refactor: cleanup exponential delay code

[poolifier.git] / src / utils.ts

diff --git a/src/utils.ts b/src/utils.ts
index 77f889c9b417ad008b0352b8c2e1779788ceb6d9..f1c0d923f2d3b15ed12ff06422996b0d5c13de19 100644 (file)
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -59,22 +59,54 @@ 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
-//  * @internal
-//  */
-// 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.
@@ -163,8 +195,7 @@ export const isAsyncFunction = (
 export const updateMeasurementStatistics = (
   measurementStatistics: MeasurementStatistics,
   measurementRequirements: MeasurementStatisticsRequirements,
-  measurementValue: number,
-  numberOfMeasurements: number
+  measurementValue: number
 ): void => {
   if (measurementRequirements.aggregate) {
     measurementStatistics.aggregate =
@@ -177,13 +208,17 @@ 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)
+      }
     }
   }
 }
@@ -211,3 +246,12 @@ export const once = (
     }
   }
 }
+
+/**
+ * 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
+}