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

   1 import type { IPool } from '../pool.js'
   2 import type { IWorker } from '../worker.js'
   3 import { AbstractWorkerChoiceStrategy } from './abstract-worker-choice-strategy.js'
   4 import type {
   5   IWorkerChoiceStrategy,
   6   WorkerChoiceStrategyOptions
   7 } from './selection-strategies-types.js'
   8
   9 /**
  10  * Selects the next worker in a round robin fashion.
  11  *
  12  * @typeParam Worker - Type of worker which manages the strategy.
  13  * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data.
  14  * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
  15  */
  16 export class RoundRobinWorkerChoiceStrategy<
  17     Worker extends IWorker,
  18     Data = unknown,
  19     Response = unknown
  20   >
  21   extends AbstractWorkerChoiceStrategy<Worker, Data, Response>
  22   implements IWorkerChoiceStrategy {
  23   /** @inheritDoc */
  24   public constructor (
  25     pool: IPool<Worker, Data, Response>,
  26     opts?: WorkerChoiceStrategyOptions
  27   ) {
  28     super(pool, opts)
  29   }
  30
  31   /** @inheritDoc */
  32   public reset (): boolean {
  33     this.resetWorkerNodeKeyProperties()
  34     return true
  35   }
  36
  37   /** @inheritDoc */
  38   public update (): boolean {
  39     return true
  40   }
  41
  42   /** @inheritDoc */
  43   public choose (): number | undefined {
  44     const chosenWorkerNodeKey = this.nextWorkerNodeKey
  45     this.setPreviousWorkerNodeKey(chosenWorkerNodeKey)
  46     this.roundRobinNextWorkerNodeKey()
  47     this.checkNextWorkerNodeKey()
  48     return chosenWorkerNodeKey
  49   }
  50
  51   /** @inheritDoc */
  52   public remove (workerNodeKey: number): boolean {
  53     if (this.pool.workerNodes.length === 0) {
  54       this.reset()
  55       return true
  56     }
  57     if (
  58       this.nextWorkerNodeKey === workerNodeKey &&
  59       this.nextWorkerNodeKey > this.pool.workerNodes.length - 1
  60     ) {
  61       this.nextWorkerNodeKey = this.pool.workerNodes.length - 1
  62     }
  63     if (
  64       this.previousWorkerNodeKey === workerNodeKey &&
  65       this.previousWorkerNodeKey > this.pool.workerNodes.length - 1
  66     ) {
  67       this.previousWorkerNodeKey = this.pool.workerNodes.length - 1
  68     }
  69     return true
  70   }
  71
  72   private roundRobinNextWorkerNodeKey (): number | undefined {
  73     this.nextWorkerNodeKey =
  74       this.nextWorkerNodeKey === this.pool.workerNodes.length - 1
  75         ? 0
  76         : (this.nextWorkerNodeKey ?? this.previousWorkerNodeKey) + 1
  77     return this.nextWorkerNodeKey
  78   }
  79 }