refactor: cleanup exponential delay code

[poolifier.git] / src / utils.ts

diff --git a/src/utils.ts b/src/utils.ts
index efd1f124084776667bd60495f202cec32c7e04a9..f1c0d923f2d3b15ed12ff06422996b0d5c13de19 100644 (file)
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -44,6 +44,7 @@ export const DEFAULT_MEASUREMENT_STATISTICS_REQUIREMENTS: MeasurementStatisticsR
  * Always returns a value greater than zero.
  *
  * @returns The host OS optimized maximum pool size.
+ * @internal
  */
 export const availableParallelism = (): number => {
   let availableParallelism = 1
@@ -58,27 +59,61 @@ export const availableParallelism = (): number => {
   return availableParallelism
 }
 
-// /**
-//  * Computes the retry delay in milliseconds using an exponential back off algorithm.
-//  *
-//  * @param retryNumber - The number of retries that have already been attempted
-//  * @param maxDelayRatio - The maximum ratio of the delay that can be randomized
-//  * @returns Delay in milliseconds
-//  */
-// export const exponentialDelay = (
-//   retryNumber = 0,
-//   maxDelayRatio = 0.2
-// ): number => {
-//   const delay = Math.pow(2, retryNumber) * 100
-//   const randomSum = delay * maxDelayRatio * Math.random() // 0-(maxDelayRatio*100)% of the delay
-//   return delay + randomSum
-// }
+/**
+ * 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) {
@@ -127,6 +162,7 @@ export const isPlainObject = (obj: unknown): boolean =>
  * @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,
@@ -154,12 +190,12 @@ export const isAsyncFunction = (
  * @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,
-  numberOfMeasurements: number
+  measurementValue: number
 ): void => {
   if (measurementRequirements.aggregate) {
     measurementStatistics.aggregate =
@@ -172,13 +208,50 @@ export const updateMeasurementStatistics = (
       measurementValue,
       measurementStatistics.maximum ?? -Infinity
     )
-    if (measurementRequirements.average && numberOfMeasurements !== 0) {
-      measurementStatistics.average =
-        measurementStatistics.aggregate / numberOfMeasurements
-    }
-    if (measurementRequirements.median && measurementValue != null) {
+    if (
+      (measurementRequirements.average || measurementRequirements.median) &&
+      measurementValue != null
+    ) {
       measurementStatistics.history.push(measurementValue)
-      measurementStatistics.median = median(measurementStatistics.history)
+      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
+}