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   TaskStatisticsRequirements,
   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 taskStatisticsRequirements: TaskStatisticsRequirements = {
  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 setTaskStatistics (opts: WorkerChoiceStrategyOptions): void {
  52     if (
  53       this.taskStatisticsRequirements.avgRunTime &&
  54       opts.medRunTime === true
  55     ) {
  56       this.taskStatisticsRequirements.avgRunTime = false
  57       this.taskStatisticsRequirements.medRunTime = opts.medRunTime as boolean
  58     }
  59     if (
  60       this.taskStatisticsRequirements.medRunTime &&
  61       opts.medRunTime === false
  62     ) {
  63       this.taskStatisticsRequirements.avgRunTime = true
  64       this.taskStatisticsRequirements.medRunTime = opts.medRunTime as boolean
  65     }
  66     if (
  67       this.taskStatisticsRequirements.avgWaitTime &&
  68       opts.medWaitTime === true
  69     ) {
  70       this.taskStatisticsRequirements.avgWaitTime = false
  71       this.taskStatisticsRequirements.medWaitTime = opts.medWaitTime as boolean
  72     }
  73     if (
  74       this.taskStatisticsRequirements.medWaitTime &&
  75       opts.medWaitTime === false
  76     ) {
  77       this.taskStatisticsRequirements.avgWaitTime = true
  78       this.taskStatisticsRequirements.medWaitTime = opts.medWaitTime as boolean
  79     }
  80   }
  81
  82   /** @inheritDoc */
  83   public abstract reset (): boolean
  84
  85   /** @inheritDoc */
  86   public abstract update (workerNodeKey: number): boolean
  87
  88   /** @inheritDoc */
  89   public abstract choose (): number
  90
  91   /** @inheritDoc */
  92   public abstract remove (workerNodeKey: number): boolean
  93
  94   /** @inheritDoc */
  95   public setOptions (opts: WorkerChoiceStrategyOptions): void {
  96     opts = opts ?? DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS
  97     this.setTaskStatistics(opts)
  98     this.opts = opts
  99   }
 100
 101   /**
 102    * Finds a free worker node key.
 103    *
 104    * @returns The free worker node key or `-1` if there is no free worker node.
 105    */
 106   protected findFreeWorkerNodeKey (): number {
 107     if (this.toggleFindLastFreeWorkerNodeKey) {
 108       this.toggleFindLastFreeWorkerNodeKey = false
 109       return this.findLastFreeWorkerNodeKey()
 110     }
 111     this.toggleFindLastFreeWorkerNodeKey = true
 112     return this.findFirstFreeWorkerNodeKey()
 113   }
 114
 115   /**
 116    * Gets the worker task runtime.
 117    * If the task statistics require `avgRunTime`, the average runtime is returned.
 118    * If the task statistics require `medRunTime`, the median runtime is returned.
 119    *
 120    * @param workerNodeKey - The worker node key.
 121    * @returns The worker task runtime.
 122    */
 123   protected getWorkerTaskRunTime (workerNodeKey: number): number {
 124     return this.taskStatisticsRequirements.medRunTime
 125       ? this.pool.workerNodes[workerNodeKey].workerUsage.runTime.median
 126       : this.pool.workerNodes[workerNodeKey].workerUsage.runTime.average
 127   }
 128
 129   /**
 130    * Gets the worker task wait time.
 131    * If the task statistics require `avgWaitTime`, the average wait time is returned.
 132    * If the task statistics require `medWaitTime`, the median wait time is returned.
 133    *
 134    * @param workerNodeKey - The worker node key.
 135    * @returns The worker task wait time.
 136    */
 137   protected getWorkerWaitTime (workerNodeKey: number): number {
 138     return this.taskStatisticsRequirements.medWaitTime
 139       ? this.pool.workerNodes[workerNodeKey].workerUsage.runTime.median
 140       : this.pool.workerNodes[workerNodeKey].workerUsage.runTime.average
 141   }
 142
 143   protected computeDefaultWorkerWeight (): number {
 144     let cpusCycleTimeWeight = 0
 145     for (const cpu of cpus()) {
 146       // CPU estimated cycle time
 147       const numberOfDigits = cpu.speed.toString().length - 1
 148       const cpuCycleTime = 1 / (cpu.speed / Math.pow(10, numberOfDigits))
 149       cpusCycleTimeWeight += cpuCycleTime * Math.pow(10, numberOfDigits)
 150     }
 151     return Math.round(cpusCycleTimeWeight / cpus().length)
 152   }
 153
 154   /**
 155    * Finds the first free worker node key based on the number of tasks the worker has applied.
 156    *
 157    * If a worker is found with `0` executing tasks, it is detected as free and its worker node key is returned.
 158    *
 159    * If no free worker is found, `-1` is returned.
 160    *
 161    * @returns A worker node key if there is one, `-1` otherwise.
 162    */
 163   private findFirstFreeWorkerNodeKey (): number {
 164     return this.pool.workerNodes.findIndex(workerNode => {
 165       return workerNode.workerUsage.tasks.executing === 0
 166     })
 167   }
 168
 169   /**
 170    * Finds the last free worker node key based on the number of tasks the worker has applied.
 171    *
 172    * If a worker is found with `0` executing tasks, it is detected as free and its worker node key is returned.
 173    *
 174    * If no free worker is found, `-1` is returned.
 175    *
 176    * @returns A worker node key if there is one, `-1` otherwise.
 177    */
 178   private findLastFreeWorkerNodeKey (): number {
 179     // It requires node >= 18.0.0:
 180     // return this.workerNodes.findLastIndex(workerNode => {
 181     //   return workerNode.workerUsage.tasks.executing === 0
 182     // })
 183     for (
 184       let workerNodeKey = this.pool.workerNodes.length - 1;
 185       workerNodeKey >= 0;
 186       workerNodeKey--
 187     ) {
 188       if (
 189         this.pool.workerNodes[workerNodeKey].workerUsage.tasks.executing === 0
 190       ) {
 191         return workerNodeKey
 192       }
 193     }
 194     return -1
 195   }
 196 }