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 {
   5   MessageValue,
   6   TaskFunctions,
   7   WorkerAsyncFunction,
   8   WorkerFunction,
   9   WorkerSyncFunction
  10 } from '../utility-types'
  11 import { EMPTY_FUNCTION, isPlainObject } from '../utils'
  12 import type { KillBehavior, WorkerOptions } from './worker-options'
  13 import { KillBehaviors } from './worker-options'
  14
  15 const DEFAULT_FUNCTION_NAME = 'default'
  16 const DEFAULT_MAX_INACTIVE_TIME = 60000
  17 const DEFAULT_KILL_BEHAVIOR: KillBehavior = KillBehaviors.SOFT
  18
  19 /**
  20  * Base class that implements some shared logic for all poolifier workers.
  21  *
  22  * @typeParam MainWorker - Type of main worker.
  23  * @typeParam Data - Type of data this worker receives from pool's execution. This can only be serializable data.
  24  * @typeParam Response - Type of response the worker sends back to the main worker. This can only be serializable data.
  25  */
  26 export abstract class AbstractWorker<
  27   MainWorker extends Worker | MessagePort,
  28   Data = unknown,
  29   Response = unknown
  30 > extends AsyncResource {
  31   /**
  32    * Task function(s) processed by the worker when the pool's `execution` function is invoked.
  33    */
  34   protected taskFunctions!: Map<string, WorkerFunction<Data, Response>>
  35   /**
  36    * Timestamp of the last task processed by this worker.
  37    */
  38   protected lastTaskTimestamp!: number
  39   /**
  40    * Handler id of the `aliveInterval` worker alive check.
  41    */
  42   protected readonly aliveInterval?: NodeJS.Timeout
  43   /**
  44    * Constructs a new poolifier worker.
  45    *
  46    * @param type - The type of async event.
  47    * @param isMain - Whether this is the main worker or not.
  48    * @param taskFunctions - Task function(s) processed by the worker when the pool's `execution` function is invoked. The first function is the default function.
  49    * @param mainWorker - Reference to main worker.
  50    * @param opts - Options for the worker.
  51    */
  52   public constructor (
  53     type: string,
  54     protected readonly isMain: boolean,
  55     taskFunctions:
  56     | WorkerFunction<Data, Response>
  57     | TaskFunctions<Data, Response>,
  58     protected mainWorker: MainWorker | undefined | null,
  59     protected readonly opts: WorkerOptions = {
  60       /**
  61        * The kill behavior option on this worker or its default value.
  62        */
  63       killBehavior: DEFAULT_KILL_BEHAVIOR,
  64       /**
  65        * The maximum time to keep this worker alive while idle.
  66        * The pool automatically checks and terminates this worker when the time expires.
  67        */
  68       maxInactiveTime: DEFAULT_MAX_INACTIVE_TIME
  69     }
  70   ) {
  71     super(type)
  72     this.checkWorkerOptions(this.opts)
  73     this.checkTaskFunctions(taskFunctions)
  74     if (!this.isMain) {
  75       this.lastTaskTimestamp = performance.now()
  76       this.aliveInterval = setInterval(
  77         this.checkAlive.bind(this),
  78         (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
  79       )
  80       this.checkAlive.bind(this)()
  81     }
  82
  83     this.mainWorker?.on('message', this.messageListener.bind(this))
  84   }
  85
  86   private checkWorkerOptions (opts: WorkerOptions): void {
  87     this.opts.killBehavior = opts.killBehavior ?? DEFAULT_KILL_BEHAVIOR
  88     this.opts.maxInactiveTime =
  89       opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME
  90     this.opts.async = opts.async ?? false
  91   }
  92
  93   /**
  94    * Checks if the `taskFunctions` parameter is passed to the constructor.
  95    *
  96    * @param taskFunctions - The task function(s) parameter that should be checked.
  97    */
  98   private checkTaskFunctions (
  99     taskFunctions:
 100     | WorkerFunction<Data, Response>
 101     | TaskFunctions<Data, Response>
 102   ): void {
 103     if (taskFunctions == null) {
 104       throw new Error('taskFunctions parameter is mandatory')
 105     }
 106     if (
 107       typeof taskFunctions !== 'function' &&
 108       typeof taskFunctions !== 'object'
 109     ) {
 110       throw new TypeError(
 111         'taskFunctions parameter is not a function or an object'
 112       )
 113     }
 114     this.taskFunctions = new Map<string, WorkerFunction<Data, Response>>()
 115     if (typeof taskFunctions === 'function') {
 116       this.taskFunctions.set(DEFAULT_FUNCTION_NAME, taskFunctions.bind(this))
 117     } else if (isPlainObject(taskFunctions)) {
 118       let firstEntry = true
 119       for (const [name, fn] of Object.entries(taskFunctions)) {
 120         if (typeof fn !== 'function') {
 121           throw new TypeError(
 122             'A taskFunctions parameter object value is not a function'
 123           )
 124         }
 125         this.taskFunctions.set(name, fn.bind(this))
 126         if (firstEntry) {
 127           this.taskFunctions.set(DEFAULT_FUNCTION_NAME, fn.bind(this))
 128           firstEntry = false
 129         }
 130       }
 131       if (firstEntry) {
 132         throw new Error('taskFunctions parameter object is empty')
 133       }
 134     } else {
 135       throw new TypeError('taskFunctions parameter is not an object literal')
 136     }
 137   }
 138
 139   /**
 140    * Worker message listener.
 141    *
 142    * @param message - Message received.
 143    */
 144   protected messageListener (message: MessageValue<Data, MainWorker>): void {
 145     if (message.id != null && message.data != null) {
 146       // Task message received
 147       const fn = this.getTaskFunction(message.name)
 148       if (fn?.constructor.name === 'AsyncFunction') {
 149         this.runInAsyncScope(this.runAsync.bind(this), this, fn, message)
 150       } else {
 151         this.runInAsyncScope(this.runSync.bind(this), this, fn, message)
 152       }
 153     } else if (message.parent != null) {
 154       // Main worker reference message received
 155       this.mainWorker = message.parent
 156     } else if (message.kill != null) {
 157       // Kill message received
 158       this.aliveInterval != null && clearInterval(this.aliveInterval)
 159       this.emitDestroy()
 160     }
 161   }
 162
 163   /**
 164    * Returns the main worker.
 165    *
 166    * @returns Reference to the main worker.
 167    */
 168   protected getMainWorker (): MainWorker {
 169     if (this.mainWorker == null) {
 170       throw new Error('Main worker was not set')
 171     }
 172     return this.mainWorker
 173   }
 174
 175   /**
 176    * Sends a message to the main worker.
 177    *
 178    * @param message - The response message.
 179    */
 180   protected abstract sendToMainWorker (message: MessageValue<Response>): void
 181
 182   /**
 183    * Checks if the worker should be terminated, because its living too long.
 184    */
 185   protected checkAlive (): void {
 186     if (
 187       performance.now() - this.lastTaskTimestamp >
 188       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 189     ) {
 190       this.sendToMainWorker({ kill: this.opts.killBehavior })
 191     }
 192   }
 193
 194   /**
 195    * Handles an error and convert it to a string so it can be sent back to the main worker.
 196    *
 197    * @param e - The error raised by the worker.
 198    * @returns Message of the error.
 199    */
 200   protected handleError (e: Error | string): string {
 201     return e as string
 202   }
 203
 204   /**
 205    * Runs the given function synchronously.
 206    *
 207    * @param fn - Function that will be executed.
 208    * @param message - Input data for the given function.
 209    */
 210   protected runSync (
 211     fn: WorkerSyncFunction<Data, Response>,
 212     message: MessageValue<Data>
 213   ): void {
 214     try {
 215       const startTimestamp = performance.now()
 216       const res = fn(message.data)
 217       const runTime = performance.now() - startTimestamp
 218       this.sendToMainWorker({
 219         data: res,
 220         id: message.id,
 221         runTime
 222       })
 223     } catch (e) {
 224       const err = this.handleError(e as Error)
 225       this.sendToMainWorker({ error: err, id: message.id })
 226     } finally {
 227       !this.isMain && (this.lastTaskTimestamp = performance.now())
 228     }
 229   }
 230
 231   /**
 232    * Runs the given function asynchronously.
 233    *
 234    * @param fn - Function that will be executed.
 235    * @param message - Input data for the given function.
 236    */
 237   protected runAsync (
 238     fn: WorkerAsyncFunction<Data, Response>,
 239     message: MessageValue<Data>
 240   ): void {
 241     const startTimestamp = performance.now()
 242     fn(message.data)
 243       .then(res => {
 244         const runTime = performance.now() - startTimestamp
 245         this.sendToMainWorker({
 246           data: res,
 247           id: message.id,
 248           runTime
 249         })
 250         return null
 251       })
 252       .catch(e => {
 253         const err = this.handleError(e as Error)
 254         this.sendToMainWorker({ error: err, id: message.id })
 255       })
 256       .finally(() => {
 257         !this.isMain && (this.lastTaskTimestamp = performance.now())
 258       })
 259       .catch(EMPTY_FUNCTION)
 260   }
 261
 262   /**
 263    * Gets the task function in the given scope.
 264    *
 265    * @param name - Name of the function that will be returned.
 266    */
 267   private getTaskFunction (name?: string): WorkerFunction<Data, Response> {
 268     name = name ?? DEFAULT_FUNCTION_NAME
 269     const fn = this.taskFunctions.get(name)
 270     if (fn == null) {
 271       throw new Error(`Task function "${name}" not found`)
 272     }
 273     return fn
 274   }
 275 }