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   ) {
  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.killBehavior = opts.killBehavior ?? DEFAULT_KILL_BEHAVIOR
 100     this.opts.maxInactiveTime =
 101       opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME
 102     delete this.opts.async
 103   }
 104
 105   /**
 106    * Checks if the `taskFunctions` parameter is passed to the constructor.
 107    *
 108    * @param taskFunctions - The task function(s) parameter that should be checked.
 109    */
 110   private checkTaskFunctions (
 111     taskFunctions: TaskFunction<Data, Response> | TaskFunctions<Data, Response>
 112   ): void {
 113     if (taskFunctions == null) {
 114       throw new Error('taskFunctions parameter is mandatory')
 115     }
 116     this.taskFunctions = new Map<string, TaskFunction<Data, Response>>()
 117     if (typeof taskFunctions === 'function') {
 118       const boundFn = taskFunctions.bind(this)
 119       this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 120       this.taskFunctions.set(
 121         typeof taskFunctions.name === 'string' &&
 122           taskFunctions.name.trim().length > 0
 123           ? taskFunctions.name
 124           : 'fn1',
 125         boundFn
 126       )
 127     } else if (isPlainObject(taskFunctions)) {
 128       let firstEntry = true
 129       for (const [name, fn] of Object.entries(taskFunctions)) {
 130         if (typeof name !== 'string') {
 131           throw new TypeError(
 132             'A taskFunctions parameter object key is not a string'
 133           )
 134         }
 135         if (typeof fn !== 'function') {
 136           throw new TypeError(
 137             'A taskFunctions parameter object value is not a function'
 138           )
 139         }
 140         const boundFn = fn.bind(this)
 141         if (firstEntry) {
 142           this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 143           firstEntry = false
 144         }
 145         this.taskFunctions.set(name, boundFn)
 146       }
 147       if (firstEntry) {
 148         throw new Error('taskFunctions parameter object is empty')
 149       }
 150     } else {
 151       throw new TypeError(
 152         'taskFunctions parameter is not a function or a plain object'
 153       )
 154     }
 155   }
 156
 157   /**
 158    * Checks if the worker has a task function with the given name.
 159    *
 160    * @param name - The name of the task function to check.
 161    * @returns Whether the worker has a task function with the given name or not.
 162    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 163    */
 164   public hasTaskFunction (name: string): boolean {
 165     if (typeof name !== 'string') {
 166       throw new TypeError('name parameter is not a string')
 167     }
 168     return this.taskFunctions.has(name)
 169   }
 170
 171   /**
 172    * Adds a task function to the worker.
 173    * If a task function with the same name already exists, it is replaced.
 174    *
 175    * @param name - The name of the task function to add.
 176    * @param fn - The task function to add.
 177    * @returns Whether the task function was added or not.
 178    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 179    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 180    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `fn` parameter is not a function.
 181    */
 182   public addTaskFunction (
 183     name: string,
 184     fn: TaskFunction<Data, Response>
 185   ): boolean {
 186     if (typeof name !== 'string') {
 187       throw new TypeError('name parameter is not a string')
 188     }
 189     if (name === DEFAULT_TASK_NAME) {
 190       throw new Error(
 191         'Cannot add a task function with the default reserved name'
 192       )
 193     }
 194     if (typeof fn !== 'function') {
 195       throw new TypeError('fn parameter is not a function')
 196     }
 197     try {
 198       const boundFn = fn.bind(this)
 199       if (
 200         this.taskFunctions.get(name) ===
 201         this.taskFunctions.get(DEFAULT_TASK_NAME)
 202       ) {
 203         this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 204       }
 205       this.taskFunctions.set(name, boundFn)
 206       return true
 207     } catch {
 208       return false
 209     }
 210   }
 211
 212   /**
 213    * Removes a task function from the worker.
 214    *
 215    * @param name - The name of the task function to remove.
 216    * @returns Whether the task function existed and was removed or not.
 217    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 218    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 219    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the task function used as default task function.
 220    */
 221   public removeTaskFunction (name: string): boolean {
 222     if (typeof name !== 'string') {
 223       throw new TypeError('name parameter is not a string')
 224     }
 225     if (name === DEFAULT_TASK_NAME) {
 226       throw new Error(
 227         'Cannot remove the task function with the default reserved name'
 228       )
 229     }
 230     if (
 231       this.taskFunctions.get(name) === this.taskFunctions.get(DEFAULT_TASK_NAME)
 232     ) {
 233       throw new Error(
 234         'Cannot remove the task function used as the default task function'
 235       )
 236     }
 237     return this.taskFunctions.delete(name)
 238   }
 239
 240   /**
 241    * Lists the names of the worker's task functions.
 242    *
 243    * @returns The names of the worker's task functions.
 244    */
 245   public listTaskFunctions (): string[] {
 246     return [...this.taskFunctions.keys()]
 247   }
 248
 249   /**
 250    * Sets the default task function to use in the worker.
 251    *
 252    * @param name - The name of the task function to use as default task function.
 253    * @returns Whether the default task function was set or not.
 254    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 255    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 256    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is a non-existing task function.
 257    */
 258   public setDefaultTaskFunction (name: string): boolean {
 259     if (typeof name !== 'string') {
 260       throw new TypeError('name parameter is not a string')
 261     }
 262     if (name === DEFAULT_TASK_NAME) {
 263       throw new Error(
 264         'Cannot set the default task function reserved name as the default task function'
 265       )
 266     }
 267     if (!this.taskFunctions.has(name)) {
 268       throw new Error(
 269         'Cannot set the default task function to a non-existing task function'
 270       )
 271     }
 272     try {
 273       this.taskFunctions.set(
 274         DEFAULT_TASK_NAME,
 275         this.taskFunctions.get(name) as TaskFunction<Data, Response>
 276       )
 277       return true
 278     } catch {
 279       return false
 280     }
 281   }
 282
 283   /**
 284    * Handles the ready message sent by the main worker.
 285    *
 286    * @param message - The ready message.
 287    */
 288   protected abstract handleReadyMessage (message: MessageValue<Data>): void
 289
 290   /**
 291    * Worker message listener.
 292    *
 293    * @param message - The received message.
 294    */
 295   protected messageListener (message: MessageValue<Data>): void {
 296     if (message.workerId === this.id) {
 297       if (message.statistics != null) {
 298         // Statistics message received
 299         this.statistics = message.statistics
 300       } else if (message.checkActive != null) {
 301         // Check active message received
 302         !this.isMain && message.checkActive
 303           ? this.startCheckActive()
 304           : this.stopCheckActive()
 305       } else if (message.id != null && message.data != null) {
 306         // Task message received
 307         this.run(message)
 308       } else if (message.kill === true) {
 309         // Kill message received
 310         this.handleKillMessage(message)
 311       }
 312     }
 313   }
 314
 315   /**
 316    * Handles a kill message sent by the main worker.
 317    *
 318    * @param message - The kill message.
 319    */
 320   protected handleKillMessage (message: MessageValue<Data>): void {
 321     !this.isMain && this.stopCheckActive()
 322     this.emitDestroy()
 323   }
 324
 325   /**
 326    * Starts the worker check active interval.
 327    */
 328   private startCheckActive (): void {
 329     this.lastTaskTimestamp = performance.now()
 330     this.activeInterval = setInterval(
 331       this.checkActive.bind(this),
 332       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
 333     )
 334   }
 335
 336   /**
 337    * Stops the worker check active interval.
 338    */
 339   private stopCheckActive (): void {
 340     if (this.activeInterval != null) {
 341       clearInterval(this.activeInterval)
 342       delete this.activeInterval
 343     }
 344   }
 345
 346   /**
 347    * Checks if the worker should be terminated, because its living too long.
 348    */
 349   private checkActive (): void {
 350     if (
 351       performance.now() - this.lastTaskTimestamp >
 352       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 353     ) {
 354       this.sendToMainWorker({ kill: this.opts.killBehavior, workerId: this.id })
 355     }
 356   }
 357
 358   /**
 359    * Returns the main worker.
 360    *
 361    * @returns Reference to the main worker.
 362    */
 363   protected getMainWorker (): MainWorker {
 364     if (this.mainWorker == null) {
 365       throw new Error('Main worker not set')
 366     }
 367     return this.mainWorker
 368   }
 369
 370   /**
 371    * Sends a message to main worker.
 372    *
 373    * @param message - The response message.
 374    */
 375   protected abstract sendToMainWorker (
 376     message: MessageValue<Response, Data>
 377   ): void
 378
 379   /**
 380    * Handles an error and convert it to a string so it can be sent back to the main worker.
 381    *
 382    * @param e - The error raised by the worker.
 383    * @returns The error message.
 384    */
 385   protected handleError (e: Error | string): string {
 386     return e instanceof Error ? e.message : e
 387   }
 388
 389   /**
 390    * Runs the given task.
 391    *
 392    * @param task - The task to execute.
 393    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 394    */
 395   protected run (task: Task<Data>): void {
 396     if (this.isMain) {
 397       throw new Error('Cannot run a task in the main worker')
 398     }
 399     const fn = this.getTaskFunction(task.name)
 400     if (isAsyncFunction(fn)) {
 401       this.runInAsyncScope(this.runAsync.bind(this), this, fn, task)
 402     } else {
 403       this.runInAsyncScope(this.runSync.bind(this), this, fn, task)
 404     }
 405   }
 406
 407   /**
 408    * Runs the given task function synchronously.
 409    *
 410    * @param fn - Task function that will be executed.
 411    * @param task - Input data for the task function.
 412    */
 413   protected runSync (
 414     fn: TaskSyncFunction<Data, Response>,
 415     task: Task<Data>
 416   ): void {
 417     try {
 418       let taskPerformance = this.beginTaskPerformance(task.name)
 419       const res = fn(task.data)
 420       taskPerformance = this.endTaskPerformance(taskPerformance)
 421       this.sendToMainWorker({
 422         data: res,
 423         taskPerformance,
 424         workerId: this.id,
 425         id: task.id
 426       })
 427     } catch (e) {
 428       const errorMessage = this.handleError(e as Error | string)
 429       this.sendToMainWorker({
 430         taskError: {
 431           name: task.name ?? DEFAULT_TASK_NAME,
 432           message: errorMessage,
 433           data: task.data
 434         },
 435         workerId: this.id,
 436         id: task.id
 437       })
 438     } finally {
 439       this.updateLastTaskTimestamp()
 440     }
 441   }
 442
 443   /**
 444    * Runs the given task function asynchronously.
 445    *
 446    * @param fn - Task function that will be executed.
 447    * @param task - Input data for the task function.
 448    */
 449   protected runAsync (
 450     fn: TaskAsyncFunction<Data, Response>,
 451     task: Task<Data>
 452   ): void {
 453     let taskPerformance = this.beginTaskPerformance(task.name)
 454     fn(task.data)
 455       .then(res => {
 456         taskPerformance = this.endTaskPerformance(taskPerformance)
 457         this.sendToMainWorker({
 458           data: res,
 459           taskPerformance,
 460           workerId: this.id,
 461           id: task.id
 462         })
 463         return null
 464       })
 465       .catch(e => {
 466         const errorMessage = this.handleError(e as Error | string)
 467         this.sendToMainWorker({
 468           taskError: {
 469             name: task.name ?? DEFAULT_TASK_NAME,
 470             message: errorMessage,
 471             data: task.data
 472           },
 473           workerId: this.id,
 474           id: task.id
 475         })
 476       })
 477       .finally(() => {
 478         this.updateLastTaskTimestamp()
 479       })
 480       .catch(EMPTY_FUNCTION)
 481   }
 482
 483   /**
 484    * Gets the task function with the given name.
 485    *
 486    * @param name - Name of the task function that will be returned.
 487    * @returns The task function.
 488    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 489    */
 490   private getTaskFunction (name?: string): TaskFunction<Data, Response> {
 491     name = name ?? DEFAULT_TASK_NAME
 492     const fn = this.taskFunctions.get(name)
 493     if (fn == null) {
 494       throw new Error(`Task function '${name}' not found`)
 495     }
 496     return fn
 497   }
 498
 499   private beginTaskPerformance (name?: string): TaskPerformance {
 500     this.checkStatistics()
 501     return {
 502       name: name ?? DEFAULT_TASK_NAME,
 503       timestamp: performance.now(),
 504       ...(this.statistics.elu && { elu: performance.eventLoopUtilization() })
 505     }
 506   }
 507
 508   private endTaskPerformance (
 509     taskPerformance: TaskPerformance
 510   ): TaskPerformance {
 511     this.checkStatistics()
 512     return {
 513       ...taskPerformance,
 514       ...(this.statistics.runTime && {
 515         runTime: performance.now() - taskPerformance.timestamp
 516       }),
 517       ...(this.statistics.elu && {
 518         elu: performance.eventLoopUtilization(taskPerformance.elu)
 519       })
 520     }
 521   }
 522
 523   private checkStatistics (): void {
 524     if (this.statistics == null) {
 525       throw new Error('Performance statistics computation requirements not set')
 526     }
 527   }
 528
 529   private updateLastTaskTimestamp (): void {
 530     if (!this.isMain && this.activeInterval != null) {
 531       this.lastTaskTimestamp = performance.now()
 532     }
 533   }
 534 }