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

   1 import type { IWorker } from '../worker'
   2 import type { IPool } from '../pool'
   3 import { DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS } from '../../utils'
   4 import { AbstractWorkerChoiceStrategy } from './abstract-worker-choice-strategy'
   5 import type {
   6   IWorkerChoiceStrategy,
   7   TaskStatisticsRequirements,
   8   WorkerChoiceStrategyOptions
   9 } from './selection-strategies-types'
  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 serializable data.
  17  * @typeParam Response - Type of execution response. This can only be serializable 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: {
  34       aggregate: false,
  35       average: false,
  36       median: false
  37     },
  38     elu: {
  39       aggregate: false,
  40       average: false,
  41       median: false
  42     }
  43   }
  44
  45   /**
  46    * Worker node id where the current task will be submitted.
  47    */
  48   private currentWorkerNodeId: number = 0
  49   /**
  50    * Default worker weight.
  51    */
  52   private readonly defaultWorkerWeight: number
  53   /**
  54    * Worker virtual task runtime.
  55    */
  56   private workerVirtualTaskRunTime: number = 0
  57
  58   /** @inheritDoc */
  59   public constructor (
  60     pool: IPool<Worker, Data, Response>,
  61     opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  62   ) {
  63     super(pool, opts)
  64     this.setTaskStatisticsRequirements(this.opts)
  65     this.defaultWorkerWeight = this.computeDefaultWorkerWeight()
  66   }
  67
  68   /** @inheritDoc */
  69   public reset (): boolean {
  70     this.currentWorkerNodeId = 0
  71     this.workerVirtualTaskRunTime = 0
  72     return true
  73   }
  74
  75   /** @inheritDoc */
  76   public update (): boolean {
  77     return true
  78   }
  79
  80   /** @inheritDoc */
  81   public choose (): number {
  82     const chosenWorkerNodeKey = this.currentWorkerNodeId
  83     const workerVirtualTaskRunTime = this.workerVirtualTaskRunTime
  84     const workerWeight =
  85       this.opts.weights?.[chosenWorkerNodeKey] ?? this.defaultWorkerWeight
  86     if (workerVirtualTaskRunTime < workerWeight) {
  87       this.workerVirtualTaskRunTime =
  88         workerVirtualTaskRunTime +
  89         this.getWorkerTaskRunTime(chosenWorkerNodeKey)
  90     } else {
  91       this.currentWorkerNodeId =
  92         this.currentWorkerNodeId === this.pool.workerNodes.length - 1
  93           ? 0
  94           : this.currentWorkerNodeId + 1
  95       this.workerVirtualTaskRunTime = 0
  96     }
  97     return chosenWorkerNodeKey
  98   }
  99
 100   /** @inheritDoc */
 101   public remove (workerNodeKey: number): boolean {
 102     if (this.currentWorkerNodeId === workerNodeKey) {
 103       if (this.pool.workerNodes.length === 0) {
 104         this.currentWorkerNodeId = 0
 105       } else if (this.currentWorkerNodeId > this.pool.workerNodes.length - 1) {
 106         this.currentWorkerNodeId = this.pool.workerNodes.length - 1
 107       }
 108       this.workerVirtualTaskRunTime = 0
 109     }
 110     return true
 111   }
 112 }