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   RequiredStatistics,
   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 requiredStatistics: RequiredStatistics = {
  28     runTime: true,
  29     avgRunTime: true,
  30     medRunTime: false,
  31     waitTime: false,
  32     avgWaitTime: false,
  33     medWaitTime: false
  34   }
  35
  36   /**
  37    * Worker node id where the current task will be submitted.
  38    */
  39   private currentWorkerNodeId: number = 0
  40   /**
  41    * Default worker weight.
  42    */
  43   private readonly defaultWorkerWeight: number
  44   /**
  45    * Worker virtual task runtime.
  46    */
  47   private workerVirtualTaskRunTime: number = 0
  48
  49   /** @inheritDoc */
  50   public constructor (
  51     pool: IPool<Worker, Data, Response>,
  52     opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  53   ) {
  54     super(pool, opts)
  55     this.setRequiredStatistics(this.opts)
  56     this.defaultWorkerWeight = this.computeDefaultWorkerWeight()
  57   }
  58
  59   /** @inheritDoc */
  60   public reset (): boolean {
  61     this.currentWorkerNodeId = 0
  62     this.workerVirtualTaskRunTime = 0
  63     return true
  64   }
  65
  66   /** @inheritDoc */
  67   public update (): boolean {
  68     return true
  69   }
  70
  71   /** @inheritDoc */
  72   public choose (): number {
  73     const chosenWorkerNodeKey = this.currentWorkerNodeId
  74     const workerVirtualTaskRunTime = this.workerVirtualTaskRunTime
  75     const workerWeight =
  76       this.opts.weights?.[chosenWorkerNodeKey] ?? this.defaultWorkerWeight
  77     if (workerVirtualTaskRunTime < workerWeight) {
  78       this.workerVirtualTaskRunTime =
  79         workerVirtualTaskRunTime +
  80         this.getWorkerTaskRunTime(chosenWorkerNodeKey)
  81     } else {
  82       this.currentWorkerNodeId =
  83         this.currentWorkerNodeId === this.pool.workerNodes.length - 1
  84           ? 0
  85           : this.currentWorkerNodeId + 1
  86       this.workerVirtualTaskRunTime = 0
  87     }
  88     return chosenWorkerNodeKey
  89   }
  90
  91   /** @inheritDoc */
  92   public remove (workerNodeKey: number): boolean {
  93     if (this.currentWorkerNodeId === workerNodeKey) {
  94       if (this.pool.workerNodes.length === 0) {
  95         this.currentWorkerNodeId = 0
  96       } else if (this.currentWorkerNodeId > this.pool.workerNodes.length - 1) {
  97         this.currentWorkerNodeId = this.pool.workerNodes.length - 1
  98       }
  99       this.workerVirtualTaskRunTime = 0
 100     }
 101     return true
 102   }
 103 }