X-Git-Url: https://git.piment-noir.org/?a=blobdiff_plain;ds=sidebyside;f=src%2Fpools%2Fabstract-pool.ts;h=38187edc41b462fc9944744f3cfbce16d9c595e4;hb=b98ec2e690d5ba33a13a2848b0f1315b885c2f4b;hp=d169afadb1df863cfbf8f37f1dbd623b211f3b07;hpb=c97c7edb14ea0699cd82bce5d0ffe50ae26af667;p=poolifier.git

diff --git a/src/pools/abstract-pool.ts b/src/pools/abstract-pool.ts
index d169afad..38187edc 100644
--- a/src/pools/abstract-pool.ts
+++ b/src/pools/abstract-pool.ts
@@ -1,17 +1,74 @@
-import EventEmitter from 'events'
-import type { MessageValue } from '../utility-types'
-import type { IPool } from './pool'
+import type {
+  MessageValue,
+  PromiseWorkerResponseWrapper
+} from '../utility-types'
+import type { IPoolInternal } from './pool-internal'
+import { PoolEmitter } from './pool-internal'
+import type { WorkerChoiceStrategy } from './selection-strategies'
+import {
+  WorkerChoiceStrategies,
+  WorkerChoiceStrategyContext
+} from './selection-strategies'
 
+/**
+ * An intentional empty function.
+ */
+const EMPTY_FUNCTION: () => void = () => {
+  /* Intentionally empty */
+}
+
+/**
+ * Callback invoked if the worker raised an error.
+ */
 export type ErrorHandler<Worker> = (this: Worker, e: Error) => void
+
+/**
+ * Callback invoked when the worker has started successfully.
+ */
 export type OnlineHandler<Worker> = (this: Worker) => void
+
+/**
+ * Callback invoked when the worker exits successfully.
+ */
 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 error event.
+   *
+   * @param event `'error'`.
+   * @param handler The error handler.
+   */
   on(event: 'error', handler: ErrorHandler<this>): void
+  /**
+   * Register a listener to the online event.
+   *
+   * @param event `'online'`.
+   * @param handler The online handler.
+   */
   on(event: 'online', handler: OnlineHandler<this>): void
+  /**
+   * Register a listener to the exit event.
+   *
+   * @param event `'exit'`.
+   * @param handler The exit handler.
+   */
   on(event: 'exit', handler: ExitHandler<this>): void
+  /**
+   * Register a listener to the exit event that will only performed once.
+   *
+   * @param event `'exit'`.
+   * @param handler The exit handler.
+   */
+  once(event: 'exit', handler: ExitHandler<this>): void
 }
 
+/**
+ * Options for a poolifier pool.
+ */
 export interface PoolOptions<Worker> {
   /**
    * A function that will listen for error event on each worker.
@@ -26,148 +83,302 @@ export interface PoolOptions<Worker> {
    */
   exitHandler?: ExitHandler<Worker>
   /**
-   * This is just to avoid not useful warnings message, is used to set `maxListeners` on event emitters (workers are event emitters).
+   * This is just to avoid non-useful warning messages.
+   *
+   * Will be used to set `maxListeners` on event emitters (workers are event emitters).
    *
    * @default 1000
+   * @see [Node events emitter.setMaxListeners(n)](https://nodejs.org/api/events.html#events_emitter_setmaxlisteners_n)
    */
   maxTasks?: number
+  /**
+   * The work choice strategy to use in this pool.
+   */
+  workerChoiceStrategy?: WorkerChoiceStrategy
 }
 
-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. 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,
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  Data = any,
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  Response = any
-> implements IPool<Data, Response> {
-  public readonly workers: Worker[] = []
-  public nextWorker: number = 0
-
+  Data = unknown,
+  Response = unknown
+> implements IPoolInternal<Worker, Data, Response> {
   /**
-   * `workerId` as key and an integer value
+   * The promise 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.
+   *
+   * When we receive a message from the worker we get a map entry and resolve/reject the promise based on the message.
    */
+  protected promiseMap: Map<
+    number,
+    PromiseWorkerResponseWrapper<Worker, Response>
+  > = new Map<number, PromiseWorkerResponseWrapper<Worker, Response>>()
+
+  /** @inheritdoc */
+  public readonly workers: Worker[] = []
+
+  /** @inheritdoc */
   public readonly tasks: Map<Worker, number> = new Map<Worker, number>()
 
+  /** @inheritdoc */
   public readonly emitter: PoolEmitter
 
-  protected id: number = 0
+  /**
+   * 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 }`
+   */
   public constructor (
-    public readonly numWorkers: number,
+    public readonly numberOfWorkers: number,
     public readonly filePath: string,
     public readonly opts: PoolOptions<Worker> = { maxTasks: 1000 }
   ) {
     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.setupHook()
 
-    for (let i = 1; i <= this.numWorkers; i++) {
-      this.internalNewWorker()
+    for (let i = 1; i <= this.numberOfWorkers; i++) {
+      this.createAndSetupWorker()
     }
 
     this.emitter = new PoolEmitter()
+    this.workerChoiceStrategyContext = new WorkerChoiceStrategyContext(
+      this,
+      opts.workerChoiceStrategy ?? WorkerChoiceStrategies.ROUND_ROBIN
+    )
+  }
+
+  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.isDynamic() && numberOfWorkers === 0) {
+      throw new Error('Cannot instantiate a fixed pool with no worker')
+    }
   }
 
+  /** @inheritdoc */
+  public isDynamic (): boolean {
+    return false
+  }
+
+  /** @inheritdoc */
+  public setWorkerChoiceStrategy (
+    workerChoiceStrategy: WorkerChoiceStrategy
+  ): void {
+    this.opts.workerChoiceStrategy = workerChoiceStrategy
+    this.workerChoiceStrategyContext.setWorkerChoiceStrategy(
+      workerChoiceStrategy
+    )
+  }
+
+  /** @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.sendToWorker(worker, { data: data || ({} as Data), id: messageId })
+    return res
+  }
+
+  /** @inheritdoc */
+  public async destroy (): Promise<void> {
+    await Promise.all(this.workers.map(worker => this.destroyWorker(worker)))
+  }
+
+  /** @inheritdoc */
+  public abstract destroyWorker (worker: Worker): void | Promise<void>
+
+  /**
+   * Setup hook that can be overridden by a Poolifier pool implementation
+   * to run code before workers are created in the abstract constructor.
+   */
   protected setupHook (): void {
     // Can be overridden
   }
 
+  /**
+   * Should return whether the worker is the main worker or not.
+   */
   protected abstract isMain (): boolean
 
-  public async destroy (): Promise<void> {
-    for (const worker of this.workers) {
-      await this.destroyWorker(worker)
-    }
+  /**
+   * Increase the number of tasks that the given workers has done.
+   *
+   * @param worker Worker whose tasks are increased.
+   */
+  protected increaseWorkersTask (worker: Worker): void {
+    this.stepWorkerNumberOfTasks(worker, 1)
   }
 
-  protected abstract destroyWorker (worker: Worker): void | Promise<void>
-
-  protected abstract sendToWorker (
-    worker: Worker,
-    message: MessageValue<Data>
-  ): void
+  /**
+   * Decrease the number of tasks that the given workers has done.
+   *
+   * @param worker Worker whose tasks are decreased.
+   */
+  protected decreaseWorkersTasks (worker: Worker): void {
+    this.stepWorkerNumberOfTasks(worker, -1)
+  }
 
-  protected addWorker (worker: Worker): void {
-    const previousWorkerIndex = this.tasks.get(worker)
-    if (previousWorkerIndex !== undefined) {
-      this.tasks.set(worker, previousWorkerIndex + 1)
+  /**
+   * Step the number of tasks that the given workers has done.
+   *
+   * @param worker Worker whose tasks are set.
+   * @param step Worker number of tasks step.
+   */
+  private stepWorkerNumberOfTasks (worker: Worker, step: number): void {
+    const numberOfTasksInProgress = this.tasks.get(worker)
+    if (numberOfTasksInProgress !== undefined) {
+      this.tasks.set(worker, numberOfTasksInProgress + step)
     } else {
       throw Error('Worker could not be found in tasks map')
     }
   }
 
   /**
-   * Execute the task specified into the constructor with the data parameter.
+   * Removes the given worker from the pool.
    *
-   * @param data The input for the task specified.
-   * @returns Promise that is resolved when the task is done.
+   * @param worker Worker that will be removed.
    */
-  public execute (data: Data): Promise<Response> {
-    // configure worker to handle message with the specified task
-    const worker = this.chooseWorker()
-    this.addWorker(worker)
-    const id = ++this.id
-    const res = this.internalExecute(worker, id)
-    this.sendToWorker(worker, { data: data || ({} as Data), id: id })
-    return res
+  protected removeWorker (worker: Worker): void {
+    // Clean worker from data structure
+    const workerIndex = this.workers.indexOf(worker)
+    this.workers.splice(workerIndex, 1)
+    this.tasks.delete(worker)
   }
 
-  protected abstract registerWorkerMessageListener (
-    port: Worker,
-    listener: (message: MessageValue<Response>) => void
-  ): void
+  /**
+   * Choose a worker for the next task.
+   *
+   * The default implementation uses a round robin algorithm to distribute the load.
+   *
+   * @returns Worker.
+   */
+  protected chooseWorker (): Worker {
+    return this.workerChoiceStrategyContext.execute()
+  }
 
-  protected abstract unregisterWorkerMessageListener (
-    port: Worker,
-    listener: (message: MessageValue<Response>) => void
+  /**
+   * Send a message to the given worker.
+   *
+   * @param worker The worker which should receive the message.
+   * @param message The message.
+   */
+  protected abstract sendToWorker (
+    worker: Worker,
+    message: MessageValue<Data>
   ): void
 
-  protected internalExecute (worker: Worker, id: number): Promise<Response> {
-    return new Promise((resolve, reject) => {
-      const listener: (message: MessageValue<Response>) => void = message => {
-        if (message.id === id) {
-          this.unregisterWorkerMessageListener(worker, listener)
-          this.addWorker(worker)
-          if (message.error) reject(message.error)
-          else resolve(message.data as Response)
-        }
-      }
-      this.registerWorkerMessageListener(worker, listener)
+  /** @inheritdoc */
+  public abstract registerWorkerMessageListener<
+    Message extends Data | Response
+  > (worker: Worker, listener: (message: MessageValue<Message>) => void): void
+
+  protected internalExecute (
+    worker: Worker,
+    messageId: number
+  ): Promise<Response> {
+    return new Promise<Response>((resolve, reject) => {
+      this.promiseMap.set(messageId, { resolve, reject, worker })
     })
   }
 
-  protected chooseWorker (): Worker {
-    if (this.workers.length - 1 === this.nextWorker) {
-      this.nextWorker = 0
-      return this.workers[this.nextWorker]
-    } else {
-      this.nextWorker++
-      return this.workers[this.nextWorker]
-    }
-  }
+  /**
+   * Returns a newly created worker.
+   */
+  protected abstract createWorker (): Worker
+
+  /**
+   * Function that can be hooked up when a worker has been newly created and moved to the workers registry.
+   *
+   * 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.
+   */
+  protected abstract afterWorkerSetup (worker: Worker): void
 
-  protected abstract newWorker (): Worker
+  /** @inheritdoc */
+  public createAndSetupWorker (): Worker {
+    const worker: Worker = this.createWorker()
 
-  protected abstract afterNewWorkerPushed (worker: Worker): void
+    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))
 
-  protected internalNewWorker (): Worker {
-    const worker: Worker = this.newWorker()
-    worker.on('error', this.opts.errorHandler ?? (() => {}))
-    worker.on('online', this.opts.onlineHandler ?? (() => {}))
-    // TODO handle properly when a worker exit
-    worker.on('exit', this.opts.exitHandler ?? (() => {}))
     this.workers.push(worker)
-    this.afterNewWorkerPushed(worker)
-    // init tasks map
+
+    // Init tasks map
     this.tasks.set(worker, 0)
+
+    this.afterWorkerSetup(worker)
+
     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 {
+    const listener: (message: MessageValue<Response>) => void = 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)
+        }
+      }
+    }
+    return listener
+  }
 }