X-Git-Url: https://git.piment-noir.org/?a=blobdiff_plain;f=src%2Futils.ts;h=f1c0d923f2d3b15ed12ff06422996b0d5c13de19;hb=147be6fe188035c47548d07ef1f7cd884bd85f60;hp=b1521c4cdfbddc0fda6b6b13293e51b082396692;hpb=6e9d10db05ac2bbc85373195a5c885d2492fee61;p=poolifier.git

diff --git a/src/utils.ts b/src/utils.ts
index b1521c4c..f1c0d923 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -1,6 +1,257 @@
+import * as os from 'node:os'
+import type {
+  MeasurementStatisticsRequirements,
+  WorkerChoiceStrategyOptions
+} from './pools/selection-strategies/selection-strategies-types'
+import type { KillBehavior } from './worker/worker-options'
+import type { MeasurementStatistics } from './pools/worker'
+
+/**
+ * Default task name.
+ */
+export const DEFAULT_TASK_NAME = 'default'
+
 /**
  * An intentional empty function.
  */
-export const EMPTY_FUNCTION: () => void = () => {
+export const EMPTY_FUNCTION: () => void = Object.freeze(() => {
   /* Intentionally empty */
+})
+
+/**
+ * Default worker choice strategy options.
+ */
+export const DEFAULT_WORKER_CHOICE_STRATEGY_OPTIONS: WorkerChoiceStrategyOptions =
+  {
+    choiceRetries: 6,
+    runTime: { median: false },
+    waitTime: { median: false },
+    elu: { median: false }
+  }
+
+/**
+ * Default measurement statistics requirements.
+ */
+export const DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS: MeasurementStatisticsRequirements =
+  {
+    aggregate: false,
+    average: false,
+    median: false
+  }
+
+/**
+ * Returns safe host OS optimized estimate of the default amount of parallelism a pool should use.
+ * Always returns a value greater than zero.
+ *
+ * @returns The host OS optimized maximum pool size.
+ * @internal
+ */
+export const availableParallelism = (): number => {
+  let availableParallelism = 1
+  try {
+    availableParallelism = os.availableParallelism()
+  } catch {
+    const numberOfCpus = os.cpus()
+    if (Array.isArray(numberOfCpus) && numberOfCpus.length > 0) {
+      availableParallelism = numberOfCpus.length
+    }
+  }
+  return availableParallelism
+}
+
+/**
+ * Sleeps for the given amount of milliseconds.
+ *
+ * @param ms - The amount of milliseconds to sleep.
+ * @returns A promise that resolves after the given amount of milliseconds.
+ */
+export const sleep = async (ms: number): Promise<void> => {
+  await new Promise((resolve) => {
+    setTimeout(resolve, ms)
+  })
+}
+
+/**
+ * Computes the retry delay in milliseconds using an exponential back off algorithm.
+ *
+ * @param retryNumber - The number of retries that have already been attempted
+ * @param delayFactor - The base delay factor in milliseconds
+ * @returns Delay in milliseconds
+ * @internal
+ */
+export const exponentialDelay = (
+  retryNumber = 0,
+  delayFactor = 100
+): number => {
+  const delay = Math.pow(2, retryNumber) * delayFactor
+  const randomSum = delay * 0.2 * secureRandom() // 0-20% of the delay
+  return delay + randomSum
+}
+
+/**
+ * Computes the average of the given data set.
+ *
+ * @param dataSet - Data set.
+ * @returns The average of the given data set.
+ * @internal
+ */
+export const average = (dataSet: number[]): number => {
+  if (Array.isArray(dataSet) && dataSet.length === 0) {
+    return 0
+  }
+  if (Array.isArray(dataSet) && dataSet.length === 1) {
+    return dataSet[0]
+  }
+  return (
+    dataSet.reduce((accumulator, number) => accumulator + number, 0) /
+    dataSet.length
+  )
+}
+
+/**
+ * Computes the median of the given data set.
+ *
+ * @param dataSet - Data set.
+ * @returns The median of the given data set.
+ * @internal
+ */
+export const median = (dataSet: number[]): number => {
+  if (Array.isArray(dataSet) && dataSet.length === 0) {
+    return 0
+  }
+  if (Array.isArray(dataSet) && dataSet.length === 1) {
+    return dataSet[0]
+  }
+  const sortedDataSet = dataSet.slice().sort((a, b) => a - b)
+  return (
+    (sortedDataSet[(sortedDataSet.length - 1) >> 1] +
+      sortedDataSet[sortedDataSet.length >> 1]) /
+    2
+  )
+}
+
+/**
+ * Rounds the given number to the given scale.
+ * The rounding is done using the "round half away from zero" method.
+ *
+ * @param num - The number to round.
+ * @param scale - The scale to round to.
+ * @returns The rounded number.
+ */
+export const round = (num: number, scale = 2): number => {
+  const rounder = Math.pow(10, scale)
+  return Math.round(num * rounder * (1 + Number.EPSILON)) / rounder
+}
+
+/**
+ * Is the given object a plain object?
+ *
+ * @param obj - The object to check.
+ * @returns `true` if the given object is a plain object, `false` otherwise.
+ */
+export const isPlainObject = (obj: unknown): boolean =>
+  typeof obj === 'object' &&
+  obj !== null &&
+  obj?.constructor === Object &&
+  Object.prototype.toString.call(obj) === '[object Object]'
+
+/**
+ * Detects whether the given value is a kill behavior or not.
+ *
+ * @typeParam KB - Which specific KillBehavior type to test against.
+ * @param killBehavior - Which kind of kill behavior to detect.
+ * @param value - Any value.
+ * @returns `true` if `value` was strictly equals to `killBehavior`, otherwise `false`.
+ * @internal
+ */
+export const isKillBehavior = <KB extends KillBehavior>(
+  killBehavior: KB,
+  value: unknown
+): value is KB => {
+  return value === killBehavior
+}
+
+/**
+ * Detects whether the given value is an asynchronous function or not.
+ *
+ * @param fn - Any value.
+ * @returns `true` if `fn` was an asynchronous function, otherwise `false`.
+ */
+export const isAsyncFunction = (
+  fn: unknown
+): fn is (...args: unknown[]) => Promise<unknown> => {
+  return typeof fn === 'function' && fn.constructor.name === 'AsyncFunction'
+}
+
+/**
+ * Updates the given measurement statistics.
+ *
+ * @param measurementStatistics - The measurement statistics to update.
+ * @param measurementRequirements - The measurement statistics requirements.
+ * @param measurementValue - The measurement value.
+ * @param numberOfMeasurements - The number of measurements.
+ * @internal
+ */
+export const updateMeasurementStatistics = (
+  measurementStatistics: MeasurementStatistics,
+  measurementRequirements: MeasurementStatisticsRequirements,
+  measurementValue: number
+): void => {
+  if (measurementRequirements.aggregate) {
+    measurementStatistics.aggregate =
+      (measurementStatistics.aggregate ?? 0) + measurementValue
+    measurementStatistics.minimum = Math.min(
+      measurementValue,
+      measurementStatistics.minimum ?? Infinity
+    )
+    measurementStatistics.maximum = Math.max(
+      measurementValue,
+      measurementStatistics.maximum ?? -Infinity
+    )
+    if (
+      (measurementRequirements.average || measurementRequirements.median) &&
+      measurementValue != null
+    ) {
+      measurementStatistics.history.push(measurementValue)
+      if (measurementRequirements.average) {
+        measurementStatistics.average = average(measurementStatistics.history)
+      }
+      if (measurementRequirements.median) {
+        measurementStatistics.median = median(measurementStatistics.history)
+      }
+    }
+  }
+}
+
+/**
+ * Executes a function once at a time.
+ *
+ * @param fn - The function to execute.
+ * @param context - The context to bind the function to.
+ * @returns The function to execute.
+ */
+export const once = (
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  fn: (...args: any[]) => void,
+  context: unknown
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+): ((...args: any[]) => void) => {
+  let called = false
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  return function (...args: any[]): void {
+    if (!called) {
+      called = true
+      fn.apply(context, args)
+      called = false
+    }
+  }
+}
+
+/**
+ * Generate a cryptographically secure random number in the [0,1[ range
+ *
+ * @returns A number in the [0,1[ range
+ */
+const secureRandom = (): number => {
+  return crypto.getRandomValues(new Uint32Array(1))[0] / 0x100000000
 }