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.nextWorkerNodeKey = 0
  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.roundRobinNextWorkerNodeKey()
  48     if (!this.isWorkerNodeEligible(this.nextWorkerNodeKey as number)) {
  49       this.nextWorkerNodeKey = undefined
  50       this.previousWorkerNodeKey =
  51         chosenWorkerNodeKey ?? this.previousWorkerNodeKey
  52     }
  53     return chosenWorkerNodeKey
  54   }
  55
  56   /** @inheritDoc */
  57   public remove (workerNodeKey: number): boolean {
  58     if (this.nextWorkerNodeKey === workerNodeKey) {
  59       if (this.pool.workerNodes.length === 0) {
  60         this.nextWorkerNodeKey = 0
  61       } else if (this.nextWorkerNodeKey > this.pool.workerNodes.length - 1) {
  62         this.nextWorkerNodeKey = this.pool.workerNodes.length - 1
  63       }
  64     }
  65     return true
  66   }
  67
  68   private roundRobinNextWorkerNodeKey (): number | undefined {
  69     this.nextWorkerNodeKey =
  70       this.nextWorkerNodeKey === this.pool.workerNodes.length - 1
  71         ? 0
  72         : (this.nextWorkerNodeKey ?? this.previousWorkerNodeKey) + 1
  73     return this.nextWorkerNodeKey
  74   }
  75 }