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 {
  18   type KillBehavior,
  19   KillBehaviors,
  20   type WorkerOptions
  21 } from './worker-options'
  22 import type {
  23   TaskAsyncFunction,
  24   TaskFunction,
  25   TaskFunctions,
  26   TaskSyncFunction
  27 } from './task-functions'
  28
  29 const DEFAULT_MAX_INACTIVE_TIME = 60000
  30 const DEFAULT_KILL_BEHAVIOR: KillBehavior = KillBehaviors.SOFT
  31
  32 /**
  33  * Base class that implements some shared logic for all poolifier workers.
  34  *
  35  * @typeParam MainWorker - Type of main worker.
  36  * @typeParam Data - Type of data this worker receives from pool's execution. This can only be structured-cloneable data.
  37  * @typeParam Response - Type of response the worker sends back to the main worker. This can only be structured-cloneable data.
  38  */
  39 export abstract class AbstractWorker<
  40   MainWorker extends Worker | MessagePort,
  41   Data = unknown,
  42   Response = unknown
  43 > extends AsyncResource {
  44   /**
  45    * Worker id.
  46    */
  47   protected abstract id: number
  48   /**
  49    * Task function(s) processed by the worker when the pool's `execution` function is invoked.
  50    */
  51   protected taskFunctions!: Map<string, TaskFunction<Data, Response>>
  52   /**
  53    * Timestamp of the last task processed by this worker.
  54    */
  55   protected lastTaskTimestamp!: number
  56   /**
  57    * Performance statistics computation requirements.
  58    */
  59   protected statistics!: WorkerStatistics
  60   /**
  61    * Handler id of the `activeInterval` worker activity check.
  62    */
  63   protected activeInterval?: NodeJS.Timeout
  64   /**
  65    * Constructs a new poolifier worker.
  66    *
  67    * @param type - The type of async event.
  68    * @param isMain - Whether this is the main worker or not.
  69    * @param mainWorker - Reference to main worker.
  70    * @param taskFunctions - Task function(s) processed by the worker when the pool's `execution` function is invoked. The first function is the default function.
  71    * @param opts - Options for the worker.
  72    */
  73   public constructor (
  74     type: string,
  75     protected readonly isMain: boolean,
  76     private readonly mainWorker: MainWorker,
  77     taskFunctions: TaskFunction<Data, Response> | TaskFunctions<Data, Response>,
  78     protected readonly opts: WorkerOptions = {
  79       /**
  80        * The kill behavior option on this worker or its default value.
  81        */
  82       killBehavior: DEFAULT_KILL_BEHAVIOR,
  83       /**
  84        * The maximum time to keep this worker active while idle.
  85        * The pool automatically checks and terminates this worker when the time expires.
  86        */
  87       maxInactiveTime: DEFAULT_MAX_INACTIVE_TIME,
  88       /**
  89        * The function to call when the worker is killed.
  90        */
  91       killHandler: EMPTY_FUNCTION
  92     }
  93   ) {
  94     super(type)
  95     this.checkWorkerOptions(this.opts)
  96     this.checkTaskFunctions(taskFunctions)
  97     if (!this.isMain) {
  98       this.getMainWorker()?.on('message', this.handleReadyMessage.bind(this))
  99     }
 100   }
 101
 102   private checkWorkerOptions (opts: WorkerOptions): void {
 103     this.opts.killBehavior = opts.killBehavior ?? DEFAULT_KILL_BEHAVIOR
 104     this.opts.maxInactiveTime =
 105       opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME
 106     this.opts.killHandler = opts.killHandler ?? EMPTY_FUNCTION
 107     delete this.opts.async
 108   }
 109
 110   /**
 111    * Checks if the `taskFunctions` parameter is passed to the constructor.
 112    *
 113    * @param taskFunctions - The task function(s) parameter that should be checked.
 114    */
 115   private checkTaskFunctions (
 116     taskFunctions: TaskFunction<Data, Response> | TaskFunctions<Data, Response>
 117   ): void {
 118     if (taskFunctions == null) {
 119       throw new Error('taskFunctions parameter is mandatory')
 120     }
 121     this.taskFunctions = new Map<string, TaskFunction<Data, Response>>()
 122     if (typeof taskFunctions === 'function') {
 123       const boundFn = taskFunctions.bind(this)
 124       this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 125       this.taskFunctions.set(
 126         typeof taskFunctions.name === 'string' &&
 127         taskFunctions.name.trim().length > 0
 128           ? taskFunctions.name
 129           : 'fn1',
 130         boundFn
 131       )
 132     } else if (isPlainObject(taskFunctions)) {
 133       let firstEntry = true
 134       for (const [name, fn] of Object.entries(taskFunctions)) {
 135         if (typeof name !== 'string') {
 136           throw new TypeError(
 137             'A taskFunctions parameter object key is not a string'
 138           )
 139         }
 140         if (typeof name === 'string' && name.trim().length === 0) {
 141           throw new TypeError(
 142             'A taskFunctions parameter object key an empty string'
 143           )
 144         }
 145         if (typeof fn !== 'function') {
 146           throw new TypeError(
 147             'A taskFunctions parameter object value is not a function'
 148           )
 149         }
 150         const boundFn = fn.bind(this)
 151         if (firstEntry) {
 152           this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 153           firstEntry = false
 154         }
 155         this.taskFunctions.set(name, boundFn)
 156       }
 157       if (firstEntry) {
 158         throw new Error('taskFunctions parameter object is empty')
 159       }
 160     } else {
 161       throw new TypeError(
 162         'taskFunctions parameter is not a function or a plain object'
 163       )
 164     }
 165   }
 166
 167   /**
 168    * Checks if the worker has a task function with the given name.
 169    *
 170    * @param name - The name of the task function to check.
 171    * @returns Whether the worker has a task function with the given name or not.
 172    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
 173    */
 174   public hasTaskFunction (name: string): boolean {
 175     if (typeof name !== 'string') {
 176       throw new TypeError('name parameter is not a string')
 177     }
 178     if (typeof name === 'string' && name.trim().length === 0) {
 179       throw new TypeError('name parameter is an empty string')
 180     }
 181     return this.taskFunctions.has(name)
 182   }
 183
 184   /**
 185    * Adds a task function to the worker.
 186    * If a task function with the same name already exists, it is replaced.
 187    *
 188    * @param name - The name of the task function to add.
 189    * @param fn - The task function to add.
 190    * @returns Whether the task function was added or not.
 191    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
 192    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 193    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `fn` parameter is not a function.
 194    */
 195   public addTaskFunction (
 196     name: string,
 197     fn: TaskFunction<Data, Response>
 198   ): boolean {
 199     if (typeof name !== 'string') {
 200       throw new TypeError('name parameter is not a string')
 201     }
 202     if (typeof name === 'string' && name.trim().length === 0) {
 203       throw new TypeError('name parameter is an empty string')
 204     }
 205     if (name === DEFAULT_TASK_NAME) {
 206       throw new Error(
 207         'Cannot add a task function with the default reserved name'
 208       )
 209     }
 210     if (typeof fn !== 'function') {
 211       throw new TypeError('fn parameter is not a function')
 212     }
 213     try {
 214       const boundFn = fn.bind(this)
 215       if (
 216         this.taskFunctions.get(name) ===
 217         this.taskFunctions.get(DEFAULT_TASK_NAME)
 218       ) {
 219         this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 220       }
 221       this.taskFunctions.set(name, boundFn)
 222       this.sendTaskFunctionsListToMainWorker()
 223       return true
 224     } catch {
 225       return false
 226     }
 227   }
 228
 229   /**
 230    * Removes a task function from the worker.
 231    *
 232    * @param name - The name of the task function to remove.
 233    * @returns Whether the task function existed and was removed or not.
 234    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
 235    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 236    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the task function used as default task function.
 237    */
 238   public removeTaskFunction (name: string): boolean {
 239     if (typeof name !== 'string') {
 240       throw new TypeError('name parameter is not a string')
 241     }
 242     if (typeof name === 'string' && name.trim().length === 0) {
 243       throw new TypeError('name parameter is an empty string')
 244     }
 245     if (name === DEFAULT_TASK_NAME) {
 246       throw new Error(
 247         'Cannot remove the task function with the default reserved name'
 248       )
 249     }
 250     if (
 251       this.taskFunctions.get(name) === this.taskFunctions.get(DEFAULT_TASK_NAME)
 252     ) {
 253       throw new Error(
 254         'Cannot remove the task function used as the default task function'
 255       )
 256     }
 257     const deleteStatus = this.taskFunctions.delete(name)
 258     this.sendTaskFunctionsListToMainWorker()
 259     return deleteStatus
 260   }
 261
 262   /**
 263    * Lists the names of the worker's task functions.
 264    *
 265    * @returns The names of the worker's task functions.
 266    */
 267   public listTaskFunctions (): string[] {
 268     const names: string[] = [...this.taskFunctions.keys()]
 269     let defaultTaskFunctionName: string = DEFAULT_TASK_NAME
 270     for (const [name, fn] of this.taskFunctions) {
 271       if (
 272         name !== DEFAULT_TASK_NAME &&
 273         fn === this.taskFunctions.get(DEFAULT_TASK_NAME)
 274       ) {
 275         defaultTaskFunctionName = name
 276         break
 277       }
 278     }
 279     return [
 280       names[names.indexOf(DEFAULT_TASK_NAME)],
 281       defaultTaskFunctionName,
 282       ...names.filter(
 283         (name) => name !== DEFAULT_TASK_NAME && name !== defaultTaskFunctionName
 284       )
 285     ]
 286   }
 287
 288   /**
 289    * Sets the default task function to use in the worker.
 290    *
 291    * @param name - The name of the task function to use as default task function.
 292    * @returns Whether the default task function was set or not.
 293    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
 294    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 295    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is a non-existing task function.
 296    */
 297   public setDefaultTaskFunction (name: string): boolean {
 298     if (typeof name !== 'string') {
 299       throw new TypeError('name parameter is not a string')
 300     }
 301     if (typeof name === 'string' && name.trim().length === 0) {
 302       throw new TypeError('name parameter is an empty string')
 303     }
 304     if (name === DEFAULT_TASK_NAME) {
 305       throw new Error(
 306         'Cannot set the default task function reserved name as the default task function'
 307       )
 308     }
 309     if (!this.taskFunctions.has(name)) {
 310       throw new Error(
 311         'Cannot set the default task function to a non-existing task function'
 312       )
 313     }
 314     try {
 315       this.taskFunctions.set(
 316         DEFAULT_TASK_NAME,
 317         this.taskFunctions.get(name) as TaskFunction<Data, Response>
 318       )
 319       return true
 320     } catch {
 321       return false
 322     }
 323   }
 324
 325   /**
 326    * Handles the ready message sent by the main worker.
 327    *
 328    * @param message - The ready message.
 329    */
 330   protected abstract handleReadyMessage (message: MessageValue<Data>): void
 331
 332   /**
 333    * Worker message listener.
 334    *
 335    * @param message - The received message.
 336    */
 337   protected messageListener (message: MessageValue<Data>): void {
 338     this.checkMessageWorkerId(message)
 339     if (message.statistics != null) {
 340       // Statistics message received
 341       this.statistics = message.statistics
 342     } else if (message.checkActive != null) {
 343       // Check active message received
 344       message.checkActive ? this.startCheckActive() : this.stopCheckActive()
 345     } else if (message.taskId != null && message.data != null) {
 346       // Task message received
 347       this.run(message)
 348     } else if (message.kill === true) {
 349       // Kill message received
 350       this.handleKillMessage(message)
 351     }
 352   }
 353
 354   /**
 355    * Handles a kill message sent by the main worker.
 356    *
 357    * @param message - The kill message.
 358    */
 359   protected handleKillMessage (message: MessageValue<Data>): void {
 360     this.stopCheckActive()
 361     if (isAsyncFunction(this.opts.killHandler)) {
 362       (this.opts.killHandler?.() as Promise<void>)
 363         .then(() => {
 364           this.sendToMainWorker({ kill: 'success', workerId: this.id })
 365           return null
 366         })
 367         .catch(() => {
 368           this.sendToMainWorker({ kill: 'failure', workerId: this.id })
 369         })
 370         .finally(() => {
 371           this.emitDestroy()
 372         })
 373         .catch(EMPTY_FUNCTION)
 374     } else {
 375       try {
 376         // eslint-disable-next-line @typescript-eslint/no-invalid-void-type
 377         this.opts.killHandler?.() as void
 378         this.sendToMainWorker({ kill: 'success', workerId: this.id })
 379       } catch {
 380         this.sendToMainWorker({ kill: 'failure', workerId: this.id })
 381       } finally {
 382         this.emitDestroy()
 383       }
 384     }
 385   }
 386
 387   /**
 388    * Check if the message worker id is set and matches the worker id.
 389    *
 390    * @param message - The message to check.
 391    * @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.
 392    */
 393   private checkMessageWorkerId (message: MessageValue<Data>): void {
 394     if (message.workerId == null) {
 395       throw new Error('Message worker id is not set')
 396     } else if (message.workerId != null && message.workerId !== this.id) {
 397       throw new Error(
 398         `Message worker id ${message.workerId} does not match the worker id ${this.id}`
 399       )
 400     }
 401   }
 402
 403   /**
 404    * Starts the worker check active interval.
 405    */
 406   private startCheckActive (): void {
 407     this.lastTaskTimestamp = performance.now()
 408     this.activeInterval = setInterval(
 409       this.checkActive.bind(this),
 410       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
 411     )
 412   }
 413
 414   /**
 415    * Stops the worker check active interval.
 416    */
 417   private stopCheckActive (): void {
 418     if (this.activeInterval != null) {
 419       clearInterval(this.activeInterval)
 420       delete this.activeInterval
 421     }
 422   }
 423
 424   /**
 425    * Checks if the worker should be terminated, because its living too long.
 426    */
 427   private checkActive (): void {
 428     if (
 429       performance.now() - this.lastTaskTimestamp >
 430       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 431     ) {
 432       this.sendToMainWorker({ kill: this.opts.killBehavior, workerId: this.id })
 433     }
 434   }
 435
 436   /**
 437    * Returns the main worker.
 438    *
 439    * @returns Reference to the main worker.
 440    */
 441   protected getMainWorker (): MainWorker {
 442     if (this.mainWorker == null) {
 443       throw new Error('Main worker not set')
 444     }
 445     return this.mainWorker
 446   }
 447
 448   /**
 449    * Sends a message to main worker.
 450    *
 451    * @param message - The response message.
 452    */
 453   protected abstract sendToMainWorker (
 454     message: MessageValue<Response, Data>
 455   ): void
 456
 457   /**
 458    * Sends the list of task function names to the main worker.
 459    */
 460   protected sendTaskFunctionsListToMainWorker (): void {
 461     this.sendToMainWorker({
 462       taskFunctions: this.listTaskFunctions(),
 463       workerId: this.id
 464     })
 465   }
 466
 467   /**
 468    * Handles an error and convert it to a string so it can be sent back to the main worker.
 469    *
 470    * @param e - The error raised by the worker.
 471    * @returns The error message.
 472    */
 473   protected handleError (e: Error | string): string {
 474     return e instanceof Error ? e.message : e
 475   }
 476
 477   /**
 478    * Runs the given task.
 479    *
 480    * @param task - The task to execute.
 481    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 482    */
 483   protected run (task: Task<Data>): void {
 484     const fn = this.getTaskFunction(task.name)
 485     if (isAsyncFunction(fn)) {
 486       this.runInAsyncScope(this.runAsync.bind(this), this, fn, task)
 487     } else {
 488       this.runInAsyncScope(this.runSync.bind(this), this, fn, task)
 489     }
 490   }
 491
 492   /**
 493    * Runs the given task function synchronously.
 494    *
 495    * @param fn - Task function that will be executed.
 496    * @param task - Input data for the task function.
 497    */
 498   protected runSync (
 499     fn: TaskSyncFunction<Data, Response>,
 500     task: Task<Data>
 501   ): void {
 502     const { name, taskId, data } = task
 503     try {
 504       let taskPerformance = this.beginTaskPerformance(name)
 505       const res = fn(data)
 506       taskPerformance = this.endTaskPerformance(taskPerformance)
 507       this.sendToMainWorker({
 508         data: res,
 509         taskPerformance,
 510         workerId: this.id,
 511         taskId
 512       })
 513     } catch (e) {
 514       const errorMessage = this.handleError(e as Error | string)
 515       this.sendToMainWorker({
 516         taskError: {
 517           name: name ?? DEFAULT_TASK_NAME,
 518           message: errorMessage,
 519           data
 520         },
 521         workerId: this.id,
 522         taskId
 523       })
 524     } finally {
 525       this.updateLastTaskTimestamp()
 526     }
 527   }
 528
 529   /**
 530    * Runs the given task function asynchronously.
 531    *
 532    * @param fn - Task function that will be executed.
 533    * @param task - Input data for the task function.
 534    */
 535   protected runAsync (
 536     fn: TaskAsyncFunction<Data, Response>,
 537     task: Task<Data>
 538   ): void {
 539     const { name, taskId, data } = task
 540     let taskPerformance = this.beginTaskPerformance(name)
 541     fn(data)
 542       .then((res) => {
 543         taskPerformance = this.endTaskPerformance(taskPerformance)
 544         this.sendToMainWorker({
 545           data: res,
 546           taskPerformance,
 547           workerId: this.id,
 548           taskId
 549         })
 550         return null
 551       })
 552       .catch((e) => {
 553         const errorMessage = this.handleError(e as Error | string)
 554         this.sendToMainWorker({
 555           taskError: {
 556             name: name ?? DEFAULT_TASK_NAME,
 557             message: errorMessage,
 558             data
 559           },
 560           workerId: this.id,
 561           taskId
 562         })
 563       })
 564       .finally(() => {
 565         this.updateLastTaskTimestamp()
 566       })
 567       .catch(EMPTY_FUNCTION)
 568   }
 569
 570   /**
 571    * Gets the task function with the given name.
 572    *
 573    * @param name - Name of the task function that will be returned.
 574    * @returns The task function.
 575    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 576    */
 577   private getTaskFunction (name?: string): TaskFunction<Data, Response> {
 578     name = name ?? DEFAULT_TASK_NAME
 579     const fn = this.taskFunctions.get(name)
 580     if (fn == null) {
 581       throw new Error(`Task function '${name}' not found`)
 582     }
 583     return fn
 584   }
 585
 586   private beginTaskPerformance (name?: string): TaskPerformance {
 587     this.checkStatistics()
 588     return {
 589       name: name ?? DEFAULT_TASK_NAME,
 590       timestamp: performance.now(),
 591       ...(this.statistics.elu && { elu: performance.eventLoopUtilization() })
 592     }
 593   }
 594
 595   private endTaskPerformance (
 596     taskPerformance: TaskPerformance
 597   ): TaskPerformance {
 598     this.checkStatistics()
 599     return {
 600       ...taskPerformance,
 601       ...(this.statistics.runTime && {
 602         runTime: performance.now() - taskPerformance.timestamp
 603       }),
 604       ...(this.statistics.elu && {
 605         elu: performance.eventLoopUtilization(taskPerformance.elu)
 606       })
 607     }
 608   }
 609
 610   private checkStatistics (): void {
 611     if (this.statistics == null) {
 612       throw new Error('Performance statistics computation requirements not set')
 613     }
 614   }
 615
 616   private updateLastTaskTimestamp (): void {
 617     if (this.activeInterval != null) {
 618       this.lastTaskTimestamp = performance.now()
 619     }
 620   }
 621 }