From 1e78b894136cfcaa8577093cf117da8f8b098860 Mon Sep 17 00:00:00 2001
From: Mike Harder <mharder@microsoft.com>
Date: Fri, 29 Jul 2022 15:39:44 -0700
Subject: [PATCH] [Perf] Display results with 4 significant figures (#22742)

- Fixes Azure/azure-sdk-tools#3554
---
 sdk/test-utils/perf/src/managerProgram.ts | 16 ++++----------
 sdk/test-utils/perf/src/utils.ts          | 27 +++++++++++++++++++++++
 2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/sdk/test-utils/perf/src/managerProgram.ts b/sdk/test-utils/perf/src/managerProgram.ts
index a00186f66751..8b1a06f0c49e 100644
--- a/sdk/test-utils/perf/src/managerProgram.ts
+++ b/sdk/test-utils/perf/src/managerProgram.ts
@@ -11,7 +11,7 @@ import { DefaultPerfOptions, ParsedPerfOptions } from "./options";
 import { Snapshot } from "./snapshot";
 import { PerfTestBase, PerfTestConstructor } from "./perfTestBase";
 import { PerfProgram } from "./program";
-import { formatDuration } from "./utils";
+import { formatDuration, formatNumber } from "./utils";
 
 /**
  * The manager program which is responsible for spawning workers which run the actual perf test.
@@ -96,17 +96,9 @@ export class ManagerPerfProgram implements PerfProgram {
         maximumFractionDigits: 0,
       })} ` +
         `operations in a weighted-average of ` +
-        `${weightedAverage.toLocaleString(undefined, {
-          maximumFractionDigits: 2,
-          minimumFractionDigits: 2,
-        })}s ` +
-        `(${operationsPerSecond.toLocaleString(undefined, {
-          maximumFractionDigits: 2,
-        })} ops/s, ` +
-        `${secondsPerOperation.toLocaleString(undefined, {
-          maximumFractionDigits: 3,
-          minimumFractionDigits: 3,
-        })} s/op)`
+        `${formatNumber(weightedAverage, 4)}s ` +
+        `(${formatNumber(operationsPerSecond, 4)} ops/s, ` +
+        `${formatNumber(secondsPerOperation, 4)} s/op)`
     );
   }
 
diff --git a/sdk/test-utils/perf/src/utils.ts b/sdk/test-utils/perf/src/utils.ts
index 98d4271ae3b8..e915f7013167 100644
--- a/sdk/test-utils/perf/src/utils.ts
+++ b/sdk/test-utils/perf/src/utils.ts
@@ -100,3 +100,30 @@ export function formatDuration(durationMilliseconds: number): string {
 
   return `${minutes < 10 ? "0" : ""}${minutes}:${seconds < 10 ? "0" : ""}${seconds}`;
 }
+
+/**
+ * Formats a number with a minimum number of significant digits.
+ * Digits to the left of the decimal point are always significant.
+ * Examples:
+ *  - formatNumber(0, 4) -> "0.000"
+ *  - formatNumber(12345, 4) -> "12,345"
+ *  - formatNumber(1.2345, 4) -> "1.235"
+ *  - formatNumber(0.00012345, 4) -> "0.0001235"
+ */
+export function formatNumber(value: number, minSignificantDigits: number) {
+  // Special case since log(0) is undefined
+  if (value == 0) {
+    return value.toLocaleString(undefined, {
+      minimumSignificantDigits: minSignificantDigits,
+      maximumSignificantDigits: minSignificantDigits,
+    });
+  }
+
+  const log = Math.log10(Math.abs(value));
+  const significantDigits = Math.max(Math.ceil(log), minSignificantDigits);
+
+  return value.toLocaleString(undefined, {
+    minimumSignificantDigits: significantDigits,
+    maximumSignificantDigits: significantDigits,
+  });
+}