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, isAsyncFunction, 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    * Worker id.
  41    */
  42   protected abstract id: number
  43   /**
  44    * Task function(s) processed by the worker when the pool's `execution` function is invoked.
  45    */
  46   protected taskFunctions!: Map<string, WorkerFunction<Data, Response>>
  47   /**
  48    * Timestamp of the last task processed by this worker.
  49    */
  50   protected lastTaskTimestamp!: number
  51   /**
  52    * Performance statistics computation requirements.
  53    */
  54   protected statistics!: WorkerStatistics
  55   /**
  56    * Handler id of the `aliveInterval` worker alive check.
  57    */
  58   protected aliveInterval?: NodeJS.Timeout
  59   /**
  60    * Constructs a new poolifier worker.
  61    *
  62    * @param type - The type of async event.
  63    * @param isMain - Whether this is the main worker or not.
  64    * @param taskFunctions - Task function(s) processed by the worker when the pool's `execution` function is invoked. The first function is the default function.
  65    * @param mainWorker - Reference to main worker.
  66    * @param opts - Options for the worker.
  67    */
  68   public constructor (
  69     type: string,
  70     protected readonly isMain: boolean,
  71     taskFunctions:
  72     | WorkerFunction<Data, Response>
  73     | TaskFunctions<Data, Response>,
  74     protected readonly mainWorker: MainWorker,
  75     protected readonly opts: WorkerOptions = {
  76       /**
  77        * The kill behavior option on this worker or its default value.
  78        */
  79       killBehavior: DEFAULT_KILL_BEHAVIOR,
  80       /**
  81        * The maximum time to keep this worker alive while idle.
  82        * The pool automatically checks and terminates this worker when the time expires.
  83        */
  84       maxInactiveTime: DEFAULT_MAX_INACTIVE_TIME
  85     }
  86   ) {
  87     super(type)
  88     this.checkWorkerOptions(this.opts)
  89     this.checkTaskFunctions(taskFunctions)
  90     if (!this.isMain) {
  91       this.mainWorker?.on('message', this.messageListener.bind(this))
  92     }
  93   }
  94
  95   private checkWorkerOptions (opts: WorkerOptions): void {
  96     this.opts.killBehavior = opts.killBehavior ?? DEFAULT_KILL_BEHAVIOR
  97     this.opts.maxInactiveTime =
  98       opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME
  99     delete this.opts.async
 100   }
 101
 102   /**
 103    * Checks if the `taskFunctions` parameter is passed to the constructor.
 104    *
 105    * @param taskFunctions - The task function(s) parameter that should be checked.
 106    */
 107   private checkTaskFunctions (
 108     taskFunctions:
 109     | WorkerFunction<Data, Response>
 110     | TaskFunctions<Data, Response>
 111   ): void {
 112     if (taskFunctions == null) {
 113       throw new Error('taskFunctions parameter is mandatory')
 114     }
 115     this.taskFunctions = new Map<string, WorkerFunction<Data, Response>>()
 116     if (typeof taskFunctions === 'function') {
 117       this.taskFunctions.set(DEFAULT_FUNCTION_NAME, taskFunctions.bind(this))
 118     } else if (isPlainObject(taskFunctions)) {
 119       let firstEntry = true
 120       for (const [name, fn] of Object.entries(taskFunctions)) {
 121         if (typeof fn !== 'function') {
 122           throw new TypeError(
 123             'A taskFunctions parameter object value is not a function'
 124           )
 125         }
 126         this.taskFunctions.set(name, fn.bind(this))
 127         if (firstEntry) {
 128           this.taskFunctions.set(DEFAULT_FUNCTION_NAME, fn.bind(this))
 129           firstEntry = false
 130         }
 131       }
 132       if (firstEntry) {
 133         throw new Error('taskFunctions parameter object is empty')
 134       }
 135     } else {
 136       throw new TypeError(
 137         'taskFunctions parameter is not a function or a plain object'
 138       )
 139     }
 140   }
 141
 142   /**
 143    * Worker message listener.
 144    *
 145    * @param message - Message received.
 146    */
 147   protected messageListener (message: MessageValue<Data, Data>): void {
 148     if (message.dynamic === true) {
 149       // Worker dynamic message received
 150       this.startCheckAlive()
 151     } else if (message.statistics != null) {
 152       // Statistics message received
 153       this.statistics = message.statistics
 154     } else if (message.id != null && message.data != null) {
 155       // Task message received
 156       const fn = this.getTaskFunction(message.name)
 157       if (isAsyncFunction(fn)) {
 158         this.runInAsyncScope(this.runAsync.bind(this), this, fn, message)
 159       } else {
 160         this.runInAsyncScope(this.runSync.bind(this), this, fn, message)
 161       }
 162     } else if (message.kill != null) {
 163       // Kill message received
 164       this.aliveInterval != null && clearInterval(this.aliveInterval)
 165       this.emitDestroy()
 166     }
 167   }
 168
 169   private startCheckAlive (): void {
 170     this.lastTaskTimestamp = performance.now()
 171     this.aliveInterval = setInterval(
 172       this.checkAlive.bind(this),
 173       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
 174     )
 175     this.checkAlive.bind(this)()
 176   }
 177
 178   /**
 179    * Returns the main worker.
 180    *
 181    * @returns Reference to the main worker.
 182    */
 183   protected getMainWorker (): MainWorker {
 184     if (this.mainWorker == null) {
 185       throw new Error('Main worker not set')
 186     }
 187     return this.mainWorker
 188   }
 189
 190   /**
 191    * Sends a message to the main worker.
 192    *
 193    * @param message - The response message.
 194    */
 195   protected abstract sendToMainWorker (
 196     message: MessageValue<Response, Data>
 197   ): void
 198
 199   /**
 200    * Checks if the worker should be terminated, because its living too long.
 201    */
 202   protected checkAlive (): void {
 203     if (
 204       performance.now() - this.lastTaskTimestamp >
 205       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 206     ) {
 207       this.sendToMainWorker({ kill: this.opts.killBehavior })
 208     }
 209   }
 210
 211   /**
 212    * Handles an error and convert it to a string so it can be sent back to the main worker.
 213    *
 214    * @param e - The error raised by the worker.
 215    * @returns The error message.
 216    */
 217   protected handleError (e: Error | string): string {
 218     return e instanceof Error ? e.message : e
 219   }
 220
 221   /**
 222    * Runs the given function synchronously.
 223    *
 224    * @param fn - Function that will be executed.
 225    * @param message - Input data for the given function.
 226    */
 227   protected runSync (
 228     fn: WorkerSyncFunction<Data, Response>,
 229     message: MessageValue<Data>
 230   ): void {
 231     try {
 232       let taskPerformance = this.beginTaskPerformance()
 233       const res = fn(message.data)
 234       taskPerformance = this.endTaskPerformance(taskPerformance)
 235       this.sendToMainWorker({
 236         data: res,
 237         taskPerformance,
 238         workerId: this.id,
 239         id: message.id
 240       })
 241     } catch (e) {
 242       const errorMessage = this.handleError(e as Error | string)
 243       this.sendToMainWorker({
 244         taskError: {
 245           workerId: this.id,
 246           message: errorMessage,
 247           data: message.data
 248         },
 249         id: message.id
 250       })
 251     } finally {
 252       if (!this.isMain && this.aliveInterval != null) {
 253         this.lastTaskTimestamp = performance.now()
 254       }
 255     }
 256   }
 257
 258   /**
 259    * Runs the given function asynchronously.
 260    *
 261    * @param fn - Function that will be executed.
 262    * @param message - Input data for the given function.
 263    */
 264   protected runAsync (
 265     fn: WorkerAsyncFunction<Data, Response>,
 266     message: MessageValue<Data>
 267   ): void {
 268     let taskPerformance = this.beginTaskPerformance()
 269     fn(message.data)
 270       .then(res => {
 271         taskPerformance = this.endTaskPerformance(taskPerformance)
 272         this.sendToMainWorker({
 273           data: res,
 274           taskPerformance,
 275           workerId: this.id,
 276           id: message.id
 277         })
 278         return null
 279       })
 280       .catch(e => {
 281         const errorMessage = this.handleError(e as Error | string)
 282         this.sendToMainWorker({
 283           taskError: {
 284             workerId: this.id,
 285             message: errorMessage,
 286             data: message.data
 287           },
 288           id: message.id
 289         })
 290       })
 291       .finally(() => {
 292         if (!this.isMain && this.aliveInterval != null) {
 293           this.lastTaskTimestamp = performance.now()
 294         }
 295       })
 296       .catch(EMPTY_FUNCTION)
 297   }
 298
 299   /**
 300    * Gets the task function in the given scope.
 301    *
 302    * @param name - Name of the function that will be returned.
 303    */
 304   private getTaskFunction (name?: string): WorkerFunction<Data, Response> {
 305     name = name ?? DEFAULT_FUNCTION_NAME
 306     const fn = this.taskFunctions.get(name)
 307     if (fn == null) {
 308       throw new Error(`Task function '${name}' not found`)
 309     }
 310     return fn
 311   }
 312
 313   private beginTaskPerformance (): TaskPerformance {
 314     this.checkStatistics()
 315     return {
 316       timestamp: performance.now(),
 317       ...(this.statistics.elu && { elu: performance.eventLoopUtilization() })
 318     }
 319   }
 320
 321   private endTaskPerformance (
 322     taskPerformance: TaskPerformance
 323   ): TaskPerformance {
 324     this.checkStatistics()
 325     return {
 326       ...taskPerformance,
 327       ...(this.statistics.runTime && {
 328         runTime: performance.now() - taskPerformance.timestamp
 329       }),
 330       ...(this.statistics.elu && {
 331         elu: performance.eventLoopUtilization(taskPerformance.elu)
 332       })
 333     }
 334   }
 335
 336   private checkStatistics (): void {
 337     if (this.statistics == null) {
 338       throw new Error('Performance statistics computation requirements not set')
 339     }
 340   }
 341 }