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 { FairShareWorkerChoiceStrategy } from './fair-share-worker-choice-strategy'
   4 import { LessBusyWorkerChoiceStrategy } from './less-busy-worker-choice-strategy'
   5 import { LessUsedWorkerChoiceStrategy } from './less-used-worker-choice-strategy'
   6 import { RoundRobinWorkerChoiceStrategy } from './round-robin-worker-choice-strategy'
   7 import type {
   8   IWorkerChoiceStrategy,
   9   RequiredStatistics,
  10   WorkerChoiceStrategy
  11 } from './selection-strategies-types'
  12 import { WorkerChoiceStrategies } from './selection-strategies-types'
  13 import { WeightedRoundRobinWorkerChoiceStrategy } from './weighted-round-robin-worker-choice-strategy'
  14
  15 /**
  16  * The worker choice strategy context.
  17  *
  18  * @typeParam Worker - Type of worker.
  19  * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
  20  * @typeParam Response - Type of response of execution. This can only be serializable data.
  21  */
  22 export class WorkerChoiceStrategyContext<
  23   Worker extends IPoolWorker,
  24   Data = unknown,
  25   Response = unknown
  26 > {
  27   private readonly workerChoiceStrategies: Map<
  28   WorkerChoiceStrategy,
  29   IWorkerChoiceStrategy<Worker, Data, Response>
  30   >
  31
  32   /**
  33    * Worker choice strategy context constructor.
  34    *
  35    * @param pool - The pool instance.
  36    * @param createWorkerCallback - The worker creation callback for dynamic pool.
  37    * @param workerChoiceStrategy - The worker choice strategy.
  38    */
  39   public constructor (
  40     pool: IPoolInternal<Worker, Data, Response>,
  41     private readonly createWorkerCallback: () => number,
  42     private workerChoiceStrategyType: WorkerChoiceStrategy = WorkerChoiceStrategies.ROUND_ROBIN
  43   ) {
  44     this.execute.bind(this)
  45     this.workerChoiceStrategies = new Map<
  46     WorkerChoiceStrategy,
  47     IWorkerChoiceStrategy<Worker, Data, Response>
  48     >([
  49       [
  50         WorkerChoiceStrategies.ROUND_ROBIN,
  51         new RoundRobinWorkerChoiceStrategy<Worker, Data, Response>(pool)
  52       ],
  53       [
  54         WorkerChoiceStrategies.LESS_USED,
  55         new LessUsedWorkerChoiceStrategy<Worker, Data, Response>(pool)
  56       ],
  57       [
  58         WorkerChoiceStrategies.LESS_BUSY,
  59         new LessBusyWorkerChoiceStrategy<Worker, Data, Response>(pool)
  60       ],
  61       [
  62         WorkerChoiceStrategies.FAIR_SHARE,
  63         new FairShareWorkerChoiceStrategy<Worker, Data, Response>(pool)
  64       ],
  65       [
  66         WorkerChoiceStrategies.WEIGHTED_ROUND_ROBIN,
  67         new WeightedRoundRobinWorkerChoiceStrategy<Worker, Data, Response>(pool)
  68       ]
  69     ])
  70   }
  71
  72   /**
  73    * Gets the worker choice strategy in the context required statistics.
  74    *
  75    * @returns The required statistics.
  76    */
  77   public getRequiredStatistics (): RequiredStatistics {
  78     return (
  79       this.workerChoiceStrategies.get(
  80         this.workerChoiceStrategyType
  81       ) as IWorkerChoiceStrategy<Worker, Data, Response>
  82     ).requiredStatistics
  83   }
  84
  85   /**
  86    * Sets the worker choice strategy to use in the context.
  87    *
  88    * @param workerChoiceStrategy - The worker choice strategy to set.
  89    */
  90   public setWorkerChoiceStrategy (
  91     workerChoiceStrategy: WorkerChoiceStrategy
  92   ): void {
  93     if (this.workerChoiceStrategyType === workerChoiceStrategy) {
  94       this.workerChoiceStrategies.get(workerChoiceStrategy)?.reset()
  95     } else {
  96       this.workerChoiceStrategyType = workerChoiceStrategy
  97     }
  98   }
  99
 100   /**
 101    * Executes the worker choice strategy algorithm in the context.
 102    *
 103    * @returns The key of the chosen one.
 104    */
 105   public execute (): number {
 106     const workerChoiceStrategy = this.workerChoiceStrategies.get(
 107       this.workerChoiceStrategyType
 108     ) as IWorkerChoiceStrategy<Worker, Data, Response>
 109     if (
 110       workerChoiceStrategy.isDynamicPool &&
 111       !workerChoiceStrategy.pool.full &&
 112       workerChoiceStrategy.pool.findFreeWorkerKey() === -1
 113     ) {
 114       return this.createWorkerCallback()
 115     }
 116     return workerChoiceStrategy.choose()
 117   }
 118
 119   /**
 120    * Removes a worker from the worker choice strategy in the context.
 121    *
 122    * @param workerKey - The key of the worker to remove.
 123    * @returns `true` if the removal is successful, `false` otherwise.
 124    */
 125   public remove (workerKey: number): boolean {
 126     return (
 127       this.workerChoiceStrategies.get(
 128         this.workerChoiceStrategyType
 129       ) as IWorkerChoiceStrategy<Worker, Data, Response>
 130     ).remove(workerKey)
 131   }
 132 }