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.
 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.
 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.
 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     return [...this.taskFunctions.keys()]
 269   }
 270
 271   /**
 272    * Sets the default task function to use in the worker.
 273    *
 274    * @param name - The name of the task function to use as default task function.
 275    * @returns Whether the default task function was set or not.
 276    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 277    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 278    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is a non-existing task function.
 279    */
 280   public setDefaultTaskFunction (name: string): boolean {
 281     if (typeof name !== 'string') {
 282       throw new TypeError('name parameter is not a string')
 283     }
 284     if (typeof name === 'string' && name.trim().length === 0) {
 285       throw new TypeError('name parameter is an empty string')
 286     }
 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   /**
 309    * Handles the ready message sent by the main worker.
 310    *
 311    * @param message - The ready message.
 312    */
 313   protected abstract handleReadyMessage (message: MessageValue<Data>): void
 314
 315   /**
 316    * Worker message listener.
 317    *
 318    * @param message - The received message.
 319    */
 320   protected messageListener (message: MessageValue<Data>): void {
 321     if (this.isMain) {
 322       throw new Error('Cannot handle message to worker in main worker')
 323     } else if (message.workerId == null) {
 324       throw new Error('Message worker id is not set')
 325     } else if (message.workerId != null && message.workerId !== this.id) {
 326       throw new Error(
 327         `Message worker id ${message.workerId} does not match the worker id ${this.id}`
 328       )
 329     }
 330     if (message.statistics != null) {
 331       // Statistics message received
 332       this.statistics = message.statistics
 333     } else if (message.checkActive != null) {
 334       // Check active message received
 335       message.checkActive ? this.startCheckActive() : this.stopCheckActive()
 336     } else if (message.taskId != null && message.data != null) {
 337       // Task message received
 338       this.run(message)
 339     } else if (message.kill === true) {
 340       // Kill message received
 341       this.handleKillMessage(message)
 342     }
 343   }
 344
 345   /**
 346    * Handles a kill message sent by the main worker.
 347    *
 348    * @param message - The kill message.
 349    */
 350   protected handleKillMessage (message: MessageValue<Data>): void {
 351     this.stopCheckActive()
 352     if (isAsyncFunction(this.opts.killHandler)) {
 353       (this.opts.killHandler?.() as Promise<void>)
 354         .then(() => {
 355           this.sendToMainWorker({ kill: 'success', workerId: this.id })
 356           return null
 357         })
 358         .catch(() => {
 359           this.sendToMainWorker({ kill: 'failure', workerId: this.id })
 360         })
 361         .finally(() => {
 362           this.emitDestroy()
 363         })
 364         .catch(EMPTY_FUNCTION)
 365     } else {
 366       try {
 367         // eslint-disable-next-line @typescript-eslint/no-invalid-void-type
 368         this.opts.killHandler?.() as void
 369         this.sendToMainWorker({ kill: 'success', workerId: this.id })
 370       } catch {
 371         this.sendToMainWorker({ kill: 'failure', workerId: this.id })
 372       } finally {
 373         this.emitDestroy()
 374       }
 375     }
 376   }
 377
 378   /**
 379    * Starts the worker check active interval.
 380    */
 381   private startCheckActive (): void {
 382     this.lastTaskTimestamp = performance.now()
 383     this.activeInterval = setInterval(
 384       this.checkActive.bind(this),
 385       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
 386     )
 387   }
 388
 389   /**
 390    * Stops the worker check active interval.
 391    */
 392   private stopCheckActive (): void {
 393     if (this.activeInterval != null) {
 394       clearInterval(this.activeInterval)
 395       delete this.activeInterval
 396     }
 397   }
 398
 399   /**
 400    * Checks if the worker should be terminated, because its living too long.
 401    */
 402   private checkActive (): void {
 403     if (
 404       performance.now() - this.lastTaskTimestamp >
 405       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 406     ) {
 407       this.sendToMainWorker({ kill: this.opts.killBehavior, workerId: this.id })
 408     }
 409   }
 410
 411   /**
 412    * Returns the main worker.
 413    *
 414    * @returns Reference to the main worker.
 415    */
 416   protected getMainWorker (): MainWorker {
 417     if (this.mainWorker == null) {
 418       throw new Error('Main worker not set')
 419     }
 420     return this.mainWorker
 421   }
 422
 423   /**
 424    * Sends a message to main worker.
 425    *
 426    * @param message - The response message.
 427    */
 428   protected abstract sendToMainWorker (
 429     message: MessageValue<Response, Data>
 430   ): void
 431
 432   /**
 433    * Sends the list of task function names to the main worker.
 434    */
 435   protected sendTaskFunctionsListToMainWorker (): void {
 436     this.sendToMainWorker({
 437       taskFunctions: this.listTaskFunctions(),
 438       workerId: this.id
 439     })
 440   }
 441
 442   /**
 443    * Handles an error and convert it to a string so it can be sent back to the main worker.
 444    *
 445    * @param e - The error raised by the worker.
 446    * @returns The error message.
 447    */
 448   protected handleError (e: Error | string): string {
 449     return e instanceof Error ? e.message : e
 450   }
 451
 452   /**
 453    * Runs the given task.
 454    *
 455    * @param task - The task to execute.
 456    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 457    */
 458   protected run (task: Task<Data>): void {
 459     const fn = this.getTaskFunction(task.name)
 460     if (isAsyncFunction(fn)) {
 461       this.runInAsyncScope(this.runAsync.bind(this), this, fn, task)
 462     } else {
 463       this.runInAsyncScope(this.runSync.bind(this), this, fn, task)
 464     }
 465   }
 466
 467   /**
 468    * Runs the given task function synchronously.
 469    *
 470    * @param fn - Task function that will be executed.
 471    * @param task - Input data for the task function.
 472    */
 473   protected runSync (
 474     fn: TaskSyncFunction<Data, Response>,
 475     task: Task<Data>
 476   ): void {
 477     const { name, taskId, data } = task
 478     try {
 479       let taskPerformance = this.beginTaskPerformance(name)
 480       const res = fn(data)
 481       taskPerformance = this.endTaskPerformance(taskPerformance)
 482       this.sendToMainWorker({
 483         data: res,
 484         taskPerformance,
 485         workerId: this.id,
 486         taskId
 487       })
 488     } catch (e) {
 489       const errorMessage = this.handleError(e as Error | string)
 490       this.sendToMainWorker({
 491         taskError: {
 492           name: name ?? DEFAULT_TASK_NAME,
 493           message: errorMessage,
 494           data
 495         },
 496         workerId: this.id,
 497         taskId
 498       })
 499     } finally {
 500       this.updateLastTaskTimestamp()
 501     }
 502   }
 503
 504   /**
 505    * Runs the given task function asynchronously.
 506    *
 507    * @param fn - Task function that will be executed.
 508    * @param task - Input data for the task function.
 509    */
 510   protected runAsync (
 511     fn: TaskAsyncFunction<Data, Response>,
 512     task: Task<Data>
 513   ): void {
 514     const { name, taskId, data } = task
 515     let taskPerformance = this.beginTaskPerformance(name)
 516     fn(data)
 517       .then((res) => {
 518         taskPerformance = this.endTaskPerformance(taskPerformance)
 519         this.sendToMainWorker({
 520           data: res,
 521           taskPerformance,
 522           workerId: this.id,
 523           taskId
 524         })
 525         return null
 526       })
 527       .catch((e) => {
 528         const errorMessage = this.handleError(e as Error | string)
 529         this.sendToMainWorker({
 530           taskError: {
 531             name: name ?? DEFAULT_TASK_NAME,
 532             message: errorMessage,
 533             data
 534           },
 535           workerId: this.id,
 536           taskId
 537         })
 538       })
 539       .finally(() => {
 540         this.updateLastTaskTimestamp()
 541       })
 542       .catch(EMPTY_FUNCTION)
 543   }
 544
 545   /**
 546    * Gets the task function with the given name.
 547    *
 548    * @param name - Name of the task function that will be returned.
 549    * @returns The task function.
 550    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 551    */
 552   private getTaskFunction (name?: string): TaskFunction<Data, Response> {
 553     name = name ?? DEFAULT_TASK_NAME
 554     const fn = this.taskFunctions.get(name)
 555     if (fn == null) {
 556       throw new Error(`Task function '${name}' not found`)
 557     }
 558     return fn
 559   }
 560
 561   private beginTaskPerformance (name?: string): TaskPerformance {
 562     this.checkStatistics()
 563     return {
 564       name: name ?? DEFAULT_TASK_NAME,
 565       timestamp: performance.now(),
 566       ...(this.statistics.elu && { elu: performance.eventLoopUtilization() })
 567     }
 568   }
 569
 570   private endTaskPerformance (
 571     taskPerformance: TaskPerformance
 572   ): TaskPerformance {
 573     this.checkStatistics()
 574     return {
 575       ...taskPerformance,
 576       ...(this.statistics.runTime && {
 577         runTime: performance.now() - taskPerformance.timestamp
 578       }),
 579       ...(this.statistics.elu && {
 580         elu: performance.eventLoopUtilization(taskPerformance.elu)
 581       })
 582     }
 583   }
 584
 585   private checkStatistics (): void {
 586     if (this.statistics == null) {
 587       throw new Error('Performance statistics computation requirements not set')
 588     }
 589   }
 590
 591   private updateLastTaskTimestamp (): void {
 592     if (this.activeInterval != null) {
 593       this.lastTaskTimestamp = performance.now()
 594     }
 595   }
 596 }