import { isMainThread, MessageChannel, SHARE_ENV, Worker } from 'worker_threads'
import type { Draft, MessageValue } from '../../utility-types'
+import type { PoolOptions } from '../abstract-pool'
+import { AbstractPool } from '../abstract-pool'
-export type WorkerWithMessageChannel = Worker & Draft<MessageChannel>
-
-export interface FixedThreadPoolOptions {
- /**
- * A function that will listen for error event on each worker thread.
- */
- errorHandler?: (this: Worker, e: Error) => void
- /**
- * A function that will listen for online event on each worker thread.
- */
- onlineHandler?: (this: Worker) => void
- /**
- * A function that will listen for exit event on each worker thread.
- */
- exitHandler?: (this: Worker, code: number) => void
- /**
- * This is just to avoid not useful warnings message, is used to set `maxListeners` on event emitters (workers are event emitters).
- *
- * @default 1000
- */
- maxTasks?: number
-}
+export type ThreadWorkerWithMessageChannel = Worker & Draft<MessageChannel>
/**
* A thread pool with a static number of threads, is possible to execute tasks in sync or async mode as you prefer.
* @since 0.0.1
*/
// eslint-disable-next-line @typescript-eslint/no-explicit-any
-export class FixedThreadPool<Data = any, Response = any> {
- public readonly workers: WorkerWithMessageChannel[] = []
- public nextWorker: number = 0
-
- // threadId as key and an integer value
- public readonly tasks: Map<WorkerWithMessageChannel, number> = new Map<
- WorkerWithMessageChannel,
- number
- >()
-
- protected id: number = 0
-
+export class FixedThreadPool<Data = any, Response = any> extends AbstractPool<
+ ThreadWorkerWithMessageChannel,
+ Data,
+ Response
+> {
/**
* @param numThreads Num of threads for this worker pool.
* @param filePath A file path with implementation of `ThreadWorker` class, relative path is fine.
* @param opts An object with possible options for example `errorHandler`, `onlineHandler`. Default: `{ maxTasks: 1000 }`
*/
public constructor (
- public readonly numThreads: number,
- public readonly filePath: string,
- public readonly opts: FixedThreadPoolOptions = { maxTasks: 1000 }
+ numThreads: number,
+ filePath: string,
+ opts: PoolOptions<ThreadWorkerWithMessageChannel> = { maxTasks: 1000 }
) {
- if (!isMainThread) {
- throw new Error('Cannot start a thread pool from a worker thread !!!')
- }
- // 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')
- }
+ super(numThreads, filePath, opts)
+ }
- for (let i = 1; i <= this.numThreads; i++) {
- this.newWorker()
- }
+ protected isMain (): boolean {
+ return isMainThread
}
- public async destroy (): Promise<void> {
- for (const worker of this.workers) {
- await worker.terminate()
- }
+ protected async destroyWorker (
+ worker: ThreadWorkerWithMessageChannel
+ ): Promise<void> {
+ await worker.terminate()
}
- /**
- * 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
- const worker = this.chooseWorker()
- 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')
- }
- const id = ++this.id
- const res = this.internalExecute(worker, id)
- worker.postMessage({ data: data || {}, id: id })
- return res
+ protected sendToWorker (
+ worker: ThreadWorkerWithMessageChannel,
+ message: MessageValue<Data>
+ ): void {
+ worker.postMessage(message)
}
- protected internalExecute (
- worker: WorkerWithMessageChannel,
- id: number
- ): Promise<Response> {
- return new Promise((resolve, reject) => {
- const listener: (message: MessageValue<Response>) => void = message => {
- if (message.id === id) {
- worker.port2?.removeListener('message', listener)
- 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')
- }
- if (message.error) reject(message.error)
- else resolve(message.data as Response)
- }
- }
- worker.port2?.on('message', listener)
- })
+ protected registerWorkerMessageListener (
+ port: ThreadWorkerWithMessageChannel,
+ listener: (message: MessageValue<Response>) => void
+ ): void {
+ port.port2?.on('message', listener)
}
- protected chooseWorker (): WorkerWithMessageChannel {
- if (this.workers.length - 1 === this.nextWorker) {
- this.nextWorker = 0
- return this.workers[this.nextWorker]
- } else {
- this.nextWorker++
- return this.workers[this.nextWorker]
- }
+ protected unregisterWorkerMessageListener (
+ port: ThreadWorkerWithMessageChannel,
+ listener: (message: MessageValue<Response>) => void
+ ): void {
+ port.port2?.removeListener('message', listener)
}
- protected newWorker (): WorkerWithMessageChannel {
- const worker: WorkerWithMessageChannel = new Worker(this.filePath, {
+ protected newWorker (): ThreadWorkerWithMessageChannel {
+ return new Worker(this.filePath, {
env: SHARE_ENV
})
- worker.on('error', this.opts.errorHandler ?? (() => {}))
- worker.on('online', this.opts.onlineHandler ?? (() => {}))
- // TODO handle properly when a thread exit
- worker.on('exit', this.opts.exitHandler ?? (() => {}))
- this.workers.push(worker)
+ }
+
+ protected afterNewWorkerPushed (
+ worker: ThreadWorkerWithMessageChannel
+ ): void {
const { port1, port2 } = new MessageChannel()
worker.postMessage({ parent: port1 }, [port1])
worker.port1 = port1
// we will attach a listener for every task,
// when task is completed the listener will be removed but to avoid warnings we are increasing the max listeners size
worker.port2.setMaxListeners(this.opts.maxTasks ?? 1000)
- // init tasks map
- this.tasks.set(worker, 0)
- return worker
}
}
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