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

   1 import type { IPool } from '../pool.js'
   2 import type { IWorker } from '../worker.js'
   3 import type {
   4   IWorkerChoiceStrategy,
   5   TaskStatisticsRequirements,
   6   WorkerChoiceStrategyOptions,
   7 } from './selection-strategies-types.js'
   8
   9 import { DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS } from '../utils.js'
  10 import { AbstractWorkerChoiceStrategy } from './abstract-worker-choice-strategy.js'
  11
  12 /**
  13  * Selects the next worker with a weighted round robin scheduling algorithm.
  14  * Loosely modeled after the weighted round robin queueing algorithm: https://en.wikipedia.org/wiki/Weighted_round_robin.
  15  * @typeParam Worker - Type of worker which manages the strategy.
  16  * @typeParam Data - Type of data sent to the worker. This can only be structured-cloneable data.
  17  * @typeParam Response - Type of execution response. This can only be structured-cloneable data.
  18  */
  19 export class WeightedRoundRobinWorkerChoiceStrategy<
  20     Worker extends IWorker,
  21     Data = unknown,
  22     Response = unknown
  23   >
  24   extends AbstractWorkerChoiceStrategy<Worker, Data, Response>
  25   implements IWorkerChoiceStrategy {
  26   /** @inheritDoc */
  27   public override readonly taskStatisticsRequirements: TaskStatisticsRequirements =
  28     Object.freeze({
  29       elu: DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS,
  30       runTime: {
  31         aggregate: true,
  32         average: true,
  33         median: false,
  34       },
  35       waitTime: {
  36         aggregate: true,
  37         average: true,
  38         median: false,
  39       },
  40     })
  41
  42   /**
  43    * Worker node virtual execution time.
  44    */
  45   private workerNodeVirtualTaskExecutionTime = 0
  46
  47   /** @inheritDoc */
  48   public constructor (
  49     pool: IPool<Worker, Data, Response>,
  50     opts?: WorkerChoiceStrategyOptions
  51   ) {
  52     super(pool, opts)
  53     this.setTaskStatisticsRequirements(this.opts)
  54   }
  55
  56   /** @inheritDoc */
  57   public choose (): number | undefined {
  58     this.setPreviousWorkerNodeKey(this.nextWorkerNodeKey)
  59     this.weightedRoundRobinNextWorkerNodeKey()
  60     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
  61     if (!this.isWorkerNodeReady(this.nextWorkerNodeKey!)) {
  62       return undefined
  63     }
  64     return this.checkWorkerNodeKey(this.nextWorkerNodeKey)
  65   }
  66
  67   /** @inheritDoc */
  68   public remove (workerNodeKey: number): boolean {
  69     if (this.pool.workerNodes.length === 0) {
  70       return this.reset()
  71     }
  72     if (this.nextWorkerNodeKey === workerNodeKey) {
  73       this.workerNodeVirtualTaskExecutionTime = 0
  74     }
  75     if (
  76       this.nextWorkerNodeKey != null &&
  77       this.nextWorkerNodeKey >= workerNodeKey
  78     ) {
  79       this.nextWorkerNodeKey =
  80         (this.nextWorkerNodeKey - 1 + this.pool.workerNodes.length) %
  81         this.pool.workerNodes.length
  82       if (this.previousWorkerNodeKey >= workerNodeKey) {
  83         this.previousWorkerNodeKey = this.nextWorkerNodeKey
  84       }
  85     }
  86     return true
  87   }
  88
  89   /** @inheritDoc */
  90   public reset (): boolean {
  91     this.resetWorkerNodeKeyProperties()
  92     this.workerNodeVirtualTaskExecutionTime = 0
  93     return true
  94   }
  95
  96   /** @inheritDoc */
  97   public update (): boolean {
  98     return true
  99   }
 100
 101   private weightedRoundRobinNextWorkerNodeKey (): number | undefined {
 102     const workerNodeKey = this.nextWorkerNodeKey ?? this.previousWorkerNodeKey
 103     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
 104     const workerWeight = this.opts!.weights![workerNodeKey]
 105     if (this.workerNodeVirtualTaskExecutionTime < workerWeight) {
 106       this.workerNodeVirtualTaskExecutionTime +=
 107         this.getWorkerNodeTaskWaitTime(workerNodeKey) +
 108         this.getWorkerNodeTaskRunTime(workerNodeKey)
 109     } else {
 110       this.nextWorkerNodeKey =
 111         this.nextWorkerNodeKey === this.pool.workerNodes.length - 1
 112           ? 0
 113           : workerNodeKey + 1
 114       this.workerNodeVirtualTaskExecutionTime = 0
 115     }
 116     return this.nextWorkerNodeKey
 117   }
 118 }