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