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   }
  91
  92   /**
  93    * Checks if the `taskFunctions` parameter is passed to the constructor.
  94    *
  95    * @param taskFunctions - The task function(s) parameter that should be checked.
  96    */
  97   private checkTaskFunctions (
  98     taskFunctions:
  99     | WorkerFunction<Data, Response>
 100     | TaskFunctions<Data, Response>
 101   ): void {
 102     if (taskFunctions == null) {
 103       throw new Error('taskFunctions parameter is mandatory')
 104     }
 105     this.taskFunctions = new Map<string, WorkerFunction<Data, Response>>()
 106     if (typeof taskFunctions === 'function') {
 107       this.taskFunctions.set(DEFAULT_FUNCTION_NAME, taskFunctions.bind(this))
 108     } else if (isPlainObject(taskFunctions)) {
 109       let firstEntry = true
 110       for (const [name, fn] of Object.entries(taskFunctions)) {
 111         if (typeof fn !== 'function') {
 112           throw new TypeError(
 113             'A taskFunctions parameter object value is not a function'
 114           )
 115         }
 116         this.taskFunctions.set(name, fn.bind(this))
 117         if (firstEntry) {
 118           this.taskFunctions.set(DEFAULT_FUNCTION_NAME, fn.bind(this))
 119           firstEntry = false
 120         }
 121       }
 122       if (firstEntry) {
 123         throw new Error('taskFunctions parameter object is empty')
 124       }
 125     } else {
 126       throw new TypeError(
 127         'taskFunctions parameter is not a function or a plain object'
 128       )
 129     }
 130   }
 131
 132   /**
 133    * Worker message listener.
 134    *
 135    * @param message - Message received.
 136    */
 137   protected messageListener (message: MessageValue<Data, MainWorker>): void {
 138     if (message.id != null && message.data != null) {
 139       // Task message received
 140       const fn = this.getTaskFunction(message.name)
 141       if (fn?.constructor.name === 'AsyncFunction') {
 142         this.runInAsyncScope(this.runAsync.bind(this), this, fn, message)
 143       } else {
 144         this.runInAsyncScope(this.runSync.bind(this), this, fn, message)
 145       }
 146     } else if (message.parent != null) {
 147       // Main worker reference message received
 148       this.mainWorker = message.parent
 149     } else if (message.kill != null) {
 150       // Kill message received
 151       this.aliveInterval != null && clearInterval(this.aliveInterval)
 152       this.emitDestroy()
 153     }
 154   }
 155
 156   /**
 157    * Returns the main worker.
 158    *
 159    * @returns Reference to the main worker.
 160    */
 161   protected getMainWorker (): MainWorker {
 162     if (this.mainWorker == null) {
 163       throw new Error('Main worker was not set')
 164     }
 165     return this.mainWorker
 166   }
 167
 168   /**
 169    * Sends a message to the main worker.
 170    *
 171    * @param message - The response message.
 172    */
 173   protected abstract sendToMainWorker (message: MessageValue<Response>): void
 174
 175   /**
 176    * Checks if the worker should be terminated, because its living too long.
 177    */
 178   protected checkAlive (): void {
 179     if (
 180       performance.now() - this.lastTaskTimestamp >
 181       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 182     ) {
 183       this.sendToMainWorker({ kill: this.opts.killBehavior })
 184     }
 185   }
 186
 187   /**
 188    * Handles an error and convert it to a string so it can be sent back to the main worker.
 189    *
 190    * @param e - The error raised by the worker.
 191    * @returns Message of the error.
 192    */
 193   protected handleError (e: Error | string): string {
 194     return e as string
 195   }
 196
 197   /**
 198    * Runs the given function synchronously.
 199    *
 200    * @param fn - Function that will be executed.
 201    * @param message - Input data for the given function.
 202    */
 203   protected runSync (
 204     fn: WorkerSyncFunction<Data, Response>,
 205     message: MessageValue<Data>
 206   ): void {
 207     try {
 208       const startTimestamp = performance.now()
 209       const res = fn(message.data)
 210       const runTime = performance.now() - startTimestamp
 211       this.sendToMainWorker({
 212         data: res,
 213         id: message.id,
 214         runTime
 215       })
 216     } catch (e) {
 217       const err = this.handleError(e as Error)
 218       this.sendToMainWorker({ error: err, id: message.id })
 219     } finally {
 220       !this.isMain && (this.lastTaskTimestamp = performance.now())
 221     }
 222   }
 223
 224   /**
 225    * Runs the given function asynchronously.
 226    *
 227    * @param fn - Function that will be executed.
 228    * @param message - Input data for the given function.
 229    */
 230   protected runAsync (
 231     fn: WorkerAsyncFunction<Data, Response>,
 232     message: MessageValue<Data>
 233   ): void {
 234     const startTimestamp = performance.now()
 235     fn(message.data)
 236       .then(res => {
 237         const runTime = performance.now() - startTimestamp
 238         this.sendToMainWorker({
 239           data: res,
 240           id: message.id,
 241           runTime
 242         })
 243         return null
 244       })
 245       .catch(e => {
 246         const err = this.handleError(e as Error)
 247         this.sendToMainWorker({ error: err, id: message.id })
 248       })
 249       .finally(() => {
 250         !this.isMain && (this.lastTaskTimestamp = performance.now())
 251       })
 252       .catch(EMPTY_FUNCTION)
 253   }
 254
 255   /**
 256    * Gets the task function in the given scope.
 257    *
 258    * @param name - Name of the function that will be returned.
 259    */
 260   private getTaskFunction (name?: string): WorkerFunction<Data, Response> {
 261     name = name ?? DEFAULT_FUNCTION_NAME
 262     const fn = this.taskFunctions.get(name)
 263     if (fn == null) {
 264       throw new Error(`Task function "${name}" not found`)
 265     }
 266     return fn
 267   }
 268 }