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 serializable data.
  32  * @typeParam Response - Type of response the worker sends back to the main worker. This can only be serializable 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.
  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 | undefined | null,
  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 (
 150     message: MessageValue<Data, Data, MainWorker>
 151   ): void {
 152     if (message.id != null && message.data != null) {
 153       // Task message received
 154       const fn = this.getTaskFunction(message.name)
 155       if (fn?.constructor.name === 'AsyncFunction') {
 156         this.runInAsyncScope(this.runAsync.bind(this), this, fn, message)
 157       } else {
 158         this.runInAsyncScope(this.runSync.bind(this), this, fn, message)
 159       }
 160     } else if (message.parent != null) {
 161       // Main worker reference message received
 162       this.mainWorker = message.parent
 163     } else if (message.kill != null) {
 164       // Kill message received
 165       this.aliveInterval != null && clearInterval(this.aliveInterval)
 166       this.emitDestroy()
 167     } else if (message.statistics != null) {
 168       // Statistics message received
 169       this.statistics = message.statistics
 170     }
 171   }
 172
 173   /**
 174    * Returns the main worker.
 175    *
 176    * @returns Reference to the main worker.
 177    */
 178   protected getMainWorker (): MainWorker {
 179     if (this.mainWorker == null) {
 180       throw new Error('Main worker was not set')
 181     }
 182     return this.mainWorker
 183   }
 184
 185   /**
 186    * Sends a message to the main worker.
 187    *
 188    * @param message - The response message.
 189    */
 190   protected abstract sendToMainWorker (
 191     message: MessageValue<Response, Data>
 192   ): void
 193
 194   /**
 195    * Checks if the worker should be terminated, because its living too long.
 196    */
 197   protected checkAlive (): void {
 198     if (
 199       performance.now() - this.lastTaskTimestamp >
 200       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 201     ) {
 202       this.sendToMainWorker({ kill: this.opts.killBehavior })
 203     }
 204   }
 205
 206   /**
 207    * Handles an error and convert it to a string so it can be sent back to the main worker.
 208    *
 209    * @param e - The error raised by the worker.
 210    * @returns Message of the error.
 211    */
 212   protected handleError (e: Error | string): string {
 213     return e as string
 214   }
 215
 216   /**
 217    * Runs the given function synchronously.
 218    *
 219    * @param fn - Function that will be executed.
 220    * @param message - Input data for the given function.
 221    */
 222   protected runSync (
 223     fn: WorkerSyncFunction<Data, Response>,
 224     message: MessageValue<Data>
 225   ): void {
 226     try {
 227       let taskPerformance = this.beginTaskPerformance()
 228       const res = fn(message.data)
 229       taskPerformance = this.endTaskPerformance(taskPerformance)
 230       this.sendToMainWorker({
 231         data: res,
 232         taskPerformance,
 233         id: message.id
 234       })
 235     } catch (e) {
 236       const err = this.handleError(e as Error)
 237       this.sendToMainWorker({
 238         taskError: {
 239           message: err,
 240           data: message.data
 241         },
 242         id: message.id
 243       })
 244     } finally {
 245       !this.isMain && (this.lastTaskTimestamp = performance.now())
 246     }
 247   }
 248
 249   /**
 250    * Runs the given function asynchronously.
 251    *
 252    * @param fn - Function that will be executed.
 253    * @param message - Input data for the given function.
 254    */
 255   protected runAsync (
 256     fn: WorkerAsyncFunction<Data, Response>,
 257     message: MessageValue<Data>
 258   ): void {
 259     let taskPerformance = this.beginTaskPerformance()
 260     fn(message.data)
 261       .then(res => {
 262         taskPerformance = this.endTaskPerformance(taskPerformance)
 263         this.sendToMainWorker({
 264           data: res,
 265           taskPerformance,
 266           id: message.id
 267         })
 268         return null
 269       })
 270       .catch(e => {
 271         const err = this.handleError(e as Error)
 272         this.sendToMainWorker({
 273           taskError: {
 274             message: err,
 275             data: message.data
 276           },
 277           id: message.id
 278         })
 279       })
 280       .finally(() => {
 281         !this.isMain && (this.lastTaskTimestamp = performance.now())
 282       })
 283       .catch(EMPTY_FUNCTION)
 284   }
 285
 286   /**
 287    * Gets the task function in the given scope.
 288    *
 289    * @param name - Name of the function that will be returned.
 290    */
 291   private getTaskFunction (name?: string): WorkerFunction<Data, Response> {
 292     name = name ?? DEFAULT_FUNCTION_NAME
 293     const fn = this.taskFunctions.get(name)
 294     if (fn == null) {
 295       throw new Error(`Task function '${name}' not found`)
 296     }
 297     return fn
 298   }
 299
 300   private beginTaskPerformance (): TaskPerformance {
 301     return {
 302       timestamp: performance.now(),
 303       ...(this.statistics.elu && { elu: performance.eventLoopUtilization() })
 304     }
 305   }
 306
 307   private endTaskPerformance (
 308     taskPerformance: TaskPerformance
 309   ): TaskPerformance {
 310     return {
 311       ...taskPerformance,
 312       ...(this.statistics.runTime && {
 313         runTime: performance.now() - taskPerformance.timestamp
 314       }),
 315       ...(this.statistics.elu && {
 316         elu: performance.eventLoopUtilization(taskPerformance.elu)
 317       })
 318     }
 319   }
 320 }