X-Git-Url: https://git.piment-noir.org/?a=blobdiff_plain;f=src%2Fpools%2Fabstract-pool.ts;h=f3a8c1c6c9a7bb0a730b6b3b10dcd9a766b64e5e;hb=35cf1c03f8379b58e410cad57189912379ee7b36;hp=4f467bf4ebe869ac8215d8c5cc6aa1842edb7aad;hpb=f416c0987c6fe2d452de7e854b0d20f094448dd4;p=poolifier.git

diff --git a/src/pools/abstract-pool.ts b/src/pools/abstract-pool.ts
index 4f467bf4..f3a8c1c6 100644
--- a/src/pools/abstract-pool.ts
+++ b/src/pools/abstract-pool.ts
@@ -1,6 +1,21 @@
-import EventEmitter from 'events'
-import type { MessageValue } from '../utility-types'
-import type { IPool } from './pool'
+import type {
+  MessageValue,
+  PromiseWorkerResponseWrapper
+} from '../utility-types'
+import { EMPTY_FUNCTION } from '../utils'
+import { isKillBehavior, KillBehaviors } from '../worker/worker-options'
+import type { IPoolInternal } from './pool-internal'
+import { PoolEmitter, PoolType } from './pool-internal'
+import type { WorkerChoiceStrategy } from './selection-strategies'
+import {
+  WorkerChoiceStrategies,
+  WorkerChoiceStrategyContext
+} from './selection-strategies'
+
+/**
+ * Callback invoked if the worker has received a message.
+ */
+export type MessageHandler<Worker> = (this: Worker, m: unknown) => void
 
 /**
  * Callback invoked if the worker raised an error.
@@ -21,6 +36,13 @@ export type ExitHandler<Worker> = (this: Worker, code: number) => void
  * Basic interface that describes the minimum required implementation of listener events for a pool-worker.
  */
 export interface IWorker {
+  /**
+   * Register a listener to the message event.
+   *
+   * @param event `'message'`.
+   * @param handler The message handler.
+   */
+  on(event: 'message', handler: MessageHandler<this>): void
   /**
    * Register a listener to the error event.
    *
@@ -55,6 +77,10 @@ export interface IWorker {
  * Options for a poolifier pool.
  */
 export interface PoolOptions<Worker> {
+  /**
+   * A function that will listen for message event on each worker.
+   */
+  messageHandler?: MessageHandler<Worker>
   /**
    * A function that will listen for error event on each worker.
    */
@@ -68,112 +94,198 @@ export interface PoolOptions<Worker> {
    */
   exitHandler?: ExitHandler<Worker>
   /**
-   * This is just to avoid non-useful warning messages.
-   *
-   * Will be used to set `maxListeners` on event emitters (workers are event emitters).
+   * The work choice strategy to use in this pool.
+   */
+  workerChoiceStrategy?: WorkerChoiceStrategy
+  /**
+   * Pool events emission.
    *
-   * @default 1000
-   * @see [Node events emitter.setMaxListeners(n)](https://nodejs.org/api/events.html#events_emitter_setmaxlisteners_n)
+   * @default true
    */
-  maxTasks?: number
+  enableEvents?: boolean
 }
 
-/**
- * Internal poolifier pool emitter.
- */
-class PoolEmitter extends EventEmitter {}
-
 /**
  * Base class containing some shared logic for all poolifier pools.
  *
  * @template Worker Type of worker which manages this pool.
- * @template Data Type of data sent to the worker.
- * @template Response Type of response of execution.
+ * @template Data Type of data sent to the worker. This can only be serializable data.
+ * @template Response Type of response of execution. This can only be serializable data.
  */
 export abstract class AbstractPool<
   Worker extends IWorker,
   Data = unknown,
   Response = unknown
-> implements IPool<Data, Response> {
-  /**
-   * List of currently available workers.
-   */
+> implements IPoolInternal<Worker, Data, Response> {
+  /** @inheritdoc */
   public readonly workers: Worker[] = []
 
-  /**
-   * Index for the next worker.
-   */
-  public nextWorkerIndex: number = 0
-
-  /**
-   * The tasks map.
-   *
-   * - `key`: The `Worker`
-   * - `value`: Number of tasks currently in progress on the worker.
-   */
+  /** @inheritdoc */
   public readonly tasks: Map<Worker, number> = new Map<Worker, number>()
 
+  /** @inheritdoc */
+  public readonly emitter?: PoolEmitter
+
+  /** @inheritdoc */
+  public readonly max?: number
+
   /**
-   * Emitter on which events can be listened to.
+   * The promise map.
    *
-   * Events that can currently be listened to:
+   * - `key`: This is the message Id of each submitted task.
+   * - `value`: An object that contains the worker, the resolve function and the reject function.
    *
-   * - `'FullPool'`
+   * When we receive a message from the worker we get a map entry and resolve/reject the promise based on the message.
    */
-  public readonly emitter: PoolEmitter
+  protected promiseMap: Map<
+    number,
+    PromiseWorkerResponseWrapper<Worker, Response>
+  > = new Map<number, PromiseWorkerResponseWrapper<Worker, Response>>()
 
   /**
-   * ID of the next message.
+   * Id of the next message.
    */
   protected nextMessageId: number = 0
 
+  /**
+   * Worker choice strategy instance implementing the worker choice algorithm.
+   *
+   * Default to a strategy implementing a round robin algorithm.
+   */
+  protected workerChoiceStrategyContext: WorkerChoiceStrategyContext<
+    Worker,
+    Data,
+    Response
+  >
+
   /**
    * Constructs a new poolifier pool.
    *
    * @param numberOfWorkers Number of workers that this pool should manage.
    * @param filePath Path to the worker-file.
-   * @param opts Options for the pool. Default: `{ maxTasks: 1000 }`
+   * @param opts Options for the pool.
    */
   public constructor (
     public readonly numberOfWorkers: number,
     public readonly filePath: string,
-    public readonly opts: PoolOptions<Worker> = { maxTasks: 1000 }
+    public readonly opts: PoolOptions<Worker>
   ) {
     if (!this.isMain()) {
       throw new Error('Cannot start a pool from a worker!')
     }
-    // TODO christopher 2021-02-07: Improve this check e.g. with a pattern or blank check
-    if (!this.filePath) {
-      throw new Error('Please specify a file with a worker implementation')
-    }
+    this.checkNumberOfWorkers(this.numberOfWorkers)
+    this.checkFilePath(this.filePath)
+    this.checkPoolOptions(this.opts)
     this.setupHook()
 
     for (let i = 1; i <= this.numberOfWorkers; i++) {
       this.createAndSetupWorker()
     }
 
-    this.emitter = new PoolEmitter()
+    if (this.opts.enableEvents) {
+      this.emitter = new PoolEmitter()
+    }
+    this.workerChoiceStrategyContext = new WorkerChoiceStrategyContext(
+      this,
+      () => {
+        const workerCreated = this.createAndSetupWorker()
+        this.registerWorkerMessageListener(workerCreated, async message => {
+          const tasksInProgress = this.tasks.get(workerCreated)
+          if (
+            isKillBehavior(KillBehaviors.HARD, message.kill) ||
+            tasksInProgress === 0
+          ) {
+            // Kill received from the worker, means that no new tasks are submitted to that worker for a while ( > maxInactiveTime)
+            await this.destroyWorker(workerCreated)
+          }
+        })
+        return workerCreated
+      },
+      this.opts.workerChoiceStrategy
+    )
   }
 
-  /**
-   * Perform the task specified in the constructor with the data parameter.
-   *
-   * @param data The input for the specified task.
-   * @returns Promise that will be resolved when the task is successfully completed.
-   */
+  private checkFilePath (filePath: string): void {
+    if (!filePath) {
+      throw new Error('Please specify a file with a worker implementation')
+    }
+  }
+
+  private checkNumberOfWorkers (numberOfWorkers: number): void {
+    if (numberOfWorkers == null) {
+      throw new Error(
+        'Cannot instantiate a pool without specifying the number of workers'
+      )
+    } else if (!Number.isSafeInteger(numberOfWorkers)) {
+      throw new Error(
+        'Cannot instantiate a pool with a non integer number of workers'
+      )
+    } else if (numberOfWorkers < 0) {
+      throw new Error(
+        'Cannot instantiate a pool with a negative number of workers'
+      )
+    } else if (this.type === PoolType.FIXED && numberOfWorkers === 0) {
+      throw new Error('Cannot instantiate a fixed pool with no worker')
+    }
+  }
+
+  private checkPoolOptions (opts: PoolOptions<Worker>): void {
+    this.opts.workerChoiceStrategy =
+      opts.workerChoiceStrategy ?? WorkerChoiceStrategies.ROUND_ROBIN
+    this.opts.enableEvents = opts.enableEvents ?? true
+  }
+
+  /** @inheritdoc */
+  public abstract get type (): PoolType
+
+  /** @inheritdoc */
+  public get numberOfRunningTasks (): number {
+    return this.promiseMap.size
+  }
+
+  /** @inheritdoc */
+  public setWorkerChoiceStrategy (
+    workerChoiceStrategy: WorkerChoiceStrategy
+  ): void {
+    this.opts.workerChoiceStrategy = workerChoiceStrategy
+    this.workerChoiceStrategyContext.setWorkerChoiceStrategy(
+      workerChoiceStrategy
+    )
+  }
+
+  /** @inheritdoc */
+  public abstract get busy (): boolean
+
+  protected internalGetBusyStatus (): boolean {
+    return (
+      this.numberOfRunningTasks >= this.numberOfWorkers &&
+      this.findFreeTasksMapEntry() === false
+    )
+  }
+
+  /** @inheritdoc */
+  public findFreeTasksMapEntry (): [Worker, number] | false {
+    for (const [worker, numberOfTasks] of this.tasks) {
+      if (numberOfTasks === 0) {
+        // A worker is free, return the matching tasks map entry
+        return [worker, numberOfTasks]
+      }
+    }
+    return false
+  }
+
+  /** @inheritdoc */
   public execute (data: Data): Promise<Response> {
     // Configure worker to handle message with the specified task
     const worker = this.chooseWorker()
-    this.increaseWorkersTask(worker)
     const messageId = ++this.nextMessageId
     const res = this.internalExecute(worker, messageId)
+    this.checkAndEmitBusy()
     this.sendToWorker(worker, { data: data || ({} as Data), id: messageId })
     return res
   }
 
-  /**
-   * Shut down every current worker in this pool.
-   */
+  /** @inheritdoc */
   public async destroy (): Promise<void> {
     await Promise.all(this.workers.map(worker => this.destroyWorker(worker)))
   }
@@ -199,7 +311,7 @@ export abstract class AbstractPool<
   protected abstract isMain (): boolean
 
   /**
-   * Increase the number of tasks that the given workers has done.
+   * Increase the number of tasks that the given worker has applied.
    *
    * @param worker Worker whose tasks are increased.
    */
@@ -208,7 +320,7 @@ export abstract class AbstractPool<
   }
 
   /**
-   * Decrease the number of tasks that the given workers has done.
+   * Decrease the number of tasks that the given worker has applied.
    *
    * @param worker Worker whose tasks are decreased.
    */
@@ -217,12 +329,12 @@ export abstract class AbstractPool<
   }
 
   /**
-   * Step the number of tasks that the given workers has done.
+   * Step the number of tasks that the given worker has applied.
    *
    * @param worker Worker whose tasks are set.
    * @param step Worker number of tasks step.
    */
-  private stepWorkerNumberOfTasks (worker: Worker, step: number) {
+  private stepWorkerNumberOfTasks (worker: Worker, step: number): void {
     const numberOfTasksInProgress = this.tasks.get(worker)
     if (numberOfTasksInProgress !== undefined) {
       this.tasks.set(worker, numberOfTasksInProgress + step)
@@ -251,12 +363,7 @@ export abstract class AbstractPool<
    * @returns Worker.
    */
   protected chooseWorker (): Worker {
-    const chosenWorker = this.workers[this.nextWorkerIndex]
-    this.nextWorkerIndex =
-      this.workers.length - 1 === this.nextWorkerIndex
-        ? 0
-        : this.nextWorkerIndex + 1
-    return chosenWorker
+    return this.workerChoiceStrategyContext.execute()
   }
 
   /**
@@ -270,28 +377,23 @@ export abstract class AbstractPool<
     message: MessageValue<Data>
   ): void
 
+  /**
+   * Register a listener callback on a given worker.
+   *
+   * @param worker A worker.
+   * @param listener A message listener callback.
+   */
   protected abstract registerWorkerMessageListener<
     Message extends Data | Response
   > (worker: Worker, listener: (message: MessageValue<Message>) => void): void
 
-  protected abstract unregisterWorkerMessageListener<
-    Message extends Data | Response
-  > (worker: Worker, listener: (message: MessageValue<Message>) => void): void
-
   protected internalExecute (
     worker: Worker,
     messageId: number
   ): Promise<Response> {
-    return new Promise((resolve, reject) => {
-      const listener: (message: MessageValue<Response>) => void = message => {
-        if (message.id === messageId) {
-          this.unregisterWorkerMessageListener(worker, listener)
-          this.decreaseWorkersTasks(worker)
-          if (message.error) reject(message.error)
-          else resolve(message.data as Response)
-        }
-      }
-      this.registerWorkerMessageListener(worker, listener)
+    this.increaseWorkersTask(worker)
+    return new Promise<Response>((resolve, reject) => {
+      this.promiseMap.set(messageId, { resolve, reject, worker })
     })
   }
 
@@ -317,9 +419,10 @@ export abstract class AbstractPool<
   protected createAndSetupWorker (): Worker {
     const worker: Worker = this.createWorker()
 
-    worker.on('error', this.opts.errorHandler ?? (() => {}))
-    worker.on('online', this.opts.onlineHandler ?? (() => {}))
-    worker.on('exit', this.opts.exitHandler ?? (() => {}))
+    worker.on('message', this.opts.messageHandler ?? EMPTY_FUNCTION)
+    worker.on('error', this.opts.errorHandler ?? EMPTY_FUNCTION)
+    worker.on('online', this.opts.onlineHandler ?? EMPTY_FUNCTION)
+    worker.on('exit', this.opts.exitHandler ?? EMPTY_FUNCTION)
     worker.once('exit', () => this.removeWorker(worker))
 
     this.workers.push(worker)
@@ -331,4 +434,29 @@ export abstract class AbstractPool<
 
     return worker
   }
+
+  /**
+   * This function is the listener registered for each worker.
+   *
+   * @returns The listener function to execute when a message is sent from a worker.
+   */
+  protected workerListener (): (message: MessageValue<Response>) => void {
+    return message => {
+      if (message.id) {
+        const value = this.promiseMap.get(message.id)
+        if (value) {
+          this.decreaseWorkersTasks(value.worker)
+          if (message.error) value.reject(message.error)
+          else value.resolve(message.data as Response)
+          this.promiseMap.delete(message.id)
+        }
+      }
+    }
+  }
+
+  private checkAndEmitBusy (): void {
+    if (this.opts.enableEvents && this.busy) {
+      this.emitter?.emit('busy')
+    }
+  }
 }