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 structured-cloneable data.
  15  * @typeParam Response - Type of execution response. This can only be structured-cloneable 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   /** @inheritDoc */
  25   public constructor (
  26     pool: IPool<Worker, Data, Response>,
  27     opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  28   ) {
  29     super(pool, opts)
  30     this.setTaskStatisticsRequirements(this.opts)
  31   }
  32
  33   /** @inheritDoc */
  34   public reset (): boolean {
  35     this.resetWorkerNodeKeyProperties()
  36     return true
  37   }
  38
  39   /** @inheritDoc */
  40   public update (): boolean {
  41     return true
  42   }
  43
  44   /** @inheritDoc */
  45   public choose (): number | undefined {
  46     const chosenWorkerNodeKey = this.nextWorkerNodeKey
  47     this.setPreviousWorkerNodeKey(chosenWorkerNodeKey)
  48     this.roundRobinNextWorkerNodeKey()
  49     return chosenWorkerNodeKey
  50   }
  51
  52   /** @inheritDoc */
  53   public remove (workerNodeKey: number): boolean {
  54     if (this.pool.workerNodes.length === 0) {
  55       this.reset()
  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 }