src/utils.ts

   1 import { getRandomValues } from 'node:crypto'
   2 import * as os from 'node:os'
   3
   4 import type { KillBehavior } from './worker/worker-options.js'
   5
   6 /**
   7  * Default task name.
   8  */
   9 export const DEFAULT_TASK_NAME = 'default'
  10
  11 /**
  12  * An intentional empty function.
  13  */
  14 export const EMPTY_FUNCTION: () => void = Object.freeze(() => {
  15   /* Intentionally empty */
  16 })
  17
  18 /**
  19  * Returns safe host OS optimized estimate of the default amount of parallelism a pool should use.
  20  * Always returns a value greater than zero.
  21  *
  22  * @returns The host OS optimized maximum pool size.
  23  */
  24 export const availableParallelism = (): number => {
  25   let availableParallelism = 1
  26   try {
  27     availableParallelism = os.availableParallelism()
  28   } catch {
  29     const cpus = os.cpus()
  30     if (Array.isArray(cpus) && cpus.length > 0) {
  31       availableParallelism = cpus.length
  32     }
  33   }
  34   return availableParallelism
  35 }
  36
  37 /**
  38  * Sleeps for the given amount of milliseconds.
  39  *
  40  * @param ms - The amount of milliseconds to sleep.
  41  * @returns A promise that resolves after the given amount of milliseconds.
  42  * @internal
  43  */
  44 export const sleep = async (ms: number): Promise<void> => {
  45   await new Promise(resolve => {
  46     setTimeout(resolve, ms)
  47   })
  48 }
  49
  50 /**
  51  * Computes the retry delay in milliseconds using an exponential back off algorithm.
  52  *
  53  * @param retryNumber - The number of retries that have already been attempted
  54  * @param delayFactor - The base delay factor in milliseconds
  55  * @returns Delay in milliseconds
  56  * @internal
  57  */
  58 export const exponentialDelay = (
  59   retryNumber = 0,
  60   delayFactor = 100
  61 ): number => {
  62   const delay = Math.pow(2, retryNumber) * delayFactor
  63   const randomSum = delay * 0.2 * secureRandom() // 0-20% of the delay
  64   return delay + randomSum
  65 }
  66
  67 /**
  68  * Computes the average of the given data set.
  69  *
  70  * @param dataSet - Data set.
  71  * @returns The average of the given data set.
  72  * @internal
  73  */
  74 export const average = (dataSet: number[]): number => {
  75   if (Array.isArray(dataSet) && dataSet.length === 0) {
  76     return 0
  77   } else if (Array.isArray(dataSet) && dataSet.length === 1) {
  78     return dataSet[0]
  79   }
  80   return (
  81     dataSet.reduce((accumulator, number) => accumulator + number, 0) /
  82     dataSet.length
  83   )
  84 }
  85
  86 /**
  87  * Computes the median of the given data set.
  88  *
  89  * @param dataSet - Data set.
  90  * @returns The median of the given data set.
  91  * @internal
  92  */
  93 export const median = (dataSet: number[]): number => {
  94   if (Array.isArray(dataSet) && dataSet.length === 0) {
  95     return 0
  96   } else if (Array.isArray(dataSet) && dataSet.length === 1) {
  97     return dataSet[0]
  98   }
  99   const sortedDataSet = dataSet.slice().sort((a, b) => a - b)
 100   return (
 101     (sortedDataSet[(sortedDataSet.length - 1) >> 1] +
 102       sortedDataSet[sortedDataSet.length >> 1]) /
 103     2
 104   )
 105 }
 106
 107 /**
 108  * Rounds the given number to the given scale.
 109  * The rounding is done using the "round half away from zero" method.
 110  *
 111  * @param num - The number to round.
 112  * @param scale - The scale to round to.
 113  * @returns The rounded number.
 114  * @internal
 115  */
 116 export const round = (num: number, scale = 2): number => {
 117   const rounder = Math.pow(10, scale)
 118   return Math.round(num * rounder * (1 + Number.EPSILON)) / rounder
 119 }
 120
 121 /**
 122  * Is the given value a plain object?
 123  *
 124  * @param value - The value to check.
 125  * @returns `true` if the given value is a plain object, `false` otherwise.
 126  * @internal
 127  */
 128 export const isPlainObject = (value: unknown): value is object =>
 129   typeof value === 'object' &&
 130   value !== null &&
 131   value.constructor === Object &&
 132   Object.prototype.toString.call(value) === '[object Object]'
 133
 134 /**
 135  * Detects whether the given value is a kill behavior or not.
 136  *
 137  * @typeParam KB - Which specific KillBehavior type to test against.
 138  * @param killBehavior - Which kind of kill behavior to detect.
 139  * @param value - Unknown value.
 140  * @returns `true` if `value` was strictly equals to `killBehavior`, otherwise `false`.
 141  * @internal
 142  */
 143 export const isKillBehavior = <KB extends KillBehavior>(
 144   killBehavior: KB,
 145   value: unknown
 146 ): value is KB => {
 147   return value === killBehavior
 148 }
 149
 150 /**
 151  * Detects whether the given value is an asynchronous function or not.
 152  *
 153  * @param fn - Unknown value.
 154  * @returns `true` if `fn` was an asynchronous function, otherwise `false`.
 155  * @internal
 156  */
 157 export const isAsyncFunction = (
 158   fn: unknown
 159 ): fn is (...args: unknown[]) => Promise<unknown> => {
 160   return typeof fn === 'function' && fn.constructor.name === 'AsyncFunction'
 161 }
 162
 163 /**
 164  * Generates a cryptographically secure random number in the [0,1[ range
 165  *
 166  * @returns A number in the [0,1[ range
 167  * @internal
 168  */
 169 export const secureRandom = (): number => {
 170   return getRandomValues(new Uint32Array(1))[0] / 0x100000000
 171 }
 172
 173 /**
 174  * Returns the minimum of the given numbers.
 175  * If no numbers are given, `Infinity` is returned.
 176  *
 177  * @param args - The numbers to get the minimum of.
 178  * @returns The minimum of the given numbers.
 179  * @internal
 180  */
 181 export const min = (...args: number[]): number =>
 182   args.reduce((minimum, num) => (minimum < num ? minimum : num), Infinity)
 183
 184 /**
 185  * Returns the maximum of the given numbers.
 186  * If no numbers are given, `-Infinity` is returned.
 187  *
 188  * @param args - The numbers to get the maximum of.
 189  * @returns The maximum of the given numbers.
 190  * @internal
 191  */
 192 export const max = (...args: number[]): number =>
 193   args.reduce((maximum, num) => (maximum > num ? maximum : num), -Infinity)
 194
 195 /**
 196  * Wraps a function so that it can only be called once.
 197  *
 198  * @param fn - The function to wrap.
 199  * @param context - The context to bind the function to.
 200  * @returns The wrapped function.
 201  *
 202  * @typeParam A - The function's arguments.
 203  * @typeParam R - The function's return value.
 204  * @typeParam C - The function's context.
 205  * @internal
 206  */
 207 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 208 export const once = <A extends any[], R, C>(
 209   fn: (...args: A) => R,
 210   context: C
 211 ): ((...args: A) => R) => {
 212   let result: R
 213   return (...args: A) => {
 214     // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
 215     if (fn != null) {
 216       result = fn.apply<C, A, R>(context, args)
 217       ;(fn as unknown as undefined) = (context as unknown as undefined) =
 218         undefined
 219     }
 220     return result
 221   }
 222 }