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   StrategyPolicy,
   8   WorkerChoiceStrategyOptions
   9 } from './selection-strategies-types'
  10
  11 /**
  12  * Selects the next worker in a round robin fashion.
  13  *
  14  * @typeParam Worker - Type of worker which manages the strategy.
  15  * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data.
  16  * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
  17  */
  18 export class RoundRobinWorkerChoiceStrategy<
  19     Worker extends IWorker,
  20     Data = unknown,
  21     Response = unknown
  22   >
  23   extends AbstractWorkerChoiceStrategy<Worker, Data, Response>
  24   implements IWorkerChoiceStrategy {
  25   /** @inheritDoc */
  26   public readonly strategyPolicy: StrategyPolicy = {
  27     dynamicWorkerUsage: true,
  28     dynamicWorkerReady: true
  29   }
  30
  31   /** @inheritDoc */
  32   public constructor (
  33     pool: IPool<Worker, Data, Response>,
  34     opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  35   ) {
  36     super(pool, opts)
  37     this.setTaskStatisticsRequirements(this.opts)
  38   }
  39
  40   /** @inheritDoc */
  41   public reset (): boolean {
  42     this.nextWorkerNodeKey = 0
  43     return true
  44   }
  45
  46   /** @inheritDoc */
  47   public update (): boolean {
  48     return true
  49   }
  50
  51   /** @inheritDoc */
  52   public choose (): number | undefined {
  53     const chosenWorkerNodeKey = this.nextWorkerNodeKey
  54     this.roundRobinNextWorkerNodeKey()
  55     if (!this.isWorkerNodeEligible(this.nextWorkerNodeKey as number)) {
  56       this.nextWorkerNodeKey = undefined
  57     }
  58     return chosenWorkerNodeKey
  59   }
  60
  61   /** @inheritDoc */
  62   public remove (workerNodeKey: number): boolean {
  63     if (this.nextWorkerNodeKey === workerNodeKey) {
  64       if (this.pool.workerNodes.length === 0) {
  65         this.nextWorkerNodeKey = 0
  66       } else if (this.nextWorkerNodeKey > this.pool.workerNodes.length - 1) {
  67         this.nextWorkerNodeKey = this.pool.workerNodes.length - 1
  68       }
  69     }
  70     return true
  71   }
  72
  73   private roundRobinNextWorkerNodeKey (): number | undefined {
  74     this.nextWorkerNodeKey =
  75       this.nextWorkerNodeKey === this.pool.workerNodes.length - 1
  76         ? 0
  77         : (this.nextWorkerNodeKey ?? 0) + 1
  78     return this.nextWorkerNodeKey
  79   }
  80 }