Prometheus: Fixes so results in Panel always are sorted by query order (#19597)

Fixes #19529

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

@@ -1,6 +1,6 @@
 import { PrometheusDatasource } from './datasource';
 import { DataSourceInstanceSettings } from '@grafana/ui';
-import { PromOptions } from './types';
+import { PromContext, PromOptions } from './types';
 import { dateTime, LoadingState } from '@grafana/data';
 
 const defaultInstanceSettings: DataSourceInstanceSettings<PromOptions> = {
@@ -67,11 +67,11 @@ describe('datasource', () => {
       });
     });
 
-    it('with 2 queries, waits for all to finish until sending Done status', done => {
+    it('with 2 queries and used from Explore, sends results as they arrive', done => {
       expect.assertions(4);
       backendSrvMock.datasourceRequest.mockReturnValue(Promise.resolve(makePromResponse()));
       const responseStatus = [LoadingState.Loading, LoadingState.Done];
-      ds.query(makeQuery([{}, {}])).subscribe({
+      ds.query(makeQuery([{ context: PromContext.Explore }, { context: PromContext.Explore }])).subscribe({
         next(next) {
           expect(next.data.length).not.toBe(0);
           expect(next.state).toBe(responseStatus.shift());
@@ -81,6 +81,20 @@ describe('datasource', () => {
         },
       });
     });
+
+    it('with 2 queries and used from Panel, waits for all to finish until sending Done status', done => {
+      expect.assertions(2);
+      backendSrvMock.datasourceRequest.mockReturnValue(Promise.resolve(makePromResponse()));
+      ds.query(makeQuery([{ context: PromContext.Panel }, { context: PromContext.Panel }])).subscribe({
+        next(next) {
+          expect(next.data.length).not.toBe(0);
+          expect(next.state).toBe(LoadingState.Done);
+        },
+        complete() {
+          done();
+        },
+      });
+    });
   });
 });
 
@@ -92,6 +106,7 @@ function makeQuery(targets: any[]): any {
         start: dateTime().subtract(5, 'minutes'),
         end: dateTime(),
         expr: 'test',
+        showingGraph: true,
         ...t,
       };
     }),

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

@@ -3,8 +3,8 @@ import _ from 'lodash';
 import $ from 'jquery';
 // Services & Utils
 import kbn from 'app/core/utils/kbn';
-import { AnnotationEvent, dateMath, DateTime, LoadingState, TimeRange } from '@grafana/data';
-import { from, merge, Observable, of } from 'rxjs';
+import { AnnotationEvent, dateMath, DateTime, LoadingState, TimeRange, TimeSeries } from '@grafana/data';
+import { from, merge, Observable, of, forkJoin } from 'rxjs';
 import { filter, map, tap } from 'rxjs/operators';
 
 import PrometheusMetricFindQuery from './metric_find_query';
@@ -28,6 +28,7 @@ import { safeStringifyValue } from 'app/core/utils/explore';
 import { TemplateSrv } from 'app/features/templating/template_srv';
 import { TimeSrv } from 'app/features/dashboard/services/TimeSrv';
 import { ExploreUrlState } from 'app/types';
+import TableModel from 'app/core/table_model';
 
 export interface PromDataQueryResponse {
   data: {
@@ -221,6 +222,18 @@ export class PrometheusDatasource extends DataSourceApi<PromQuery, PromOptions>
     };
   };
 
+  calledFromExplore = (options: DataQueryRequest<PromQuery>): boolean => {
+    let exploreTargets = 0;
+    for (let index = 0; index < options.targets.length; index++) {
+      const target = options.targets[index];
+      if (target.context === PromContext.Explore) {
+        exploreTargets++;
+      }
+    }
+
+    return exploreTargets === options.targets.length;
+  };
+
   query(options: DataQueryRequest<PromQuery>): Observable<DataQueryResponse> {
     const start = this.getPrometheusTime(options.range.from, false);
     const end = this.getPrometheusTime(options.range.to, true);
@@ -234,6 +247,14 @@ export class PrometheusDatasource extends DataSourceApi<PromQuery, PromOptions>
       });
     }
 
+    if (this.calledFromExplore(options)) {
+      return this.exploreQuery(queries, activeTargets, end);
+    }
+
+    return this.panelsQuery(queries, activeTargets, end, options.requestId);
+  }
+
+  private exploreQuery(queries: PromQueryRequest[], activeTargets: PromQuery[], end: number) {
     let runningQueriesCount = queries.length;
     const subQueries = queries.map((query, index) => {
       const target = activeTargets[index];
@@ -264,6 +285,40 @@ export class PrometheusDatasource extends DataSourceApi<PromQuery, PromOptions>
     return merge(...subQueries);
   }
 
+  private panelsQuery(queries: PromQueryRequest[], activeTargets: PromQuery[], end: number, requestId: string) {
+    const observables: Array<Observable<Array<TableModel | TimeSeries>>> = queries.map((query, index) => {
+      const target = activeTargets[index];
+      let observable: Observable<any> = null;
+
+      if (query.instant) {
+        observable = from(this.performInstantQuery(query, end));
+      } else {
+        observable = from(this.performTimeSeriesQuery(query, query.start, query.end));
+      }
+
+      return observable.pipe(
+        filter((response: any) => (response.cancelled ? false : true)),
+        map((response: any) => {
+          const data = this.processResult(response, query, target, queries.length);
+          return data;
+        })
+      );
+    });
+
+    return forkJoin(observables).pipe(
+      map((results: Array<Array<TableModel | TimeSeries>>) => {
+        const data = results.reduce((result, current) => {
+          return [...result, ...current];
+        }, []);
+        return {
+          data,
+          key: requestId,
+          state: LoadingState.Done,
+        };
+      })
+    );
+  }
+
   createQuery(target: PromQuery, options: DataQueryRequest<PromQuery>, start: number, end: number) {
     const query: PromQueryRequest = {
       hinting: target.hinting,