-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
-}
+import type {
+ MessageValue,
+ PromiseWorkerResponseWrapper
+} from '../utility-types'
+import { EMPTY_FUNCTION } from '../utils'
+import { isKillBehavior, KillBehaviors } from '../worker/worker-options'
+import type { PoolOptions } from './pool'
+import { PoolEmitter } from './pool'
+import type { IPoolInternal, TasksUsage } from './pool-internal'
+import { PoolType } from './pool-internal'
+import type { IPoolWorker } from './pool-worker'
+import {
+ WorkerChoiceStrategies,
+ 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.
+ *
+ * @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 IPoolWorker,
+ Data = unknown,
+ Response = unknown
+> implements IPoolInternal<Worker, Data, Response> {
+ /** @inheritDoc */
+ public readonly workers: Worker[] = []
+
+ /** @inheritDoc */
+ public readonly workersTasksUsage: Map<Worker, TasksUsage> = new Map<
+ Worker,
+ TasksUsage
+ >()
+
+ /** @inheritDoc */
+ public readonly emitter?: PoolEmitter
-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.
+ * 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.
*/
- onlineHandler?: OnlineHandler<Worker>
+ protected promiseMap: Map<
+ number,
+ PromiseWorkerResponseWrapper<Worker, Response>
+ > = new Map<number, PromiseWorkerResponseWrapper<Worker, Response>>()
+
/**
- * A function that will listen for exit event on each worker.
+ * Id of the next message.
*/
- exitHandler?: ExitHandler<Worker>
+ protected nextMessageId: number = 0
+
/**
- * This is just to avoid not useful warnings message, is used to set `maxListeners` on event emitters (workers are event emitters).
+ * Worker choice strategy instance implementing the worker choice algorithm.
*
- * @default 1000
+ * Default to a strategy implementing a round robin algorithm.
*/
- maxTasks?: number
-}
-
-class PoolEmitter extends EventEmitter {}
-
-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
+ protected workerChoiceStrategyContext: WorkerChoiceStrategyContext<
+ Worker,
+ Data,
+ Response
+ >
/**
- * `workerId` as key and an integer value
+ * 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 readonly tasks: Map<Worker, number> = new Map<Worker, number>()
-
- public readonly emitter: PoolEmitter
-
- protected id: number = 0
-
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()) {
+ if (this.isMain() === false) {
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.setupHook()
+
+ for (let i = 1; i <= this.numberOfWorkers; i++) {
+ this.createAndSetupWorker()
+ }
+
+ 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)
+ this.destroyWorker(workerCreated) as void
+ }
+ })
+ return workerCreated
+ },
+ this.opts.workerChoiceStrategy
+ )
+ }
+
+ private checkFilePath (filePath: string): void {
+ if (!filePath) {
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) === false) {
+ 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
+ }
+
+ /** @inheritDoc */
+ public getWorkerIndex (worker: Worker): number {
+ return this.workers.indexOf(worker)
+ }
+
+ /** @inheritDoc */
+ public getWorkerRunningTasks (worker: Worker): number | undefined {
+ return this.workersTasksUsage.get(worker)?.running
+ }
+
+ /** @inheritDoc */
+ public getWorkerAverageTasksRunTime (worker: Worker): number | undefined {
+ return this.workersTasksUsage.get(worker)?.avgRunTime
+ }
+
+ /** @inheritDoc */
+ public setWorkerChoiceStrategy (
+ workerChoiceStrategy: WorkerChoiceStrategy
+ ): void {
+ this.opts.workerChoiceStrategy = workerChoiceStrategy
+ for (const worker of this.workers) {
+ this.resetWorkerTasksUsage(worker)
+ }
+ this.workerChoiceStrategyContext.setWorkerChoiceStrategy(
+ workerChoiceStrategy
+ )
+ }
+
+ /** @inheritDoc */
+ public abstract get busy (): boolean
+
+ protected internalGetBusyStatus (): boolean {
+ return (
+ this.numberOfRunningTasks >= this.numberOfWorkers &&
+ this.findFreeWorker() === false
+ )
+ }
- for (let i = 1; i <= this.numWorkers; i++) {
- this.internalNewWorker()
+ /** @inheritDoc */
+ public findFreeWorker (): Worker | false {
+ for (const worker of this.workers) {
+ if (this.getWorkerRunningTasks(worker) === 0) {
+ // A worker is free, return the matching worker
+ return worker
+ }
}
+ return false
+ }
+
+ /** @inheritDoc */
+ public execute (data: Data): Promise<Response> {
+ // Configure worker to handle message with the specified task
+ const worker = this.chooseWorker()
+ const res = this.internalExecute(worker, this.nextMessageId)
+ this.checkAndEmitBusy()
+ this.sendToWorker(worker, {
+ data: data ?? ({} as Data),
+ id: this.nextMessageId
+ })
+ ++this.nextMessageId
+ return res
+ }
- this.emitter = new PoolEmitter()
+ /** @inheritDoc */
+ public async destroy (): Promise<void> {
+ await Promise.all(this.workers.map(worker => this.destroyWorker(worker)))
}
+ /**
+ * Shutdowns given worker.
+ *
+ * @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.
+ */
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)
- }
+ /**
+ * Hook executed before the worker task promise resolution.
+ * Can be overridden.
+ *
+ * @param worker The worker.
+ */
+ protected beforePromiseWorkerResponseHook (worker: Worker): void {
+ this.increaseWorkerRunningTasks(worker)
}
- protected abstract destroyWorker (worker: Worker): void | Promise<void>
+ /**
+ * Hook executed after the worker task promise resolution.
+ * Can be overridden.
+ *
+ * @param message The received message.
+ * @param promise The Promise response.
+ */
+ 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 The worker that will be removed.
+ */
+ protected removeWorker (worker: Worker): void {
+ // Clean worker from data structure
+ this.workers.splice(this.getWorkerIndex(worker), 1)
+ this.removeWorkerTasksUsage(worker)
+ }
+
+ /**
+ * Chooses 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()
+ }
+ /**
+ * 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
+
+ protected internalExecute (
+ worker: Worker,
+ messageId: number
+ ): Promise<Response> {
+ this.beforePromiseWorkerResponseHook(worker)
+ return new Promise<Response>((resolve, reject) => {
+ this.promiseMap.set(messageId, { resolve, reject, worker })
+ })
+ }
+
+ /**
+ * 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
+
+ /**
+ * 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()
+
+ 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)
+
+ // Init worker tasks usage map
+ this.initWorkerTasksUsage(worker)
+
+ 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) {
+ promise.reject(message.error)
+ } else {
+ promise.resolve(message.data as Response)
+ }
+ this.afterPromiseWorkerResponseHook(message, promise)
+ this.promiseMap.delete(message.id)
+ }
+ }
+ }
+ }
+
+ private checkAndEmitBusy (): void {
+ if (this.opts.enableEvents === true && this.busy === true) {
+ this.emitter?.emit('busy')
}
}
/**
- * Execute the task specified into the constructor with the data parameter.
+ * Increases the number of tasks that the given worker has applied.
*
- * @param data The input for the task specified.
- * @returns Promise that is resolved when the task is done.
+ * @param worker Worker which running tasks is increased.
*/
- 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
+ private increaseWorkerRunningTasks (worker: Worker): void {
+ this.stepWorkerRunningTasks(worker, 1)
}
- protected abstract registerWorkerMessageListener (
- port: Worker,
- listener: (message: MessageValue<Response>) => void
- ): void
+ /**
+ * 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)
+ }
- protected abstract unregisterWorkerMessageListener (
- port: Worker,
- listener: (message: MessageValue<Response>) => void
- ): void
+ /**
+ * 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 {
+ if (this.checkWorkerTasksUsage(worker) === true) {
+ const tasksUsage = this.workersTasksUsage.get(worker) as TasksUsage
+ tasksUsage.running = tasksUsage.running + step
+ this.workersTasksUsage.set(worker, tasksUsage)
+ }
+ }
- 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)
- }
+ /**
+ * 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 {
+ if (this.checkWorkerTasksUsage(worker) === true) {
+ const tasksUsage = this.workersTasksUsage.get(worker) as TasksUsage
+ tasksUsage.run = tasksUsage.run + step
+ this.workersTasksUsage.set(worker, tasksUsage)
+ }
+ }
+
+ /**
+ * 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 === true &&
+ this.checkWorkerTasksUsage(worker) === true
+ ) {
+ const tasksUsage = this.workersTasksUsage.get(worker) as TasksUsage
+ tasksUsage.runTime += taskRunTime ?? 0
+ if (tasksUsage.run !== 0) {
+ tasksUsage.avgRunTime = tasksUsage.runTime / tasksUsage.run
}
- this.registerWorkerMessageListener(worker, listener)
- })
+ this.workersTasksUsage.set(worker, tasksUsage)
+ }
}
- 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]
+ /**
+ * Checks if the given worker is registered in the workers tasks usage map.
+ *
+ * @param worker Worker to check.
+ * @returns `true` if the worker is registered in the workers tasks usage map. `false` otherwise.
+ */
+ private checkWorkerTasksUsage (worker: Worker): boolean {
+ const hasTasksUsage = this.workersTasksUsage.has(worker)
+ if (hasTasksUsage === false) {
+ throw new Error('Worker could not be found in workers tasks usage map')
}
+ return hasTasksUsage
}
- protected abstract newWorker (): Worker
+ /**
+ * Initializes tasks usage statistics.
+ *
+ * @param worker The worker.
+ */
+ private initWorkerTasksUsage (worker: Worker): void {
+ this.workersTasksUsage.set(worker, {
+ run: 0,
+ running: 0,
+ runTime: 0,
+ avgRunTime: 0
+ })
+ }
- protected abstract afterNewWorkerPushed (worker: Worker): void
+ /**
+ * Removes worker tasks usage statistics.
+ *
+ * @param worker The worker.
+ */
+ private removeWorkerTasksUsage (worker: Worker): void {
+ this.workersTasksUsage.delete(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
- this.tasks.set(worker, 0)
- return worker
+ /**
+ * Resets worker tasks usage statistics.
+ *
+ * @param worker The worker.
+ */
+ private resetWorkerTasksUsage (worker: Worker): void {
+ this.removeWorkerTasksUsage(worker)
+ this.initWorkerTasksUsage(worker)
}
}
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