-import EventEmitter from 'events'
-import type { MessageValue } from '../utility-types'
-import type { IPool } from './pool'
+import crypto from 'node:crypto'
+import type {
+ MessageValue,
+ PromiseWorkerResponseWrapper
+} from '../utility-types'
+import { EMPTY_FUNCTION } from '../utils'
+import { KillBehaviors, isKillBehavior } from '../worker/worker-options'
+import 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'
/**
- * 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 {
- on(event: 'error', handler: ErrorHandler<this>): void
- on(event: 'online', handler: OnlineHandler<this>): void
- on(event: 'exit', handler: ExitHandler<this>): void
- 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.
- */
- 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 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
-}
-
-/**
- * Internal poolifier pool emitter.
- */
-class PoolEmitter extends EventEmitter {}
-
-/**
- * Base class containing some shared logic for all poolifier pools.
+ * Base class that implements 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.
+ * @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> {
- /**
- * List of currently available workers.
- */
- public readonly workers: Worker[] = []
+> implements IPoolInternal<Worker, Data, Response> {
+ /** {@inheritDoc} */
+ public readonly workers: Map<number, WorkerType<Worker>> = new Map<
+ number,
+ WorkerType<Worker>
+ >()
- /**
- * Index for the next worker.
- */
- public nextWorkerIndex: number = 0
+ /** {@inheritDoc} */
+ public readonly emitter?: PoolEmitter
/**
- * - `key`: The `Worker`
- * - `value`: Number of tasks currently in progress on the worker.
+ * Id of the next worker.
*/
- public readonly tasks: Map<Worker, number> = new Map<Worker, number>()
+ protected nextWorkerId: number = 0
/**
- * 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<
+ string,
+ PromiseWorkerResponseWrapper<Worker, Response>
+ > = new Map<string, PromiseWorkerResponseWrapper<Worker, Response>>()
/**
- * ID of the next message.
+ * Worker choice strategy instance implementing the worker choice algorithm.
+ *
+ * Default to a strategy implementing a round robin algorithm.
*/
- protected nextMessageId: number = 0
+ 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 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 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 === true) {
+ this.emitter = new PoolEmitter()
+ }
+ this.workerChoiceStrategyContext = new WorkerChoiceStrategyContext(
+ this,
+ () => {
+ const workerCreated = this.createAndSetupWorker()
+ this.registerWorkerMessageListener(workerCreated, message => {
+ if (
+ isKillBehavior(KillBehaviors.HARD, message.kill) ||
+ this.getWorkerRunningTasks(workerCreated) === 0
+ ) {
+ // Kill received from the worker, means that no new tasks are submitted to that worker for a while ( > maxInactiveTime)
+ void this.destroyWorker(workerCreated)
+ }
+ })
+ return workerCreated
+ },
+ this.opts.workerChoiceStrategy
+ )
}
- /**
- * Number of workers that this pool should manage.
- *
- * @returns Number of workers that this pool manages.
- * @deprecated Only here for backward compatibility.
- */
- // eslint-disable-next-line spellcheck/spell-checker
- public get numWorkers (): number {
- return this.numberOfWorkers
+ 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')
+ }
+ }
+
+ 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.opts.enableEvents = opts.enableEvents ?? true
+ }
+
+ /** {@inheritDoc} */
+ public abstract get type (): PoolType
+
+ /** {@inheritDoc} */
+ public get numberOfRunningTasks (): number {
+ return this.promiseMap.size
}
/**
- * Index for the next worker.
+ * Gets the given worker key.
*
- * @returns Index for the next worker.
- * @deprecated Only here for backward compatibility.
+ * @param worker - The worker.
+ * @returns The worker key.
*/
- public get nextWorker (): number {
- return this.nextWorkerIndex
+ private getWorkerKey (worker: Worker): number | undefined {
+ return [...this.workers].find(([, value]) => value.worker === worker)?.[0]
+ }
+
+ /** {@inheritDoc} */
+ public getWorkerRunningTasks (worker: Worker): number | undefined {
+ return this.getWorkerTasksUsage(worker)?.running
+ }
+
+ /** {@inheritDoc} */
+ public getWorkerRunTasks (worker: Worker): number | undefined {
+ return this.getWorkerTasksUsage(worker)?.run
+ }
+
+ /** {@inheritDoc} */
+ public getWorkerAverageTasksRunTime (worker: Worker): number | undefined {
+ return this.getWorkerTasksUsage(worker)?.avgRunTime
}
- public execute (data: Data): Promise<Response> {
- // Configure worker to handle message with the specified task
+ /** {@inheritDoc} */
+ public setWorkerChoiceStrategy (
+ workerChoiceStrategy: WorkerChoiceStrategy
+ ): void {
+ this.opts.workerChoiceStrategy = workerChoiceStrategy
+ for (const [key, value] of this.workers) {
+ this.setWorker(key, value.worker, {
+ run: 0,
+ running: 0,
+ runTime: 0,
+ avgRunTime: 0
+ })
+ }
+ this.workerChoiceStrategyContext.setWorkerChoiceStrategy(
+ workerChoiceStrategy
+ )
+ }
+
+ /** {@inheritDoc} */
+ public abstract get busy (): boolean
+
+ protected internalGetBusyStatus (): boolean {
+ return (
+ this.numberOfRunningTasks >= this.numberOfWorkers &&
+ this.findFreeWorker() === false
+ )
+ }
+
+ /** {@inheritDoc} */
+ public findFreeWorker (): Worker | false {
+ for (const value of this.workers.values()) {
+ if (value.tasksUsage.running === 0) {
+ // A worker is free, return the matching worker
+ return value.worker
+ }
+ }
+ return false
+ }
+
+ /** {@inheritDoc} */
+ public async execute (data: Data): Promise<Response> {
const worker = this.chooseWorker()
- this.increaseWorkersTask(worker)
- const messageId = ++this.nextMessageId
+ const messageId = crypto.randomUUID()
const res = this.internalExecute(worker, messageId)
- this.sendToWorker(worker, { data: data || ({} as Data), id: messageId })
+ 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(worker => this.destroyWorker(worker)))
+ await Promise.all(
+ [...this.workers].map(async ([, value]) => {
+ await this.destroyWorker(value.worker)
+ })
+ )
}
/**
- * Shut down given worker.
+ * Shutdowns given worker.
*
- * @param worker A worker within `workers`.
+ * @param worker - A worker within `workers`.
*/
protected abstract destroyWorker (worker: Worker): void | Promise<void>
protected abstract isMain (): boolean
/**
- * Increase the number of tasks that the given workers has done.
+ * Hook executed before the worker task promise resolution.
+ * Can be overridden.
*
- * @param worker Workers whose tasks are increased.
+ * @param worker - The worker.
*/
- protected increaseWorkersTask (worker: Worker): void {
- const numberOfTasksInProgress = this.tasks.get(worker)
- if (numberOfTasksInProgress !== undefined) {
- this.tasks.set(worker, numberOfTasksInProgress + 1)
- } else {
- throw Error('Worker could not be found in tasks map')
- }
+ protected beforePromiseWorkerResponseHook (worker: Worker): void {
+ this.increaseWorkerRunningTasks(worker)
}
/**
- * Decrease the number of tasks that the given workers has done.
+ * Hook executed after the worker task promise resolution.
+ * Can be overridden.
*
- * @param worker Workers whose tasks are decreased.
+ * @param message - The received message.
+ * @param promise - The Promise response.
*/
- protected decreaseWorkersTasks (worker: Worker): void {
- const numberOfTasksInProgress = this.tasks.get(worker)
- if (numberOfTasksInProgress !== undefined) {
- this.tasks.set(worker, numberOfTasksInProgress - 1)
- } else {
- throw Error('Worker could not be found in tasks map')
- }
+ protected afterPromiseWorkerResponseHook (
+ message: MessageValue<Response>,
+ promise: PromiseWorkerResponseWrapper<Worker, Response>
+ ): void {
+ this.decreaseWorkerRunningTasks(promise.worker)
+ this.stepWorkerRunTasks(promise.worker, 1)
+ this.updateWorkerTasksRunTime(promise.worker, message.taskRunTime)
}
/**
* Removes the given worker from the pool.
*
- * @param worker Worker that will be removed.
+ * @param worker - The worker that will be removed.
*/
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)
+ this.workers.delete(this.getWorkerKey(worker) as number)
+ --this.nextWorkerId
}
/**
- * Choose a worker for the next task.
+ * Chooses a worker for the next task.
*
* The default implementation uses a round robin algorithm to distribute the load.
*
* @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()
}
/**
- * Send a message to the given worker.
+ * Sends a message to the given worker.
*
- * @param worker The worker which should receive the message.
- * @param message The message.
+ * @param worker - The worker which should receive the message.
+ * @param message - The message.
*/
protected abstract sendToWorker (
worker: Worker,
message: MessageValue<Data>
): void
+ /**
+ * 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
-
- 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)
- })
- }
+ >(worker: Worker, listener: (message: MessageValue<Message>) => void): void
/**
* Returns a newly created 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.
+ * 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.
+ * @param worker - The newly created worker.
*/
protected abstract afterWorkerSetup (worker: Worker): void
* @returns New, completely set up worker.
*/
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.once('exit', () => this.removeWorker(worker))
-
- this.workers.push(worker)
+ const worker = this.createWorker()
+
+ 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)
+ })
- // Init tasks map
- this.tasks.set(worker, 0)
+ this.setWorker(this.nextWorkerId, worker, {
+ run: 0,
+ running: 0,
+ runTime: 0,
+ avgRunTime: 0
+ })
+ ++this.nextWorkerId
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 !== undefined) {
+ const promise = this.promiseMap.get(message.id)
+ if (promise !== undefined) {
+ if (message.error != null) {
+ promise.reject(message.error)
+ } else {
+ promise.resolve(message.data as Response)
+ }
+ this.afterPromiseWorkerResponseHook(message, promise)
+ this.promiseMap.delete(message.id)
+ }
+ }
+ }
+ }
+
+ private async internalExecute (
+ worker: Worker,
+ messageId: string
+ ): Promise<Response> {
+ this.beforePromiseWorkerResponseHook(worker)
+ return await new Promise<Response>((resolve, reject) => {
+ this.promiseMap.set(messageId, { resolve, reject, worker })
+ })
+ }
+
+ private checkAndEmitBusy (): void {
+ if (this.opts.enableEvents === true && this.busy) {
+ this.emitter?.emit('busy')
+ }
+ }
+
+ /**
+ * Increases the number of tasks that the given worker has applied.
+ *
+ * @param worker - Worker which running tasks is increased.
+ */
+ private increaseWorkerRunningTasks (worker: Worker): void {
+ this.stepWorkerRunningTasks(worker, 1)
+ }
+
+ /**
+ * Decreases the number of tasks that the given worker has applied.
+ *
+ * @param worker - Worker which running tasks is decreased.
+ */
+ private decreaseWorkerRunningTasks (worker: Worker): void {
+ this.stepWorkerRunningTasks(worker, -1)
+ }
+
+ /**
+ * Gets tasks usage of the given worker.
+ *
+ * @param worker - Worker which tasks usage is returned.
+ */
+ private getWorkerTasksUsage (worker: Worker): TasksUsage | undefined {
+ if (this.checkWorker(worker)) {
+ const workerKey = this.getWorkerKey(worker) as number
+ const workerEntry = this.workers.get(workerKey) as WorkerType<Worker>
+ return workerEntry.tasksUsage
+ }
+ }
+
+ /**
+ * Steps the number of tasks that the given worker has applied.
+ *
+ * @param worker - Worker which running tasks are stepped.
+ * @param step - Number of running tasks step.
+ */
+ private stepWorkerRunningTasks (worker: Worker, step: number): void {
+ // prettier-ignore
+ (this.getWorkerTasksUsage(worker) as TasksUsage).running += step
+ }
+
+ /**
+ * Steps the number of tasks that the given worker has run.
+ *
+ * @param worker - Worker which has run tasks.
+ * @param step - Number of run tasks step.
+ */
+ private stepWorkerRunTasks (worker: Worker, step: number): void {
+ // prettier-ignore
+ (this.getWorkerTasksUsage(worker) as TasksUsage).run += step
+ }
+
+ /**
+ * Updates tasks runtime for the given worker.
+ *
+ * @param worker - Worker which run the task.
+ * @param taskRunTime - Worker task runtime.
+ */
+ private updateWorkerTasksRunTime (
+ worker: Worker,
+ taskRunTime: number | undefined
+ ): void {
+ if (
+ this.workerChoiceStrategyContext.getWorkerChoiceStrategy()
+ .requiredStatistics.runTime
+ ) {
+ const workerTasksUsage = this.getWorkerTasksUsage(worker) as TasksUsage
+ workerTasksUsage.runTime += taskRunTime ?? 0
+ if (workerTasksUsage.run !== 0) {
+ workerTasksUsage.avgRunTime =
+ workerTasksUsage.runTime / workerTasksUsage.run
+ }
+ }
+ }
+
+ /**
+ * Sets the given worker.
+ *
+ * @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.set(workerKey, {
+ worker,
+ tasksUsage
+ })
+ }
+
+ /**
+ * Checks if the given worker is registered in the pool.
+ *
+ * @param worker - Worker to check.
+ * @returns `true` if the worker is registered in the pool.
+ */
+ private checkWorker (worker: Worker): boolean {
+ if (this.getWorkerKey(worker) == null) {
+ throw new Error('Worker could not be found in the pool')
+ }
+ return true
+ }
}