import type { MessageValue } from '../utility-types'
import type { IPool } from './pool'
+/**
+ * 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
}
+/**
+ * Options for a poolifier pool.
+ */
export interface PoolOptions<Worker> {
/**
* A function that will listen for error 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).
+ * 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.
+ *
+ * @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.
+ */
export abstract class AbstractPool<
Worker extends IWorker,
Data = unknown,
Response = unknown
> implements IPool<Data, Response> {
+ /**
+ * List of currently available workers.
+ */
public readonly workers: Worker[] = []
+
+ /**
+ * ID for the next worker.
+ */
public nextWorker: number = 0
/**
- * `workerId` as key and an integer value
+ * - `key`: The `Worker`
+ * - `value`: Number of tasks that has been assigned to that worker since it started
*/
public readonly tasks: Map<Worker, number> = new Map<Worker, number>()
+ /**
+ * Emitter on which events can be listened to.
+ *
+ * Events that can currently be listened to:
+ *
+ * - `'FullPool'`
+ */
public readonly emitter: PoolEmitter
+ /**
+ * ID of the next message.
+ */
protected id: number = 0
+ /**
+ * Constructs a new poolifier pool.
+ *
+ * @param numWorkers 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 filePath: string,
this.emitter = new PoolEmitter()
}
+ /**
+ * Setup hook that can be overridden by a Poolifer 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> {
}
}
+ /**
+ * Shut down given worker.
+ *
+ * @param worker A worker within `workers`.
+ */
protected abstract destroyWorker (worker: Worker): void | Promise<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
+ /**
+ * Adds the given worker to the pool.
+ *
+ * @param worker Worker that will be added.
+ */
protected addWorker (worker: Worker): void {
const previousWorkerIndex = this.tasks.get(worker)
if (previousWorkerIndex !== undefined) {
}
}
+ /**
+ * Removes the given worker from the pool.
+ *
+ * @param worker Worker that will be removed.
+ */
protected removeWorker (worker: Worker): void {
// Clean worker from data structure
const workerIndex = this.workers.indexOf(worker)
this.tasks.delete(worker)
}
- /**
- * Execute the task specified into the constructor with the data parameter.
- *
- * @param data The input for the task specified.
- * @returns Promise that is resolved when the task is done.
- */
public execute (data: Data): Promise<Response> {
- // configure worker to handle message with the specified task
+ // Configure worker to handle message with the specified task
const worker = this.chooseWorker()
this.addWorker(worker)
const id = ++this.id
})
}
+ /**
+ * Choose a worker for the next task.
+ *
+ * The default implementation uses a round robin algorithm to distribute the load.
+ *
+ * @returns 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]
- }
+ 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
+ /**
+ * 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 afterNewWorkerPushed (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 ?? (() => {}))
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