src/utils.ts

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