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