src/utils.ts

   1 import * as os from 'node:os'
   2 import { webcrypto } from 'node:crypto'
   3 import { Worker as ClusterWorker } from 'node:cluster'
   4 import { Worker as ThreadWorker } from 'node:worker_threads'
   5 import type {
   6   MeasurementStatisticsRequirements,
   7   WorkerChoiceStrategyOptions
   8 } from './pools/selection-strategies/selection-strategies-types'
   9 import type { KillBehavior } from './worker/worker-options'
  10 import { type IWorker, type WorkerType, WorkerTypes } from './pools/worker'
  11
  12 /**
  13  * Default task name.
  14  */
  15 export const DEFAULT_TASK_NAME = 'default'
  16
  17 /**
  18  * An intentional empty function.
  19  */
  20 export const EMPTY_FUNCTION: () => void = Object.freeze(() => {
  21   /* Intentionally empty */
  22 })
  23
  24 /**
  25  * Default worker choice strategy options.
  26  */
  27 export const DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS: WorkerChoiceStrategyOptions =
  28   {
  29     retries: 6,
  30     runTime: { median: false },
  31     waitTime: { median: false },
  32     elu: { median: false }
  33   }
  34
  35 /**
  36  * Default measurement statistics requirements.
  37  */
  38 export const DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS: MeasurementStatisticsRequirements =
  39   {
  40     aggregate: false,
  41     average: false,
  42     median: false
  43   }
  44
  45 /**
  46  * Returns safe host OS optimized estimate of the default amount of parallelism a pool should use.
  47  * Always returns a value greater than zero.
  48  *
  49  * @returns The host OS optimized maximum pool size.
  50  */
  51 export const availableParallelism = (): number => {
  52   let availableParallelism = 1
  53   try {
  54     availableParallelism = os.availableParallelism()
  55   } catch {
  56     const cpus = os.cpus()
  57     if (Array.isArray(cpus) && cpus.length > 0) {
  58       availableParallelism = cpus.length
  59     }
  60   }
  61   return availableParallelism
  62 }
  63
  64 /**
  65  * Returns the worker type of the given worker.
  66  *
  67  * @param worker - The worker to get the type of.
  68  * @returns The worker type of the given worker.
  69  * @internal
  70  */
  71 export const getWorkerType = (worker: IWorker): WorkerType | undefined => {
  72   if (worker instanceof ThreadWorker) {
  73     return WorkerTypes.thread
  74   } else if (worker instanceof ClusterWorker) {
  75     return WorkerTypes.cluster
  76   }
  77 }
  78
  79 /**
  80  * Returns the worker id of the given worker.
  81  *
  82  * @param worker - The worker to get the id of.
  83  * @returns The worker id of the given worker.
  84  * @internal
  85  */
  86 export const getWorkerId = (worker: IWorker): number | undefined => {
  87   if (worker instanceof ThreadWorker) {
  88     return worker.threadId
  89   } else if (worker instanceof ClusterWorker) {
  90     return worker.id
  91   }
  92 }
  93
  94 /**
  95  * Sleeps for the given amount of milliseconds.
  96  *
  97  * @param ms - The amount of milliseconds to sleep.
  98  * @returns A promise that resolves after the given amount of milliseconds.
  99  * @internal
 100  */
 101 export const sleep = async (ms: number): Promise<void> => {
 102   await new Promise(resolve => {
 103     setTimeout(resolve, ms)
 104   })
 105 }
 106
 107 /**
 108  * Computes the retry delay in milliseconds using an exponential back off algorithm.
 109  *
 110  * @param retryNumber - The number of retries that have already been attempted
 111  * @param delayFactor - The base delay factor in milliseconds
 112  * @returns Delay in milliseconds
 113  * @internal
 114  */
 115 export const exponentialDelay = (
 116   retryNumber = 0,
 117   delayFactor = 100
 118 ): number => {
 119   const delay = Math.pow(2, retryNumber) * delayFactor
 120   const randomSum = delay * 0.2 * secureRandom() // 0-20% of the delay
 121   return delay + randomSum
 122 }
 123
 124 /**
 125  * Computes the average of the given data set.
 126  *
 127  * @param dataSet - Data set.
 128  * @returns The average of the given data set.
 129  * @internal
 130  */
 131 export const average = (dataSet: number[]): number => {
 132   if (Array.isArray(dataSet) && dataSet.length === 0) {
 133     return 0
 134   }
 135   if (Array.isArray(dataSet) && dataSet.length === 1) {
 136     return dataSet[0]
 137   }
 138   return (
 139     dataSet.reduce((accumulator, number) => accumulator + number, 0) /
 140     dataSet.length
 141   )
 142 }
 143
 144 /**
 145  * Computes the median of the given data set.
 146  *
 147  * @param dataSet - Data set.
 148  * @returns The median of the given data set.
 149  * @internal
 150  */
 151 export const median = (dataSet: number[]): number => {
 152   if (Array.isArray(dataSet) && dataSet.length === 0) {
 153     return 0
 154   }
 155   if (Array.isArray(dataSet) && dataSet.length === 1) {
 156     return dataSet[0]
 157   }
 158   const sortedDataSet = dataSet.slice().sort((a, b) => a - b)
 159   return (
 160     (sortedDataSet[(sortedDataSet.length - 1) >> 1] +
 161       sortedDataSet[sortedDataSet.length >> 1]) /
 162     2
 163   )
 164 }
 165
 166 /**
 167  * Rounds the given number to the given scale.
 168  * The rounding is done using the "round half away from zero" method.
 169  *
 170  * @param num - The number to round.
 171  * @param scale - The scale to round to.
 172  * @returns The rounded number.
 173  * @internal
 174  */
 175 export const round = (num: number, scale = 2): number => {
 176   const rounder = Math.pow(10, scale)
 177   return Math.round(num * rounder * (1 + Number.EPSILON)) / rounder
 178 }
 179
 180 /**
 181  * Is the given object a plain object?
 182  *
 183  * @param obj - The object to check.
 184  * @returns `true` if the given object is a plain object, `false` otherwise.
 185  * @internal
 186  */
 187 export const isPlainObject = (obj: unknown): boolean =>
 188   typeof obj === 'object' &&
 189   obj !== null &&
 190   obj?.constructor === Object &&
 191   Object.prototype.toString.call(obj) === '[object Object]'
 192
 193 /**
 194  * Detects whether the given value is a kill behavior or not.
 195  *
 196  * @typeParam KB - Which specific KillBehavior type to test against.
 197  * @param killBehavior - Which kind of kill behavior to detect.
 198  * @param value - Any value.
 199  * @returns `true` if `value` was strictly equals to `killBehavior`, otherwise `false`.
 200  * @internal
 201  */
 202 export const isKillBehavior = <KB extends KillBehavior>(
 203   killBehavior: KB,
 204   value: unknown
 205 ): value is KB => {
 206   return value === killBehavior
 207 }
 208
 209 /**
 210  * Detects whether the given value is an asynchronous function or not.
 211  *
 212  * @param fn - Any value.
 213  * @returns `true` if `fn` was an asynchronous function, otherwise `false`.
 214  * @internal
 215  */
 216 export const isAsyncFunction = (
 217   fn: unknown
 218 ): fn is (...args: unknown[]) => Promise<unknown> => {
 219   return typeof fn === 'function' && fn.constructor.name === 'AsyncFunction'
 220 }
 221
 222 /**
 223  * Generates a cryptographically secure random number in the [0,1[ range
 224  *
 225  * @returns A number in the [0,1[ range
 226  * @internal
 227  */
 228 export const secureRandom = (): number => {
 229   return webcrypto.getRandomValues(new Uint32Array(1))[0] / 0x100000000
 230 }
 231
 232 /**
 233  * Returns the minimum of the given numbers.
 234  * If no numbers are given, `Infinity` is returned.
 235  *
 236  * @param args - The numbers to get the minimum of.
 237  * @returns The minimum of the given numbers.
 238  * @internal
 239  */
 240 export const min = (...args: number[]): number =>
 241   args.reduce((minimum, num) => (minimum < num ? minimum : num), Infinity)
 242
 243 /**
 244  * Returns the maximum of the given numbers.
 245  * If no numbers are given, `-Infinity` is returned.
 246  *
 247  * @param args - The numbers to get the maximum of.
 248  * @returns The maximum of the given numbers.
 249  * @internal
 250  */
 251 export const max = (...args: number[]): number =>
 252   args.reduce((maximum, num) => (maximum > num ? maximum : num), -Infinity)