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 fn !== 'function') {
 141           throw new TypeError(
 142             'A taskFunctions parameter object value is not a function'
 143           )
 144         }
 145         const boundFn = fn.bind(this)
 146         if (firstEntry) {
 147           this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 148           firstEntry = false
 149         }
 150         this.taskFunctions.set(name, boundFn)
 151       }
 152       if (firstEntry) {
 153         throw new Error('taskFunctions parameter object is empty')
 154       }
 155     } else {
 156       throw new TypeError(
 157         'taskFunctions parameter is not a function or a plain object'
 158       )
 159     }
 160   }
 161
 162   /**
 163    * Checks if the worker has a task function with the given name.
 164    *
 165    * @param name - The name of the task function to check.
 166    * @returns Whether the worker has a task function with the given name or not.
 167    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 168    */
 169   public hasTaskFunction (name: string): boolean {
 170     if (typeof name !== 'string') {
 171       throw new TypeError('name parameter is not a string')
 172     }
 173     return this.taskFunctions.has(name)
 174   }
 175
 176   /**
 177    * Adds a task function to the worker.
 178    * If a task function with the same name already exists, it is replaced.
 179    *
 180    * @param name - The name of the task function to add.
 181    * @param fn - The task function to add.
 182    * @returns Whether the task function was added or not.
 183    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 184    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 185    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `fn` parameter is not a function.
 186    */
 187   public addTaskFunction (
 188     name: string,
 189     fn: TaskFunction<Data, Response>
 190   ): boolean {
 191     if (typeof name !== 'string') {
 192       throw new TypeError('name parameter is not a string')
 193     }
 194     if (name === DEFAULT_TASK_NAME) {
 195       throw new Error(
 196         'Cannot add a task function with the default reserved name'
 197       )
 198     }
 199     if (typeof fn !== 'function') {
 200       throw new TypeError('fn parameter is not a function')
 201     }
 202     try {
 203       const boundFn = fn.bind(this)
 204       if (
 205         this.taskFunctions.get(name) ===
 206         this.taskFunctions.get(DEFAULT_TASK_NAME)
 207       ) {
 208         this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
 209       }
 210       this.taskFunctions.set(name, boundFn)
 211       return true
 212     } catch {
 213       return false
 214     }
 215   }
 216
 217   /**
 218    * Removes a task function from the worker.
 219    *
 220    * @param name - The name of the task function to remove.
 221    * @returns Whether the task function existed and was removed or not.
 222    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 223    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 224    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the task function used as default task function.
 225    */
 226   public removeTaskFunction (name: string): boolean {
 227     if (typeof name !== 'string') {
 228       throw new TypeError('name parameter is not a string')
 229     }
 230     if (name === DEFAULT_TASK_NAME) {
 231       throw new Error(
 232         'Cannot remove the task function with the default reserved name'
 233       )
 234     }
 235     if (
 236       this.taskFunctions.get(name) === this.taskFunctions.get(DEFAULT_TASK_NAME)
 237     ) {
 238       throw new Error(
 239         'Cannot remove the task function used as the default task function'
 240       )
 241     }
 242     return this.taskFunctions.delete(name)
 243   }
 244
 245   /**
 246    * Lists the names of the worker's task functions.
 247    *
 248    * @returns The names of the worker's task functions.
 249    */
 250   public listTaskFunctions (): string[] {
 251     return [...this.taskFunctions.keys()]
 252   }
 253
 254   /**
 255    * Sets the default task function to use in the worker.
 256    *
 257    * @param name - The name of the task function to use as default task function.
 258    * @returns Whether the default task function was set or not.
 259    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 260    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 261    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is a non-existing task function.
 262    */
 263   public setDefaultTaskFunction (name: string): boolean {
 264     if (typeof name !== 'string') {
 265       throw new TypeError('name parameter is not a string')
 266     }
 267     if (name === DEFAULT_TASK_NAME) {
 268       throw new Error(
 269         'Cannot set the default task function reserved name as the default task function'
 270       )
 271     }
 272     if (!this.taskFunctions.has(name)) {
 273       throw new Error(
 274         'Cannot set the default task function to a non-existing task function'
 275       )
 276     }
 277     try {
 278       this.taskFunctions.set(
 279         DEFAULT_TASK_NAME,
 280         this.taskFunctions.get(name) as TaskFunction<Data, Response>
 281       )
 282       return true
 283     } catch {
 284       return false
 285     }
 286   }
 287
 288   /**
 289    * Handles the ready message sent by the main worker.
 290    *
 291    * @param message - The ready message.
 292    */
 293   protected abstract handleReadyMessage (message: MessageValue<Data>): void
 294
 295   /**
 296    * Worker message listener.
 297    *
 298    * @param message - The received message.
 299    */
 300   protected messageListener (message: MessageValue<Data>): void {
 301     if (message.workerId != null && message.workerId !== this.id) {
 302       throw new Error('Message worker id does not match worker id')
 303     } else if (message.workerId === this.id) {
 304       if (message.statistics != null) {
 305         // Statistics message received
 306         this.statistics = message.statistics
 307       } else if (message.checkActive != null) {
 308         // Check active message received
 309         !this.isMain && message.checkActive
 310           ? this.startCheckActive()
 311           : this.stopCheckActive()
 312       } else if (message.taskId != null && message.data != null) {
 313         // Task message received
 314         this.run(message)
 315       } else if (message.kill === true) {
 316         // Kill message received
 317         this.handleKillMessage(message)
 318       }
 319     }
 320   }
 321
 322   /**
 323    * Handles a kill message sent by the main worker.
 324    *
 325    * @param message - The kill message.
 326    */
 327   protected handleKillMessage (message: MessageValue<Data>): void {
 328     if (!this.isMain) {
 329       this.stopCheckActive()
 330       this.opts.killHandler?.()
 331       this.emitDestroy()
 332     }
 333   }
 334
 335   /**
 336    * Starts the worker check active interval.
 337    */
 338   private startCheckActive (): void {
 339     this.lastTaskTimestamp = performance.now()
 340     this.activeInterval = setInterval(
 341       this.checkActive.bind(this),
 342       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
 343     )
 344   }
 345
 346   /**
 347    * Stops the worker check active interval.
 348    */
 349   private stopCheckActive (): void {
 350     if (this.activeInterval != null) {
 351       clearInterval(this.activeInterval)
 352       delete this.activeInterval
 353     }
 354   }
 355
 356   /**
 357    * Checks if the worker should be terminated, because its living too long.
 358    */
 359   private checkActive (): void {
 360     if (
 361       performance.now() - this.lastTaskTimestamp >
 362       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 363     ) {
 364       this.sendToMainWorker({ kill: this.opts.killBehavior, workerId: this.id })
 365     }
 366   }
 367
 368   /**
 369    * Returns the main worker.
 370    *
 371    * @returns Reference to the main worker.
 372    */
 373   protected getMainWorker (): MainWorker {
 374     if (this.mainWorker == null) {
 375       throw new Error('Main worker not set')
 376     }
 377     return this.mainWorker
 378   }
 379
 380   /**
 381    * Sends a message to main worker.
 382    *
 383    * @param message - The response message.
 384    */
 385   protected abstract sendToMainWorker (
 386     message: MessageValue<Response, Data>
 387   ): void
 388
 389   /**
 390    * Handles an error and convert it to a string so it can be sent back to the main worker.
 391    *
 392    * @param e - The error raised by the worker.
 393    * @returns The error message.
 394    */
 395   protected handleError (e: Error | string): string {
 396     return e instanceof Error ? e.message : e
 397   }
 398
 399   /**
 400    * Runs the given task.
 401    *
 402    * @param task - The task to execute.
 403    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 404    */
 405   protected run (task: Task<Data>): void {
 406     if (this.isMain) {
 407       throw new Error('Cannot run a task in the main worker')
 408     }
 409     const fn = this.getTaskFunction(task.name)
 410     if (isAsyncFunction(fn)) {
 411       this.runInAsyncScope(this.runAsync.bind(this), this, fn, task)
 412     } else {
 413       this.runInAsyncScope(this.runSync.bind(this), this, fn, task)
 414     }
 415   }
 416
 417   /**
 418    * Runs the given task function synchronously.
 419    *
 420    * @param fn - Task function that will be executed.
 421    * @param task - Input data for the task function.
 422    */
 423   protected runSync (
 424     fn: TaskSyncFunction<Data, Response>,
 425     task: Task<Data>
 426   ): void {
 427     try {
 428       let taskPerformance = this.beginTaskPerformance(task.name)
 429       const res = fn(task.data)
 430       taskPerformance = this.endTaskPerformance(taskPerformance)
 431       this.sendToMainWorker({
 432         data: res,
 433         taskPerformance,
 434         workerId: this.id,
 435         taskId: task.taskId
 436       })
 437     } catch (e) {
 438       const errorMessage = this.handleError(e as Error | string)
 439       this.sendToMainWorker({
 440         taskError: {
 441           name: task.name ?? DEFAULT_TASK_NAME,
 442           message: errorMessage,
 443           data: task.data
 444         },
 445         workerId: this.id,
 446         taskId: task.taskId
 447       })
 448     } finally {
 449       this.updateLastTaskTimestamp()
 450     }
 451   }
 452
 453   /**
 454    * Runs the given task function asynchronously.
 455    *
 456    * @param fn - Task function that will be executed.
 457    * @param task - Input data for the task function.
 458    */
 459   protected runAsync (
 460     fn: TaskAsyncFunction<Data, Response>,
 461     task: Task<Data>
 462   ): void {
 463     let taskPerformance = this.beginTaskPerformance(task.name)
 464     fn(task.data)
 465       .then((res) => {
 466         taskPerformance = this.endTaskPerformance(taskPerformance)
 467         this.sendToMainWorker({
 468           data: res,
 469           taskPerformance,
 470           workerId: this.id,
 471           taskId: task.taskId
 472         })
 473         return null
 474       })
 475       .catch((e) => {
 476         const errorMessage = this.handleError(e as Error | string)
 477         this.sendToMainWorker({
 478           taskError: {
 479             name: task.name ?? DEFAULT_TASK_NAME,
 480             message: errorMessage,
 481             data: task.data
 482           },
 483           workerId: this.id,
 484           taskId: task.taskId
 485         })
 486       })
 487       .finally(() => {
 488         this.updateLastTaskTimestamp()
 489       })
 490       .catch(EMPTY_FUNCTION)
 491   }
 492
 493   /**
 494    * Gets the task function with the given name.
 495    *
 496    * @param name - Name of the task function that will be returned.
 497    * @returns The task function.
 498    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 499    */
 500   private getTaskFunction (name?: string): TaskFunction<Data, Response> {
 501     name = name ?? DEFAULT_TASK_NAME
 502     const fn = this.taskFunctions.get(name)
 503     if (fn == null) {
 504       throw new Error(`Task function '${name}' not found`)
 505     }
 506     return fn
 507   }
 508
 509   private beginTaskPerformance (name?: string): TaskPerformance {
 510     this.checkStatistics()
 511     return {
 512       name: name ?? DEFAULT_TASK_NAME,
 513       timestamp: performance.now(),
 514       ...(this.statistics.elu && { elu: performance.eventLoopUtilization() })
 515     }
 516   }
 517
 518   private endTaskPerformance (
 519     taskPerformance: TaskPerformance
 520   ): TaskPerformance {
 521     this.checkStatistics()
 522     return {
 523       ...taskPerformance,
 524       ...(this.statistics.runTime && {
 525         runTime: performance.now() - taskPerformance.timestamp
 526       }),
 527       ...(this.statistics.elu && {
 528         elu: performance.eventLoopUtilization(taskPerformance.elu)
 529       })
 530     }
 531   }
 532
 533   private checkStatistics (): void {
 534     if (this.statistics == null) {
 535       throw new Error('Performance statistics computation requirements not set')
 536     }
 537   }
 538
 539   private updateLastTaskTimestamp (): void {
 540     if (!this.isMain && this.activeInterval != null) {
 541       this.lastTaskTimestamp = performance.now()
 542     }
 543   }
 544 }