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   }
  32
  33   /**
  34    * Constructs a worker choice strategy bound to the pool.
  35    *
  36    * @param pool - The pool instance.
  37    * @param opts - The worker choice strategy options.
  38    */
  39   public constructor (
  40     protected readonly pool: IPool<Worker, Data, Response>,
  41     protected opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  42   ) {
  43     this.choose = this.choose.bind(this)
  44   }
  45
  46   protected setRequiredStatistics (opts: WorkerChoiceStrategyOptions): void {
  47     if (this.requiredStatistics.avgRunTime && opts.medRunTime === true) {
  48       this.requiredStatistics.avgRunTime = false
  49       this.requiredStatistics.medRunTime = opts.medRunTime as boolean
  50     }
  51     if (this.requiredStatistics.medRunTime && opts.medRunTime === false) {
  52       this.requiredStatistics.avgRunTime = true
  53       this.requiredStatistics.medRunTime = opts.medRunTime as boolean
  54     }
  55   }
  56
  57   /** @inheritDoc */
  58   public abstract reset (): boolean
  59
  60   /** @inheritDoc */
  61   public abstract update (workerNodeKey: number): boolean
  62
  63   /** @inheritDoc */
  64   public abstract choose (): number
  65
  66   /** @inheritDoc */
  67   public abstract remove (workerNodeKey: number): boolean
  68
  69   /** @inheritDoc */
  70   public setOptions (opts: WorkerChoiceStrategyOptions): void {
  71     opts = opts ?? DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  72     this.setRequiredStatistics(opts)
  73     this.opts = opts
  74   }
  75
  76   /**
  77    * Finds a free worker node key.
  78    *
  79    * @returns The free worker node key or `-1` if there is no free worker node.
  80    */
  81   protected findFreeWorkerNodeKey (): number {
  82     if (this.toggleFindLastFreeWorkerNodeKey) {
  83       this.toggleFindLastFreeWorkerNodeKey = false
  84       return this.findLastFreeWorkerNodeKey()
  85     }
  86     this.toggleFindLastFreeWorkerNodeKey = true
  87     return this.findFirstFreeWorkerNodeKey()
  88   }
  89
  90   /**
  91    * Gets the worker task runtime.
  92    * If the required statistics are `avgRunTime`, the average runtime is returned.
  93    * If the required statistics are `medRunTime`, the median runtime is returned.
  94    *
  95    * @param workerNodeKey - The worker node key.
  96    * @returns The worker task runtime.
  97    */
  98   protected getWorkerTaskRunTime (workerNodeKey: number): number {
  99     return this.requiredStatistics.medRunTime
 100       ? this.pool.workerNodes[workerNodeKey].tasksUsage.medRunTime
 101       : this.pool.workerNodes[workerNodeKey].tasksUsage.avgRunTime
 102   }
 103
 104   /**
 105    * Finds the first free worker node key based on the number of tasks the worker has applied.
 106    *
 107    * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
 108    *
 109    * If no free worker is found, `-1` is returned.
 110    *
 111    * @returns A worker node key if there is one, `-1` otherwise.
 112    */
 113   private findFirstFreeWorkerNodeKey (): number {
 114     return this.pool.workerNodes.findIndex(workerNode => {
 115       return workerNode.tasksUsage.running === 0
 116     })
 117   }
 118
 119   /**
 120    * Finds the last free worker node key based on the number of tasks the worker has applied.
 121    *
 122    * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
 123    *
 124    * If no free worker is found, `-1` is returned.
 125    *
 126    * @returns A worker node key if there is one, `-1` otherwise.
 127    */
 128   private findLastFreeWorkerNodeKey (): number {
 129     // It requires node >= 18.0.0:
 130     // return this.workerNodes.findLastIndex(workerNode => {
 131     //   return workerNode.tasksUsage.running === 0
 132     // })
 133     for (
 134       let workerNodeKey = this.pool.workerNodes.length - 1;
 135       workerNodeKey >= 0;
 136       workerNodeKey--
 137     ) {
 138       if (this.pool.workerNodes[workerNodeKey].tasksUsage.running === 0) {
 139         return workerNodeKey
 140       }
 141     }
 142     return -1
 143   }
 144 }