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

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