X-Git-Url: https://git.piment-noir.org/?a=blobdiff_plain;f=src%2Fworker%2Fabstract-worker.ts;h=242c46982236357626ae50fae5f3a33d7c3f04eb;hb=facb41d7d33bd6c11970da5e946c51347824fd54;hp=fbb8f8390eff2207253195eb3817c68dc879e2b7;hpb=dc5d0cb3855a09adaafc0af99301b485a30eb77e;p=poolifier.git

diff --git a/src/worker/abstract-worker.ts b/src/worker/abstract-worker.ts
index fbb8f839..a0d78dbd 100644
--- a/src/worker/abstract-worker.ts
+++ b/src/worker/abstract-worker.ts
@@ -1,202 +1,611 @@
-import { AsyncResource } from 'async_hooks'
-import type { Worker } from 'cluster'
-import type { MessagePort } from 'worker_threads'
-import type { MessageValue } from '../utility-types'
-import { EMPTY_FUNCTION } from '../utils'
-import type { KillBehavior, WorkerOptions } from './worker-options'
-import { KillBehaviors } from './worker-options'
+import { AsyncResource } from 'node:async_hooks'
+import type { Worker } from 'node:cluster'
+import type { MessagePort } from 'node:worker_threads'
+import { performance } from 'node:perf_hooks'
+import type {
+  MessageValue,
+  Task,
+  TaskPerformance,
+  WorkerStatistics
+} from '../utility-types'
+import {
+  DEFAULT_TASK_NAME,
+  EMPTY_FUNCTION,
+  isAsyncFunction,
+  isPlainObject
+} from '../utils'
+import { KillBehaviors, type WorkerOptions } from './worker-options'
+import type {
+  TaskAsyncFunction,
+  TaskFunction,
+  TaskFunctions,
+  TaskSyncFunction
+} from './task-functions'
 
-const DEFAULT_MAX_INACTIVE_TIME = 1000 * 60
-const DEFAULT_KILL_BEHAVIOR: KillBehavior = KillBehaviors.SOFT
+const DEFAULT_MAX_INACTIVE_TIME = 60000
+const DEFAULT_WORKER_OPTIONS: WorkerOptions = {
+  /**
+   * The kill behavior option on this worker or its default value.
+   */
+  killBehavior: KillBehaviors.SOFT,
+  /**
+   * The maximum time to keep this worker active while idle.
+   * The pool automatically checks and terminates this worker when the time expires.
+   */
+  maxInactiveTime: DEFAULT_MAX_INACTIVE_TIME,
+  /**
+   * The function to call when the worker is killed.
+   */
+  killHandler: EMPTY_FUNCTION
+}
 
 /**
- * Base class containing some shared logic for all poolifier workers.
+ * Base class that implements some shared logic for all poolifier workers.
  *
- * @template MainWorker Type of main worker.
- * @template Data Type of data this worker receives from pool's execution. This can only be serializable data.
- * @template Response Type of response the worker sends back to the main worker. This can only be serializable data.
+ * @typeParam MainWorker - Type of main worker.
+ * @typeParam Data - Type of data this worker receives from pool's execution. This can only be structured-cloneable data.
+ * @typeParam Response - Type of response the worker sends back to the main worker. This can only be structured-cloneable data.
  */
 export abstract class AbstractWorker<
   MainWorker extends Worker | MessagePort,
   Data = unknown,
   Response = unknown
 > extends AsyncResource {
+  /**
+   * Worker id.
+   */
+  protected abstract id: number
+  /**
+   * Task function(s) processed by the worker when the pool's `execution` function is invoked.
+   */
+  protected taskFunctions!: Map<string, TaskFunction<Data, Response>>
   /**
    * Timestamp of the last task processed by this worker.
    */
-  protected lastTaskTimestamp: number
+  protected lastTaskTimestamp!: number
   /**
-   * Handler Id of the `aliveInterval` worker alive check.
+   * Performance statistics computation requirements.
    */
-  protected readonly aliveInterval?: NodeJS.Timeout
+  protected statistics!: WorkerStatistics
   /**
-   * Options for the worker.
+   * Handler id of the `activeInterval` worker activity check.
    */
-  public readonly opts: WorkerOptions
-
+  protected activeInterval?: NodeJS.Timeout
   /**
    * Constructs a new poolifier worker.
    *
-   * @param type The type of async event.
-   * @param isMain Whether this is the main worker or not.
-   * @param fn Function processed by the worker when the pool's `execution` function is invoked.
-   * @param mainWorker Reference to main worker.
-   * @param opts Options for the worker.
+   * @param type - The type of async event.
+   * @param isMain - Whether this is the main worker or not.
+   * @param mainWorker - Reference to main worker.
+   * @param taskFunctions - Task function(s) processed by the worker when the pool's `execution` function is invoked. The first function is the default function.
+   * @param opts - Options for the worker.
    */
   public constructor (
     type: string,
-    isMain: boolean,
-    fn: (data: Data) => Response,
-    protected mainWorker: MainWorker | undefined | null,
-    opts: WorkerOptions = {
-      /**
-       * The kill behavior option on this Worker or its default value.
-       */
-      killBehavior: DEFAULT_KILL_BEHAVIOR,
-      /**
-       * The maximum time to keep this worker alive while idle.
-       * The pool automatically checks and terminates this worker when the time expires.
-       */
-      maxInactiveTime: DEFAULT_MAX_INACTIVE_TIME
-    }
+    protected readonly isMain: boolean,
+    private readonly mainWorker: MainWorker,
+    taskFunctions: TaskFunction<Data, Response> | TaskFunctions<Data, Response>,
+    protected opts: WorkerOptions = DEFAULT_WORKER_OPTIONS
   ) {
     super(type)
-    this.opts = opts
-    this.checkFunctionInput(fn)
+    if (this.isMain == null) {
+      throw new Error('isMain parameter is mandatory')
+    }
+    this.checkTaskFunctions(taskFunctions)
     this.checkWorkerOptions(this.opts)
-    this.lastTaskTimestamp = Date.now()
-    // Keep the worker active
-    if (!isMain) {
-      this.aliveInterval = setInterval(
-        this.checkAlive.bind(this),
-        (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
+    if (!this.isMain) {
+      this.getMainWorker().on('message', this.handleReadyMessage.bind(this))
+    }
+  }
+
+  private checkWorkerOptions (opts: WorkerOptions): void {
+    this.opts = { ...DEFAULT_WORKER_OPTIONS, ...opts }
+    delete this.opts.async
+  }
+
+  private checkValidTaskFunction (
+    name: string,
+    fn: TaskFunction<Data, Response>
+  ): void {
+    if (typeof name !== 'string') {
+      throw new TypeError(
+        'A taskFunctions parameter object key is not a string'
+      )
+    }
+    if (typeof name === 'string' && name.trim().length === 0) {
+      throw new TypeError(
+        'A taskFunctions parameter object key is an empty string'
+      )
+    }
+    if (typeof fn !== 'function') {
+      throw new TypeError(
+        'A taskFunctions parameter object value is not a function'
       )
-      this.checkAlive.bind(this)()
     }
+  }
 
-    this.mainWorker?.on('message', (value: MessageValue<Data, MainWorker>) => {
-      if (value?.data && value.id) {
-        // Here you will receive messages
-        if (this.opts.async) {
-          this.runInAsyncScope(this.runAsync.bind(this), this, fn, value)
-        } else {
-          this.runInAsyncScope(this.run.bind(this), this, fn, value)
+  /**
+   * Checks if the `taskFunctions` parameter is passed to the constructor.
+   *
+   * @param taskFunctions - The task function(s) parameter that should be checked.
+   */
+  private checkTaskFunctions (
+    taskFunctions: TaskFunction<Data, Response> | TaskFunctions<Data, Response>
+  ): void {
+    if (taskFunctions == null) {
+      throw new Error('taskFunctions parameter is mandatory')
+    }
+    this.taskFunctions = new Map<string, TaskFunction<Data, Response>>()
+    if (typeof taskFunctions === 'function') {
+      const boundFn = taskFunctions.bind(this)
+      this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
+      this.taskFunctions.set(
+        typeof taskFunctions.name === 'string' &&
+        taskFunctions.name.trim().length > 0
+          ? taskFunctions.name
+          : 'fn1',
+        boundFn
+      )
+    } else if (isPlainObject(taskFunctions)) {
+      let firstEntry = true
+      for (const [name, fn] of Object.entries(taskFunctions)) {
+        this.checkValidTaskFunction(name, fn)
+        const boundFn = fn.bind(this)
+        if (firstEntry) {
+          this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
+          firstEntry = false
         }
-      } else if (value.parent) {
-        // Save a reference of the main worker to communicate with it
-        // This will be received once
-        this.mainWorker = value.parent
-      } else if (value.kill) {
-        // Here is time to kill this worker, just clearing the interval
-        if (this.aliveInterval) clearInterval(this.aliveInterval)
-        this.emitDestroy()
+        this.taskFunctions.set(name, boundFn)
       }
-    })
+      if (firstEntry) {
+        throw new Error('taskFunctions parameter object is empty')
+      }
+    } else {
+      throw new TypeError(
+        'taskFunctions parameter is not a function or a plain object'
+      )
+    }
   }
 
-  private checkWorkerOptions (opts: WorkerOptions) {
-    this.opts.killBehavior = opts.killBehavior ?? DEFAULT_KILL_BEHAVIOR
-    this.opts.maxInactiveTime =
-      opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME
-    /**
-     * Whether the worker is working asynchronously or not.
-     */
-    this.opts.async = !!opts.async
+  /**
+   * Checks if the worker has a task function with the given name.
+   *
+   * @param name - The name of the task function to check.
+   * @returns Whether the worker has a task function with the given name or not.
+   * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
+   */
+  public hasTaskFunction (name: string): boolean {
+    this.checkTaskFunctionName(name)
+    return this.taskFunctions.has(name)
   }
 
   /**
-   * Check if the `fn` parameter is passed to the constructor.
+   * Adds a task function to the worker.
+   * If a task function with the same name already exists, it is replaced.
    *
-   * @param fn The function that should be defined.
+   * @param name - The name of the task function to add.
+   * @param fn - The task function to add.
+   * @returns Whether the task function was added or not.
+   * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
+   * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
+   * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `fn` parameter is not a function.
    */
-  private checkFunctionInput (fn: (data: Data) => Response): void {
-    if (!fn) throw new Error('fn parameter is mandatory')
+  public addTaskFunction (
+    name: string,
+    fn: TaskFunction<Data, Response>
+  ): boolean {
+    this.checkTaskFunctionName(name)
+    if (name === DEFAULT_TASK_NAME) {
+      throw new Error(
+        'Cannot add a task function with the default reserved name'
+      )
+    }
+    if (typeof fn !== 'function') {
+      throw new TypeError('fn parameter is not a function')
+    }
+    try {
+      const boundFn = fn.bind(this)
+      if (
+        this.taskFunctions.get(name) ===
+        this.taskFunctions.get(DEFAULT_TASK_NAME)
+      ) {
+        this.taskFunctions.set(DEFAULT_TASK_NAME, boundFn)
+      }
+      this.taskFunctions.set(name, boundFn)
+      this.sendTaskFunctionsListToMainWorker()
+      return true
+    } catch {
+      return false
+    }
   }
 
   /**
-   * Returns the main worker.
+   * Removes a task function from the worker.
    *
-   * @returns Reference to the main worker.
+   * @param name - The name of the task function to remove.
+   * @returns Whether the task function existed and was removed or not.
+   * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
+   * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
+   * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the task function used as default task function.
    */
-  protected getMainWorker (): MainWorker {
-    if (!this.mainWorker) {
-      throw new Error('Main worker was not set')
+  public removeTaskFunction (name: string): boolean {
+    this.checkTaskFunctionName(name)
+    if (name === DEFAULT_TASK_NAME) {
+      throw new Error(
+        'Cannot remove the task function with the default reserved name'
+      )
+    }
+    if (
+      this.taskFunctions.get(name) === this.taskFunctions.get(DEFAULT_TASK_NAME)
+    ) {
+      throw new Error(
+        'Cannot remove the task function used as the default task function'
+      )
+    }
+    const deleteStatus = this.taskFunctions.delete(name)
+    this.sendTaskFunctionsListToMainWorker()
+    return deleteStatus
+  }
+
+  /**
+   * Lists the names of the worker's task functions.
+   *
+   * @returns The names of the worker's task functions.
+   */
+  public listTaskFunctions (): string[] {
+    const names: string[] = [...this.taskFunctions.keys()]
+    let defaultTaskFunctionName: string = DEFAULT_TASK_NAME
+    for (const [name, fn] of this.taskFunctions) {
+      if (
+        name !== DEFAULT_TASK_NAME &&
+        fn === this.taskFunctions.get(DEFAULT_TASK_NAME)
+      ) {
+        defaultTaskFunctionName = name
+        break
+      }
+    }
+    return [
+      names[names.indexOf(DEFAULT_TASK_NAME)],
+      defaultTaskFunctionName,
+      ...names.filter(
+        (name) => name !== DEFAULT_TASK_NAME && name !== defaultTaskFunctionName
+      )
+    ]
+  }
+
+  /**
+   * Sets the default task function to use in the worker.
+   *
+   * @param name - The name of the task function to use as default task function.
+   * @returns Whether the default task function was set or not.
+   * @throws {@link https://nodejs.org/api/errors.html#class-typeerror} If the `name` parameter is not a string or an empty string.
+   * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is the default task function reserved name.
+   * @throws {@link https://nodejs.org/api/errors.html#class-error} If the `name` parameter is a non-existing task function.
+   */
+  public setDefaultTaskFunction (name: string): boolean {
+    this.checkTaskFunctionName(name)
+    if (name === DEFAULT_TASK_NAME) {
+      throw new Error(
+        'Cannot set the default task function reserved name as the default task function'
+      )
+    }
+    if (!this.taskFunctions.has(name)) {
+      throw new Error(
+        'Cannot set the default task function to a non-existing task function'
+      )
+    }
+    try {
+      this.taskFunctions.set(
+        DEFAULT_TASK_NAME,
+        this.taskFunctions.get(name) as TaskFunction<Data, Response>
+      )
+      return true
+    } catch {
+      return false
+    }
+  }
+
+  private checkTaskFunctionName (name: string): void {
+    if (typeof name !== 'string') {
+      throw new TypeError('name parameter is not a string')
+    }
+    if (typeof name === 'string' && name.trim().length === 0) {
+      throw new TypeError('name parameter is an empty string')
+    }
+  }
+
+  /**
+   * Handles the ready message sent by the main worker.
+   *
+   * @param message - The ready message.
+   */
+  protected abstract handleReadyMessage (message: MessageValue<Data>): void
+
+  /**
+   * Worker message listener.
+   *
+   * @param message - The received message.
+   */
+  protected messageListener (message: MessageValue<Data>): void {
+    this.checkMessageWorkerId(message)
+    if (message.statistics != null) {
+      // Statistics message received
+      this.statistics = message.statistics
+    } else if (message.checkActive != null) {
+      // Check active message received
+      message.checkActive ? this.startCheckActive() : this.stopCheckActive()
+    } else if (message.taskId != null && message.data != null) {
+      // Task message received
+      this.run(message)
+    } else if (message.kill === true) {
+      // Kill message received
+      this.handleKillMessage(message)
+    }
+  }
+
+  /**
+   * Handles a kill message sent by the main worker.
+   *
+   * @param message - The kill message.
+   */
+  protected handleKillMessage (message: MessageValue<Data>): void {
+    this.stopCheckActive()
+    if (isAsyncFunction(this.opts.killHandler)) {
+      ;(this.opts.killHandler?.() as Promise<void>)
+        .then(() => {
+          this.sendToMainWorker({ kill: 'success', workerId: this.id })
+          return null
+        })
+        .catch(() => {
+          this.sendToMainWorker({ kill: 'failure', workerId: this.id })
+        })
+        .finally(() => {
+          this.emitDestroy()
+        })
+        .catch(EMPTY_FUNCTION)
+    } else {
+      try {
+        // eslint-disable-next-line @typescript-eslint/no-invalid-void-type
+        this.opts.killHandler?.() as void
+        this.sendToMainWorker({ kill: 'success', workerId: this.id })
+      } catch {
+        this.sendToMainWorker({ kill: 'failure', workerId: this.id })
+      } finally {
+        this.emitDestroy()
+      }
     }
-    return this.mainWorker
   }
 
   /**
-   * Send a message to the main worker.
+   * Check if the message worker id is set and matches the worker id.
    *
-   * @param message The response message.
+   * @param message - The message to check.
+   * @throws {@link https://nodejs.org/api/errors.html#class-error} If the message worker id is not set or does not match the worker id.
+   */
+  private checkMessageWorkerId (message: MessageValue<Data>): void {
+    if (message.workerId == null) {
+      throw new Error('Message worker id is not set')
+    } else if (message.workerId != null && message.workerId !== this.id) {
+      throw new Error(
+        `Message worker id ${message.workerId} does not match the worker id ${this.id}`
+      )
+    }
+  }
+
+  /**
+   * Starts the worker check active interval.
    */
-  protected abstract sendToMainWorker (message: MessageValue<Response>): void
+  private startCheckActive (): void {
+    this.lastTaskTimestamp = performance.now()
+    this.activeInterval = setInterval(
+      this.checkActive.bind(this),
+      (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME) / 2
+    )
+  }
 
   /**
-   * Check to see if the worker should be terminated, because its living too long.
+   * Stops the worker check active interval.
    */
-  protected checkAlive (): void {
+  private stopCheckActive (): void {
+    if (this.activeInterval != null) {
+      clearInterval(this.activeInterval)
+      delete this.activeInterval
+    }
+  }
+
+  /**
+   * Checks if the worker should be terminated, because its living too long.
+   */
+  private checkActive (): void {
     if (
-      Date.now() - this.lastTaskTimestamp >
+      performance.now() - this.lastTaskTimestamp >
       (this.opts.maxInactiveTime ?? DEFAULT_MAX_INACTIVE_TIME)
     ) {
-      this.sendToMainWorker({ kill: this.opts.killBehavior })
+      this.sendToMainWorker({ kill: this.opts.killBehavior, workerId: this.id })
     }
   }
 
   /**
-   * Handle an error and convert it to a string so it can be sent back to the main worker.
+   * Returns the main worker.
    *
-   * @param e The error raised by the worker.
-   * @returns Message of the error.
+   * @returns Reference to the main worker.
+   * @throws {@link https://nodejs.org/api/errors.html#class-error} If the main worker is not set.
+   */
+  protected getMainWorker (): MainWorker {
+    if (this.mainWorker == null) {
+      throw new Error('Main worker not set')
+    }
+    return this.mainWorker
+  }
+
+  /**
+   * Sends a message to main worker.
+   *
+   * @param message - The response message.
+   */
+  protected abstract sendToMainWorker (
+    message: MessageValue<Response, Data>
+  ): void
+
+  /**
+   * Sends the list of task function names to the main worker.
+   */
+  protected sendTaskFunctionsListToMainWorker (): void {
+    this.sendToMainWorker({
+      taskFunctions: this.listTaskFunctions(),
+      workerId: this.id
+    })
+  }
+
+  /**
+   * Handles an error and convert it to a string so it can be sent back to the main worker.
+   *
+   * @param e - The error raised by the worker.
+   * @returns The error message.
    */
   protected handleError (e: Error | string): string {
-    return e as string
+    return e instanceof Error ? e.message : e
   }
 
   /**
-   * Run the given function synchronously.
+   * Runs the given task.
    *
-   * @param fn Function that will be executed.
-   * @param value Input data for the given function.
+   * @param task - The task to execute.
+   * @throws {@link https://nodejs.org/api/errors.html#class-error} If the task function is not found.
    */
-  protected run (
-    fn: (data?: Data) => Response,
-    value: MessageValue<Data>
+  protected run (task: Task<Data>): void {
+    const { name, taskId, data } = task
+    const fn = this.taskFunctions.get(name ?? DEFAULT_TASK_NAME)
+    if (fn == null) {
+      this.sendToMainWorker({
+        taskError: {
+          name: name as string,
+          message: `Task function '${name as string}' not found`,
+          data
+        },
+        workerId: this.id,
+        taskId
+      })
+      return
+    }
+    if (isAsyncFunction(fn)) {
+      this.runInAsyncScope(this.runAsync.bind(this), this, fn, task)
+    } else {
+      this.runInAsyncScope(this.runSync.bind(this), this, fn, task)
+    }
+  }
+
+  /**
+   * Runs the given task function synchronously.
+   *
+   * @param fn - Task function that will be executed.
+   * @param task - Input data for the task function.
+   */
+  protected runSync (
+    fn: TaskSyncFunction<Data, Response>,
+    task: Task<Data>
   ): void {
+    const { name, taskId, data } = task
     try {
-      const res = fn(value.data)
-      this.sendToMainWorker({ data: res, id: value.id })
+      let taskPerformance = this.beginTaskPerformance(name)
+      const res = fn(data)
+      taskPerformance = this.endTaskPerformance(taskPerformance)
+      this.sendToMainWorker({
+        data: res,
+        taskPerformance,
+        workerId: this.id,
+        taskId
+      })
     } catch (e) {
-      const err = this.handleError(e as Error)
-      this.sendToMainWorker({ error: err, id: value.id })
+      const errorMessage = this.handleError(e as Error | string)
+      this.sendToMainWorker({
+        taskError: {
+          name: name as string,
+          message: errorMessage,
+          data
+        },
+        workerId: this.id,
+        taskId
+      })
     } finally {
-      this.lastTaskTimestamp = Date.now()
+      this.updateLastTaskTimestamp()
     }
   }
 
   /**
-   * Run the given function asynchronously.
+   * Runs the given task function asynchronously.
    *
-   * @param fn Function that will be executed.
-   * @param value Input data for the given function.
+   * @param fn - Task function that will be executed.
+   * @param task - Input data for the task function.
    */
   protected runAsync (
-    fn: (data?: Data) => Promise<Response>,
-    value: MessageValue<Data>
+    fn: TaskAsyncFunction<Data, Response>,
+    task: Task<Data>
   ): void {
-    fn(value.data)
-      .then(res => {
-        this.sendToMainWorker({ data: res, id: value.id })
+    const { name, taskId, data } = task
+    let taskPerformance = this.beginTaskPerformance(name)
+    fn(data)
+      .then((res) => {
+        taskPerformance = this.endTaskPerformance(taskPerformance)
+        this.sendToMainWorker({
+          data: res,
+          taskPerformance,
+          workerId: this.id,
+          taskId
+        })
         return null
       })
-      .catch(e => {
-        const err = this.handleError(e)
-        this.sendToMainWorker({ error: err, id: value.id })
+      .catch((e) => {
+        const errorMessage = this.handleError(e as Error | string)
+        this.sendToMainWorker({
+          taskError: {
+            name: name as string,
+            message: errorMessage,
+            data
+          },
+          workerId: this.id,
+          taskId
+        })
       })
       .finally(() => {
-        this.lastTaskTimestamp = Date.now()
+        this.updateLastTaskTimestamp()
       })
       .catch(EMPTY_FUNCTION)
   }
+
+  private beginTaskPerformance (name?: string): TaskPerformance {
+    this.checkStatistics()
+    return {
+      name: name ?? DEFAULT_TASK_NAME,
+      timestamp: performance.now(),
+      ...(this.statistics.elu && { elu: performance.eventLoopUtilization() })
+    }
+  }
+
+  private endTaskPerformance (
+    taskPerformance: TaskPerformance
+  ): TaskPerformance {
+    this.checkStatistics()
+    return {
+      ...taskPerformance,
+      ...(this.statistics.runTime && {
+        runTime: performance.now() - taskPerformance.timestamp
+      }),
+      ...(this.statistics.elu && {
+        elu: performance.eventLoopUtilization(taskPerformance.elu)
+      })
+    }
+  }
+
+  private checkStatistics (): void {
+    if (this.statistics == null) {
+      throw new Error('Performance statistics computation requirements not set')
+    }
+  }
+
+  private updateLastTaskTimestamp (): void {
+    if (this.activeInterval != null) {
+      this.lastTaskTimestamp = performance.now()
+    }
+  }
 }