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

   1 import type { IPool } from '../pool.js'
   2 import { DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS } from '../utils.js'
   3 import type { IWorker } from '../worker.js'
   4 import { AbstractWorkerChoiceStrategy } from './abstract-worker-choice-strategy.js'
   5 import type {
   6   IWorkerChoiceStrategy,
   7   TaskStatisticsRequirements,
   8   WorkerChoiceStrategyOptions
   9 } from './selection-strategies-types.js'
  10
  11 /**
  12  * Selects the next worker with a weighted round robin scheduling algorithm.
  13  * Loosely modeled after the weighted round robin queueing algorithm: https://en.wikipedia.org/wiki/Weighted_round_robin.
  14  *
  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 readonly taskStatisticsRequirements: TaskStatisticsRequirements = {
  28     runTime: {
  29       aggregate: true,
  30       average: true,
  31       median: false
  32     },
  33     waitTime: DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS,
  34     elu: DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS
  35   }
  36
  37   /**
  38    * Worker node virtual task runtime.
  39    */
  40   private workerNodeVirtualTaskRunTime = 0
  41
  42   /** @inheritDoc */
  43   public constructor (
  44     pool: IPool<Worker, Data, Response>,
  45     opts?: WorkerChoiceStrategyOptions
  46   ) {
  47     super(pool, opts)
  48     this.setTaskStatisticsRequirements(this.opts)
  49   }
  50
  51   /** @inheritDoc */
  52   public reset (): boolean {
  53     this.resetWorkerNodeKeyProperties()
  54     this.workerNodeVirtualTaskRunTime = 0
  55     return true
  56   }
  57
  58   /** @inheritDoc */
  59   public update (): boolean {
  60     return true
  61   }
  62
  63   /** @inheritDoc */
  64   public choose (): number | undefined {
  65     this.setPreviousWorkerNodeKey(this.nextWorkerNodeKey)
  66     this.weightedRoundRobinNextWorkerNodeKey()
  67     this.checkNextWorkerNodeKey()
  68     return this.nextWorkerNodeKey
  69   }
  70
  71   /** @inheritDoc */
  72   public remove (workerNodeKey: number): boolean {
  73     if (this.pool.workerNodes.length === 0) {
  74       this.reset()
  75       return true
  76     }
  77     if (this.nextWorkerNodeKey === workerNodeKey) {
  78       this.workerNodeVirtualTaskRunTime = 0
  79       if (this.nextWorkerNodeKey > this.pool.workerNodes.length - 1) {
  80         this.nextWorkerNodeKey = this.pool.workerNodes.length - 1
  81       }
  82     }
  83     if (
  84       this.previousWorkerNodeKey === workerNodeKey &&
  85       this.previousWorkerNodeKey > this.pool.workerNodes.length - 1
  86     ) {
  87       this.previousWorkerNodeKey = this.pool.workerNodes.length - 1
  88     }
  89     return true
  90   }
  91
  92   private weightedRoundRobinNextWorkerNodeKey (): number | undefined {
  93     const workerWeight =
  94       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
  95       this.opts!.weights![this.nextWorkerNodeKey ?? this.previousWorkerNodeKey]
  96     if (this.workerNodeVirtualTaskRunTime < workerWeight) {
  97       this.workerNodeVirtualTaskRunTime =
  98         this.workerNodeVirtualTaskRunTime +
  99         this.getWorkerNodeTaskRunTime(
 100           this.nextWorkerNodeKey ?? this.previousWorkerNodeKey
 101         )
 102     } else {
 103       this.nextWorkerNodeKey =
 104         this.nextWorkerNodeKey === this.pool.workerNodes.length - 1
 105           ? 0
 106           : (this.nextWorkerNodeKey ?? this.previousWorkerNodeKey) + 1
 107       this.workerNodeVirtualTaskRunTime = 0
 108     }
 109     return this.nextWorkerNodeKey
 110   }
 111 }