Bug 1716952 - Implement the Memory Distribution Metric

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 [Full changelog](https://github.com/mozilla/glean.js/compare/v1.2.0...main)
 
+* [#1514](https://github.com/mozilla/glean.js/pull/1514): Implement the Memory Distribution metric type.
 * [#1475](https://github.com/mozilla/glean.js/pull/1475): Implement the Timing Distribution metric type.
 
 # v1.2.0 (2022-09-21)

automation/size/utils.js

@@ -20,6 +20,7 @@ export const METRIC_TYPES = [
   "datetime",
   "event",
   "labeled",
+  "memory_distribution",
   "quantity",
   "string",
   "text",

glean/src/core/metrics/distributions.ts

@@ -0,0 +1,64 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+import type { Histogram } from "../../histogram/histogram";
+import type { JSONValue } from "../utils";
+
+export interface DistributionData {
+  // A map containing the bucket index mapped to the accumulated count.
+  //
+  // This can contain buckets with a count of `0`.
+  values: Record<number, number>;
+
+  // The accumulated sum of all the samples in the distribution.
+  sum: number;
+
+  // The number of entries in the histogram.
+  count: number;
+}
+
+/**
+ * Create a snapshot of the histogram with a time unit.
+ *
+ * Utility function for testing.
+ *
+ * @param hist Histogram to get the snapshot of.
+ * @returns Snapshot of the current histogram.
+ */
+export function snapshot(hist: Histogram): DistributionData {
+  const snapshotValues = hist.snapshotValues();
+
+  const utilizedValues: Record<number, number> = {};
+  Object.entries(snapshotValues).forEach(([key, value]) => {
+    const numericKey = Number(key);
+    if (value > 0 && !isNaN(numericKey)) {
+      utilizedValues[numericKey] = value;
+    }
+  });
+
+  return {
+    count: hist.count,
+    values: utilizedValues,
+    sum: hist.sum,
+  };
+}
+
+/**
+ * Takes the previous values and casts as a `number[]` or creates a new empty `number[]`. We store
+ * previous values as an array so that we can always reconstruct our histogram. We
+ * are unable to store complex objects in Glean as they must be JSON parse-able objects.
+ *
+ * @param jsonValue Will always be either undefined or a `number[]`.
+ * @returns An array of previous values or an empty array if nothing was previously stored.
+ */
+export function extractAccumulatedValuesFromJsonValue(jsonValue?: JSONValue): number[] {
+  let values: number[];
+  if (jsonValue) {
+    values = jsonValue as number[];
+  } else {
+    values = [];
+  }
+
+  return values;
+}

glean/src/core/metrics/memory_unit.ts

@@ -0,0 +1,34 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+export enum MemoryUnit {
+  // 1 byte
+  Byte = "byte",
+  // 2^10 bytes
+  Kilobyte = "kilobyte",
+  // 2^20 bytes
+  Megabyte = "megabyte",
+  // 2^30 bytes
+  Gigabyte = "gigabyte",
+}
+
+/**
+ * Converts a value in a given unit to bytes.
+ *
+ * @param value The value to convert.
+ * @param memoryUnit The `MemoryUnit` to convert from.
+ * @returns The integer representation of the byte value.
+ */
+export function convertMemoryUnitToBytes(value: number, memoryUnit: MemoryUnit): number {
+  switch (memoryUnit) {
+  case MemoryUnit.Byte:
+    return value;
+  case MemoryUnit.Kilobyte:
+    return value * (2 ** 10);
+  case MemoryUnit.Megabyte:
+    return value * (2 ** 20);
+  case MemoryUnit.Gigabyte:
+    return value * (2 ** 30);
+  }
+}

glean/src/core/metrics/time_unit.ts

@@ -23,4 +23,30 @@ enum TimeUnit {
   Day = "day",
 }
 
+/**
+ * Converts a number from any `TimeUnit` to nanoseconds.
+ *
+ * @param duration Difference between start and stop time stamps.
+ * @param timeUnit Time unit for the duration.
+ * @returns Duration converted to nanoseconds.
+ */
+export function convertTimeUnitToNanos(duration: number, timeUnit: TimeUnit): number {
+  switch (timeUnit) {
+  case TimeUnit.Nanosecond:
+    return duration;
+  case TimeUnit.Microsecond:
+    return duration * 10 ** 3;
+  case TimeUnit.Millisecond:
+    return duration * 10 ** 6;
+  case TimeUnit.Second:
+    return duration * 10 ** 9;
+  case TimeUnit.Minute:
+    return duration * 10 ** 9 * 60;
+  case TimeUnit.Hour:
+    return duration * 10 ** 9 * 60 * 60;
+  case TimeUnit.Day:
+    return duration * 10 ** 9 * 60 * 60 * 24;
+  }
+}
+
 export default TimeUnit;