| 1 | import type { JSONValue } from '../../utility-types' |
| 2 | import type { PoolOptions } from '../abstract-pool' |
| 3 | import type { ThreadWorkerWithMessageChannel } from './fixed' |
| 4 | import { FixedThreadPool } from './fixed' |
| 5 | |
| 6 | /** |
| 7 | * A thread pool with a dynamic number of threads, but a guaranteed minimum number of threads. |
| 8 | * |
| 9 | * This thread pool creates new threads when the others are busy, up to the maximum number of threads. |
| 10 | * When the maximum number of threads is reached, an event is emitted. If you want to listen to this event, use the pool's `emitter`. |
| 11 | * |
| 12 | * @template Data Type of data sent to the worker. |
| 13 | * @template Response Type of response of execution. |
| 14 | * |
| 15 | * @author [Alessandro Pio Ardizio](https://github.com/pioardi) |
| 16 | * @since 0.0.1 |
| 17 | */ |
| 18 | export class DynamicThreadPool< |
| 19 | Data extends JSONValue = JSONValue, |
| 20 | Response extends JSONValue = JSONValue |
| 21 | > extends FixedThreadPool<Data, Response> { |
| 22 | /** |
| 23 | * Constructs a new poolifier dynamic thread pool. |
| 24 | * |
| 25 | * @param min Minimum number of threads which are always active. |
| 26 | * @param max Maximum number of threads that can be created by this pool. |
| 27 | * @param filename Path to an implementation of a `ThreadWorker` file, which can be relative or absolute. |
| 28 | * @param opts Options for this fixed thread pool. Default: `{ maxTasks: 1000 }` |
| 29 | */ |
| 30 | public constructor ( |
| 31 | min: number, |
| 32 | public readonly max: number, |
| 33 | filename: string, |
| 34 | opts: PoolOptions<ThreadWorkerWithMessageChannel> = { maxTasks: 1000 } |
| 35 | ) { |
| 36 | super(min, filename, opts) |
| 37 | } |
| 38 | |
| 39 | /** |
| 40 | * Choose a thread for the next task. |
| 41 | * |
| 42 | * It will first check for and return an idle thread. |
| 43 | * If all threads are busy, then it will try to create a new one up to the `max` thread count. |
| 44 | * If the max thread count is reached, the emitter will emit a `FullPool` event and it will fall back to using a round robin algorithm to distribute the load. |
| 45 | * |
| 46 | * @returns Thread worker. |
| 47 | */ |
| 48 | protected chooseWorker (): ThreadWorkerWithMessageChannel { |
| 49 | for (const [worker, numberOfTasks] of this.tasks) { |
| 50 | if (numberOfTasks === 0) { |
| 51 | // A worker is free, use it |
| 52 | return worker |
| 53 | } |
| 54 | } |
| 55 | |
| 56 | if (this.workers.length === this.max) { |
| 57 | this.emitter.emit('FullPool') |
| 58 | return super.chooseWorker() |
| 59 | } |
| 60 | |
| 61 | // All workers are busy, create a new worker |
| 62 | const worker = this.createAndSetupWorker() |
| 63 | this.registerWorkerMessageListener<Data>(worker, message => { |
| 64 | if (message.kill) { |
| 65 | this.sendToWorker(worker, { kill: 1 }) |
| 66 | void this.destroyWorker(worker) |
| 67 | } |
| 68 | }) |
| 69 | return worker |
| 70 | } |
| 71 | } |