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 type { MessageValue } from '../utility-types'
   5 import { EMPTY_FUNCTION } from '../utils'
   6 import type { KillBehavior, WorkerOptions } from './worker-options'
   7 import { KillBehaviors } from './worker-options'
   8
   9 const DEFAULT_MAX_INACTIVE_TIME = 60000
  10 const DEFAULT_KILL_BEHAVIOR: KillBehavior = KillBehaviors.SOFT
  11
  12 /**
  13  * Base class that implements some shared logic for all poolifier workers.
  14  *
  15  * @typeParam MainWorker - Type of main worker.
  16  * @typeParam Data - Type of data this worker receives from pool's execution. This can only be serializable data.
  17  * @typeParam Response - Type of response the worker sends back to the main worker. This can only be serializable data.
  18  */
  19 export abstract class AbstractWorker<
  20   MainWorker extends Worker | MessagePort,
  21   Data = unknown,
  22   Response = unknown
  23 > extends AsyncResource {
  24   /**
  25    * Timestamp of the last task processed by this worker.
  26    */
  27   protected lastTaskTimestamp!: number
  28   /**
  29    * Handler id of the `aliveInterval` worker alive check.
  30    */
  31   protected readonly aliveInterval?: NodeJS.Timeout
  32   /**
  33    * Constructs a new poolifier worker.
  34    *
  35    * @param type - The type of async event.
  36    * @param isMain - Whether this is the main worker or not.
  37    * @param fn - Function processed by the worker when the pool's `execution` function is invoked.
  38    * @param mainWorker - Reference to main worker.
  39    * @param opts - Options for the worker.
  40    */
  41   public constructor (
  42     type: string,
  43     protected readonly isMain: boolean,
  44     fn: (data: Data) => Response | Promise<Response>,
  45     protected mainWorker: MainWorker | undefined | null,
  46     protected readonly opts: WorkerOptions = {
  47       /**
  48        * The kill behavior option on this worker or its default value.
  49        */
  50       killBehavior: DEFAULT_KILL_BEHAVIOR,
  51       /**
  52        * The maximum time to keep this worker alive while idle.
  53        * The pool automatically checks and terminates this worker when the time expires.
  54        */
  55       maxInactiveTime: DEFAULT_MAX_INACTIVE_TIME
  56     }
  57   ) {
  58     super(type)
  59     this.checkWorkerOptions(this.opts)
  60     this.checkFunctionInput(fn)
  61     if (!this.isMain) {
  62       this.lastTaskTimestamp = performance.now()
  63       this.aliveInterval = setInterval(
  64         this.checkAlive.bind(this),
  65         (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
  66       )
  67       this.checkAlive.bind(this)()
  68     }
  69
  70     this.mainWorker?.on(
  71       'message',
  72       (message: MessageValue<Data, MainWorker>) => {
  73         this.messageListener(message, fn)
  74       }
  75     )
  76   }
  77
  78   /**
  79    * Worker message listener.
  80    *
  81    * @param message - Message received.
  82    * @param fn - Function processed by the worker when the pool's `execution` function is invoked.
  83    */
  84   protected messageListener (
  85     message: MessageValue<Data, MainWorker>,
  86     fn: (data: Data) => Response | Promise<Response>
  87   ): void {
  88     if (message.id != null && message.data != null) {
  89       // Task message received
  90       if (this.opts.async === true) {
  91         this.runInAsyncScope(this.runAsync.bind(this), this, fn, message)
  92       } else {
  93         this.runInAsyncScope(this.run.bind(this), this, fn, message)
  94       }
  95     } else if (message.parent != null) {
  96       // Main worker reference message received
  97       this.mainWorker = message.parent
  98     } else if (message.kill != null) {
  99       // Kill message received
 100       this.aliveInterval != null && clearInterval(this.aliveInterval)
 101       this.emitDestroy()
 102     }
 103   }
 104
 105   private checkWorkerOptions (opts: WorkerOptions): void {
 106     this.opts.killBehavior = opts.killBehavior ?? DEFAULT_KILL_BEHAVIOR
 107     this.opts.maxInactiveTime =
 108       opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME
 109     this.opts.async = opts.async ?? false
 110   }
 111
 112   /**
 113    * Checks if the `fn` parameter is passed to the constructor.
 114    *
 115    * @param fn - The function that should be defined.
 116    */
 117   private checkFunctionInput (
 118     fn: (data: Data) => Response | Promise<Response>
 119   ): void {
 120     if (fn == null) throw new Error('fn parameter is mandatory')
 121     if (typeof fn !== 'function') {
 122       throw new TypeError('fn parameter is not a function')
 123     }
 124     if (fn.constructor.name === 'AsyncFunction' && this.opts.async === false) {
 125       throw new Error(
 126         'fn parameter is an async function, please set the async option to true'
 127       )
 128     }
 129   }
 130
 131   /**
 132    * Returns the main worker.
 133    *
 134    * @returns Reference to the main worker.
 135    */
 136   protected getMainWorker (): MainWorker {
 137     if (this.mainWorker == null) {
 138       throw new Error('Main worker was not set')
 139     }
 140     return this.mainWorker
 141   }
 142
 143   /**
 144    * Sends a message to the main worker.
 145    *
 146    * @param message - The response message.
 147    */
 148   protected abstract sendToMainWorker (message: MessageValue<Response>): void
 149
 150   /**
 151    * Checks if the worker should be terminated, because its living too long.
 152    */
 153   protected checkAlive (): void {
 154     if (
 155       performance.now() - this.lastTaskTimestamp >
 156       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 157     ) {
 158       this.sendToMainWorker({ kill: this.opts.killBehavior })
 159     }
 160   }
 161
 162   /**
 163    * Handles an error and convert it to a string so it can be sent back to the main worker.
 164    *
 165    * @param e - The error raised by the worker.
 166    * @returns Message of the error.
 167    */
 168   protected handleError (e: Error | string): string {
 169     return e as string
 170   }
 171
 172   /**
 173    * Runs the given function synchronously.
 174    *
 175    * @param fn - Function that will be executed.
 176    * @param message - Input data for the given function.
 177    */
 178   protected run (
 179     fn: (data?: Data) => Response,
 180     message: MessageValue<Data>
 181   ): void {
 182     try {
 183       const startTimestamp = performance.now()
 184       const res = fn(message.data)
 185       const runTime = performance.now() - startTimestamp
 186       this.sendToMainWorker({
 187         data: res,
 188         id: message.id,
 189         runTime
 190       })
 191     } catch (e) {
 192       const err = this.handleError(e as Error)
 193       this.sendToMainWorker({ error: err, id: message.id })
 194     } finally {
 195       !this.isMain && (this.lastTaskTimestamp = performance.now())
 196     }
 197   }
 198
 199   /**
 200    * Runs the given function asynchronously.
 201    *
 202    * @param fn - Function that will be executed.
 203    * @param message - Input data for the given function.
 204    */
 205   protected runAsync (
 206     fn: (data?: Data) => Promise<Response>,
 207     message: MessageValue<Data>
 208   ): void {
 209     const startTimestamp = performance.now()
 210     fn(message.data)
 211       .then(res => {
 212         const runTime = performance.now() - startTimestamp
 213         this.sendToMainWorker({
 214           data: res,
 215           id: message.id,
 216           runTime
 217         })
 218         return null
 219       })
 220       .catch(e => {
 221         const err = this.handleError(e as Error)
 222         this.sendToMainWorker({ error: err, id: message.id })
 223       })
 224       .finally(() => {
 225         !this.isMain && (this.lastTaskTimestamp = performance.now())
 226       })
 227       .catch(EMPTY_FUNCTION)
 228   }
 229 }