src/utils.ts

   1 import os from 'node:os'
   2 import type {
   3   MeasurementStatisticsRequirements,
   4   WorkerChoiceStrategyOptions
   5 } from './pools/selection-strategies/selection-strategies-types'
   6 import type { KillBehavior } from './worker/worker-options'
   7
   8 /**
   9  * An intentional empty function.
  10  */
  11 export const EMPTY_FUNCTION: () => void = Object.freeze(() => {
  12   /* Intentionally empty */
  13 })
  14
  15 /**
  16  * Default worker choice strategy options.
  17  */
  18 export const DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS: WorkerChoiceStrategyOptions =
  19   {
  20     runTime: { median: false },
  21     waitTime: { median: false },
  22     elu: { median: false }
  23   }
  24
  25 /**
  26  * Default measurement statistics requirements.
  27  */
  28 export const DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS: MeasurementStatisticsRequirements =
  29   {
  30     aggregate: false,
  31     average: false,
  32     median: false
  33   }
  34
  35 /**
  36  * Returns safe host OS optimized estimate of the default amount of parallelism a pool should use.
  37  * Always returns a value greater than zero.
  38  *
  39  * @returns The host OS optimized maximum pool size.
  40  */
  41 export const availableParallelism = (): number => {
  42   let availableParallelism = 1
  43   try {
  44     availableParallelism = os.availableParallelism()
  45   } catch {
  46     const cpus = os.cpus()
  47     if (Array.isArray(cpus) && cpus.length > 0) {
  48       availableParallelism = cpus.length
  49     }
  50   }
  51   return availableParallelism
  52 }
  53
  54 /**
  55  * Computes the median of the given data set.
  56  *
  57  * @param dataSet - Data set.
  58  * @returns The median of the given data set.
  59  */
  60 export const median = (dataSet: number[]): number => {
  61   if (Array.isArray(dataSet) && dataSet.length === 0) {
  62     return 0
  63   }
  64   if (Array.isArray(dataSet) && dataSet.length === 1) {
  65     return dataSet[0]
  66   }
  67   const sortedDataSet = dataSet.slice().sort((a, b) => a - b)
  68   return (
  69     (sortedDataSet[(sortedDataSet.length - 1) >> 1] +
  70       sortedDataSet[sortedDataSet.length >> 1]) /
  71     2
  72   )
  73 }
  74
  75 /**
  76  * Rounds the given number to the given scale.
  77  * The rounding is done using the "round half away from zero" method.
  78  *
  79  * @param num - The number to round.
  80  * @param scale - The scale to round to.
  81  * @returns The rounded number.
  82  */
  83 export const round = (num: number, scale = 2): number => {
  84   const rounder = Math.pow(10, scale)
  85   return Math.round(num * rounder * (1 + Number.EPSILON)) / rounder
  86 }
  87
  88 /**
  89  * Is the given object a plain object?
  90  *
  91  * @param obj - The object to check.
  92  * @returns `true` if the given object is a plain object, `false` otherwise.
  93  */
  94 export const isPlainObject = (obj: unknown): boolean =>
  95   typeof obj === 'object' &&
  96   obj !== null &&
  97   obj?.constructor === Object &&
  98   Object.prototype.toString.call(obj) === '[object Object]'
  99
 100 /**
 101  * Detects whether the given value is a kill behavior or not.
 102  *
 103  * @typeParam KB - Which specific KillBehavior type to test against.
 104  * @param killBehavior - Which kind of kill behavior to detect.
 105  * @param value - Any value.
 106  * @returns `true` if `value` was strictly equals to `killBehavior`, otherwise `false`.
 107  */
 108 export const isKillBehavior = <KB extends KillBehavior>(
 109   killBehavior: KB,
 110   value: unknown
 111 ): value is KB => {
 112   return value === killBehavior
 113 }