src/pools/selection-strategies/dynamic-pool-worker-choice-strategy.ts

   1 import type { IPoolInternal } from '../pool-internal'
   2 import type { IPoolWorker } from '../pool-worker'
   3 import { AbstractWorkerChoiceStrategy } from './abstract-worker-choice-strategy'
   4 import type {
   5   IWorkerChoiceStrategy,
   6   WorkerChoiceStrategy
   7 } from './selection-strategies-types'
   8 import { WorkerChoiceStrategies } from './selection-strategies-types'
   9 import { SelectionStrategiesUtils } from './selection-strategies-utils'
  10
  11 /**
  12  * Selects the next worker for dynamic pool.
  13  *
  14  * @template Worker Type of worker which manages the strategy.
  15  * @template Data Type of data sent to the worker. This can only be serializable data.
  16  * @template Response Type of response of execution. This can only be serializable data.
  17  */
  18 export class DynamicPoolWorkerChoiceStrategy<
  19   Worker extends IPoolWorker,
  20   Data,
  21   Response
  22 > extends AbstractWorkerChoiceStrategy<Worker, Data, Response> {
  23   private workerChoiceStrategy: IWorkerChoiceStrategy<Worker>
  24
  25   /**
  26    * Constructs a worker choice strategy for dynamic pool.
  27    *
  28    * @param pool The pool instance.
  29    * @param createDynamicallyWorkerCallback The worker creation callback for dynamic pool.
  30    * @param workerChoiceStrategy The worker choice strategy when the pull is busy.
  31    */
  32   public constructor (
  33     pool: IPoolInternal<Worker, Data, Response>,
  34     private readonly createDynamicallyWorkerCallback: () => Worker,
  35     workerChoiceStrategy: WorkerChoiceStrategy = WorkerChoiceStrategies.ROUND_ROBIN
  36   ) {
  37     super(pool)
  38     this.workerChoiceStrategy = SelectionStrategiesUtils.getWorkerChoiceStrategy(
  39       this.pool,
  40       workerChoiceStrategy
  41     )
  42     this.requiredStatistics = this.workerChoiceStrategy.requiredStatistics
  43   }
  44
  45   /** @inheritDoc */
  46   public reset (): boolean {
  47     return this.workerChoiceStrategy.reset()
  48   }
  49
  50   /** @inheritDoc */
  51   public choose (): Worker {
  52     const freeWorker = this.pool.findFreeWorker()
  53     if (freeWorker) {
  54       return freeWorker
  55     }
  56
  57     if (this.pool.busy === true) {
  58       return this.workerChoiceStrategy.choose()
  59     }
  60
  61     // All workers are busy, create a new worker
  62     return this.createDynamicallyWorkerCallback()
  63   }
  64 }