Prometheus: Remove running of duplicated metrics query (#30108)

* Remove metrics rerenders

* Refactor

* Update public/app/plugins/datasource/prometheus/components/PromQueryField.tsx

Co-authored-by: Zoltán Bedi <zoltan.bedi@gmail.com>

* Update public/app/plugins/datasource/prometheus/language_utils.ts

Co-authored-by: Zoltán Bedi <zoltan.bedi@gmail.com>

* Add test

* Update public/app/plugins/datasource/prometheus/components/PromQueryField.test.tsx

Co-authored-by: Zoltán Bedi <zoltan.bedi@gmail.com>

public/app/plugins/datasource/prometheus/components/PromQueryField.test.tsx

@@ -94,6 +94,55 @@ describe('PromQueryField', () => {
     checkMetricsInCascader(await screen.findByRole('button'), changedMetrics);
   });
 
+  it('does not refreshes metrics when after rounding to minute time range does not change', async () => {
+    const defaultProps = {
+      query: { expr: '', refId: '' },
+      onRunQuery: () => {},
+      onChange: () => {},
+      history: [],
+    };
+    const metrics = ['foo', 'bar'];
+    const changedMetrics = ['foo', 'baz'];
+    const range = {
+      from: dateTime('2020-10-28T00:00:00Z'),
+      to: dateTime('2020-10-28T01:00:00Z'),
+    };
+
+    const languageProvider = makeLanguageProvider({ metrics: [metrics, changedMetrics] });
+    const queryField = render(
+      <PromQueryField
+        // @ts-ignore
+        datasource={{ languageProvider }}
+        range={{
+          ...range,
+          raw: range,
+        }}
+        {...defaultProps}
+      />
+    );
+    checkMetricsInCascader(await screen.findByRole('button'), metrics);
+
+    const newRange = {
+      from: dateTime('2020-10-28T00:00:01Z'),
+      to: dateTime('2020-10-28T01:00:01Z'),
+    };
+    queryField.rerender(
+      <PromQueryField
+        // @ts-ignore
+        datasource={{ languageProvider }}
+        range={{
+          ...newRange,
+          raw: newRange,
+        }}
+        {...defaultProps}
+      />
+    );
+    let cascader = screen.getByRole('button');
+    // Should not show loading
+    expect(cascader.textContent).toContain('Metrics');
+    checkMetricsInCascader(await screen.findByRole('button'), metrics);
+  });
+
   it('refreshes metrics when time range changes but dont show loading state', async () => {
     const defaultProps = {
       query: { expr: '', refId: '' },

public/app/plugins/datasource/prometheus/components/PromQueryField.tsx

@@ -16,8 +16,16 @@ import { LanguageMap, languages as prismLanguages } from 'prismjs';
 
 // dom also includes Element polyfills
 import { PromQuery, PromOptions, PromMetricsMetadata } from '../types';
+import { roundMsToMin } from '../language_utils';
 import { CancelablePromise, makePromiseCancelable } from 'app/core/utils/CancelablePromise';
-import { ExploreQueryFieldProps, QueryHint, isDataFrame, toLegacyResponseData, HistoryItem } from '@grafana/data';
+import {
+  ExploreQueryFieldProps,
+  QueryHint,
+  isDataFrame,
+  toLegacyResponseData,
+  HistoryItem,
+  TimeRange,
+} from '@grafana/data';
 import { DOMUtil, SuggestionsState } from '@grafana/ui';
 import { PrometheusDatasource } from '../datasource';
 
@@ -168,17 +176,6 @@ class PromQueryField extends React.PureComponent<PromQueryFieldProps, PromQueryF
       range,
     } = this.props;
 
-    const rangeChanged =
-      range &&
-      prevProps.range &&
-      !_.isEqual(
-        { from: range.from.valueOf(), to: range.to.valueOf() },
-        {
-          from: prevProps.range.from.valueOf(),
-          to: prevProps.range.to.valueOf(),
-        }
-      );
-
     if (languageProvider !== prevProps.datasource.languageProvider) {
       // We reset this only on DS change so we do not flesh loading state on every rangeChange which happens on every
       // query run if using relative range.
@@ -188,7 +185,9 @@ class PromQueryField extends React.PureComponent<PromQueryFieldProps, PromQueryF
       });
     }
 
-    if (languageProvider !== prevProps.datasource.languageProvider || rangeChanged) {
+    const changedRangeToRefresh = this.rangeChangedToRefresh(range, prevProps.range);
+    // We want to refresh metrics when language provider changes and/or when range changes (we round up intervals to a minute)
+    if (languageProvider !== prevProps.datasource.languageProvider || changedRangeToRefresh) {
       this.refreshMetrics();
     }
 
@@ -237,6 +236,16 @@ class PromQueryField extends React.PureComponent<PromQueryFieldProps, PromQueryF
     }
   };
 
+  rangeChangedToRefresh(range?: TimeRange, prevRange?: TimeRange): boolean {
+    if (range && prevRange) {
+      const sameMinuteFrom = roundMsToMin(range.from.valueOf()) === roundMsToMin(prevRange.from.valueOf());
+      const sameMinuteTo = roundMsToMin(range.to.valueOf()) === roundMsToMin(prevRange.to.valueOf());
+      // If both are same, don't need to refresh.
+      return !(sameMinuteFrom && sameMinuteTo);
+    }
+    return false;
+  }
+
   onChangeMetrics = (values: string[], selectedOptions: CascaderOption[]) => {
     let query;
     if (selectedOptions.length === 1) {

public/app/plugins/datasource/prometheus/language_provider.ts

@@ -5,7 +5,13 @@ import { Value } from 'slate';
 import { dateTime, HistoryItem, LanguageProvider } from '@grafana/data';
 import { CompletionItem, CompletionItemGroup, TypeaheadInput, TypeaheadOutput } from '@grafana/ui';
 
-import { fixSummariesMetadata, parseSelector, processHistogramLabels, processLabels } from './language_utils';
+import {
+  fixSummariesMetadata,
+  parseSelector,
+  processHistogramLabels,
+  processLabels,
+  roundSecToMin,
+} from './language_utils';
 import PromqlSyntax, { FUNCTIONS, RATE_RANGES } from './promql';
 
 import { PrometheusDatasource } from './datasource';
@@ -421,10 +427,6 @@ export default class PromQlLanguageProvider extends LanguageProvider {
     return { [key]: data };
   };
 
-  roundToMinutes(seconds: number): number {
-    return Math.floor(seconds / 60);
-  }
-
   /**
    * Fetch labels for a series. This is cached by it's args but also by the global timeRange currently selected as
    * they can change over requested time.
@@ -443,8 +445,8 @@ export default class PromQlLanguageProvider extends LanguageProvider {
     // The rounding may seem strange but makes relative intervals like now-1h less prone to need separate request every
     // millisecond while still actually getting all the keys for the correct interval. This still can create problems
     // when user does not the newest values for a minute if already cached.
-    params.set('start', this.roundToMinutes(tRange['start']).toString());
+    params.set('start', roundSecToMin(tRange['start']).toString());
-    params.set('end', this.roundToMinutes(tRange['end']).toString());
+    params.set('end', roundSecToMin(tRange['end']).toString());
     params.append('withName', withName ? 'true' : 'false');
     const cacheKey = `/api/v1/series?${params.toString()}`;
     let value = this.labelsCache.get(cacheKey);

public/app/plugins/datasource/prometheus/language_utils.ts

@@ -185,3 +185,11 @@ export function fixSummariesMetadata(metadata: PromMetricsMetadata): PromMetrics
   }
   return { ...metadata, ...summaryMetadata };
 }
+
+export function roundMsToMin(milliseconds: number): number {
+  return roundSecToMin(milliseconds / 1000);
+}
+
+export function roundSecToMin(seconds: number): number {
+  return Math.floor(seconds / 60);
+}