-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.
*/
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
+ }
}
repositories / poolifier.git / blobdiff