 520       const errorMessage = this.handleError(e as Error | string)
 521       this.sendToMainWorker({
 522         taskError: {
 523           name: name as string,
 524           message: errorMessage,
 525           data
 526         },
 527         workerId: this.id,
 528         taskId
 529       })
 530     } finally {
 531       this.updateLastTaskTimestamp()
 532     }
 533   }
 534
 535   /**
 536    * Runs the given task function asynchronously.
 537    *
 538    * @param fn - Task function that will be executed.
 539    * @param task - Input data for the task function.
 540    */
 541   protected runAsync (
 542     fn: TaskAsyncFunction<Data, Response>,
 543     task: Task<Data>
 544   ): void {
 545     const { name, taskId, data } = task
 546     let taskPerformance = this.beginTaskPerformance(name)
 547     fn(data)
 548       .then(res => {
 549         taskPerformance = this.endTaskPerformance(taskPerformance)
 550         this.sendToMainWorker({
 551           data: res,
 552           taskPerformance,
 553           workerId: this.id,
 554           taskId
 555         })
 556         return null
 557       })
 558       .catch(e => {
 559         const errorMessage = this.handleError(e as Error | string)
 560         this.sendToMainWorker({
 561           taskError: {
 562             name: name as string,
 563             message: errorMessage,
 564             data
 565           },
 566           workerId: this.id,
 567           taskId
 568         })
 569       })
 570       .finally(() => {
 571         this.updateLastTaskTimestamp()
 572       })
 573       .catch(EMPTY_FUNCTION)
 574   }
 575
 576   private beginTaskPerformance (name?: string): TaskPerformance {
 577     this.checkStatistics()
 578     return {
 579       name: name ?? DEFAULT_TASK_NAME,
 580       timestamp: performance.now(),
 581       ...(this.statistics.elu && { elu: performance.eventLoopUtilization() })
 582     }
 583   }
 584
 585   private endTaskPerformance (
 586     taskPerformance: TaskPerformance
 587   ): TaskPerformance {
 588     this.checkStatistics()
 589     return {
 590       ...taskPerformance,
 591       ...(this.statistics.runTime && {
 592         runTime: performance.now() - taskPerformance.timestamp
 593       }),
 594       ...(this.statistics.elu && {
 595         elu: performance.eventLoopUtilization(taskPerformance.elu)
 596       })
 597     }
 598   }
 599
 600   private checkStatistics (): void {
 601     if (this.statistics == null) {
 602       throw new Error('Performance statistics computation requirements not set')
 603     }
 604   }
 605
 606   private updateLastTaskTimestamp (): void {
 607     if (this.activeInterval != null) {
 608       this.lastTaskTimestamp = performance.now()
 609     }
 610   }
 611 }