-import EventEmitter from 'events'
-import type { MessageValue } from '../utility-types'
-import type { IPool } from './pool'
-
-export type ErrorHandler<Worker> = (this: Worker, e: Error) => void
-export type OnlineHandler<Worker> = (this: Worker) => void
-export type ExitHandler<Worker> = (this: Worker, code: number) => void
-
-export interface IWorker {
- on(event: 'error', handler: ErrorHandler<this>): void
- on(event: 'online', handler: OnlineHandler<this>): void
- on(event: 'exit', handler: ExitHandler<this>): void
-}
-
-export interface PoolOptions<Worker> {
- /**
- * A function that will listen for error event on each worker.
- */
- errorHandler?: ErrorHandler<Worker>
- /**
- * A function that will listen for online event on each worker.
- */
- onlineHandler?: OnlineHandler<Worker>
- /**
- * A function that will listen for exit 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).
- *
- * @default 1000
- */
- maxTasks?: number
-}
-
-class PoolEmitter extends EventEmitter {}
+import crypto from 'node:crypto'
+import type { MessageValue, PromiseResponseWrapper } from '../utility-types'
+import { EMPTY_FUNCTION } from '../utils'
+import { KillBehaviors, isKillBehavior } from '../worker/worker-options'
+import { PoolEvents, type PoolOptions } from './pool'
+import { PoolEmitter } from './pool'
+import type { IPoolInternal, TasksUsage, WorkerType } from './pool-internal'
+import { PoolType } from './pool-internal'
+import type { IPoolWorker } from './pool-worker'
+import {
+ WorkerChoiceStrategies,
+ type WorkerChoiceStrategy
+} from './selection-strategies/selection-strategies-types'
+import { WorkerChoiceStrategyContext } from './selection-strategies/worker-choice-strategy-context'
+/**
+ * Base class that implements some shared logic for all poolifier pools.
+ *
+ * @typeParam Worker - Type of worker which manages this pool.
+ * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
+ * @typeParam Response - Type of response of execution. This can only be serializable data.
+ */
export abstract class AbstractPool<
- Worker extends IWorker,
+ Worker extends IPoolWorker,
Data = unknown,
Response = unknown
-> implements IPool<Data, Response> {
- public readonly workers: Worker[] = []
- public nextWorker: number = 0
+> implements IPoolInternal<Worker, Data, Response> {
+ /** @inheritDoc */
+ public readonly workers: Array<WorkerType<Worker>> = []
+
+ /** @inheritDoc */
+ public readonly emitter?: PoolEmitter
/**
- * `workerId` as key and an integer value
+ * The promise response map.
+ *
+ * - `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 with the promise resolve/reject bound to the message.
*/
- public readonly tasks: Map<Worker, number> = new Map<Worker, number>()
-
- public readonly emitter: PoolEmitter
+ protected promiseResponseMap: Map<
+ string,
+ PromiseResponseWrapper<Worker, Response>
+ > = new Map<string, PromiseResponseWrapper<Worker, Response>>()
- protected id: number = 0
+ /**
+ * Worker choice strategy context referencing a worker choice algorithm implementation.
+ *
+ * Default to 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.
+ */
public constructor (
- public readonly numWorkers: number,
+ 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) {
+ 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++) {
+ this.createAndSetupWorker()
+ }
+
+ if (this.opts.enableEvents === true) {
+ this.emitter = new PoolEmitter()
+ }
+ this.workerChoiceStrategyContext = new WorkerChoiceStrategyContext<
+ Worker,
+ Data,
+ Response
+ >(this, this.opts.workerChoiceStrategy)
+ }
+
+ private checkFilePath (filePath: string): void {
+ if (
+ filePath == null ||
+ (typeof filePath === 'string' && filePath.trim().length === 0)
+ ) {
throw new Error('Please specify a file with a worker implementation')
}
+ }
- this.setupHook()
+ 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 TypeError(
+ 'Cannot instantiate a pool with a non integer number of workers'
+ )
+ } else if (numberOfWorkers < 0) {
+ throw new RangeError(
+ '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.checkValidWorkerChoiceStrategy(this.opts.workerChoiceStrategy)
+ this.opts.enableEvents = opts.enableEvents ?? true
+ }
- for (let i = 1; i <= this.numWorkers; i++) {
- this.internalNewWorker()
+ private checkValidWorkerChoiceStrategy (
+ workerChoiceStrategy: WorkerChoiceStrategy
+ ): void {
+ if (!Object.values(WorkerChoiceStrategies).includes(workerChoiceStrategy)) {
+ throw new Error(
+ `Invalid worker choice strategy '${workerChoiceStrategy}'`
+ )
}
+ }
- this.emitter = new PoolEmitter()
+ /** @inheritDoc */
+ public abstract get type (): PoolType
+
+ /**
+ * 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 if the worker is found in the pool, `-1` otherwise.
+ */
+ private getWorkerKey (worker: Worker): number {
+ return this.workers.findIndex(workerItem => workerItem.worker === worker)
+ }
+
+ /** @inheritDoc */
+ public setWorkerChoiceStrategy (
+ workerChoiceStrategy: WorkerChoiceStrategy
+ ): void {
+ this.checkValidWorkerChoiceStrategy(workerChoiceStrategy)
+ this.opts.workerChoiceStrategy = workerChoiceStrategy
+ for (const [index, workerItem] of this.workers.entries()) {
+ this.setWorker(index, workerItem.worker, {
+ run: 0,
+ running: 0,
+ runTime: 0,
+ avgRunTime: 0,
+ error: 0
+ })
+ }
+ this.workerChoiceStrategyContext.setWorkerChoiceStrategy(
+ workerChoiceStrategy
+ )
+ }
+
+ /** @inheritDoc */
+ public abstract get full (): boolean
+
+ /** @inheritDoc */
+ public abstract get busy (): boolean
+
+ protected internalBusy (): boolean {
+ return (
+ this.numberOfRunningTasks >= this.numberOfWorkers &&
+ this.findFreeWorkerKey() === -1
+ )
+ }
+
+ /** @inheritDoc */
+ public findFreeWorkerKey (): number {
+ return this.workers.findIndex(workerItem => {
+ return workerItem.tasksUsage.running === 0
+ })
+ }
+
+ /** @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
+ data: data ?? ({} as Data),
+ id: messageId
+ })
+ // eslint-disable-next-line @typescript-eslint/return-await
+ return res
+ }
+
+ /** @inheritDoc */
+ public async destroy (): Promise<void> {
+ await Promise.all(
+ this.workers.map(async workerItem => {
+ await this.destroyWorker(workerItem.worker)
+ })
+ )
}
+ /**
+ * Shutdowns given worker in the pool.
+ *
+ * @param worker - A worker within `workers`.
+ */
+ protected 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.
+ * Can be overridden
+ *
+ * @virtual
+ */
protected setupHook (): void {
- // Can be overridden
+ // Intentionally empty
}
+ /**
+ * 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)
+ /**
+ * Hook executed before the worker task promise resolution.
+ * Can be overridden.
+ *
+ * @param workerKey - The worker key.
+ */
+ 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.
+ */
+ protected afterPromiseResponseHook (
+ worker: Worker,
+ message: MessageValue<Response>
+ ): void {
+ const workerTasksUsage = this.getWorkerTasksUsage(worker) as TasksUsage
+ --workerTasksUsage.running
+ ++workerTasksUsage.run
+ 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
+ }
}
}
- protected abstract destroyWorker (worker: Worker): void | Promise<void>
+ /**
+ * Chooses a worker for the next task.
+ *
+ * The default uses a round robin algorithm to distribute the load.
+ *
+ * @returns [worker key, worker].
+ */
+ 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]
+ }
+ /**
+ * Sends 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 addWorker (worker: Worker): void {
- const previousWorkerIndex = this.tasks.get(worker)
- if (previousWorkerIndex !== undefined) {
- this.tasks.set(worker, previousWorkerIndex + 1)
- } else {
- throw Error('Worker could not be found in tasks map')
- }
- }
+ /**
+ * Registers a listener callback on a given worker.
+ *
+ * @param worker - The worker which should register a listener.
+ * @param listener - The message listener callback.
+ */
+ protected abstract registerWorkerMessageListener<
+ Message extends Data | Response
+ >(worker: Worker, listener: (message: MessageValue<Message>) => void): void
+
+ /**
+ * Returns a newly created worker.
+ */
+ protected abstract createWorker (): Worker
/**
- * Execute the task specified into the constructor with the data parameter.
+ * Function that can be hooked up when a worker has been newly created and moved to the workers registry.
*
- * @param data The input for the task specified.
- * @returns Promise that is resolved when the task is done.
+ * 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
*/
- 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 abstract afterWorkerSetup (worker: Worker): void
- protected abstract registerWorkerMessageListener (
- port: Worker,
- listener: (message: MessageValue<Response>) => void
- ): void
+ /**
+ * Creates a new worker for this pool and sets it up completely.
+ *
+ * @returns New, completely set up worker.
+ */
+ protected createAndSetupWorker (): Worker {
+ const worker = this.createWorker()
- protected abstract unregisterWorkerMessageListener (
- port: Worker,
- listener: (message: MessageValue<Response>) => void
- ): void
+ 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)
+ })
- 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.pushWorker(worker, {
+ run: 0,
+ running: 0,
+ runTime: 0,
+ avgRunTime: 0,
+ error: 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 received from a worker.
+ */
+ protected workerListener (): (message: MessageValue<Response>) => void {
+ return message => {
+ if (message.id != null) {
+ // Task response received
+ const promiseResponse = this.promiseResponseMap.get(message.id)
+ if (promiseResponse != null) {
+ if (message.error != null) {
+ promiseResponse.reject(message.error)
+ } else {
+ promiseResponse.resolve(message.data as Response)
+ }
+ this.afterPromiseResponseHook(promiseResponse.worker, message)
+ this.promiseResponseMap.delete(message.id)
}
}
- this.registerWorkerMessageListener(worker, listener)
+ }
+ }
+
+ private async internalExecute (
+ workerKey: number,
+ worker: Worker,
+ messageId: string
+ ): Promise<Response> {
+ this.beforePromiseResponseHook(workerKey)
+ return await new Promise<Response>((resolve, reject) => {
+ this.promiseResponseMap.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]
+ private checkAndEmitBusy (): void {
+ if (this.opts.enableEvents === true && this.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)
+ }
+ }
+
+ /**
+ * 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 !== -1) {
+ return this.workers[workerKey].tasksUsage
}
+ throw new Error('Worker could not be found in the pool')
}
- protected abstract newWorker (): 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
+ })
+ }
- protected abstract afterNewWorkerPushed (worker: Worker): void
+ /**
+ * Sets the given worker in the pool.
+ *
+ * @param workerKey - The worker key.
+ * @param worker - The worker.
+ * @param tasksUsage - The worker tasks usage.
+ */
+ private setWorker (
+ workerKey: number,
+ worker: Worker,
+ tasksUsage: TasksUsage
+ ): void {
+ this.workers[workerKey] = {
+ worker,
+ tasksUsage
+ }
+ }
- 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
- this.tasks.set(worker, 0)
- return worker
+ /**
+ * 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)
}
}
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