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     this.checkWorkerOptions(this.opts)
  92     this.checkTaskFunctions(taskFunctions)
  93     if (!this.isMain) {
  94       this.getMainWorker()?.on('message', this.handleReadyMessage.bind(this))
  95     }
  96   }
  97
  98   private checkWorkerOptions (opts: WorkerOptions): void {
  99     this.opts = { ...DEFAULT_WORKER_OPTIONS, ...opts }
 100     delete this.opts.async
 101   }
 102
 103   /**
 104    * Checks if the `taskFunctions` parameter is passed to the constructor.
 105    *
 106    * @param taskFunctions - The task function(s) parameter that should be checked.
 107    */
 108   private checkTaskFunctions (
 109     taskFunctions: TaskFunction<Data, Response> | TaskFunctions<Data, Response>
 110   ): void {
 111     if (taskFunctions == null) {
 112       throw new Error('taskFunctions parameter is mandatory')
 113     }
 114     this.taskFunctions = new Map<string, TaskFunction<Data, Response>>()
 115     if (typeof taskFunctions === 'function') {
 116       const boundFn = taskFunctions.bind(this)
 117       this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 118       this.taskFunctions.set(
 119         typeof taskFunctions.name === 'string' &&
 120         taskFunctions.name.trim().length > 0
 121           ? taskFunctions.name
 122           : 'fn1',
 123         boundFn
 124       )
 125     } else if (isPlainObject(taskFunctions)) {
 126       let firstEntry = true
 127       for (const [name, fn] of Object.entries(taskFunctions)) {
 128         if (typeof name !== 'string') {
 129           throw new TypeError(
 130             'A taskFunctions parameter object key is not a string'
 131           )
 132         }
 133         if (typeof name === 'string' && name.trim().length === 0) {
 134           throw new TypeError(
 135             'A taskFunctions parameter object key an empty string'
 136           )
 137         }
 138         if (typeof fn !== 'function') {
 139           throw new TypeError(
 140             'A taskFunctions parameter object value is not a function'
 141           )
 142         }
 143         const boundFn = fn.bind(this)
 144         if (firstEntry) {
 145           this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 146           firstEntry = false
 147         }
 148         this.taskFunctions.set(name, boundFn)
 149       }
 150       if (firstEntry) {
 151         throw new Error('taskFunctions parameter object is empty')
 152       }
 153     } else {
 154       throw new TypeError(
 155         'taskFunctions parameter is not a function or a plain object'
 156       )
 157     }
 158   }
 159
 160   /**
 161    * Checks if the worker has a task function with the given name.
 162    *
 163    * @param name - The name of the task function to check.
 164    * @returns Whether the worker has a task function with the given name or not.
 165    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
 166    */
 167   public hasTaskFunction (name: string): boolean {
 168     if (typeof name !== 'string') {
 169       throw new TypeError('name parameter is not a string')
 170     }
 171     if (typeof name === 'string' && name.trim().length === 0) {
 172       throw new TypeError('name parameter is an empty string')
 173     }
 174     return this.taskFunctions.has(name)
 175   }
 176
 177   /**
 178    * Adds a task function to the worker.
 179    * If a task function with the same name already exists, it is replaced.
 180    *
 181    * @param name - The name of the task function to add.
 182    * @param fn - The task function to add.
 183    * @returns Whether the task function was added or not.
 184    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
 185    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 186    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `fn` parameter is not a function.
 187    */
 188   public addTaskFunction (
 189     name: string,
 190     fn: TaskFunction<Data, Response>
 191   ): boolean {
 192     if (typeof name !== 'string') {
 193       throw new TypeError('name parameter is not a string')
 194     }
 195     if (typeof name === 'string' && name.trim().length === 0) {
 196       throw new TypeError('name parameter is an empty string')
 197     }
 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     if (typeof name !== 'string') {
 233       throw new TypeError('name parameter is not a string')
 234     }
 235     if (typeof name === 'string' && name.trim().length === 0) {
 236       throw new TypeError('name parameter is an empty string')
 237     }
 238     if (name === DEFAULT_TASK_NAME) {
 239       throw new Error(
 240         'Cannot remove the task function with the default reserved name'
 241       )
 242     }
 243     if (
 244       this.taskFunctions.get(name) === this.taskFunctions.get(DEFAULT_TASK_NAME)
 245     ) {
 246       throw new Error(
 247         'Cannot remove the task function used as the default task function'
 248       )
 249     }
 250     const deleteStatus = this.taskFunctions.delete(name)
 251     this.sendTaskFunctionsListToMainWorker()
 252     return deleteStatus
 253   }
 254
 255   /**
 256    * Lists the names of the worker's task functions.
 257    *
 258    * @returns The names of the worker's task functions.
 259    */
 260   public listTaskFunctions (): string[] {
 261     const names: string[] = [...this.taskFunctions.keys()]
 262     let defaultTaskFunctionName: string = DEFAULT_TASK_NAME
 263     for (const [name, fn] of this.taskFunctions) {
 264       if (
 265         name !== DEFAULT_TASK_NAME &&
 266         fn === this.taskFunctions.get(DEFAULT_TASK_NAME)
 267       ) {
 268         defaultTaskFunctionName = name
 269         break
 270       }
 271     }
 272     return [
 273       names[names.indexOf(DEFAULT_TASK_NAME)],
 274       defaultTaskFunctionName,
 275       ...names.filter(
 276         (name) => name !== DEFAULT_TASK_NAME && name !== defaultTaskFunctionName
 277       )
 278     ]
 279   }
 280
 281   /**
 282    * Sets the default task function to use in the worker.
 283    *
 284    * @param name - The name of the task function to use as default task function.
 285    * @returns Whether the default task function was set or not.
 286    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
 287    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 288    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is a non-existing task function.
 289    */
 290   public setDefaultTaskFunction (name: string): boolean {
 291     if (typeof name !== 'string') {
 292       throw new TypeError('name parameter is not a string')
 293     }
 294     if (typeof name === 'string' && name.trim().length === 0) {
 295       throw new TypeError('name parameter is an empty string')
 296     }
 297     if (name === DEFAULT_TASK_NAME) {
 298       throw new Error(
 299         'Cannot set the default task function reserved name as the default task function'
 300       )
 301     }
 302     if (!this.taskFunctions.has(name)) {
 303       throw new Error(
 304         'Cannot set the default task function to a non-existing task function'
 305       )
 306     }
 307     try {
 308       this.taskFunctions.set(
 309         DEFAULT_TASK_NAME,
 310         this.taskFunctions.get(name) as TaskFunction<Data, Response>
 311       )
 312       return true
 313     } catch {
 314       return false
 315     }
 316   }
 317
 318   /**
 319    * Handles the ready message sent by the main worker.
 320    *
 321    * @param message - The ready message.
 322    */
 323   protected abstract handleReadyMessage (message: MessageValue<Data>): void
 324
 325   /**
 326    * Worker message listener.
 327    *
 328    * @param message - The received message.
 329    */
 330   protected messageListener (message: MessageValue<Data>): void {
 331     this.checkMessageWorkerId(message)
 332     if (message.statistics != null) {
 333       // Statistics message received
 334       this.statistics = message.statistics
 335     } else if (message.checkActive != null) {
 336       // Check active message received
 337       message.checkActive ? this.startCheckActive() : this.stopCheckActive()
 338     } else if (message.taskId != null && message.data != null) {
 339       // Task message received
 340       this.run(message)
 341     } else if (message.kill === true) {
 342       // Kill message received
 343       this.handleKillMessage(message)
 344     }
 345   }
 346
 347   /**
 348    * Handles a kill message sent by the main worker.
 349    *
 350    * @param message - The kill message.
 351    */
 352   protected handleKillMessage (message: MessageValue<Data>): void {
 353     this.stopCheckActive()
 354     if (isAsyncFunction(this.opts.killHandler)) {
 355       (this.opts.killHandler?.() as Promise<void>)
 356         .then(() => {
 357           this.sendToMainWorker({ kill: 'success', workerId: this.id })
 358           return null
 359         })
 360         .catch(() => {
 361           this.sendToMainWorker({ kill: 'failure', workerId: this.id })
 362         })
 363         .finally(() => {
 364           this.emitDestroy()
 365         })
 366         .catch(EMPTY_FUNCTION)
 367     } else {
 368       try {
 369         // eslint-disable-next-line @typescript-eslint/no-invalid-void-type
 370         this.opts.killHandler?.() as void
 371         this.sendToMainWorker({ kill: 'success', workerId: this.id })
 372       } catch {
 373         this.sendToMainWorker({ kill: 'failure', workerId: this.id })
 374       } finally {
 375         this.emitDestroy()
 376       }
 377     }
 378   }
 379
 380   /**
 381    * Check if the message worker id is set and matches the worker id.
 382    *
 383    * @param message - The message to check.
 384    * @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.
 385    */
 386   private checkMessageWorkerId (message: MessageValue<Data>): void {
 387     if (message.workerId == null) {
 388       throw new Error('Message worker id is not set')
 389     } else if (message.workerId != null && message.workerId !== this.id) {
 390       throw new Error(
 391         `Message worker id ${message.workerId} does not match the worker id ${this.id}`
 392       )
 393     }
 394   }
 395
 396   /**
 397    * Starts the worker check active interval.
 398    */
 399   private startCheckActive (): void {
 400     this.lastTaskTimestamp = performance.now()
 401     this.activeInterval = setInterval(
 402       this.checkActive.bind(this),
 403       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
 404     )
 405   }
 406
 407   /**
 408    * Stops the worker check active interval.
 409    */
 410   private stopCheckActive (): void {
 411     if (this.activeInterval != null) {
 412       clearInterval(this.activeInterval)
 413       delete this.activeInterval
 414     }
 415   }
 416
 417   /**
 418    * Checks if the worker should be terminated, because its living too long.
 419    */
 420   private checkActive (): void {
 421     if (
 422       performance.now() - this.lastTaskTimestamp >
 423       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 424     ) {
 425       this.sendToMainWorker({ kill: this.opts.killBehavior, workerId: this.id })
 426     }
 427   }
 428
 429   /**
 430    * Returns the main worker.
 431    *
 432    * @returns Reference to the main worker.
 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 fn = this.getTaskFunction(task.name)
 478     if (isAsyncFunction(fn)) {
 479       this.runInAsyncScope(this.runAsync.bind(this), this, fn, task)
 480     } else {
 481       this.runInAsyncScope(this.runSync.bind(this), this, fn, task)
 482     }
 483   }
 484
 485   /**
 486    * Runs the given task function synchronously.
 487    *
 488    * @param fn - Task function that will be executed.
 489    * @param task - Input data for the task function.
 490    */
 491   protected runSync (
 492     fn: TaskSyncFunction<Data, Response>,
 493     task: Task<Data>
 494   ): void {
 495     const { name, taskId, data } = task
 496     try {
 497       let taskPerformance = this.beginTaskPerformance(name)
 498       const res = fn(data)
 499       taskPerformance = this.endTaskPerformance(taskPerformance)
 500       this.sendToMainWorker({
 501         data: res,
 502         taskPerformance,
 503         workerId: this.id,
 504         taskId
 505       })
 506     } catch (e) {
 507       const errorMessage = this.handleError(e as Error | string)
 508       this.sendToMainWorker({
 509         taskError: {
 510           name: name ?? DEFAULT_TASK_NAME,
 511           message: errorMessage,
 512           data
 513         },
 514         workerId: this.id,
 515         taskId
 516       })
 517     } finally {
 518       this.updateLastTaskTimestamp()
 519     }
 520   }
 521
 522   /**
 523    * Runs the given task function asynchronously.
 524    *
 525    * @param fn - Task function that will be executed.
 526    * @param task - Input data for the task function.
 527    */
 528   protected runAsync (
 529     fn: TaskAsyncFunction<Data, Response>,
 530     task: Task<Data>
 531   ): void {
 532     const { name, taskId, data } = task
 533     let taskPerformance = this.beginTaskPerformance(name)
 534     fn(data)
 535       .then((res) => {
 536         taskPerformance = this.endTaskPerformance(taskPerformance)
 537         this.sendToMainWorker({
 538           data: res,
 539           taskPerformance,
 540           workerId: this.id,
 541           taskId
 542         })
 543         return null
 544       })
 545       .catch((e) => {
 546         const errorMessage = this.handleError(e as Error | string)
 547         this.sendToMainWorker({
 548           taskError: {
 549             name: name ?? DEFAULT_TASK_NAME,
 550             message: errorMessage,
 551             data
 552           },
 553           workerId: this.id,
 554           taskId
 555         })
 556       })
 557       .finally(() => {
 558         this.updateLastTaskTimestamp()
 559       })
 560       .catch(EMPTY_FUNCTION)
 561   }
 562
 563   /**
 564    * Gets the task function with the given name.
 565    *
 566    * @param name - Name of the task function that will be returned.
 567    * @returns The task function.
 568    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 569    */
 570   private getTaskFunction (name?: string): TaskFunction<Data, Response> {
 571     name = name ?? DEFAULT_TASK_NAME
 572     const fn = this.taskFunctions.get(name)
 573     if (fn == null) {
 574       throw new Error(`Task function '${name}' not found`)
 575     }
 576     return fn
 577   }
 578
 579   private beginTaskPerformance (name?: string): TaskPerformance {
 580     this.checkStatistics()
 581     return {
 582       name: name ?? DEFAULT_TASK_NAME,
 583       timestamp: performance.now(),
 584       ...(this.statistics.elu && { elu: performance.eventLoopUtilization() })
 585     }
 586   }
 587
 588   private endTaskPerformance (
 589     taskPerformance: TaskPerformance
 590   ): TaskPerformance {
 591     this.checkStatistics()
 592     return {
 593       ...taskPerformance,
 594       ...(this.statistics.runTime && {
 595         runTime: performance.now() - taskPerformance.timestamp
 596       }),
 597       ...(this.statistics.elu && {
 598         elu: performance.eventLoopUtilization(taskPerformance.elu)
 599       })
 600     }
 601   }
 602
 603   private checkStatistics (): void {
 604     if (this.statistics == null) {
 605       throw new Error('Performance statistics computation requirements not set')
 606     }
 607   }
 608
 609   private updateLastTaskTimestamp (): void {
 610     if (this.activeInterval != null) {
 611       this.lastTaskTimestamp = performance.now()
 612     }
 613   }
 614 }