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    * Options for the worker.
  34    */
  35   public readonly opts: WorkerOptions
  36   /**
  37    * Constructs a new poolifier worker.
  38    *
  39    * @param type - The type of async event.
  40    * @param isMain - Whether this is the main worker or not.
  41    * @param fn - Function processed by the worker when the pool's `execution` function is invoked.
  42    * @param mainWorker - Reference to main worker.
  43    * @param opts - Options for the worker.
  44    */
  45   public constructor (
  46     type: string,
  47     protected readonly isMain: boolean,
  48     fn: (data: Data) => Response,
  49     protected mainWorker: MainWorker | undefined | null,
  50     opts: WorkerOptions = {
  51       /**
  52        * The kill behavior option on this Worker or its default value.
  53        */
  54       killBehavior: DEFAULT_KILL_BEHAVIOR,
  55       /**
  56        * The maximum time to keep this worker alive while idle.
  57        * The pool automatically checks and terminates this worker when the time expires.
  58        */
  59       maxInactiveTime: DEFAULT_MAX_INACTIVE_TIME
  60     }
  61   ) {
  62     super(type)
  63     this.opts = opts
  64     this.checkFunctionInput(fn)
  65     this.checkWorkerOptions(this.opts)
  66     if (!this.isMain) {
  67       this.lastTaskTimestamp = Date.now()
  68       this.aliveInterval = setInterval(
  69         this.checkAlive.bind(this),
  70         (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
  71       )
  72       this.checkAlive.bind(this)()
  73     }
  74
  75     this.mainWorker?.on('message', (value: MessageValue<Data, MainWorker>) => {
  76       this.messageListener(value, fn)
  77     })
  78   }
  79
  80   protected messageListener (
  81     value: MessageValue<Data, MainWorker>,
  82     fn: (data: Data) => Response
  83   ): void {
  84     if (value.data !== undefined && value.id !== undefined) {
  85       // Here you will receive messages
  86       if (this.opts.async === true) {
  87         this.runInAsyncScope(this.runAsync.bind(this), this, fn, value)
  88       } else {
  89         this.runInAsyncScope(this.run.bind(this), this, fn, value)
  90       }
  91     } else if (value.parent !== undefined) {
  92       // Save a reference of the main worker to communicate with it
  93       // This will be received once
  94       this.mainWorker = value.parent
  95     } else if (value.kill !== undefined) {
  96       // Here is time to kill this worker, just clearing the interval
  97       this.aliveInterval != null && clearInterval(this.aliveInterval)
  98       this.emitDestroy()
  99     }
 100   }
 101
 102   private checkWorkerOptions (opts: WorkerOptions): void {
 103     this.opts.killBehavior = opts.killBehavior ?? DEFAULT_KILL_BEHAVIOR
 104     this.opts.maxInactiveTime =
 105       opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME
 106     this.opts.async = opts.async ?? false
 107   }
 108
 109   /**
 110    * Checks if the `fn` parameter is passed to the constructor.
 111    *
 112    * @param fn - The function that should be defined.
 113    */
 114   private checkFunctionInput (fn: (data: Data) => Response): void {
 115     if (fn == null) throw new Error('fn parameter is mandatory')
 116     if (typeof fn !== 'function') {
 117       throw new TypeError('fn parameter is not a function')
 118     }
 119   }
 120
 121   /**
 122    * Returns the main worker.
 123    *
 124    * @returns Reference to the main worker.
 125    */
 126   protected getMainWorker (): MainWorker {
 127     if (this.mainWorker == null) {
 128       throw new Error('Main worker was not set')
 129     }
 130     return this.mainWorker
 131   }
 132
 133   /**
 134    * Sends a message to the main worker.
 135    *
 136    * @param message - The response message.
 137    */
 138   protected abstract sendToMainWorker (message: MessageValue<Response>): void
 139
 140   /**
 141    * Checks if the worker should be terminated, because its living too long.
 142    */
 143   protected checkAlive (): void {
 144     if (
 145       Date.now() - this.lastTaskTimestamp >
 146       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 147     ) {
 148       this.sendToMainWorker({ kill: this.opts.killBehavior })
 149     }
 150   }
 151
 152   /**
 153    * Handles an error and convert it to a string so it can be sent back to the main worker.
 154    *
 155    * @param e - The error raised by the worker.
 156    * @returns Message of the error.
 157    */
 158   protected handleError (e: Error | string): string {
 159     return e as string
 160   }
 161
 162   /**
 163    * Runs the given function synchronously.
 164    *
 165    * @param fn - Function that will be executed.
 166    * @param value - Input data for the given function.
 167    */
 168   protected run (
 169     fn: (data?: Data) => Response,
 170     value: MessageValue<Data>
 171   ): void {
 172     try {
 173       const startTaskTimestamp = Date.now()
 174       const res = fn(value.data)
 175       const taskRunTime = Date.now() - startTaskTimestamp
 176       this.sendToMainWorker({ data: res, id: value.id, taskRunTime })
 177     } catch (e) {
 178       const err = this.handleError(e as Error)
 179       this.sendToMainWorker({ error: err, id: value.id })
 180     } finally {
 181       !this.isMain && (this.lastTaskTimestamp = Date.now())
 182     }
 183   }
 184
 185   /**
 186    * Runs the given function asynchronously.
 187    *
 188    * @param fn - Function that will be executed.
 189    * @param value - Input data for the given function.
 190    */
 191   protected runAsync (
 192     fn: (data?: Data) => Promise<Response>,
 193     value: MessageValue<Data>
 194   ): void {
 195     const startTaskTimestamp = Date.now()
 196     fn(value.data)
 197       .then(res => {
 198         const taskRunTime = Date.now() - startTaskTimestamp
 199         this.sendToMainWorker({ data: res, id: value.id, taskRunTime })
 200         return null
 201       })
 202       .catch(e => {
 203         const err = this.handleError(e as Error)
 204         this.sendToMainWorker({ error: err, id: value.id })
 205       })
 206       .finally(() => {
 207         !this.isMain && (this.lastTaskTimestamp = Date.now())
 208       })
 209       .catch(EMPTY_FUNCTION)
 210   }
 211 }