src/pools/selection-strategies/abstract-worker-choice-strategy.ts

   1 import { DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS } from '../../utils'
   2 import type { IPool } from '../pool'
   3 import type { IWorker } from '../worker'
   4 import type {
   5   IWorkerChoiceStrategy,
   6   RequiredStatistics,
   7   WorkerChoiceStrategyOptions
   8 } from './selection-strategies-types'
   9
  10 /**
  11  * Worker choice strategy abstract base class.
  12  *
  13  * @typeParam Worker - Type of worker which manages the strategy.
  14  * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
  15  * @typeParam Response - Type of execution response. This can only be serializable data.
  16  */
  17 export abstract class AbstractWorkerChoiceStrategy<
  18   Worker extends IWorker,
  19   Data = unknown,
  20   Response = unknown
  21 > implements IWorkerChoiceStrategy {
  22   /**
  23    * Toggles finding the last free worker node key.
  24    */
  25   private toggleFindLastFreeWorkerNodeKey: boolean = false
  26   /** @inheritDoc */
  27   public readonly requiredStatistics: RequiredStatistics = {
  28     runTime: false,
  29     avgRunTime: false,
  30     medRunTime: false,
  31     waitTime: false,
  32     avgWaitTime: false,
  33     medWaitTime: false
  34   }
  35
  36   /**
  37    * Constructs a worker choice strategy bound to the pool.
  38    *
  39    * @param pool - The pool instance.
  40    * @param opts - The worker choice strategy options.
  41    */
  42   public constructor (
  43     protected readonly pool: IPool<Worker, Data, Response>,
  44     protected opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  45   ) {
  46     this.choose = this.choose.bind(this)
  47   }
  48
  49   protected setRequiredStatistics (opts: WorkerChoiceStrategyOptions): void {
  50     if (this.requiredStatistics.avgRunTime && opts.medRunTime === true) {
  51       this.requiredStatistics.avgRunTime = false
  52       this.requiredStatistics.medRunTime = opts.medRunTime as boolean
  53     }
  54     if (this.requiredStatistics.medRunTime && opts.medRunTime === false) {
  55       this.requiredStatistics.avgRunTime = true
  56       this.requiredStatistics.medRunTime = opts.medRunTime as boolean
  57     }
  58     if (this.requiredStatistics.avgWaitTime && opts.medWaitTime === true) {
  59       this.requiredStatistics.avgWaitTime = false
  60       this.requiredStatistics.medWaitTime = opts.medWaitTime as boolean
  61     }
  62     if (this.requiredStatistics.medWaitTime && opts.medWaitTime === false) {
  63       this.requiredStatistics.avgWaitTime = true
  64       this.requiredStatistics.medWaitTime = opts.medWaitTime as boolean
  65     }
  66   }
  67
  68   /** @inheritDoc */
  69   public abstract reset (): boolean
  70
  71   /** @inheritDoc */
  72   public abstract update (workerNodeKey: number): boolean
  73
  74   /** @inheritDoc */
  75   public abstract choose (): number
  76
  77   /** @inheritDoc */
  78   public abstract remove (workerNodeKey: number): boolean
  79
  80   /** @inheritDoc */
  81   public setOptions (opts: WorkerChoiceStrategyOptions): void {
  82     opts = opts ?? DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  83     this.setRequiredStatistics(opts)
  84     this.opts = opts
  85   }
  86
  87   /**
  88    * Finds a free worker node key.
  89    *
  90    * @returns The free worker node key or `-1` if there is no free worker node.
  91    */
  92   protected findFreeWorkerNodeKey (): number {
  93     if (this.toggleFindLastFreeWorkerNodeKey) {
  94       this.toggleFindLastFreeWorkerNodeKey = false
  95       return this.findLastFreeWorkerNodeKey()
  96     }
  97     this.toggleFindLastFreeWorkerNodeKey = true
  98     return this.findFirstFreeWorkerNodeKey()
  99   }
 100
 101   /**
 102    * Gets the worker task runtime.
 103    * If the required statistics are `avgRunTime`, the average runtime is returned.
 104    * If the required statistics are `medRunTime`, the median runtime is returned.
 105    *
 106    * @param workerNodeKey - The worker node key.
 107    * @returns The worker task runtime.
 108    */
 109   protected getWorkerTaskRunTime (workerNodeKey: number): number {
 110     return this.requiredStatistics.medRunTime
 111       ? this.pool.workerNodes[workerNodeKey].tasksUsage.medRunTime
 112       : this.pool.workerNodes[workerNodeKey].tasksUsage.avgRunTime
 113   }
 114
 115   /**
 116    * Finds the first free worker node key based on the number of tasks the worker has applied.
 117    *
 118    * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
 119    *
 120    * If no free worker is found, `-1` is returned.
 121    *
 122    * @returns A worker node key if there is one, `-1` otherwise.
 123    */
 124   private findFirstFreeWorkerNodeKey (): number {
 125     return this.pool.workerNodes.findIndex(workerNode => {
 126       return workerNode.tasksUsage.running === 0
 127     })
 128   }
 129
 130   /**
 131    * Finds the last free worker node key based on the number of tasks the worker has applied.
 132    *
 133    * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
 134    *
 135    * If no free worker is found, `-1` is returned.
 136    *
 137    * @returns A worker node key if there is one, `-1` otherwise.
 138    */
 139   private findLastFreeWorkerNodeKey (): number {
 140     // It requires node >= 18.0.0:
 141     // return this.workerNodes.findLastIndex(workerNode => {
 142     //   return workerNode.tasksUsage.running === 0
 143     // })
 144     for (
 145       let workerNodeKey = this.pool.workerNodes.length - 1;
 146       workerNodeKey >= 0;
 147       workerNodeKey--
 148     ) {
 149       if (this.pool.workerNodes[workerNodeKey].tasksUsage.running === 0) {
 150         return workerNodeKey
 151       }
 152     }
 153     return -1
 154   }
 155 }