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  * @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 WeightedRoundRobinWorkerChoiceStrategy<
  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 taskStatisticsRequirements: TaskStatisticsRequirements = {
  27     runTime: {
  28       aggregate: true,
  29       average: true,
  30       median: false,
  31     },
  32     waitTime: {
  33       aggregate: true,
  34       average: true,
  35       median: false,
  36     },
  37     elu: DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS,
  38   }
  39
  40   /**
  41    * Worker node virtual execution time.
  42    */
  43   private workerNodeVirtualTaskExecutionTime = 0
  44
  45   /** @inheritDoc */
  46   public constructor (
  47     pool: IPool<Worker, Data, Response>,
  48     opts?: WorkerChoiceStrategyOptions
  49   ) {
  50     super(pool, opts)
  51     this.setTaskStatisticsRequirements(this.opts)
  52   }
  53
  54   /** @inheritDoc */
  55   public reset (): boolean {
  56     this.resetWorkerNodeKeyProperties()
  57     this.workerNodeVirtualTaskExecutionTime = 0
  58     return true
  59   }
  60
  61   /** @inheritDoc */
  62   public update (): boolean {
  63     return true
  64   }
  65
  66   /** @inheritDoc */
  67   public choose (): number | undefined {
  68     this.setPreviousWorkerNodeKey(this.nextWorkerNodeKey)
  69     this.weightedRoundRobinNextWorkerNodeKey()
  70     this.checkNextWorkerNodeKey()
  71     return this.nextWorkerNodeKey
  72   }
  73
  74   /** @inheritDoc */
  75   public remove (workerNodeKey: number): boolean {
  76     if (this.pool.workerNodes.length === 0) {
  77       this.reset()
  78       return true
  79     }
  80     if (this.nextWorkerNodeKey === workerNodeKey) {
  81       this.workerNodeVirtualTaskExecutionTime = 0
  82       if (this.nextWorkerNodeKey > this.pool.workerNodes.length - 1) {
  83         this.nextWorkerNodeKey = this.pool.workerNodes.length - 1
  84       }
  85     }
  86     if (
  87       this.previousWorkerNodeKey === workerNodeKey &&
  88       this.previousWorkerNodeKey > this.pool.workerNodes.length - 1
  89     ) {
  90       this.previousWorkerNodeKey = this.pool.workerNodes.length - 1
  91     }
  92     return true
  93   }
  94
  95   private weightedRoundRobinNextWorkerNodeKey (): number | undefined {
  96     const workerWeight =
  97       // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
  98       this.opts!.weights![this.nextWorkerNodeKey ?? this.previousWorkerNodeKey]
  99     if (this.workerNodeVirtualTaskExecutionTime < workerWeight) {
 100       this.workerNodeVirtualTaskExecutionTime +=
 101         this.getWorkerNodeTaskWaitTime(
 102           this.nextWorkerNodeKey ?? this.previousWorkerNodeKey
 103         ) +
 104         this.getWorkerNodeTaskRunTime(
 105           this.nextWorkerNodeKey ?? this.previousWorkerNodeKey
 106         )
 107     } else {
 108       this.nextWorkerNodeKey =
 109         this.nextWorkerNodeKey === this.pool.workerNodes.length - 1
 110           ? 0
 111           : (this.nextWorkerNodeKey ?? this.previousWorkerNodeKey) + 1
 112       this.workerNodeVirtualTaskExecutionTime = 0
 113     }
 114     return this.nextWorkerNodeKey
 115   }
 116 }