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

   1 import { cpus } from 'node:os'
   2 import { DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS } from '../../utils'
   3 import type { IPool } from '../pool'
   4 import type { IWorker } from '../worker'
   5 import type {
   6   IWorkerChoiceStrategy,
   7   RequiredStatistics,
   8   WorkerChoiceStrategyOptions
   9 } from './selection-strategies-types'
  10
  11 /**
  12  * Worker choice strategy abstract base class.
  13  *
  14  * @typeParam Worker - Type of worker which manages the strategy.
  15  * @typeParam Data - Type of data sent to the worker. This can only be serializable data.
  16  * @typeParam Response - Type of execution response. This can only be serializable data.
  17  */
  18 export abstract class AbstractWorkerChoiceStrategy<
  19   Worker extends IWorker,
  20   Data = unknown,
  21   Response = unknown
  22 > implements IWorkerChoiceStrategy {
  23   /**
  24    * Toggles finding the last free worker node key.
  25    */
  26   private toggleFindLastFreeWorkerNodeKey: boolean = false
  27   /** @inheritDoc */
  28   public readonly requiredStatistics: RequiredStatistics = {
  29     runTime: false,
  30     avgRunTime: false,
  31     medRunTime: false,
  32     waitTime: false,
  33     avgWaitTime: false,
  34     medWaitTime: false,
  35     elu: false
  36   }
  37
  38   /**
  39    * Constructs a worker choice strategy bound to the pool.
  40    *
  41    * @param pool - The pool instance.
  42    * @param opts - The worker choice strategy options.
  43    */
  44   public constructor (
  45     protected readonly pool: IPool<Worker, Data, Response>,
  46     protected opts: WorkerChoiceStrategyOptions = DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  47   ) {
  48     this.choose = this.choose.bind(this)
  49   }
  50
  51   protected setRequiredStatistics (opts: WorkerChoiceStrategyOptions): void {
  52     if (this.requiredStatistics.avgRunTime && opts.medRunTime === true) {
  53       this.requiredStatistics.avgRunTime = false
  54       this.requiredStatistics.medRunTime = opts.medRunTime as boolean
  55     }
  56     if (this.requiredStatistics.medRunTime && opts.medRunTime === false) {
  57       this.requiredStatistics.avgRunTime = true
  58       this.requiredStatistics.medRunTime = opts.medRunTime as boolean
  59     }
  60     if (this.requiredStatistics.avgWaitTime && opts.medWaitTime === true) {
  61       this.requiredStatistics.avgWaitTime = false
  62       this.requiredStatistics.medWaitTime = opts.medWaitTime as boolean
  63     }
  64     if (this.requiredStatistics.medWaitTime && opts.medWaitTime === false) {
  65       this.requiredStatistics.avgWaitTime = true
  66       this.requiredStatistics.medWaitTime = opts.medWaitTime as boolean
  67     }
  68   }
  69
  70   /** @inheritDoc */
  71   public abstract reset (): boolean
  72
  73   /** @inheritDoc */
  74   public abstract update (workerNodeKey: number): boolean
  75
  76   /** @inheritDoc */
  77   public abstract choose (): number
  78
  79   /** @inheritDoc */
  80   public abstract remove (workerNodeKey: number): boolean
  81
  82   /** @inheritDoc */
  83   public setOptions (opts: WorkerChoiceStrategyOptions): void {
  84     opts = opts ?? DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  85     this.setRequiredStatistics(opts)
  86     this.opts = opts
  87   }
  88
  89   /**
  90    * Finds a free worker node key.
  91    *
  92    * @returns The free worker node key or `-1` if there is no free worker node.
  93    */
  94   protected findFreeWorkerNodeKey (): number {
  95     if (this.toggleFindLastFreeWorkerNodeKey) {
  96       this.toggleFindLastFreeWorkerNodeKey = false
  97       return this.findLastFreeWorkerNodeKey()
  98     }
  99     this.toggleFindLastFreeWorkerNodeKey = true
 100     return this.findFirstFreeWorkerNodeKey()
 101   }
 102
 103   /**
 104    * Gets the worker task runtime.
 105    * If the required statistics are `avgRunTime`, the average runtime is returned.
 106    * If the required statistics are `medRunTime`, the median runtime is returned.
 107    *
 108    * @param workerNodeKey - The worker node key.
 109    * @returns The worker task runtime.
 110    */
 111   protected getWorkerTaskRunTime (workerNodeKey: number): number {
 112     return this.requiredStatistics.medRunTime
 113       ? this.pool.workerNodes[workerNodeKey].tasksUsage.medRunTime
 114       : this.pool.workerNodes[workerNodeKey].tasksUsage.avgRunTime
 115   }
 116
 117   /**
 118    * Gets the worker task wait time.
 119    * If the required statistics are `avgWaitTime`, the average wait time is returned.
 120    * If the required statistics are `medWaitTime`, the median wait time is returned.
 121    *
 122    * @param workerNodeKey - The worker node key.
 123    * @returns The worker task wait time.
 124    */
 125   protected getWorkerWaitTime (workerNodeKey: number): number {
 126     return this.requiredStatistics.medWaitTime
 127       ? this.pool.workerNodes[workerNodeKey].tasksUsage.medWaitTime
 128       : this.pool.workerNodes[workerNodeKey].tasksUsage.avgWaitTime
 129   }
 130
 131   protected computeDefaultWorkerWeight (): number {
 132     let cpusCycleTimeWeight = 0
 133     for (const cpu of cpus()) {
 134       // CPU estimated cycle time
 135       const numberOfDigits = cpu.speed.toString().length - 1
 136       const cpuCycleTime = 1 / (cpu.speed / Math.pow(10, numberOfDigits))
 137       cpusCycleTimeWeight += cpuCycleTime * Math.pow(10, numberOfDigits)
 138     }
 139     return Math.round(cpusCycleTimeWeight / cpus().length)
 140   }
 141
 142   /**
 143    * Finds the first free worker node key based on the number of tasks the worker has applied.
 144    *
 145    * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
 146    *
 147    * If no free worker is found, `-1` is returned.
 148    *
 149    * @returns A worker node key if there is one, `-1` otherwise.
 150    */
 151   private findFirstFreeWorkerNodeKey (): number {
 152     return this.pool.workerNodes.findIndex(workerNode => {
 153       return workerNode.tasksUsage.running === 0
 154     })
 155   }
 156
 157   /**
 158    * Finds the last free worker node key based on the number of tasks the worker has applied.
 159    *
 160    * If a worker is found with `0` running tasks, it is detected as free and its worker node key is returned.
 161    *
 162    * If no free worker is found, `-1` is returned.
 163    *
 164    * @returns A worker node key if there is one, `-1` otherwise.
 165    */
 166   private findLastFreeWorkerNodeKey (): number {
 167     // It requires node >= 18.0.0:
 168     // return this.workerNodes.findLastIndex(workerNode => {
 169     //   return workerNode.tasksUsage.running === 0
 170     // })
 171     for (
 172       let workerNodeKey = this.pool.workerNodes.length - 1;
 173       workerNodeKey >= 0;
 174       workerNodeKey--
 175     ) {
 176       if (this.pool.workerNodes[workerNodeKey].tasksUsage.running === 0) {
 177         return workerNodeKey
 178       }
 179     }
 180     return -1
 181   }
 182 }