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