refactor: add PoolEvents/PoolEvent types
[poolifier.git] / src / pools / abstract-pool.ts
index 2c4559a34dd1f5079f7ce7d0e8efaf70b979372e..9ac81ce56558ec76fbd66d7789b2399e910a2e69 100644 (file)
@@ -1,11 +1,8 @@
 import crypto from 'node:crypto'
-import type {
-  MessageValue,
-  PromiseWorkerResponseWrapper
-} from '../utility-types'
+import type { MessageValue, PromiseResponseWrapper } from '../utility-types'
 import { EMPTY_FUNCTION } from '../utils'
 import { KillBehaviors, isKillBehavior } from '../worker/worker-options'
-import type { PoolOptions } from './pool'
+import { PoolEvents, type PoolOptions } from './pool'
 import { PoolEmitter } from './pool'
 import type { IPoolInternal, TasksUsage, WorkerType } from './pool-internal'
 import { PoolType } from './pool-internal'
@@ -28,37 +25,29 @@ export abstract class AbstractPool<
   Data = unknown,
   Response = unknown
 > implements IPoolInternal<Worker, Data, Response> {
-  /** {@inheritDoc} */
-  public readonly workers: Map<number, WorkerType<Worker>> = new Map<
-  number,
-  WorkerType<Worker>
-  >()
+  /** @inheritDoc */
+  public readonly workers: Array<WorkerType<Worker>> = []
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public readonly emitter?: PoolEmitter
 
   /**
-   * Id of the next worker.
-   */
-  protected nextWorkerId: number = 0
-
-  /**
-   * The promise map.
+   * The promise response map.
    *
-   * - `key`: This is the message id of each submitted task.
-   * - `value`: An object that contains the worker, the resolve function and the reject function.
+   * - `key`: The message id of each submitted task.
+   * - `value`: An object that contains the worker, the promise resolve and reject callbacks.
    *
-   * When we receive a message from the worker we get a map entry and resolve/reject the promise based on the message.
+   * When we receive a message from the worker we get a map entry with the promise resolve/reject bound to the message.
    */
-  protected promiseMap: Map<
+  protected promiseResponseMap: Map<
   string,
-  PromiseWorkerResponseWrapper<Worker, Response>
-  > = new Map<string, PromiseWorkerResponseWrapper<Worker, Response>>()
+  PromiseResponseWrapper<Worker, Response>
+  > = new Map<string, PromiseResponseWrapper<Worker, Response>>()
 
   /**
-   * Worker choice strategy instance implementing the worker choice algorithm.
+   * Worker choice strategy context referencing a worker choice algorithm implementation.
    *
-   * Default to a strategy implementing a round robin algorithm.
+   * Default to a round robin algorithm.
    */
   protected workerChoiceStrategyContext: WorkerChoiceStrategyContext<
   Worker,
@@ -84,6 +73,13 @@ export abstract class AbstractPool<
     this.checkNumberOfWorkers(this.numberOfWorkers)
     this.checkFilePath(this.filePath)
     this.checkPoolOptions(this.opts)
+
+    this.chooseWorker.bind(this)
+    this.internalExecute.bind(this)
+    this.checkAndEmitFull.bind(this)
+    this.checkAndEmitBusy.bind(this)
+    this.sendToWorker.bind(this)
+
     this.setupHook()
 
     for (let i = 1; i <= this.numberOfWorkers; i++) {
@@ -93,23 +89,11 @@ export abstract class AbstractPool<
     if (this.opts.enableEvents === true) {
       this.emitter = new PoolEmitter()
     }
-    this.workerChoiceStrategyContext = new WorkerChoiceStrategyContext(
-      this,
-      () => {
-        const workerCreated = this.createAndSetupWorker()
-        this.registerWorkerMessageListener(workerCreated, message => {
-          if (
-            isKillBehavior(KillBehaviors.HARD, message.kill) ||
-            this.getWorkerTasksUsage(workerCreated)?.running === 0
-          ) {
-            // Kill received from the worker, means that no new tasks are submitted to that worker for a while ( > maxInactiveTime)
-            void this.destroyWorker(workerCreated)
-          }
-        })
-        return workerCreated
-      },
-      this.opts.workerChoiceStrategy
-    )
+    this.workerChoiceStrategyContext = new WorkerChoiceStrategyContext<
+    Worker,
+    Data,
+    Response
+    >(this, this.opts.workerChoiceStrategy)
   }
 
   private checkFilePath (filePath: string): void {
@@ -142,38 +126,53 @@ export abstract class AbstractPool<
   private checkPoolOptions (opts: PoolOptions<Worker>): void {
     this.opts.workerChoiceStrategy =
       opts.workerChoiceStrategy ?? WorkerChoiceStrategies.ROUND_ROBIN
+    this.checkValidWorkerChoiceStrategy(this.opts.workerChoiceStrategy)
     this.opts.enableEvents = opts.enableEvents ?? true
   }
 
-  /** {@inheritDoc} */
+  private checkValidWorkerChoiceStrategy (
+    workerChoiceStrategy: WorkerChoiceStrategy
+  ): void {
+    if (!Object.values(WorkerChoiceStrategies).includes(workerChoiceStrategy)) {
+      throw new Error(
+        `Invalid worker choice strategy '${workerChoiceStrategy}'`
+      )
+    }
+  }
+
+  /** @inheritDoc */
   public abstract get type (): PoolType
 
-  /** {@inheritDoc} */
-  public get numberOfRunningTasks (): number {
-    return this.promiseMap.size
+  /**
+   * Number of tasks concurrently running in the pool.
+   */
+  private get numberOfRunningTasks (): number {
+    return this.promiseResponseMap.size
   }
 
   /**
    * Gets the given worker key.
    *
    * @param worker - The worker.
-   * @returns The worker key.
+   * @returns The worker key if the worker is found in the pool, `-1` otherwise.
    */
-  private getWorkerKey (worker: Worker): number | undefined {
-    return [...this.workers].find(([, value]) => value.worker === worker)?.[0]
+  private getWorkerKey (worker: Worker): number {
+    return this.workers.findIndex(workerItem => workerItem.worker === worker)
   }
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public setWorkerChoiceStrategy (
     workerChoiceStrategy: WorkerChoiceStrategy
   ): void {
+    this.checkValidWorkerChoiceStrategy(workerChoiceStrategy)
     this.opts.workerChoiceStrategy = workerChoiceStrategy
-    for (const [key, value] of this.workers) {
-      this.setWorker(key, value.worker, {
+    for (const [index, workerItem] of this.workers.entries()) {
+      this.setWorker(index, workerItem.worker, {
         run: 0,
         running: 0,
         runTime: 0,
-        avgRunTime: 0
+        avgRunTime: 0,
+        error: 0
       })
     }
     this.workerChoiceStrategyContext.setWorkerChoiceStrategy(
@@ -181,32 +180,32 @@ export abstract class AbstractPool<
     )
   }
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
+  public abstract get full (): boolean
+
+  /** @inheritDoc */
   public abstract get busy (): boolean
 
-  protected internalGetBusyStatus (): boolean {
+  protected internalBusy (): boolean {
     return (
       this.numberOfRunningTasks >= this.numberOfWorkers &&
-      this.findFreeWorker() === false
+      this.findFreeWorkerKey() === -1
     )
   }
 
-  /** {@inheritDoc} */
-  public findFreeWorker (): Worker | false {
-    for (const value of this.workers.values()) {
-      if (value.tasksUsage.running === 0) {
-        // A worker is free, return the matching worker
-        return value.worker
-      }
-    }
-    return false
+  /** @inheritDoc */
+  public findFreeWorkerKey (): number {
+    return this.workers.findIndex(workerItem => {
+      return workerItem.tasksUsage.running === 0
+    })
   }
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public async execute (data: Data): Promise<Response> {
-    const worker = this.chooseWorker()
+    const [workerKey, worker] = this.chooseWorker()
     const messageId = crypto.randomUUID()
-    const res = this.internalExecute(worker, messageId)
+    const res = this.internalExecute(workerKey, worker, messageId)
+    this.checkAndEmitFull()
     this.checkAndEmitBusy()
     this.sendToWorker(worker, {
       // eslint-disable-next-line @typescript-eslint/consistent-type-assertions
@@ -217,17 +216,17 @@ export abstract class AbstractPool<
     return res
   }
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public async destroy (): Promise<void> {
     await Promise.all(
-      [...this.workers].map(async ([, value]) => {
-        await this.destroyWorker(value.worker)
+      this.workers.map(async workerItem => {
+        await this.destroyWorker(workerItem.worker)
       })
     )
   }
 
   /**
-   * Shutdowns given worker.
+   * Shutdowns given worker in the pool.
    *
    * @param worker - A worker within `workers`.
    */
@@ -236,9 +235,12 @@ export abstract class AbstractPool<
   /**
    * Setup hook that can be overridden by a Poolifier pool implementation
    * to run code before workers are created in the abstract constructor.
+   * Can be overridden
+   *
+   * @virtual
    */
   protected setupHook (): void {
-    // Can be overridden
+    // Intentionally empty
   }
 
   /**
@@ -250,59 +252,71 @@ export abstract class AbstractPool<
    * Hook executed before the worker task promise resolution.
    * Can be overridden.
    *
-   * @param worker - The worker.
+   * @param workerKey - The worker key.
    */
-  protected beforePromiseWorkerResponseHook (worker: Worker): void {
-    ++(this.getWorkerTasksUsage(worker) as TasksUsage).running
+  protected beforePromiseResponseHook (workerKey: number): void {
+    ++this.workers[workerKey].tasksUsage.running
   }
 
   /**
    * Hook executed after the worker task promise resolution.
    * Can be overridden.
    *
+   * @param worker - The worker.
    * @param message - The received message.
-   * @param promise - The Promise response.
    */
-  protected afterPromiseWorkerResponseHook (
-    message: MessageValue<Response>,
-    promise: PromiseWorkerResponseWrapper<Worker, Response>
+  protected afterPromiseResponseHook (
+    worker: Worker,
+    message: MessageValue<Response>
   ): void {
-    const workerTasksUsage = this.getWorkerTasksUsage(
-      promise.worker
-    ) as TasksUsage
+    const workerTasksUsage = this.getWorkerTasksUsage(worker) as TasksUsage
     --workerTasksUsage.running
     ++workerTasksUsage.run
-    if (
-      this.workerChoiceStrategyContext.getWorkerChoiceStrategy()
-        .requiredStatistics.runTime
-    ) {
-      workerTasksUsage.runTime += message.taskRunTime ?? 0
-      if (workerTasksUsage.run !== 0) {
+    if (message.error != null) {
+      ++workerTasksUsage.error
+    }
+    if (this.workerChoiceStrategyContext.getRequiredStatistics().runTime) {
+      workerTasksUsage.runTime += message.runTime ?? 0
+      if (
+        this.workerChoiceStrategyContext.getRequiredStatistics().avgRunTime &&
+        workerTasksUsage.run !== 0
+      ) {
         workerTasksUsage.avgRunTime =
           workerTasksUsage.runTime / workerTasksUsage.run
       }
     }
   }
 
-  /**
-   * Removes the given worker from the pool.
-   *
-   * @param worker - The worker that will be removed.
-   */
-  protected removeWorker (worker: Worker): void {
-    this.workers.delete(this.getWorkerKey(worker) as number)
-    --this.nextWorkerId
-  }
-
   /**
    * Chooses a worker for the next task.
    *
-   * The default implementation uses a round robin algorithm to distribute the load.
+   * The default uses a round robin algorithm to distribute the load.
    *
-   * @returns Worker.
+   * @returns [worker key, worker].
    */
-  protected chooseWorker (): Worker {
-    return this.workerChoiceStrategyContext.execute()
+  protected chooseWorker (): [number, Worker] {
+    let workerKey: number
+    if (
+      this.type === PoolType.DYNAMIC &&
+      !this.full &&
+      this.findFreeWorkerKey() === -1
+    ) {
+      const createdWorker = this.createAndSetupWorker()
+      this.registerWorkerMessageListener(createdWorker, message => {
+        if (
+          isKillBehavior(KillBehaviors.HARD, message.kill) ||
+          (message.kill != null &&
+            this.getWorkerTasksUsage(createdWorker)?.running === 0)
+        ) {
+          // Kill message received from the worker, means that no new tasks are submitted to that worker for a while ( > maxInactiveTime)
+          void this.destroyWorker(createdWorker)
+        }
+      })
+      workerKey = this.getWorkerKey(createdWorker)
+    } else {
+      workerKey = this.workerChoiceStrategyContext.execute()
+    }
+    return [workerKey, this.workers[workerKey].worker]
   }
 
   /**
@@ -337,6 +351,7 @@ export abstract class AbstractPool<
    * Can be used to update the `maxListeners` or binding the `main-worker`\<-\>`worker` connection if not bind by default.
    *
    * @param worker - The newly created worker.
+   * @virtual
    */
   protected abstract afterWorkerSetup (worker: Worker): void
 
@@ -356,13 +371,13 @@ export abstract class AbstractPool<
       this.removeWorker(worker)
     })
 
-    this.setWorker(this.nextWorkerId, worker, {
+    this.pushWorker(worker, {
       run: 0,
       running: 0,
       runTime: 0,
-      avgRunTime: 0
+      avgRunTime: 0,
+      error: 0
     })
-    ++this.nextWorkerId
 
     this.afterWorkerSetup(worker)
 
@@ -376,49 +391,78 @@ export abstract class AbstractPool<
    */
   protected workerListener (): (message: MessageValue<Response>) => void {
     return message => {
-      if (message.id !== undefined) {
-        const promise = this.promiseMap.get(message.id)
-        if (promise !== undefined) {
+      if (message.id != null) {
+        // Task response received
+        const promiseResponse = this.promiseResponseMap.get(message.id)
+        if (promiseResponse != null) {
           if (message.error != null) {
-            promise.reject(message.error)
+            promiseResponse.reject(message.error)
           } else {
-            promise.resolve(message.data as Response)
+            promiseResponse.resolve(message.data as Response)
           }
-          this.afterPromiseWorkerResponseHook(message, promise)
-          this.promiseMap.delete(message.id)
+          this.afterPromiseResponseHook(promiseResponse.worker, message)
+          this.promiseResponseMap.delete(message.id)
         }
       }
     }
   }
 
   private async internalExecute (
+    workerKey: number,
     worker: Worker,
     messageId: string
   ): Promise<Response> {
-    this.beforePromiseWorkerResponseHook(worker)
+    this.beforePromiseResponseHook(workerKey)
     return await new Promise<Response>((resolve, reject) => {
-      this.promiseMap.set(messageId, { resolve, reject, worker })
+      this.promiseResponseMap.set(messageId, { resolve, reject, worker })
     })
   }
 
   private checkAndEmitBusy (): void {
     if (this.opts.enableEvents === true && this.busy) {
-      this.emitter?.emit('busy')
+      this.emitter?.emit(PoolEvents.busy)
+    }
+  }
+
+  private checkAndEmitFull (): void {
+    if (
+      this.type === PoolType.DYNAMIC &&
+      this.opts.enableEvents === true &&
+      this.full
+    ) {
+      this.emitter?.emit(PoolEvents.full)
     }
   }
 
-  /** {@inheritDoc} */
-  public getWorkerTasksUsage (worker: Worker): TasksUsage | undefined {
+  /**
+   * Gets the given worker tasks usage in the pool.
+   *
+   * @param worker - The worker.
+   * @returns The worker tasks usage.
+   */
+  private getWorkerTasksUsage (worker: Worker): TasksUsage | undefined {
     const workerKey = this.getWorkerKey(worker)
-    if (workerKey !== undefined) {
-      const workerEntry = this.workers.get(workerKey) as WorkerType<Worker>
-      return workerEntry.tasksUsage
+    if (workerKey !== -1) {
+      return this.workers[workerKey].tasksUsage
     }
     throw new Error('Worker could not be found in the pool')
   }
 
   /**
-   * Sets the given worker.
+   * Pushes the given worker in the pool.
+   *
+   * @param worker - The worker.
+   * @param tasksUsage - The worker tasks usage.
+   */
+  private pushWorker (worker: Worker, tasksUsage: TasksUsage): void {
+    this.workers.push({
+      worker,
+      tasksUsage
+    })
+  }
+
+  /**
+   * Sets the given worker in the pool.
    *
    * @param workerKey - The worker key.
    * @param worker - The worker.
@@ -429,9 +473,20 @@ export abstract class AbstractPool<
     worker: Worker,
     tasksUsage: TasksUsage
   ): void {
-    this.workers.set(workerKey, {
+    this.workers[workerKey] = {
       worker,
       tasksUsage
-    })
+    }
+  }
+
+  /**
+   * Removes the given worker from the pool.
+   *
+   * @param worker - The worker that will be removed.
+   */
+  protected removeWorker (worker: Worker): void {
+    const workerKey = this.getWorkerKey(worker)
+    this.workers.splice(workerKey, 1)
+    this.workerChoiceStrategyContext.remove(workerKey)
   }
 }