import type { MessageValue } from '../utility-types'
import type { IPool } from './pool'
+/**
+ * An intentional empty function.
+ */
+function emptyFunction () {
+ // intentionally left blank
+}
+
/**
* 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
}
/**
* 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,
public readonly workers: Worker[] = []
/**
- * ID for the next worker.
+ * Index for the next worker.
*/
- public nextWorker: number = 0
+ public nextWorkerIndex: number = 0
/**
+ * The tasks map.
+ *
* - `key`: The `Worker`
- * - `value`: Number of tasks that has been assigned to that worker since it started
+ * - `value`: Number of tasks currently in progress on the worker.
*/
public readonly tasks: Map<Worker, number> = new Map<Worker, number>()
/**
* ID of the next message.
*/
- protected id: number = 0
+ protected nextMessageId: number = 0
/**
* Constructs a new poolifier pool.
*
- * @param numWorkers Number of workers that this pool should manage.
+ * @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.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()
}
+ private checkFilePath (filePath: string) {
+ if (!filePath) {
+ throw new Error('Please specify a file with a worker implementation')
+ }
+ }
+
/**
- * Setup hook that can be overridden by a Poolifer pool implementation
- * to run code before workers are created in the abstract constructor.
+ * Perform the task specified in the constructor with the data parameter.
+ *
+ * @param data The input for the specified task. This can only be serializable data.
+ * @returns Promise that will be resolved when the task is successfully completed.
*/
- protected setupHook (): void {
- // Can be overridden
+ 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
}
/**
- * Should return whether the worker is the main worker or not.
+ * Shut down every current worker in this pool.
*/
- protected abstract isMain (): boolean
-
public async destroy (): Promise<void> {
- for (const worker of this.workers) {
- await this.destroyWorker(worker)
- }
+ await Promise.all(this.workers.map(worker => this.destroyWorker(worker)))
}
/**
protected abstract destroyWorker (worker: Worker): void | Promise<void>
/**
- * Send a message to the given worker.
+ * 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
+
+ /**
+ * Increase the number of tasks that the given workers has done.
*
- * @param worker The worker which should receive the message.
- * @param message The message.
+ * @param worker Worker whose tasks are increased.
*/
- protected abstract sendToWorker (
- worker: Worker,
- message: MessageValue<Data>
- ): void
+ protected increaseWorkersTask (worker: Worker): void {
+ this.stepWorkerNumberOfTasks(worker, 1)
+ }
/**
- * Adds the given worker to the pool.
+ * Decrease the number of tasks that the given workers has done.
*
- * @param worker Worker that will be added.
+ * @param worker Worker whose tasks are decreased.
*/
- protected addWorker (worker: Worker): void {
- const previousWorkerIndex = this.tasks.get(worker)
- if (previousWorkerIndex !== undefined) {
- this.tasks.set(worker, previousWorkerIndex + 1)
+ protected decreaseWorkersTasks (worker: Worker): void {
+ this.stepWorkerNumberOfTasks(worker, -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) {
+ 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')
}
this.tasks.delete(worker)
}
- 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
+ /**
+ * Choose 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
}
- protected abstract registerWorkerMessageListener (
- 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 abstract unregisterWorkerMessageListener (
- port: Worker,
- listener: (message: MessageValue<Response>) => void
- ): void
+ 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, id: number): Promise<Response> {
+ protected internalExecute (
+ worker: Worker,
+ messageId: number
+ ): Promise<Response> {
return new Promise((resolve, reject) => {
const listener: (message: MessageValue<Response>) => void = message => {
- if (message.id === id) {
+ if (message.id === messageId) {
this.unregisterWorkerMessageListener(worker, listener)
- this.addWorker(worker)
+ this.decreaseWorkersTasks(worker)
if (message.error) reject(message.error)
else resolve(message.data as Response)
}
})
}
- /**
- * Choose a worker for the next task.
- *
- * The default implementation uses a round robin algorithm to distribute the load.
- */
- protected chooseWorker (): Worker {
- this.nextWorker =
- this.nextWorker === this.workers.length - 1 ? 0 : this.nextWorker + 1
- return this.workers[this.nextWorker]
- }
-
/**
* Returns a newly created worker.
*/
- protected abstract newWorker (): Worker
+ protected abstract createWorker (): Worker
/**
* Function that can be hooked up when a worker has been newly created and moved to the workers registry.
*
* @param worker The newly created worker.
*/
- protected abstract afterNewWorkerPushed (worker: Worker): void
+ 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 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 ?? (() => {}))
+ protected createAndSetupWorker (): Worker {
+ const worker: Worker = this.createWorker()
+
+ worker.on('error', this.opts.errorHandler ?? emptyFunction)
+ worker.on('online', this.opts.onlineHandler ?? emptyFunction)
+ worker.on('exit', this.opts.exitHandler ?? emptyFunction)
+ worker.once('exit', () => this.removeWorker(worker))
+
this.workers.push(worker)
- this.afterNewWorkerPushed(worker)
- // init tasks map
+
+ // Init tasks map
this.tasks.set(worker, 0)
+
+ this.afterWorkerSetup(worker)
+
return worker
}
}