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     delete this.opts.async
  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     this.taskFunctions = new Map<string, WorkerFunction<Data, Response>>()
 107     if (typeof taskFunctions === 'function') {
 108       this.taskFunctions.set(DEFAULT_FUNCTION_NAME, taskFunctions.bind(this))
 109     } else if (isPlainObject(taskFunctions)) {
 110       let firstEntry = true
 111       for (const [name, fn] of Object.entries(taskFunctions)) {
 112         if (typeof fn !== 'function') {
 113           throw new TypeError(
 114             'A taskFunctions parameter object value is not a function'
 115           )
 116         }
 117         this.taskFunctions.set(name, fn.bind(this))
 118         if (firstEntry) {
 119           this.taskFunctions.set(DEFAULT_FUNCTION_NAME, fn.bind(this))
 120           firstEntry = false
 121         }
 122       }
 123       if (firstEntry) {
 124         throw new Error('taskFunctions parameter object is empty')
 125       }
 126     } else {
 127       throw new TypeError(
 128         'taskFunctions parameter is not a function or a plain object'
 129       )
 130     }
 131   }
 132
 133   /**
 134    * Worker message listener.
 135    *
 136    * @param message - Message received.
 137    */
 138   protected messageListener (message: MessageValue<Data, MainWorker>): void {
 139     if (message.id != null && message.data != null) {
 140       // Task message received
 141       const fn = this.getTaskFunction(message.name)
 142       if (fn?.constructor.name === 'AsyncFunction') {
 143         this.runInAsyncScope(this.runAsync.bind(this), this, fn, message)
 144       } else {
 145         this.runInAsyncScope(this.runSync.bind(this), this, fn, message)
 146       }
 147     } else if (message.parent != null) {
 148       // Main worker reference message received
 149       this.mainWorker = message.parent
 150     } else if (message.kill != null) {
 151       // Kill message received
 152       this.aliveInterval != null && clearInterval(this.aliveInterval)
 153       this.emitDestroy()
 154     }
 155   }
 156
 157   /**
 158    * Returns the main worker.
 159    *
 160    * @returns Reference to the main worker.
 161    */
 162   protected getMainWorker (): MainWorker {
 163     if (this.mainWorker == null) {
 164       throw new Error('Main worker was not set')
 165     }
 166     return this.mainWorker
 167   }
 168
 169   /**
 170    * Sends a message to the main worker.
 171    *
 172    * @param message - The response message.
 173    */
 174   protected abstract sendToMainWorker (message: MessageValue<Response>): void
 175
 176   /**
 177    * Checks if the worker should be terminated, because its living too long.
 178    */
 179   protected checkAlive (): void {
 180     if (
 181       performance.now() - this.lastTaskTimestamp >
 182       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
 183     ) {
 184       this.sendToMainWorker({ kill: this.opts.killBehavior })
 185     }
 186   }
 187
 188   /**
 189    * Handles an error and convert it to a string so it can be sent back to the main worker.
 190    *
 191    * @param e - The error raised by the worker.
 192    * @returns Message of the error.
 193    */
 194   protected handleError (e: Error | string): string {
 195     return e as string
 196   }
 197
 198   /**
 199    * Runs the given function synchronously.
 200    *
 201    * @param fn - Function that will be executed.
 202    * @param message - Input data for the given function.
 203    */
 204   protected runSync (
 205     fn: WorkerSyncFunction<Data, Response>,
 206     message: MessageValue<Data>
 207   ): void {
 208     try {
 209       const startTimestamp = performance.now()
 210       const waitTime = startTimestamp - (message.submissionTimestamp ?? 0)
 211       const res = fn(message.data)
 212       const runTime = performance.now() - startTimestamp
 213       this.sendToMainWorker({
 214         data: res,
 215         id: message.id,
 216         runTime,
 217         waitTime
 218       })
 219     } catch (e) {
 220       const err = this.handleError(e as Error)
 221       this.sendToMainWorker({ error: err, id: message.id })
 222     } finally {
 223       !this.isMain && (this.lastTaskTimestamp = performance.now())
 224     }
 225   }
 226
 227   /**
 228    * Runs the given function asynchronously.
 229    *
 230    * @param fn - Function that will be executed.
 231    * @param message - Input data for the given function.
 232    */
 233   protected runAsync (
 234     fn: WorkerAsyncFunction<Data, Response>,
 235     message: MessageValue<Data>
 236   ): void {
 237     const startTimestamp = performance.now()
 238     const waitTime = startTimestamp - (message.submissionTimestamp ?? 0)
 239     fn(message.data)
 240       .then(res => {
 241         const runTime = performance.now() - startTimestamp
 242         this.sendToMainWorker({
 243           data: res,
 244           id: message.id,
 245           runTime,
 246           waitTime
 247         })
 248         return null
 249       })
 250       .catch(e => {
 251         const err = this.handleError(e as Error)
 252         this.sendToMainWorker({ error: err, id: message.id })
 253       })
 254       .finally(() => {
 255         !this.isMain && (this.lastTaskTimestamp = performance.now())
 256       })
 257       .catch(EMPTY_FUNCTION)
 258   }
 259
 260   /**
 261    * Gets the task function in the given scope.
 262    *
 263    * @param name - Name of the function that will be returned.
 264    */
 265   private getTaskFunction (name?: string): WorkerFunction<Data, Response> {
 266     name = name ?? DEFAULT_FUNCTION_NAME
 267     const fn = this.taskFunctions.get(name)
 268     if (fn == null) {
 269       throw new Error(`Task function '${name}' not found`)
 270     }
 271     return fn
 272   }
 273 }