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  *
  24  * @returns The host OS optimized maximum pool size.
  25  */
  26 export const availableParallelism = (): number => {
  27   let availableParallelism = 1
  28   try {
  29     availableParallelism = os.availableParallelism()
  30   } catch {
  31     const cpus = os.cpus()
  32     if (Array.isArray(cpus) && cpus.length > 0) {
  33       availableParallelism = cpus.length
  34     }
  35   }
  36   return availableParallelism
  37 }
  38
  39 /**
  40  * Sleeps for the given amount of milliseconds.
  41  *
  42  * @param ms - The amount of milliseconds to sleep.
  43  * @returns A promise that resolves after the given amount of milliseconds.
  44  * @internal
  45  */
  46 export const sleep = async (ms: number): Promise<void> => {
  47   await new Promise(resolve => {
  48     setTimeout(resolve, ms)
  49   })
  50 }
  51
  52 /**
  53  * Computes the retry delay in milliseconds using an exponential back off algorithm.
  54  *
  55  * @param retryNumber - The number of retries that have already been attempted
  56  * @param delayFactor - The base delay factor in milliseconds
  57  * @returns Delay in milliseconds
  58  * @internal
  59  */
  60 export const exponentialDelay = (
  61   retryNumber = 0,
  62   delayFactor = 100
  63 ): number => {
  64   const delay = Math.pow(2, retryNumber) * delayFactor
  65   const randomSum = delay * 0.2 * secureRandom() // 0-20% of the delay
  66   return delay + randomSum
  67 }
  68
  69 /**
  70  * Computes the average of the given data set.
  71  *
  72  * @param dataSet - Data set.
  73  * @returns The average of the given data set.
  74  * @internal
  75  */
  76 export const average = (dataSet: number[]): number => {
  77   if (Array.isArray(dataSet) && dataSet.length === 0) {
  78     return 0
  79   } else if (Array.isArray(dataSet) && dataSet.length === 1) {
  80     return dataSet[0]
  81   }
  82   return (
  83     dataSet.reduce((accumulator, number) => accumulator + number, 0) /
  84     dataSet.length
  85   )
  86 }
  87
  88 /**
  89  * Computes the median of the given data set.
  90  *
  91  * @param dataSet - Data set.
  92  * @returns The median of the given data set.
  93  * @internal
  94  */
  95 export const median = (dataSet: number[]): number => {
  96   if (Array.isArray(dataSet) && dataSet.length === 0) {
  97     return 0
  98   } else if (Array.isArray(dataSet) && dataSet.length === 1) {
  99     return dataSet[0]
 100   }
 101   const sortedDataSet = dataSet.slice().sort((a, b) => a - b)
 102   return (
 103     (sortedDataSet[(sortedDataSet.length - 1) >> 1] +
 104       sortedDataSet[sortedDataSet.length >> 1]) /
 105     2
 106   )
 107 }
 108
 109 /**
 110  * Rounds the given number to the given scale.
 111  * The rounding is done using the "round half away from zero" method.
 112  *
 113  * @param num - The number to round.
 114  * @param scale - The scale to round to.
 115  * @returns The rounded number.
 116  * @internal
 117  */
 118 export const round = (num: number, scale = 2): number => {
 119   const rounder = Math.pow(10, scale)
 120   return Math.round(num * rounder * (1 + Number.EPSILON)) / rounder
 121 }
 122
 123 /**
 124  * Is the given value a plain object?
 125  *
 126  * @param value - The value to check.
 127  * @returns `true` if the given value is a plain object, `false` otherwise.
 128  * @internal
 129  */
 130 export const isPlainObject = (value: unknown): value is object =>
 131   typeof value === 'object' &&
 132   value !== null &&
 133   value.constructor === Object &&
 134   Object.prototype.toString.call(value) === '[object Object]'
 135
 136 /**
 137  * Detects whether the given value is a kill behavior or not.
 138  *
 139  * @typeParam KB - Which specific KillBehavior type to test against.
 140  * @param killBehavior - Which kind of kill behavior to detect.
 141  * @param value - Unknown value.
 142  * @returns `true` if `value` was strictly equals to `killBehavior`, otherwise `false`.
 143  * @internal
 144  */
 145 export const isKillBehavior = <KB extends KillBehavior>(
 146   killBehavior: KB,
 147   value: unknown
 148 ): value is KB => {
 149   return value === killBehavior
 150 }
 151
 152 /**
 153  * Detects whether the given value is an asynchronous function or not.
 154  *
 155  * @param fn - Unknown value.
 156  * @returns `true` if `fn` was an asynchronous function, otherwise `false`.
 157  * @internal
 158  */
 159 export const isAsyncFunction = (
 160   fn: unknown
 161 ): fn is (...args: unknown[]) => Promise<unknown> => {
 162   return typeof fn === 'function' && fn.constructor.name === 'AsyncFunction'
 163 }
 164
 165 /**
 166  * Generates a cryptographically secure random number in the [0,1[ range
 167  *
 168  * @returns A number in the [0,1[ range
 169  * @internal
 170  */
 171 export const secureRandom = (): number => {
 172   return getRandomValues(new Uint32Array(1))[0] / 0x100000000
 173 }
 174
 175 /**
 176  * Returns the minimum of the given numbers.
 177  * If no numbers are given, `Number.POSITIVE_INFINITY` is returned.
 178  *
 179  * @param args - The numbers to get the minimum of.
 180  * @returns The minimum of the given numbers.
 181  * @internal
 182  */
 183 export const min = (...args: number[]): number =>
 184   args.reduce(
 185     (minimum, num) => (minimum < num ? minimum : num),
 186     Number.POSITIVE_INFINITY
 187   )
 188
 189 /**
 190  * Returns the maximum of the given numbers.
 191  * If no numbers are given, `Number.NEGATIVE_INFINITY` is returned.
 192  *
 193  * @param args - The numbers to get the maximum of.
 194  * @returns The maximum of the given numbers.
 195  * @internal
 196  */
 197 export const max = (...args: number[]): number =>
 198   args.reduce(
 199     (maximum, num) => (maximum > num ? maximum : num),
 200     Number.NEGATIVE_INFINITY
 201   )
 202
 203 /**
 204  * Wraps a function so that it can only be called once.
 205  *
 206  * @param fn - The function to wrap.
 207  * @param context - The context to bind the function to.
 208  * @returns The wrapped function.
 209  *
 210  * @typeParam A - The function's arguments.
 211  * @typeParam R - The function's return value.
 212  * @typeParam C - The function's context.
 213  * @internal
 214  */
 215 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 216 export const once = <A extends any[], R, C extends ThisType<any>>(
 217   fn: (...args: A) => R,
 218   context: C
 219 ): ((...args: A) => R) => {
 220   let result: R
 221   return (...args: A) => {
 222     // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
 223     if (fn != null) {
 224       result = fn.apply<C, A, R>(context, args)
 225       ;(fn as unknown as undefined) = (context as unknown as undefined) =
 226         undefined
 227     }
 228     return result
 229   }
 230 }
 231
 232 export const buildTaskFunctionProperties = <Data, Response>(
 233   name: string,
 234   taskFunctionObject: TaskFunctionObject<Data, Response> | undefined
 235 ): TaskFunctionProperties => {
 236   return {
 237     name,
 238     ...(taskFunctionObject?.priority != null && {
 239       priority: taskFunctionObject.priority
 240     }),
 241     ...(taskFunctionObject?.strategy != null && {
 242       strategy: taskFunctionObject.strategy
 243     })
 244   }
 245 }