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 `aliveInterval` worker alive check.
  62    */
  63   protected aliveInterval?: 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 alive 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       this.taskFunctions.set(DEFAULT_TASK_NAME, taskFunctions.bind(this))
 123     } else if (isPlainObject(taskFunctions)) {
 124       let firstEntry = true
 125       for (const [name, fn] of Object.entries(taskFunctions)) {
 126         if (typeof name !== 'string') {
 127           throw new TypeError(
 128             'A taskFunctions parameter object key is not a string'
 129           )
 130         }
 131         if (typeof fn !== 'function') {
 132           throw new TypeError(
 133             'A taskFunctions parameter object value is not a function'
 134           )
 135         }
 136         this.taskFunctions.set(name, fn.bind(this))
 137         if (firstEntry) {
 138           this.taskFunctions.set(DEFAULT_TASK_NAME, fn.bind(this))
 139           firstEntry = false
 140         }
 141       }
 142       if (firstEntry) {
 143         throw new Error('taskFunctions parameter object is empty')
 144       }
 145     } else {
 146       throw new TypeError(
 147         'taskFunctions parameter is not a function or a plain object'
 148       )
 149     }
 150   }
 151
 152   /**
 153    * Checks if the worker has a task function with the given name.
 154    *
 155    * @param name - The name of the task function to check.
 156    * @returns Whether the worker has a task function with the given name or not.
 157    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 158    */
 159   public hasTaskFunction (name: string): boolean {
 160     if (typeof name !== 'string') {
 161       throw new TypeError('name parameter is not a string')
 162     }
 163     return this.taskFunctions.has(name)
 164   }
 165
 166   /**
 167    * Adds a task function to the worker.
 168    * If a task function with the same name already exists, it is replaced.
 169    *
 170    * @param name - The name of the task function to add.
 171    * @param fn - The task function to add.
 172    * @returns Whether the task function was added or not.
 173    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 174    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 175    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `fn` parameter is not a function.
 176    */
 177   public addTaskFunction (
 178     name: string,
 179     fn: WorkerFunction<Data, Response>
 180   ): boolean {
 181     if (typeof name !== 'string') {
 182       throw new TypeError('name parameter is not a string')
 183     }
 184     if (name === DEFAULT_TASK_NAME) {
 185       throw new Error(
 186         'Cannot add a task function with the default reserved name'
 187       )
 188     }
 189     if (typeof fn !== 'function') {
 190       throw new TypeError('fn parameter is not a function')
 191     }
 192     try {
 193       if (
 194         this.taskFunctions.get(name) ===
 195         this.taskFunctions.get(DEFAULT_TASK_NAME)
 196       ) {
 197         this.taskFunctions.set(DEFAULT_TASK_NAME, fn.bind(this))
 198       }
 199       this.taskFunctions.set(name, fn.bind(this))
 200       return true
 201     } catch {
 202       return false
 203     }
 204   }
 205
 206   /**
 207    * Removes a task function from the worker.
 208    *
 209    * @param name - The name of the task function to remove.
 210    * @returns Whether the task function existed and was removed or not.
 211    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 212    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 213    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the task function used as default task function.
 214    */
 215   public removeTaskFunction (name: string): boolean {
 216     if (typeof name !== 'string') {
 217       throw new TypeError('name parameter is not a string')
 218     }
 219     if (name === DEFAULT_TASK_NAME) {
 220       throw new Error(
 221         'Cannot remove the task function with the default reserved name'
 222       )
 223     }
 224     if (
 225       this.taskFunctions.get(name) === this.taskFunctions.get(DEFAULT_TASK_NAME)
 226     ) {
 227       throw new Error(
 228         'Cannot remove the task function used as the default task function'
 229       )
 230     }
 231     return this.taskFunctions.delete(name)
 232   }
 233
 234   /**
 235    * Sets the default task function to use when no task function name is specified.
 236    *
 237    * @param name - The name of the task function to use as default task function.
 238    * @returns Whether the default task function was set or not.
 239    * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string.
 240    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
 241    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is a non-existing task function.
 242    */
 243   public setDefaultTaskFunction (name: string): boolean {
 244     if (typeof name !== 'string') {
 245       throw new TypeError('name parameter is not a string')
 246     }
 247     if (name === DEFAULT_TASK_NAME) {
 248       throw new Error(
 249         'Cannot set the default task function reserved name as the default task function'
 250       )
 251     }
 252     if (!this.taskFunctions.has(name)) {
 253       throw new Error(
 254         'Cannot set the default task function to a non-existing task function'
 255       )
 256     }
 257     try {
 258       this.taskFunctions.set(
 259         DEFAULT_TASK_NAME,
 260         this.taskFunctions.get(name)?.bind(this) as WorkerFunction<
 261         Data,
 262         Response
 263         >
 264       )
 265       return true
 266     } catch {
 267       return false
 268     }
 269   }
 270
 271   /**
 272    * Worker message listener.
 273    *
 274    * @param message - The received message.
 275    */
 276   protected messageListener (message: MessageValue<Data, Data>): void {
 277     if (message.workerId === this.id) {
 278       if (message.ready != null) {
 279         // Startup message received
 280         this.workerReady()
 281       } else if (message.statistics != null) {
 282         // Statistics message received
 283         this.statistics = message.statistics
 284       } else if (message.checkAlive != null) {
 285         // Check alive message received
 286         message.checkAlive ? this.startCheckAlive() : this.stopCheckAlive()
 287       } else if (message.id != null && message.data != null) {
 288         // Task message received
 289         this.run(message)
 290       } else if (message.kill === true) {
 291         // Kill message received
 292         this.stopCheckAlive()
 293         this.emitDestroy()
 294       }
 295     }
 296   }
 297
 298   /**
 299    * Notifies the main worker that this worker is ready to process tasks.
 300    */
 301   protected workerReady (): void {
 302     !this.isMain && this.sendToMainWorker({ ready: true, workerId: this.id })
 303   }
 304
 305   /**
 306    * Starts the worker aliveness check interval.
 307    */
 308   private startCheckAlive (): void {
 309     this.lastTaskTimestamp = performance.now()
 310     this.aliveInterval = setInterval(
 311       this.checkAlive.bind(this),
 312       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
 313     )
 314   }
 315
 316   /**
 317    * Stops the worker aliveness check interval.
 318    */
 319   private stopCheckAlive (): void {
 320     this.aliveInterval != null && clearInterval(this.aliveInterval)
 321   }
 322
 323   /**
 324    * Checks if the worker should be terminated, because its living too long.
 325    */
 326   private checkAlive (): void {
 327     if (
 328       performance.now() - this.lastTaskTimestamp >
 329       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 330     ) {
 331       this.sendToMainWorker({ kill: this.opts.killBehavior, workerId: this.id })
 332     }
 333   }
 334
 335   /**
 336    * Returns the main worker.
 337    *
 338    * @returns Reference to the main worker.
 339    */
 340   protected getMainWorker (): MainWorker {
 341     if (this.mainWorker == null) {
 342       throw new Error('Main worker not set')
 343     }
 344     return this.mainWorker
 345   }
 346
 347   /**
 348    * Sends a message to the main worker.
 349    *
 350    * @param message - The response message.
 351    */
 352   protected abstract sendToMainWorker (
 353     message: MessageValue<Response, Data>
 354   ): void
 355
 356   /**
 357    * Handles an error and convert it to a string so it can be sent back to the main worker.
 358    *
 359    * @param e - The error raised by the worker.
 360    * @returns The error message.
 361    */
 362   protected handleError (e: Error | string): string {
 363     return e instanceof Error ? e.message : e
 364   }
 365
 366   /**
 367    * Runs the given task.
 368    *
 369    * @param task - The task to execute.
 370    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 371    */
 372   protected run (task: Task<Data>): void {
 373     const fn = this.getTaskFunction(task.name)
 374     if (isAsyncFunction(fn)) {
 375       this.runInAsyncScope(this.runAsync.bind(this), this, fn, task)
 376     } else {
 377       this.runInAsyncScope(this.runSync.bind(this), this, fn, task)
 378     }
 379   }
 380
 381   /**
 382    * Runs the given task function synchronously.
 383    *
 384    * @param fn - Task function that will be executed.
 385    * @param task - Input data for the task function.
 386    */
 387   protected runSync (
 388     fn: WorkerSyncFunction<Data, Response>,
 389     task: Task<Data>
 390   ): void {
 391     try {
 392       let taskPerformance = this.beginTaskPerformance(task.name)
 393       const res = fn(task.data)
 394       taskPerformance = this.endTaskPerformance(taskPerformance)
 395       this.sendToMainWorker({
 396         data: res,
 397         taskPerformance,
 398         workerId: this.id,
 399         id: task.id
 400       })
 401     } catch (e) {
 402       const errorMessage = this.handleError(e as Error | string)
 403       this.sendToMainWorker({
 404         taskError: {
 405           name: task.name ?? DEFAULT_TASK_NAME,
 406           message: errorMessage,
 407           data: task.data
 408         },
 409         workerId: this.id,
 410         id: task.id
 411       })
 412     } finally {
 413       if (!this.isMain && this.aliveInterval != null) {
 414         this.lastTaskTimestamp = performance.now()
 415       }
 416     }
 417   }
 418
 419   /**
 420    * Runs the given task function asynchronously.
 421    *
 422    * @param fn - Task function that will be executed.
 423    * @param task - Input data for the task function.
 424    */
 425   protected runAsync (
 426     fn: WorkerAsyncFunction<Data, Response>,
 427     task: Task<Data>
 428   ): void {
 429     let taskPerformance = this.beginTaskPerformance(task.name)
 430     fn(task.data)
 431       .then(res => {
 432         taskPerformance = this.endTaskPerformance(taskPerformance)
 433         this.sendToMainWorker({
 434           data: res,
 435           taskPerformance,
 436           workerId: this.id,
 437           id: task.id
 438         })
 439         return null
 440       })
 441       .catch(e => {
 442         const errorMessage = this.handleError(e as Error | string)
 443         this.sendToMainWorker({
 444           taskError: {
 445             name: task.name ?? DEFAULT_TASK_NAME,
 446             message: errorMessage,
 447             data: task.data
 448           },
 449           workerId: this.id,
 450           id: task.id
 451         })
 452       })
 453       .finally(() => {
 454         if (!this.isMain && this.aliveInterval != null) {
 455           this.lastTaskTimestamp = performance.now()
 456         }
 457       })
 458       .catch(EMPTY_FUNCTION)
 459   }
 460
 461   /**
 462    * Gets the task function with the given name.
 463    *
 464    * @param name - Name of the task function that will be returned.
 465    * @returns The task function.
 466    * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
 467    */
 468   private getTaskFunction (name?: string): WorkerFunction<Data, Response> {
 469     name = name ?? DEFAULT_TASK_NAME
 470     const fn = this.taskFunctions.get(name)
 471     if (fn == null) {
 472       throw new Error(`Task function '${name}' not found`)
 473     }
 474     return fn
 475   }
 476
 477   private beginTaskPerformance (name?: string): TaskPerformance {
 478     this.checkStatistics()
 479     return {
 480       name: name ?? DEFAULT_TASK_NAME,
 481       timestamp: performance.now(),
 482       ...(this.statistics.elu && { elu: performance.eventLoopUtilization() })
 483     }
 484   }
 485
 486   private endTaskPerformance (
 487     taskPerformance: TaskPerformance
 488   ): TaskPerformance {
 489     this.checkStatistics()
 490     return {
 491       ...taskPerformance,
 492       ...(this.statistics.runTime && {
 493         runTime: performance.now() - taskPerformance.timestamp
 494       }),
 495       ...(this.statistics.elu && {
 496         elu: performance.eventLoopUtilization(taskPerformance.elu)
 497       })
 498     }
 499   }
 500
 501   private checkStatistics (): void {
 502     if (this.statistics == null) {
 503       throw new Error('Performance statistics computation requirements not set')
 504     }
 505   }
 506 }