src/utils.ts

   1 import { getRandomValues } from 'node:crypto'
   2 import * as os from 'node:os'
   3
   4 import type { TaskFunctionProperties } from './utility-types.js'
   5 import type { TaskFunctionObject } from './worker/task-functions.js'
   6 import type { KillBehavior } from './worker/worker-options.js'
   7
   8 /**
   9  * Default task name.
  10  */
  11 export const DEFAULT_TASK_NAME = 'default'
  12
  13 /**
  14  * An intentional empty function.
  15  */
  16 export const EMPTY_FUNCTION: () => void = Object.freeze(() => {
  17   /* Intentionally empty */
  18 })
  19
  20 /**
  21  * Returns safe host OS optimized estimate of the default amount of parallelism a pool should use.
  22  * Always returns a value greater than zero.
  23  * @returns The host OS optimized maximum pool size.
  24  */
  25 export const availableParallelism = (): number => {
  26   let availableParallelism = 1
  27   try {
  28     availableParallelism = os.availableParallelism()
  29   } catch {
  30     const cpus = os.cpus()
  31     if (Array.isArray(cpus) && cpus.length > 0) {
  32       availableParallelism = cpus.length
  33     }
  34   }
  35   return availableParallelism
  36 }
  37
  38 /**
  39  * Sleeps for the given amount of milliseconds.
  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  * @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  * @param dataSet - Data set.
  69  * @returns The average of the given data set.
  70  * @internal
  71  */
  72 export const average = (dataSet: number[]): number => {
  73   if (Array.isArray(dataSet) && dataSet.length === 0) {
  74     return 0
  75   } else if (Array.isArray(dataSet) && dataSet.length === 1) {
  76     return dataSet[0]
  77   }
  78   return (
  79     dataSet.reduce((accumulator, number) => accumulator + number, 0) /
  80     dataSet.length
  81   )
  82 }
  83
  84 /**
  85  * Computes the median of the given data set.
  86  * @param dataSet - Data set.
  87  * @returns The median of the given data set.
  88  * @internal
  89  */
  90 export const median = (dataSet: number[]): number => {
  91   if (Array.isArray(dataSet) && dataSet.length === 0) {
  92     return 0
  93   } else if (Array.isArray(dataSet) && dataSet.length === 1) {
  94     return dataSet[0]
  95   }
  96   const sortedDataSet = dataSet.slice().sort((a, b) => a - b)
  97   return (
  98     (sortedDataSet[(sortedDataSet.length - 1) >> 1] +
  99       sortedDataSet[sortedDataSet.length >> 1]) /
 100     2
 101   )
 102 }
 103
 104 /**
 105  * Rounds the given number to the given scale.
 106  * The rounding is done using the "round half away from zero" method.
 107  * @param num - The number to round.
 108  * @param scale - The scale to round to.
 109  * @returns The rounded number.
 110  * @internal
 111  */
 112 export const round = (num: number, scale = 2): number => {
 113   const rounder = Math.pow(10, scale)
 114   return Math.round(num * rounder * (1 + Number.EPSILON)) / rounder
 115 }
 116
 117 /**
 118  * Is the given value a plain object?
 119  * @param value - The value to check.
 120  * @returns `true` if the given value is a plain object, `false` otherwise.
 121  * @internal
 122  */
 123 export const isPlainObject = (value: unknown): value is object =>
 124   typeof value === 'object' &&
 125   value !== null &&
 126   value.constructor === Object &&
 127   Object.prototype.toString.call(value) === '[object Object]'
 128
 129 /**
 130  * Detects whether the given value is a kill behavior or not.
 131  * @typeParam KB - Which specific KillBehavior type to test against.
 132  * @param killBehavior - Which kind of kill behavior to detect.
 133  * @param value - Unknown value.
 134  * @returns `true` if `value` was strictly equals to `killBehavior`, otherwise `false`.
 135  * @internal
 136  */
 137 export const isKillBehavior = <KB extends KillBehavior>(
 138   killBehavior: KB,
 139   value: unknown
 140 ): value is KB => {
 141   return value === killBehavior
 142 }
 143
 144 /**
 145  * Detects whether the given value is an asynchronous function or not.
 146  * @param fn - Unknown value.
 147  * @returns `true` if `fn` was an asynchronous function, otherwise `false`.
 148  * @internal
 149  */
 150 export const isAsyncFunction = (
 151   fn: unknown
 152 ): fn is (...args: unknown[]) => Promise<unknown> => {
 153   return typeof fn === 'function' && fn.constructor.name === 'AsyncFunction'
 154 }
 155
 156 /**
 157  * Generates a cryptographically secure random number in the [0,1[ range
 158  * @returns A number in the [0,1[ range
 159  * @internal
 160  */
 161 export const secureRandom = (): number => {
 162   return getRandomValues(new Uint32Array(1))[0] / 0x100000000
 163 }
 164
 165 /**
 166  * Returns the minimum of the given numbers.
 167  * If no numbers are given, `Number.POSITIVE_INFINITY` is returned.
 168  * @param args - The numbers to get the minimum of.
 169  * @returns The minimum of the given numbers.
 170  * @internal
 171  */
 172 export const min = (...args: number[]): number =>
 173   args.reduce(
 174     (minimum, num) => (minimum < num ? minimum : num),
 175     Number.POSITIVE_INFINITY
 176   )
 177
 178 /**
 179  * Returns the maximum of the given numbers.
 180  * If no numbers are given, `Number.NEGATIVE_INFINITY` is returned.
 181  * @param args - The numbers to get the maximum of.
 182  * @returns The maximum of the given numbers.
 183  * @internal
 184  */
 185 export const max = (...args: number[]): number =>
 186   args.reduce(
 187     (maximum, num) => (maximum > num ? maximum : num),
 188     Number.NEGATIVE_INFINITY
 189   )
 190
 191 /**
 192  * Wraps a function so that it can only be called once.
 193  * @param fn - The function to wrap.
 194  * @param context - The context to bind the function to.
 195  * @returns The wrapped function.
 196  * @typeParam A - The function's arguments.
 197  * @typeParam R - The function's return value.
 198  * @typeParam C - The function's context.
 199  * @internal
 200  */
 201 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 202 export const once = <A extends any[], R, C extends ThisType<any>>(
 203   fn: (...args: A) => R,
 204   context: C
 205 ): ((...args: A) => R) => {
 206   let result: R
 207   return (...args: A) => {
 208     // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
 209     if (fn != null) {
 210       result = fn.apply<C, A, R>(context, args)
 211       ;(fn as unknown as undefined) = (context as unknown as undefined) =
 212         undefined
 213     }
 214     return result
 215   }
 216 }
 217
 218 export const buildTaskFunctionProperties = <Data, Response>(
 219   name: string,
 220   taskFunctionObject: TaskFunctionObject<Data, Response> | undefined
 221 ): TaskFunctionProperties => {
 222   return {
 223     name,
 224     ...(taskFunctionObject?.priority != null && {
 225       priority: taskFunctionObject.priority,
 226     }),
 227     ...(taskFunctionObject?.strategy != null && {
 228       strategy: taskFunctionObject.strategy,
 229     }),
 230   }
 231 }