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   TaskPerformance,
   8   WorkerStatistics
   9 } from '../utility-types'
  10 import { EMPTY_FUNCTION, isPlainObject } from '../utils'
  11 import {
  12   type KillBehavior,
  13   KillBehaviors,
  14   type WorkerOptions
  15 } from './worker-options'
  16 import type {
  17   TaskFunctions,
  18   WorkerAsyncFunction,
  19   WorkerFunction,
  20   WorkerSyncFunction
  21 } from './worker-functions'
  22
  23 const DEFAULT_FUNCTION_NAME = 'default'
  24 const DEFAULT_MAX_INACTIVE_TIME = 60000
  25 const DEFAULT_KILL_BEHAVIOR: KillBehavior = KillBehaviors.SOFT
  26
  27 /**
  28  * Base class that implements some shared logic for all poolifier workers.
  29  *
  30  * @typeParam MainWorker - Type of main worker.
  31  * @typeParam Data - Type of data this worker receives from pool's execution. This can only be structured-cloneable data.
  32  * @typeParam Response - Type of response the worker sends back to the main worker. This can only be structured-cloneable data.
  33  */
  34 export abstract class AbstractWorker<
  35   MainWorker extends Worker | MessagePort,
  36   Data = unknown,
  37   Response = unknown
  38 > extends AsyncResource {
  39   /**
  40    * Task function(s) processed by the worker when the pool's `execution` function is invoked.
  41    */
  42   protected taskFunctions!: Map<string, WorkerFunction<Data, Response>>
  43   /**
  44    * Timestamp of the last task processed by this worker.
  45    */
  46   protected lastTaskTimestamp!: number
  47   /**
  48    * Performance statistics computation requirements.
  49    */
  50   protected statistics!: WorkerStatistics
  51   /**
  52    * Handler id of the `aliveInterval` worker alive check.
  53    */
  54   protected readonly aliveInterval?: NodeJS.Timeout
  55   /**
  56    * Constructs a new poolifier worker.
  57    *
  58    * @param type - The type of async event.
  59    * @param isMain - Whether this is the main worker or not.
  60    * @param taskFunctions - Task function(s) processed by the worker when the pool's `execution` function is invoked. The first function is the default function.
  61    * @param mainWorker - Reference to main worker.
  62    * @param opts - Options for the worker.
  63    */
  64   public constructor (
  65     type: string,
  66     protected readonly isMain: boolean,
  67     taskFunctions:
  68     | WorkerFunction<Data, Response>
  69     | TaskFunctions<Data, Response>,
  70     protected mainWorker: MainWorker,
  71     protected readonly opts: WorkerOptions = {
  72       /**
  73        * The kill behavior option on this worker or its default value.
  74        */
  75       killBehavior: DEFAULT_KILL_BEHAVIOR,
  76       /**
  77        * The maximum time to keep this worker alive while idle.
  78        * The pool automatically checks and terminates this worker when the time expires.
  79        */
  80       maxInactiveTime: DEFAULT_MAX_INACTIVE_TIME
  81     }
  82   ) {
  83     super(type)
  84     this.checkWorkerOptions(this.opts)
  85     this.checkTaskFunctions(taskFunctions)
  86     if (!this.isMain) {
  87       this.lastTaskTimestamp = performance.now()
  88       this.aliveInterval = setInterval(
  89         this.checkAlive.bind(this),
  90         (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
  91       )
  92       this.checkAlive.bind(this)()
  93     }
  94     this.mainWorker?.on('message', this.messageListener.bind(this))
  95   }
  96
  97   private checkWorkerOptions (opts: WorkerOptions): void {
  98     this.opts.killBehavior = opts.killBehavior ?? DEFAULT_KILL_BEHAVIOR
  99     this.opts.maxInactiveTime =
 100       opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME
 101     delete this.opts.async
 102   }
 103
 104   /**
 105    * Checks if the `taskFunctions` parameter is passed to the constructor.
 106    *
 107    * @param taskFunctions - The task function(s) parameter that should be checked.
 108    */
 109   private checkTaskFunctions (
 110     taskFunctions:
 111     | WorkerFunction<Data, Response>
 112     | TaskFunctions<Data, Response>
 113   ): void {
 114     if (taskFunctions == null) {
 115       throw new Error('taskFunctions parameter is mandatory')
 116     }
 117     this.taskFunctions = new Map<string, WorkerFunction<Data, Response>>()
 118     if (typeof taskFunctions === 'function') {
 119       this.taskFunctions.set(DEFAULT_FUNCTION_NAME, taskFunctions.bind(this))
 120     } else if (isPlainObject(taskFunctions)) {
 121       let firstEntry = true
 122       for (const [name, fn] of Object.entries(taskFunctions)) {
 123         if (typeof fn !== 'function') {
 124           throw new TypeError(
 125             'A taskFunctions parameter object value is not a function'
 126           )
 127         }
 128         this.taskFunctions.set(name, fn.bind(this))
 129         if (firstEntry) {
 130           this.taskFunctions.set(DEFAULT_FUNCTION_NAME, fn.bind(this))
 131           firstEntry = false
 132         }
 133       }
 134       if (firstEntry) {
 135         throw new Error('taskFunctions parameter object is empty')
 136       }
 137     } else {
 138       throw new TypeError(
 139         'taskFunctions parameter is not a function or a plain object'
 140       )
 141     }
 142   }
 143
 144   /**
 145    * Worker message listener.
 146    *
 147    * @param message - Message received.
 148    */
 149   protected messageListener (message: MessageValue<Data, Data>): void {
 150     if (message.id != null && message.data != null) {
 151       // Task message received
 152       const fn = this.getTaskFunction(message.name)
 153       if (fn?.constructor.name === 'AsyncFunction') {
 154         this.runInAsyncScope(this.runAsync.bind(this), this, fn, message)
 155       } else {
 156         this.runInAsyncScope(this.runSync.bind(this), this, fn, message)
 157       }
 158     } else if (message.statistics != null) {
 159       // Statistics message received
 160       this.statistics = message.statistics
 161     } else if (message.kill != null) {
 162       // Kill message received
 163       this.aliveInterval != null && clearInterval(this.aliveInterval)
 164       this.emitDestroy()
 165     }
 166   }
 167
 168   /**
 169    * Returns the main worker.
 170    *
 171    * @returns Reference to the main worker.
 172    */
 173   protected getMainWorker (): MainWorker {
 174     if (this.mainWorker == null) {
 175       throw new Error('Main worker not set')
 176     }
 177     return this.mainWorker
 178   }
 179
 180   /**
 181    * Sends a message to the main worker.
 182    *
 183    * @param message - The response message.
 184    */
 185   protected abstract sendToMainWorker (
 186     message: MessageValue<Response, Data>
 187   ): void
 188
 189   /**
 190    * Checks if the worker should be terminated, because its living too long.
 191    */
 192   protected checkAlive (): void {
 193     if (
 194       performance.now() - this.lastTaskTimestamp >
 195       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 196     ) {
 197       this.sendToMainWorker({ kill: this.opts.killBehavior })
 198     }
 199   }
 200
 201   /**
 202    * Handles an error and convert it to a string so it can be sent back to the main worker.
 203    *
 204    * @param e - The error raised by the worker.
 205    * @returns Message of the error.
 206    */
 207   protected handleError (e: Error | string): string {
 208     return e as string
 209   }
 210
 211   /**
 212    * Runs the given function synchronously.
 213    *
 214    * @param fn - Function that will be executed.
 215    * @param message - Input data for the given function.
 216    */
 217   protected runSync (
 218     fn: WorkerSyncFunction<Data, Response>,
 219     message: MessageValue<Data>
 220   ): void {
 221     try {
 222       let taskPerformance = this.beginTaskPerformance()
 223       const res = fn(message.data)
 224       taskPerformance = this.endTaskPerformance(taskPerformance)
 225       this.sendToMainWorker({
 226         data: res,
 227         taskPerformance,
 228         id: message.id
 229       })
 230     } catch (e) {
 231       const err = this.handleError(e as Error)
 232       this.sendToMainWorker({
 233         taskError: {
 234           message: err,
 235           data: message.data
 236         },
 237         id: message.id
 238       })
 239     } finally {
 240       !this.isMain && (this.lastTaskTimestamp = performance.now())
 241     }
 242   }
 243
 244   /**
 245    * Runs the given function asynchronously.
 246    *
 247    * @param fn - Function that will be executed.
 248    * @param message - Input data for the given function.
 249    */
 250   protected runAsync (
 251     fn: WorkerAsyncFunction<Data, Response>,
 252     message: MessageValue<Data>
 253   ): void {
 254     let taskPerformance = this.beginTaskPerformance()
 255     fn(message.data)
 256       .then(res => {
 257         taskPerformance = this.endTaskPerformance(taskPerformance)
 258         this.sendToMainWorker({
 259           data: res,
 260           taskPerformance,
 261           id: message.id
 262         })
 263         return null
 264       })
 265       .catch(e => {
 266         const err = this.handleError(e as Error)
 267         this.sendToMainWorker({
 268           taskError: {
 269             message: err,
 270             data: message.data
 271           },
 272           id: message.id
 273         })
 274       })
 275       .finally(() => {
 276         !this.isMain && (this.lastTaskTimestamp = performance.now())
 277       })
 278       .catch(EMPTY_FUNCTION)
 279   }
 280
 281   /**
 282    * Gets the task function in the given scope.
 283    *
 284    * @param name - Name of the function that will be returned.
 285    */
 286   private getTaskFunction (name?: string): WorkerFunction<Data, Response> {
 287     name = name ?? DEFAULT_FUNCTION_NAME
 288     const fn = this.taskFunctions.get(name)
 289     if (fn == null) {
 290       throw new Error(`Task function '${name}' not found`)
 291     }
 292     return fn
 293   }
 294
 295   private beginTaskPerformance (): TaskPerformance {
 296     this.checkStatistics()
 297     return {
 298       timestamp: performance.now(),
 299       ...(this.statistics.elu && { elu: performance.eventLoopUtilization() })
 300     }
 301   }
 302
 303   private endTaskPerformance (
 304     taskPerformance: TaskPerformance
 305   ): TaskPerformance {
 306     this.checkStatistics()
 307     return {
 308       ...taskPerformance,
 309       ...(this.statistics.runTime && {
 310         runTime: performance.now() - taskPerformance.timestamp
 311       }),
 312       ...(this.statistics.elu && {
 313         elu: performance.eventLoopUtilization(taskPerformance.elu)
 314       })
 315     }
 316   }
 317
 318   private checkStatistics (): void {
 319     if (this.statistics == null) {
 320       throw new Error('Performance statistics computation requirements not set')
 321     }
 322   }
 323 }