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,
  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.checkFunctionInput(fn)
  60     this.checkWorkerOptions(this.opts)
  61     if (!this.isMain) {
  62       this.lastTaskTimestamp = Date.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('message', (value: MessageValue<Data, MainWorker>) => {
  71       this.messageListener(value, fn)
  72     })
  73   }
  74
  75   protected messageListener (
  76     value: MessageValue<Data, MainWorker>,
  77     fn: (data: Data) => Response
  78   ): void {
  79     if (value.data != null && value.id != null) {
  80       // Here you will receive messages
  81       if (this.opts.async === true) {
  82         this.runInAsyncScope(this.runAsync.bind(this), this, fn, value)
  83       } else {
  84         this.runInAsyncScope(this.run.bind(this), this, fn, value)
  85       }
  86     } else if (value.parent != null) {
  87       // Save a reference of the main worker to communicate with it
  88       // This will be received once
  89       this.mainWorker = value.parent
  90     } else if (value.kill != null) {
  91       // Here is time to kill this worker, just clearing the interval
  92       this.aliveInterval != null && clearInterval(this.aliveInterval)
  93       this.emitDestroy()
  94     }
  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     this.opts.async = opts.async ?? false
 102   }
 103
 104   /**
 105    * Checks if the `fn` parameter is passed to the constructor.
 106    *
 107    * @param fn - The function that should be defined.
 108    */
 109   private checkFunctionInput (fn: (data: Data) => Response): void {
 110     if (fn == null) throw new Error('fn parameter is mandatory')
 111     if (typeof fn !== 'function') {
 112       throw new TypeError('fn parameter is not a function')
 113     }
 114   }
 115
 116   /**
 117    * Returns the main worker.
 118    *
 119    * @returns Reference to the main worker.
 120    */
 121   protected getMainWorker (): MainWorker {
 122     if (this.mainWorker == null) {
 123       throw new Error('Main worker was not set')
 124     }
 125     return this.mainWorker
 126   }
 127
 128   /**
 129    * Sends a message to the main worker.
 130    *
 131    * @param message - The response message.
 132    */
 133   protected abstract sendToMainWorker (message: MessageValue<Response>): void
 134
 135   /**
 136    * Checks if the worker should be terminated, because its living too long.
 137    */
 138   protected checkAlive (): void {
 139     if (
 140       Date.now() - this.lastTaskTimestamp >
 141       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 142     ) {
 143       this.sendToMainWorker({ kill: this.opts.killBehavior })
 144     }
 145   }
 146
 147   /**
 148    * Handles an error and convert it to a string so it can be sent back to the main worker.
 149    *
 150    * @param e - The error raised by the worker.
 151    * @returns Message of the error.
 152    */
 153   protected handleError (e: Error | string): string {
 154     return e as string
 155   }
 156
 157   /**
 158    * Runs the given function synchronously.
 159    *
 160    * @param fn - Function that will be executed.
 161    * @param value - Input data for the given function.
 162    */
 163   protected run (
 164     fn: (data?: Data) => Response,
 165     value: MessageValue<Data>
 166   ): void {
 167     try {
 168       const startTaskTimestamp = Date.now()
 169       const res = fn(value.data)
 170       const taskRunTime = Date.now() - startTaskTimestamp
 171       this.sendToMainWorker({ data: res, id: value.id, taskRunTime })
 172     } catch (e) {
 173       const err = this.handleError(e as Error)
 174       this.sendToMainWorker({ error: err, id: value.id })
 175     } finally {
 176       !this.isMain && (this.lastTaskTimestamp = Date.now())
 177     }
 178   }
 179
 180   /**
 181    * Runs the given function asynchronously.
 182    *
 183    * @param fn - Function that will be executed.
 184    * @param value - Input data for the given function.
 185    */
 186   protected runAsync (
 187     fn: (data?: Data) => Promise<Response>,
 188     value: MessageValue<Data>
 189   ): void {
 190     const startTaskTimestamp = Date.now()
 191     fn(value.data)
 192       .then(res => {
 193         const taskRunTime = Date.now() - startTaskTimestamp
 194         this.sendToMainWorker({ data: res, id: value.id, taskRunTime })
 195         return null
 196       })
 197       .catch(e => {
 198         const err = this.handleError(e as Error)
 199         this.sendToMainWorker({ error: err, id: value.id })
 200       })
 201       .finally(() => {
 202         !this.isMain && (this.lastTaskTimestamp = Date.now())
 203       })
 204       .catch(EMPTY_FUNCTION)
 205   }
 206 }