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 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     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     this.lastTaskTimestamp = Date.now()
  67     // Keep the worker active
  68     if (!isMain) {
  69       this.aliveInterval = setInterval(
  70         this.checkAlive.bind(this),
  71         (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
  72       )
  73       this.checkAlive.bind(this)()
  74     }
  75
  76     this.mainWorker?.on('message', (value: MessageValue<Data, MainWorker>) => {
  77       this.messageListener(value, fn)
  78     })
  79   }
  80
  81   protected messageListener (
  82     value: MessageValue<Data, MainWorker>,
  83     fn: (data: Data) => Response
  84   ): void {
  85     if (value.data !== undefined && value.id !== undefined) {
  86       // Here you will receive messages
  87       if (this.opts.async === true) {
  88         this.runInAsyncScope(this.runAsync.bind(this), this, fn, value)
  89       } else {
  90         this.runInAsyncScope(this.run.bind(this), this, fn, value)
  91       }
  92     } else if (value.parent !== undefined) {
  93       // Save a reference of the main worker to communicate with it
  94       // This will be received once
  95       this.mainWorker = value.parent
  96     } else if (value.kill !== undefined) {
  97       // Here is time to kill this worker, just clearing the interval
  98       if (this.aliveInterval != null) clearInterval(this.aliveInterval)
  99       this.emitDestroy()
 100     }
 101   }
 102
 103   private checkWorkerOptions (opts: WorkerOptions): void {
 104     this.opts.killBehavior = opts.killBehavior ?? DEFAULT_KILL_BEHAVIOR
 105     this.opts.maxInactiveTime =
 106       opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME
 107     this.opts.async = opts.async ?? false
 108   }
 109
 110   /**
 111    * Checks if the `fn` parameter is passed to the constructor.
 112    *
 113    * @param fn - The function that should be defined.
 114    */
 115   private checkFunctionInput (fn: (data: Data) => Response): void {
 116     if (fn == null) throw new Error('fn parameter is mandatory')
 117     if (typeof fn !== 'function') {
 118       throw new TypeError('fn parameter is not a function')
 119     }
 120   }
 121
 122   /**
 123    * Returns the main worker.
 124    *
 125    * @returns Reference to the main worker.
 126    */
 127   protected getMainWorker (): MainWorker {
 128     if (this.mainWorker == null) {
 129       throw new Error('Main worker was not set')
 130     }
 131     return this.mainWorker
 132   }
 133
 134   /**
 135    * Sends a message to the main worker.
 136    *
 137    * @param message - The response message.
 138    */
 139   protected abstract sendToMainWorker (message: MessageValue<Response>): void
 140
 141   /**
 142    * Checks if the worker should be terminated, because its living too long.
 143    */
 144   protected checkAlive (): void {
 145     if (
 146       Date.now() - this.lastTaskTimestamp >
 147       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 148     ) {
 149       this.sendToMainWorker({ kill: this.opts.killBehavior })
 150     }
 151   }
 152
 153   /**
 154    * Handles an error and convert it to a string so it can be sent back to the main worker.
 155    *
 156    * @param e - The error raised by the worker.
 157    * @returns Message of the error.
 158    */
 159   protected handleError (e: Error | string): string {
 160     return e as string
 161   }
 162
 163   /**
 164    * Runs the given function synchronously.
 165    *
 166    * @param fn - Function that will be executed.
 167    * @param value - Input data for the given function.
 168    */
 169   protected run (
 170     fn: (data?: Data) => Response,
 171     value: MessageValue<Data>
 172   ): void {
 173     try {
 174       const startTaskTimestamp = Date.now()
 175       const res = fn(value.data)
 176       const taskRunTime = Date.now() - startTaskTimestamp
 177       this.sendToMainWorker({ data: res, id: value.id, taskRunTime })
 178     } catch (e) {
 179       const err = this.handleError(e as Error)
 180       this.sendToMainWorker({ error: err, id: value.id })
 181     } finally {
 182       this.lastTaskTimestamp = Date.now()
 183     }
 184   }
 185
 186   /**
 187    * Runs the given function asynchronously.
 188    *
 189    * @param fn - Function that will be executed.
 190    * @param value - Input data for the given function.
 191    */
 192   protected runAsync (
 193     fn: (data?: Data) => Promise<Response>,
 194     value: MessageValue<Data>
 195   ): void {
 196     const startTaskTimestamp = Date.now()
 197     fn(value.data)
 198       .then(res => {
 199         const taskRunTime = Date.now() - startTaskTimestamp
 200         this.sendToMainWorker({ data: res, id: value.id, taskRunTime })
 201         return null
 202       })
 203       .catch(e => {
 204         const err = this.handleError(e as Error)
 205         this.sendToMainWorker({ error: err, id: value.id })
 206       })
 207       .finally(() => {
 208         this.lastTaskTimestamp = Date.now()
 209       })
 210       .catch(EMPTY_FUNCTION)
 211   }
 212 }