src/pools/selection-strategies/worker-choice-strategy-context.ts

   1 import type { IPoolInternal } from '../pool-internal'
   2 import { PoolType } from '../pool-internal'
   3 import type { IPoolWorker } from '../pool-worker'
   4 import type {
   5   IWorkerChoiceStrategy,
   6   RequiredStatistics,
   7   WorkerChoiceStrategy
   8 } from './selection-strategies-types'
   9 import { WorkerChoiceStrategies } from './selection-strategies-types'
  10 import { getWorkerChoiceStrategy } from './selection-strategies-utils'
  11
  12 /**
  13  * The worker choice strategy context.
  14  *
  15  * @typeParam Worker - Type of worker.
  16  * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
  17  * @typeParam Response - Type of response of execution. This can only be serializable data.
  18  */
  19 export class WorkerChoiceStrategyContext<
  20   Worker extends IPoolWorker,
  21   Data,
  22   Response
  23 > {
  24   private workerChoiceStrategy!: IWorkerChoiceStrategy
  25
  26   /**
  27    * Worker choice strategy context constructor.
  28    *
  29    * @param pool - The pool instance.
  30    * @param createWorkerCallback - The worker creation callback for dynamic pool.
  31    * @param workerChoiceStrategy - The worker choice strategy.
  32    */
  33   public constructor (
  34     private readonly pool: IPoolInternal<Worker, Data, Response>,
  35     private readonly createWorkerCallback: () => number,
  36     workerChoiceStrategy: WorkerChoiceStrategy = WorkerChoiceStrategies.ROUND_ROBIN
  37   ) {
  38     this.execute.bind(this)
  39     this.setWorkerChoiceStrategy(workerChoiceStrategy)
  40   }
  41
  42   /**
  43    * Gets the worker choice strategy required statistics.
  44    *
  45    * @returns The required statistics.
  46    */
  47   public getRequiredStatistics (): RequiredStatistics {
  48     return this.workerChoiceStrategy.requiredStatistics
  49   }
  50
  51   /**
  52    * Sets the worker choice strategy to use in the context.
  53    *
  54    * @param workerChoiceStrategy - The worker choice strategy to set.
  55    */
  56   public setWorkerChoiceStrategy (
  57     workerChoiceStrategy: WorkerChoiceStrategy
  58   ): void {
  59     this.workerChoiceStrategy?.reset()
  60     this.workerChoiceStrategy = getWorkerChoiceStrategy(
  61       this.pool,
  62       workerChoiceStrategy
  63     )
  64   }
  65
  66   /**
  67    * Chooses a worker with the worker choice strategy.
  68    *
  69    * @returns The key of the chosen one.
  70    */
  71   public execute (): number {
  72     if (
  73       this.pool.type === PoolType.DYNAMIC &&
  74       !this.pool.full &&
  75       this.pool.findFreeWorkerKey() === -1
  76     ) {
  77       return this.createWorkerCallback()
  78     }
  79     return this.workerChoiceStrategy.choose()
  80   }
  81
  82   /**
  83    * Removes a worker in the worker choice strategy internals.
  84    *
  85    * @param workerKey - The key of the worker to remove.
  86    * @returns `true` if the removal is successful, `false` otherwise.
  87    */
  88   public remove (workerKey: number): boolean {
  89     return this.workerChoiceStrategy.remove(workerKey)
  90   }
  91 }