From 01a4951da08dc144f93d927cc53cb2817952de83 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Torkel=20=C3=96degaard?= <torkel@grafana.org>
Date: Fri, 13 Nov 2020 10:28:03 +0100
Subject: [PATCH] StatPanel: Fixes hanging issue when all values are zero
 (#29077)

* StatPanel: Fixes hanging issue when all values are zero

* Minor tweak
---
 .../src/field/fieldOverrides.test.ts          | 15 ++++++++++++--
 .../grafana-data/src/field/fieldOverrides.ts  | 20 ++++++-------------
 2 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/packages/grafana-data/src/field/fieldOverrides.test.ts b/packages/grafana-data/src/field/fieldOverrides.test.ts
index b193f022699..6551b922acf 100644
--- a/packages/grafana-data/src/field/fieldOverrides.test.ts
+++ b/packages/grafana-data/src/field/fieldOverrides.test.ts
@@ -88,6 +88,17 @@ describe('Global MinMax', () => {
     expect(minmax.max).toEqual(1234);
   });
 
+  it('find global min max when all values are zero', () => {
+    const f0 = new ArrayDataFrame<{ title: string; value: number; value2: number | null }>([
+      { title: 'AAA', value: 0, value2: 0 },
+      { title: 'CCC', value: 0, value2: 0 },
+    ]);
+
+    const minmax = findNumericFieldMinMax([f0]);
+    expect(minmax.min).toEqual(0);
+    expect(minmax.max).toEqual(0);
+  });
+
   describe('when value is null', () => {
     it('then global min max should be null', () => {
       const frame = toDataFrame({
@@ -98,8 +109,8 @@ describe('Global MinMax', () => {
       });
       const { min, max } = findNumericFieldMinMax([frame]);
 
-      expect(min).toBe(Number.MIN_VALUE);
-      expect(max).toBe(Number.MAX_VALUE);
+      expect(min).toBe(null);
+      expect(max).toBe(null);
     });
   });
 
diff --git a/packages/grafana-data/src/field/fieldOverrides.ts b/packages/grafana-data/src/field/fieldOverrides.ts
index dd00c243e43..839aaa28aba 100644
--- a/packages/grafana-data/src/field/fieldOverrides.ts
+++ b/packages/grafana-data/src/field/fieldOverrides.ts
@@ -41,13 +41,13 @@ interface OverrideProps {
 }
 
 interface GlobalMinMax {
-  min: number;
-  max: number;
+  min?: number | null;
+  max?: number | null;
 }
 
 export function findNumericFieldMinMax(data: DataFrame[]): GlobalMinMax {
-  let min = Number.MAX_VALUE;
-  let max = Number.MIN_VALUE;
+  let min: number | null = null;
+  let max: number | null = null;
 
   const reducers = [ReducerID.min, ReducerID.max];
 
@@ -58,25 +58,17 @@ export function findNumericFieldMinMax(data: DataFrame[]): GlobalMinMax {
         const statsMin = stats[ReducerID.min];
         const statsMax = stats[ReducerID.max];
 
-        if (statsMin !== undefined && statsMin !== null && statsMin < min) {
+        if (min === null || statsMin < min) {
           min = statsMin;
         }
 
-        if (statsMax !== undefined && statsMax !== null && statsMax > max) {
+        if (max === null || statsMax > max) {
           max = statsMax;
         }
       }
     }
   }
 
-  if (min === Number.MAX_VALUE) {
-    min = Number.MIN_VALUE;
-  }
-
-  if (max === Number.MIN_VALUE) {
-    max = Number.MAX_VALUE;
-  }
-
   return { min, max };
 }