refactor: untangle worker choosing code from worker creation code
[poolifier.git] / src / pools / abstract-pool.ts
index c1e6ddc09a9a41ce18d34ced63a162225f66818f..2e033fc1614c0a778c85569d98cb8e014f010bcc 100644 (file)
@@ -25,10 +25,10 @@ export abstract class AbstractPool<
   Data = unknown,
   Response = unknown
 > implements IPoolInternal<Worker, Data, Response> {
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public readonly workers: Array<WorkerType<Worker>> = []
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public readonly emitter?: PoolEmitter
 
   /**
@@ -45,9 +45,9 @@ export abstract class AbstractPool<
   > = 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,
@@ -76,6 +76,7 @@ export abstract class AbstractPool<
 
     this.chooseWorker.bind(this)
     this.internalExecute.bind(this)
+    this.checkAndEmitFull.bind(this)
     this.checkAndEmitBusy.bind(this)
     this.sendToWorker.bind(this)
 
@@ -92,23 +93,7 @@ export abstract class AbstractPool<
     Worker,
     Data,
     Response
-    >(
-      this,
-      () => {
-        const createdWorker = this.createAndSetupWorker()
-        this.registerWorkerMessageListener(createdWorker, message => {
-          if (
-            isKillBehavior(KillBehaviors.HARD, message.kill) ||
-            this.getWorkerTasksUsage(createdWorker)?.running === 0
-          ) {
-            // Kill received from the worker, means that no new tasks are submitted to that worker for a while ( > maxInactiveTime)
-            void this.destroyWorker(createdWorker)
-          }
-        })
-        return this.getWorkerKey(createdWorker)
-      },
-      this.opts.workerChoiceStrategy
-    )
+    >(this, this.opts.workerChoiceStrategy)
   }
 
   private checkFilePath (filePath: string): void {
@@ -141,14 +126,23 @@ export abstract class AbstractPool<
   private checkPoolOptions (opts: PoolOptions<Worker>): void {
     this.opts.workerChoiceStrategy =
       opts.workerChoiceStrategy ?? WorkerChoiceStrategies.ROUND_ROBIN
+    if (
+      !Object.values(WorkerChoiceStrategies).includes(
+        this.opts.workerChoiceStrategy
+      )
+    ) {
+      throw new Error(
+        `Invalid worker choice strategy '${this.opts.workerChoiceStrategy}'`
+      )
+    }
     this.opts.enableEvents = opts.enableEvents ?? true
   }
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public abstract get type (): PoolType
 
   /**
-   * Number of tasks concurrently running.
+   * Number of tasks concurrently running in the pool.
    */
   private get numberOfRunningTasks (): number {
     return this.promiseResponseMap.size
@@ -164,7 +158,7 @@ export abstract class AbstractPool<
     return this.workers.findIndex(workerItem => workerItem.worker === worker)
   }
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public setWorkerChoiceStrategy (
     workerChoiceStrategy: WorkerChoiceStrategy
   ): void {
@@ -179,15 +173,14 @@ export abstract class AbstractPool<
       })
     }
     this.workerChoiceStrategyContext.setWorkerChoiceStrategy(
-      this,
       workerChoiceStrategy
     )
   }
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public abstract get full (): boolean
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public abstract get busy (): boolean
 
   protected internalBusy (): boolean {
@@ -197,18 +190,19 @@ export abstract class AbstractPool<
     )
   }
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public findFreeWorkerKey (): number {
     return this.workers.findIndex(workerItem => {
       return workerItem.tasksUsage.running === 0
     })
   }
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public async execute (data: Data): Promise<Response> {
     const [workerKey, worker] = this.chooseWorker()
     const messageId = crypto.randomUUID()
     const res = this.internalExecute(workerKey, worker, messageId)
+    this.checkAndEmitFull()
     this.checkAndEmitBusy()
     this.sendToWorker(worker, {
       // eslint-disable-next-line @typescript-eslint/consistent-type-assertions
@@ -219,7 +213,7 @@ export abstract class AbstractPool<
     return res
   }
 
-  /** {@inheritDoc} */
+  /** @inheritDoc */
   public async destroy (): Promise<void> {
     await Promise.all(
       this.workers.map(async workerItem => {
@@ -229,7 +223,7 @@ export abstract class AbstractPool<
   }
 
   /**
-   * Shutdowns given worker.
+   * Shutdowns given worker in the pool.
    *
    * @param worker - A worker within `workers`.
    */
@@ -238,9 +232,12 @@ 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
   }
 
   /**
@@ -287,26 +284,34 @@ export abstract class AbstractPool<
     }
   }
 
-  /**
-   * 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)
-  }
-
   /**
    * 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 key, worker].
    */
   protected chooseWorker (): [number, Worker] {
-    const workerKey = this.workerChoiceStrategyContext.execute()
+    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) ||
+          this.getWorkerTasksUsage(createdWorker)?.running === 0
+        ) {
+          // Kill 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]
   }
 
@@ -342,6 +347,7 @@ 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
 
@@ -381,9 +387,9 @@ export abstract class AbstractPool<
    */
   protected workerListener (): (message: MessageValue<Response>) => void {
     return message => {
-      if (message.id !== undefined) {
+      if (message.id != null) {
         const promiseResponse = this.promiseResponseMap.get(message.id)
-        if (promiseResponse !== undefined) {
+        if (promiseResponse != null) {
           if (message.error != null) {
             promiseResponse.reject(message.error)
           } else {
@@ -413,8 +419,18 @@ export abstract class AbstractPool<
     }
   }
 
+  private checkAndEmitFull (): void {
+    if (
+      this.type === PoolType.DYNAMIC &&
+      this.opts.enableEvents === true &&
+      this.full
+    ) {
+      this.emitter?.emit('full')
+    }
+  }
+
   /**
-   * Gets worker tasks usage.
+   * Gets the given worker tasks usage in the pool.
    *
    * @param worker - The worker.
    * @returns The worker tasks usage.
@@ -428,7 +444,7 @@ export abstract class AbstractPool<
   }
 
   /**
-   * Pushes the given worker.
+   * Pushes the given worker in the pool.
    *
    * @param worker - The worker.
    * @param tasksUsage - The worker tasks usage.
@@ -441,7 +457,7 @@ export abstract class AbstractPool<
   }
 
   /**
-   * Sets the given worker.
+   * Sets the given worker in the pool.
    *
    * @param workerKey - The worker key.
    * @param worker - The worker.
@@ -457,4 +473,15 @@ export abstract class AbstractPool<
       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)
+  }
 }