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   TaskFunctions,
  24   WorkerAsyncFunction,
  25   WorkerFunction,
  26   WorkerSyncFunction
  27 } from './worker-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, WorkerFunction<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 taskFunctions - Task function(s) processed by the worker when the pool's `execution` function is invoked. The first function is the default function.
  70    * @param mainWorker - Reference to main worker.
  71    * @param opts - Options for the worker.
  72    */
  73   public constructor (
  74     type: string,
  75     protected readonly isMain: boolean,
  76     taskFunctions:
  77     | WorkerFunction<Data, Response>
  78     | TaskFunctions<Data, Response>,
  79     protected readonly mainWorker: MainWorker,
  80     protected readonly opts: WorkerOptions = {
  81       /**
  82        * The kill behavior option on this worker or its default value.
  83        */
  84       killBehavior: DEFAULT_KILL_BEHAVIOR,
  85       /**
  86        * The maximum time to keep this worker active while idle.
  87        * The pool automatically checks and terminates this worker when the time expires.
  88        */
  89       maxInactiveTime: DEFAULT_MAX_INACTIVE_TIME
  90     }
  91   ) {
  92     super(type)
  93     this.checkWorkerOptions(this.opts)
  94     this.checkTaskFunctions(taskFunctions)
  95     if (!this.isMain) {
  96       this.mainWorker?.on('message', this.messageListener.bind(this))
  97     }
  98   }
  99
 100   private checkWorkerOptions (opts: WorkerOptions): void {
 101     this.opts.killBehavior = opts.killBehavior ?? DEFAULT_KILL_BEHAVIOR
 102     this.opts.maxInactiveTime =
 103       opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME
 104     delete this.opts.async
 105   }
 106
 107   /**
 108    * Checks if the `taskFunctions` parameter is passed to the constructor.
 109    *
 110    * @param taskFunctions - The task function(s) parameter that should be checked.
 111    */
 112   private checkTaskFunctions (
 113     taskFunctions:
 114     | WorkerFunction<Data, Response>
 115     | TaskFunctions<Data, Response>
 116   ): void {
 117     if (taskFunctions == null) {
 118       throw new Error('taskFunctions parameter is mandatory')
 119     }
 120     this.taskFunctions = new Map<string, WorkerFunction<Data, Response>>()
 121     if (typeof taskFunctions === 'function') {
 122       const boundFn = taskFunctions.bind(this)
 123       this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 124       this.taskFunctions.set(
 125         typeof taskFunctions.name === 'string' &&
 126           taskFunctions.name.trim().length > 0
 127           ? taskFunctions.name
 128           : 'fn1',
 129         boundFn
 130       )
 131     } else if (isPlainObject(taskFunctions)) {
 132       let firstEntry = true
 133       for (const [name, fn] of Object.entries(taskFunctions)) {
 134         if (typeof name !== 'string') {
 135           throw new TypeError(
 136             'A taskFunctions parameter object key is not a string'
 137           )
 138         }
 139         if (typeof fn !== 'function') {
 140           throw new TypeError(
 141             'A taskFunctions parameter object value is not a function'
 142           )
 143         }
 144         const boundFn = fn.bind(this)
 145         if (firstEntry) {
 146           this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 147           firstEntry = false
 148         }
 149         this.taskFunctions.set(name, boundFn)
 150       }
 151       if (firstEntry) {
 152         throw new Error('taskFunctions parameter object is empty')
 153       }
 154     } else {
 155       throw new TypeError(
 156         'taskFunctions parameter is not a function or a plain object'
 157       )
 158     }
 159   }
 160
 161   /**
 162    * Checks if the worker has a task function with the given name.
 163    *
 164    * @param name - The name of the task function to check.
 165    * @returns Whether the worker has a task function with the given name or not.
 166    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 167    */
 168   public hasTaskFunction (name: string): boolean {
 169     if (typeof name !== 'string') {
 170       throw new TypeError('name parameter is not a string')
 171     }
 172     return this.taskFunctions.has(name)
 173   }
 174
 175   /**
 176    * Adds a task function to the worker.
 177    * If a task function with the same name already exists, it is replaced.
 178    *
 179    * @param name - The name of the task function to add.
 180    * @param fn - The task function to add.
 181    * @returns Whether the task function was added or not.
 182    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 183    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 184    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `fn` parameter is not a function.
 185    */
 186   public addTaskFunction (
 187     name: string,
 188     fn: WorkerFunction<Data, Response>
 189   ): boolean {
 190     if (typeof name !== 'string') {
 191       throw new TypeError('name parameter is not a string')
 192     }
 193     if (name === DEFAULT_TASK_NAME) {
 194       throw new Error(
 195         'Cannot add a task function with the default reserved name'
 196       )
 197     }
 198     if (typeof fn !== 'function') {
 199       throw new TypeError('fn parameter is not a function')
 200     }
 201     try {
 202       const boundFn = fn.bind(this)
 203       if (
 204         this.taskFunctions.get(name) ===
 205         this.taskFunctions.get(DEFAULT_TASK_NAME)
 206       ) {
 207         this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 208       }
 209       this.taskFunctions.set(name, boundFn)
 210       return true
 211     } catch {
 212       return false
 213     }
 214   }
 215
 216   /**
 217    * Removes a task function from the worker.
 218    *
 219    * @param name - The name of the task function to remove.
 220    * @returns Whether the task function existed and was removed or not.
 221    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 222    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 223    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the task function used as default task function.
 224    */
 225   public removeTaskFunction (name: string): boolean {
 226     if (typeof name !== 'string') {
 227       throw new TypeError('name parameter is not a string')
 228     }
 229     if (name === DEFAULT_TASK_NAME) {
 230       throw new Error(
 231         'Cannot remove the task function with the default reserved name'
 232       )
 233     }
 234     if (
 235       this.taskFunctions.get(name) === this.taskFunctions.get(DEFAULT_TASK_NAME)
 236     ) {
 237       throw new Error(
 238         'Cannot remove the task function used as the default task function'
 239       )
 240     }
 241     return this.taskFunctions.delete(name)
 242   }
 243
 244   /**
 245    * Lists the names of the worker's task functions.
 246    *
 247    * @returns The names of the worker's task functions.
 248    */
 249   public listTaskFunctions (): string[] {
 250     return Array.from(this.taskFunctions.keys())
 251   }
 252
 253   /**
 254    * Sets the default task function to use in the worker.
 255    *
 256    * @param name - The name of the task function to use as default task function.
 257    * @returns Whether the default task function was set or not.
 258    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 259    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 260    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is a non-existing task function.
 261    */
 262   public setDefaultTaskFunction (name: string): boolean {
 263     if (typeof name !== 'string') {
 264       throw new TypeError('name parameter is not a string')
 265     }
 266     if (name === DEFAULT_TASK_NAME) {
 267       throw new Error(
 268         'Cannot set the default task function reserved name as the default task function'
 269       )
 270     }
 271     if (!this.taskFunctions.has(name)) {
 272       throw new Error(
 273         'Cannot set the default task function to a non-existing task function'
 274       )
 275     }
 276     try {
 277       this.taskFunctions.set(
 278         DEFAULT_TASK_NAME,
 279         this.taskFunctions.get(name) as WorkerFunction<Data, Response>
 280       )
 281       return true
 282     } catch {
 283       return false
 284     }
 285   }
 286
 287   /**
 288    * Worker message listener.
 289    *
 290    * @param message - The received message.
 291    */
 292   protected messageListener (message: MessageValue<Data, Data>): void {
 293     if (message.workerId === this.id) {
 294       if (message.ready != null) {
 295         // Startup message received
 296         this.sendReadyResponse()
 297       } else 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         message.checkActive ? this.startCheckActive() : this.stopCheckActive()
 303       } else if (message.id != null && message.data != null) {
 304         // Task message received
 305         this.run(message)
 306       } else if (message.kill === true) {
 307         // Kill message received
 308         this.stopCheckActive()
 309         this.emitDestroy()
 310       }
 311     }
 312   }
 313
 314   /**
 315    * Sends the ready response to the main worker.
 316    */
 317   protected sendReadyResponse (): void {
 318     !this.isMain && this.sendToMainWorker({ ready: true, workerId: this.id })
 319   }
 320
 321   /**
 322    * Starts the worker check active interval.
 323    */
 324   private startCheckActive (): void {
 325     this.lastTaskTimestamp = performance.now()
 326     this.activeInterval = setInterval(
 327       this.checkActive.bind(this),
 328       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
 329     ).unref()
 330   }
 331
 332   /**
 333    * Stops the worker check active interval.
 334    */
 335   private stopCheckActive (): void {
 336     if (this.activeInterval != null) {
 337       clearInterval(this.activeInterval)
 338       delete this.activeInterval
 339     }
 340   }
 341
 342   /**
 343    * Checks if the worker should be terminated, because its living too long.
 344    */
 345   private checkActive (): void {
 346     if (
 347       performance.now() - this.lastTaskTimestamp >
 348       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 349     ) {
 350       this.sendToMainWorker({ kill: this.opts.killBehavior, workerId: this.id })
 351     }
 352   }
 353
 354   /**
 355    * Returns the main worker.
 356    *
 357    * @returns Reference to the main worker.
 358    */
 359   protected getMainWorker (): MainWorker {
 360     if (this.mainWorker == null) {
 361       throw new Error('Main worker not set')
 362     }
 363     return this.mainWorker
 364   }
 365
 366   /**
 367    * Sends a message to the main worker.
 368    *
 369    * @param message - The response message.
 370    */
 371   protected abstract sendToMainWorker (
 372     message: MessageValue<Response, Data>
 373   ): void
 374
 375   /**
 376    * Handles an error and convert it to a string so it can be sent back to the main worker.
 377    *
 378    * @param e - The error raised by the worker.
 379    * @returns The error message.
 380    */
 381   protected handleError (e: Error | string): string {
 382     return e instanceof Error ? e.message : e
 383   }
 384
 385   /**
 386    * Runs the given task.
 387    *
 388    * @param task - The task to execute.
 389    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 390    */
 391   protected run (task: Task<Data>): void {
 392     const fn = this.getTaskFunction(task.name)
 393     if (isAsyncFunction(fn)) {
 394       this.runInAsyncScope(this.runAsync.bind(this), this, fn, task)
 395     } else {
 396       this.runInAsyncScope(this.runSync.bind(this), this, fn, task)
 397     }
 398   }
 399
 400   /**
 401    * Runs the given task function synchronously.
 402    *
 403    * @param fn - Task function that will be executed.
 404    * @param task - Input data for the task function.
 405    */
 406   protected runSync (
 407     fn: WorkerSyncFunction<Data, Response>,
 408     task: Task<Data>
 409   ): void {
 410     try {
 411       let taskPerformance = this.beginTaskPerformance(task.name)
 412       const res = fn(task.data)
 413       taskPerformance = this.endTaskPerformance(taskPerformance)
 414       this.sendToMainWorker({
 415         data: res,
 416         taskPerformance,
 417         workerId: this.id,
 418         id: task.id
 419       })
 420     } catch (e) {
 421       const errorMessage = this.handleError(e as Error | string)
 422       this.sendToMainWorker({
 423         taskError: {
 424           name: task.name ?? DEFAULT_TASK_NAME,
 425           message: errorMessage,
 426           data: task.data
 427         },
 428         workerId: this.id,
 429         id: task.id
 430       })
 431     } finally {
 432       this.updateLastTaskTimestamp()
 433     }
 434   }
 435
 436   /**
 437    * Runs the given task function asynchronously.
 438    *
 439    * @param fn - Task function that will be executed.
 440    * @param task - Input data for the task function.
 441    */
 442   protected runAsync (
 443     fn: WorkerAsyncFunction<Data, Response>,
 444     task: Task<Data>
 445   ): void {
 446     let taskPerformance = this.beginTaskPerformance(task.name)
 447     fn(task.data)
 448       .then(res => {
 449         taskPerformance = this.endTaskPerformance(taskPerformance)
 450         this.sendToMainWorker({
 451           data: res,
 452           taskPerformance,
 453           workerId: this.id,
 454           id: task.id
 455         })
 456         return null
 457       })
 458       .catch(e => {
 459         const errorMessage = this.handleError(e as Error | string)
 460         this.sendToMainWorker({
 461           taskError: {
 462             name: task.name ?? DEFAULT_TASK_NAME,
 463             message: errorMessage,
 464             data: task.data
 465           },
 466           workerId: this.id,
 467           id: task.id
 468         })
 469       })
 470       .finally(() => {
 471         this.updateLastTaskTimestamp()
 472       })
 473       .catch(EMPTY_FUNCTION)
 474   }
 475
 476   /**
 477    * Gets the task function with the given name.
 478    *
 479    * @param name - Name of the task function that will be returned.
 480    * @returns The task function.
 481    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 482    */
 483   private getTaskFunction (name?: string): WorkerFunction<Data, Response> {
 484     name = name ?? DEFAULT_TASK_NAME
 485     const fn = this.taskFunctions.get(name)
 486     if (fn == null) {
 487       throw new Error(`Task function '${name}' not found`)
 488     }
 489     return fn
 490   }
 491
 492   private beginTaskPerformance (name?: string): TaskPerformance {
 493     this.checkStatistics()
 494     return {
 495       name: name ?? DEFAULT_TASK_NAME,
 496       timestamp: performance.now(),
 497       ...(this.statistics.elu && { elu: performance.eventLoopUtilization() })
 498     }
 499   }
 500
 501   private endTaskPerformance (
 502     taskPerformance: TaskPerformance
 503   ): TaskPerformance {
 504     this.checkStatistics()
 505     return {
 506       ...taskPerformance,
 507       ...(this.statistics.runTime && {
 508         runTime: performance.now() - taskPerformance.timestamp
 509       }),
 510       ...(this.statistics.elu && {
 511         elu: performance.eventLoopUtilization(taskPerformance.elu)
 512       })
 513     }
 514   }
 515
 516   private checkStatistics (): void {
 517     if (this.statistics == null) {
 518       throw new Error('Performance statistics computation requirements not set')
 519     }
 520   }
 521
 522   private updateLastTaskTimestamp (): void {
 523     if (!this.isMain && this.activeInterval != null) {
 524       this.lastTaskTimestamp = performance.now()
 525     }
 526   }
 527 }