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     useDynamicWorker: true
  28   }
  29
  30   /** @inheritDoc */
  31   public constructor (
  32     pool: IPool<Worker, Data, Response>,
  33     opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  34   ) {
  35     super(pool, opts)
  36     this.setTaskStatisticsRequirements(this.opts)
  37   }
  38
  39   /** @inheritDoc */
  40   public reset (): boolean {
  41     this.nextWorkerNodeKey = 0
  42     return true
  43   }
  44
  45   /** @inheritDoc */
  46   public update (): boolean {
  47     return true
  48   }
  49
  50   /** @inheritDoc */
  51   public choose (): number {
  52     const chosenWorkerNodeKey = this.nextWorkerNodeKey
  53     do {
  54       this.roundRobinNextWorkerNodeKey()
  55     } while (!this.isWorkerNodeEligible(this.nextWorkerNodeKey))
  56     return chosenWorkerNodeKey
  57   }
  58
  59   /** @inheritDoc */
  60   public remove (workerNodeKey: number): boolean {
  61     if (this.nextWorkerNodeKey === workerNodeKey) {
  62       if (this.pool.workerNodes.length === 0) {
  63         this.nextWorkerNodeKey = 0
  64       } else if (this.nextWorkerNodeKey > this.pool.workerNodes.length - 1) {
  65         this.nextWorkerNodeKey = this.pool.workerNodes.length - 1
  66       }
  67     }
  68     return true
  69   }
  70
  71   private roundRobinNextWorkerNodeKey (): number {
  72     this.nextWorkerNodeKey =
  73       this.nextWorkerNodeKey === this.pool.workerNodes.length - 1
  74         ? 0
  75         : this.nextWorkerNodeKey + 1
  76     return this.nextWorkerNodeKey
  77   }
  78 }