src/pools/cluster/dynamic.ts

   1 import { EventEmitter } from 'events'
   2 import type { FixedClusterPoolOptions, WorkerWithMessageChannel } from './fixed'
   3 import { FixedClusterPool } from './fixed'
   4
   5 class MyEmitter extends EventEmitter {}
   6
   7 export type DynamicClusterPoolOptions = FixedClusterPoolOptions
   8
   9 /**
  10  * A cluster pool with a min/max number of workers, is possible to execute tasks in sync or async mode as you prefer.
  11  *
  12  * This cluster pool will create new workers when the other ones are busy, until the max number of workers,
  13  * when the max number of workers is reached, an event will be emitted, if you want to listen this event use the emitter method.
  14  *
  15  * @author [Christopher Quadflieg](https://github.com/Shinigami92)
  16  * @since 2.0.0
  17  */
  18 export class DynamicClusterPool<
  19   // eslint-disable-next-line @typescript-eslint/no-explicit-any
  20   Data = any,
  21   // eslint-disable-next-line @typescript-eslint/no-explicit-any
  22   Response = any
  23 > extends FixedClusterPool<Data, Response> {
  24   public readonly emitter: MyEmitter
  25
  26   /**
  27    * @param min Min number of workers that will be always active
  28    * @param max Max number of workers that will be active
  29    * @param filename A file path with implementation of `ClusterWorker` class, relative path is fine.
  30    * @param opts An object with possible options for example `errorHandler`, `onlineHandler`. Default: `{ maxTasks: 1000 }`
  31    */
  32   public constructor (
  33     public readonly min: number,
  34     public readonly max: number,
  35     public readonly filename: string,
  36     public readonly opts: DynamicClusterPoolOptions = { maxTasks: 1000 }
  37   ) {
  38     super(min, filename, opts)
  39
  40     this.emitter = new MyEmitter()
  41   }
  42
  43   protected chooseWorker (): WorkerWithMessageChannel {
  44     let worker: WorkerWithMessageChannel | undefined
  45     for (const entry of this.tasks) {
  46       if (entry[1] === 0) {
  47         worker = entry[0]
  48         break
  49       }
  50     }
  51
  52     if (worker) {
  53       // a worker is free, use it
  54       return worker
  55     } else {
  56       if (this.workers.length === this.max) {
  57         this.emitter.emit('FullPool')
  58         return super.chooseWorker()
  59       }
  60       // all workers are busy create a new worker
  61       const worker = this.newWorker()
  62       worker.on('message', (message: { kill?: number }) => {
  63         if (message.kill) {
  64           worker.send({ kill: 1 })
  65           worker.kill()
  66           // clean workers from data structures
  67           const workerIndex = this.workers.indexOf(worker)
  68           this.workers.splice(workerIndex, 1)
  69           this.tasks.delete(worker)
  70         }
  71       })
  72       return worker
  73     }
  74   }
  75 }