src/worker/abstract-worker.ts

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