src/pools/selection-strategies/round-robin-worker-choice-strategy.ts

   1 import { DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS } from '../../utils'
   2 import type { IPool } from '../pool'
   3 import type { IWorker } from '../worker'
   4 import { AbstractWorkerChoiceStrategy } from './abstract-worker-choice-strategy'
   5 import type {
   6   IWorkerChoiceStrategy,
   7   WorkerChoiceStrategyOptions
   8 } from './selection-strategies-types'
   9
  10 /**
  11  * Selects the next worker in a round robin fashion.
  12  *
  13  * @typeParam Worker - Type of worker which manages the strategy.
  14  * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
  15  * @typeParam Response - Type of execution response. This can only be serializable data.
  16  */
  17 export class RoundRobinWorkerChoiceStrategy<
  18     Worker extends IWorker,
  19     Data = unknown,
  20     Response = unknown
  21   >
  22   extends AbstractWorkerChoiceStrategy<Worker, Data, Response>
  23   implements IWorkerChoiceStrategy {
  24   /**
  25    * Id of the next worker node.
  26    */
  27   private nextWorkerNodeId: number = 0
  28
  29   /** @inheritDoc */
  30   public constructor (
  31     pool: IPool<Worker, Data, Response>,
  32     opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  33   ) {
  34     super(pool, opts)
  35     this.checkOptions(this.opts)
  36   }
  37
  38   /** @inheritDoc */
  39   public reset (): boolean {
  40     this.nextWorkerNodeId = 0
  41     return true
  42   }
  43
  44   /** @inheritDoc */
  45   public choose (): number {
  46     const chosenWorkerNodeKey = this.nextWorkerNodeId
  47     this.nextWorkerNodeId =
  48       this.nextWorkerNodeId === this.pool.workerNodes.length - 1
  49         ? 0
  50         : this.nextWorkerNodeId + 1
  51     return chosenWorkerNodeKey
  52   }
  53
  54   /** @inheritDoc */
  55   public remove (workerNodeKey: number): boolean {
  56     if (this.nextWorkerNodeId === workerNodeKey) {
  57       if (this.pool.workerNodes.length === 0) {
  58         this.nextWorkerNodeId = 0
  59       } else {
  60         this.nextWorkerNodeId =
  61           this.nextWorkerNodeId > this.pool.workerNodes.length - 1
  62             ? this.pool.workerNodes.length - 1
  63             : this.nextWorkerNodeId
  64       }
  65     }
  66     return true
  67   }
  68 }