-import EventEmitter from 'events'
-import type { MessageValue } from '../utility-types'
-import type { IPool } from './pool'
+import type {
+ MessageValue,
+ PromiseWorkerResponseWrapper
+} from '../utility-types'
+import { EMPTY_FUNCTION } from '../utils'
+import { isKillBehavior, KillBehaviors } from '../worker/worker-options'
+import type { IPoolInternal } from './pool-internal'
+import { PoolEmitter, PoolType } from './pool-internal'
+import type { WorkerChoiceStrategy } from './selection-strategies'
+import {
+ WorkerChoiceStrategies,
+ WorkerChoiceStrategyContext
+} from './selection-strategies'
/**
* Callback invoked if the worker raised an error.
* 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
}
*/
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).
+ * The work choice strategy to use in this pool.
+ */
+ workerChoiceStrategy?: WorkerChoiceStrategy
+ /**
+ * Pool events emission.
*
- * @default 1000
- * @see [Node events emitter.setMaxListeners(n)](https://nodejs.org/api/events.html#events_emitter_setmaxlisteners_n)
+ * Default to true.
*/
- maxTasks?: number
+ enableEvents?: boolean
}
-/**
- * Internal poolifier pool emitter.
- */
-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.
- * @template Response Type of response of execution.
+ * @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,
Data = unknown,
Response = unknown
-> implements IPool<Data, Response> {
- /**
- * List of currently available workers.
- */
+> implements IPoolInternal<Worker, Data, Response> {
+ /** @inheritdoc */
public readonly workers: Worker[] = []
- /**
- * Index for the next worker.
- */
- public nextWorkerIndex: number = 0
-
- /**
- * - `key`: The `Worker`
- * - `value`: Number of tasks currently in progress on the worker.
- */
+ /** @inheritdoc */
public readonly tasks: Map<Worker, number> = new Map<Worker, number>()
+ /** @inheritdoc */
+ public readonly emitter?: PoolEmitter
+
+ /** @inheritdoc */
+ public readonly max?: number
+
/**
- * 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<
+ number,
+ PromiseWorkerResponseWrapper<Worker, Response>
+ > = new Map<number, PromiseWorkerResponseWrapper<Worker, Response>>()
/**
* 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 }`
+ * @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) {
+ this.emitter = new PoolEmitter()
+ }
+ this.workerChoiceStrategyContext = new WorkerChoiceStrategyContext(
+ this,
+ () => {
+ const workerCreated = this.createAndSetupWorker()
+ this.registerWorkerMessageListener(workerCreated, message => {
+ const tasksInProgress = this.tasks.get(workerCreated)
+ if (
+ isKillBehavior(KillBehaviors.HARD, message.kill) ||
+ tasksInProgress === 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) {
+ throw new Error('Please specify a file with a worker implementation')
+ }
}
- /**
- * Index for the next worker.
- *
- * @returns Index for the next worker.
- * @deprecated Only here for backward compatibility.
- */
- public get nextWorker (): number {
- return this.nextWorkerIndex
+ 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.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 setWorkerChoiceStrategy (
+ workerChoiceStrategy: WorkerChoiceStrategy
+ ): void {
+ this.opts.workerChoiceStrategy = workerChoiceStrategy
+ this.workerChoiceStrategyContext.setWorkerChoiceStrategy(
+ workerChoiceStrategy
+ )
+ }
+
+ /** @inheritdoc */
+ public abstract get busy (): boolean
+
+ protected internalGetBusyStatus (): boolean {
+ return (
+ this.numberOfRunningTasks >= this.numberOfWorkers &&
+ this.findFreeTasksMapEntry() === false
+ )
}
+ /** @inheritdoc */
+ public findFreeTasksMapEntry (): [Worker, number] | false {
+ for (const [worker, numberOfTasks] of this.tasks) {
+ if (numberOfTasks === 0) {
+ // A worker is free, return the matching tasks map entry
+ return [worker, numberOfTasks]
+ }
+ }
+ return false
+ }
+
+ /** @inheritdoc */
public execute (data: Data): Promise<Response> {
// Configure worker to handle message with the specified task
const worker = this.chooseWorker()
this.increaseWorkersTask(worker)
+ this.checkAndEmitBusy()
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)))
}
protected abstract isMain (): boolean
/**
- * Increase the number of tasks that the given workers has done.
+ * Increase the number of tasks that the given workers has applied.
*
- * @param worker Workers whose tasks are increased.
+ * @param worker Worker whose tasks are increased.
*/
protected increaseWorkersTask (worker: Worker): void {
- const numberOfTasksTheWorkerHas = this.tasks.get(worker)
- if (numberOfTasksTheWorkerHas !== undefined) {
- this.tasks.set(worker, numberOfTasksTheWorkerHas + 1)
- } else {
- throw Error('Worker could not be found in tasks map')
- }
+ this.stepWorkerNumberOfTasks(worker, 1)
}
/**
- * Increase the number of tasks that the given workers has done.
+ * Decrease the number of tasks that the given workers has applied.
*
- * @param worker Workers whose tasks are increased.
+ * @param worker Worker whose tasks are decreased.
*/
protected decreaseWorkersTasks (worker: Worker): void {
- const numberOfTasksTheWorkerHas = this.tasks.get(worker)
- if (numberOfTasksTheWorkerHas !== undefined) {
- this.tasks.set(worker, numberOfTasksTheWorkerHas - 1)
+ this.stepWorkerNumberOfTasks(worker, -1)
+ }
+
+ /**
+ * Step the number of tasks that the given workers has applied.
+ *
+ * @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')
}
* @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()
}
/**
message: MessageValue<Data>
): void
+ /**
+ * Register a listener callback on a given worker.
+ *
+ * @param worker A worker.
+ * @param listener A 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)
+ return new Promise<Response>((resolve, reject) => {
+ this.promiseMap.set(messageId, { resolve, reject, 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.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)
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 {
+ return 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)
+ }
+ }
+ }
+ }
+
+ private checkAndEmitBusy (): void {
+ if (this.opts.enableEvents && this.busy) {
+ this.emitter?.emit('busy')
+ }
+ }
}
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