Panels: Skip re-rendering panel/visualisation in loading state (#19518)

* Loading states and partial rendering, set loading state in mixed data source, and do not render loading states for react panels

* Updated mixed data source tests

public/app/features/dashboard/dashgrid/PanelChrome.tsx

@@ -115,27 +115,34 @@ export class PanelChrome extends PureComponent<Props, State> {
         return;
       }
 
-      let { errorMessage, isFirstLoad } = this.state;
+      let { isFirstLoad } = this.state;
+      let errorMessage: string | null = null;
 
-      if (data.state === LoadingState.Error) {
-        const { error } = data;
-        if (error) {
-          if (errorMessage !== error.message) {
-            errorMessage = error.message;
+      switch (data.state) {
+        case LoadingState.Loading:
+          // Skip updating state data if it is already in loading state
+          // This is to avoid rendering partial loading responses
+          if (this.state.data.state === LoadingState.Loading) {
+            return;
           }
-        }
-      } else {
-        errorMessage = null;
-      }
-
-      if (data.state === LoadingState.Done) {
-        // If we are doing a snapshot save data in panel model
-        if (this.props.dashboard.snapshot) {
-          this.props.panel.snapshotData = data.series.map(frame => toDataFrameDTO(frame));
-        }
-        if (isFirstLoad) {
-          isFirstLoad = false;
-        }
+          break;
+        case LoadingState.Error:
+          const { error } = data;
+          if (error) {
+            if (errorMessage !== error.message) {
+              errorMessage = error.message;
+            }
+          }
+          break;
+        case LoadingState.Done:
+          // If we are doing a snapshot save data in panel model
+          if (this.props.dashboard.snapshot) {
+            this.props.panel.snapshotData = data.series.map(frame => toDataFrameDTO(frame));
+          }
+          if (isFirstLoad) {
+            isFirstLoad = false;
+          }
+          break;
       }
 
       this.setState({ isFirstLoad, errorMessage, data });

public/app/plugins/datasource/mixed/MixedDataSource.test.ts

@@ -2,6 +2,7 @@ import { DatasourceSrvMock, MockDataSourceApi } from 'test/mocks/datasource_srv'
 import { getDataSourceSrv } from '@grafana/runtime';
 import { getQueryOptions } from 'test/helpers/getQueryOptions';
 import { DataSourceInstanceSettings } from '@grafana/ui';
+import { LoadingState } from '@grafana/data';
 import { MixedDatasource } from './module';
 import { from } from 'rxjs';
 
@@ -29,17 +30,23 @@ describe('MixedDatasource', () => {
   });
   const results: any[] = [];
 
-  beforeEach(async () => {
+  beforeEach(async done => {
     const ds = await getDataSourceSrv().get('-- Mixed --');
+
     from(ds.query(requestMixed)).subscribe(result => {
       results.push(result);
+      if (result.state === LoadingState.Done) {
+        done();
+      }
     });
   });
 
   it('direct query should return results', async () => {
     expect(results.length).toBe(3);
     expect(results[0].data).toEqual(['AAAA']);
+    expect(results[0].state).toEqual(LoadingState.Loading);
     expect(results[1].data).toEqual(['BBBB']);
     expect(results[2].data).toEqual(['CCCC']);
+    expect(results[2].state).toEqual(LoadingState.Done);
   });
 });

public/app/plugins/datasource/mixed/MixedDataSource.ts

@@ -1,10 +1,12 @@
 import cloneDeep from 'lodash/cloneDeep';
 import groupBy from 'lodash/groupBy';
 import { from, of, Observable, merge } from 'rxjs';
+import { tap } from 'rxjs/operators';
 
+import { LoadingState } from '@grafana/data';
 import { DataSourceApi, DataQuery, DataQueryRequest, DataQueryResponse, DataSourceInstanceSettings } from '@grafana/ui';
 import { getDataSourceSrv } from '@grafana/runtime';
-import { mergeMap, map, filter } from 'rxjs/operators';
+import { mergeMap, map } from 'rxjs/operators';
 
 export const MIXED_DATASOURCE_NAME = '-- Mixed --';
 
@@ -25,13 +27,14 @@ export class MixedDatasource extends DataSourceApi<DataQuery> {
 
     const sets: { [key: string]: DataQuery[] } = groupBy(queries, 'datasource');
     const observables: Array<Observable<DataQueryResponse>> = [];
+    let runningSubRequests = 0;
 
     for (const key in sets) {
       const targets = sets[key];
       const dsName = targets[0].datasource;
 
       const observable = from(getDataSourceSrv().get(dsName)).pipe(
-        map((dataSourceApi: DataSourceApi) => {
+        mergeMap((dataSourceApi: DataSourceApi) => {
           const datasourceRequest = cloneDeep(request);
 
           // Remove any unused hidden queries
@@ -42,28 +45,41 @@ export class MixedDatasource extends DataSourceApi<DataQuery> {
 
           datasourceRequest.targets = newTargets;
           datasourceRequest.requestId = `${dsName}${datasourceRequest.requestId || ''}`;
-          return {
-            dataSourceApi,
-            datasourceRequest,
-          };
-        })
-      );
 
-      const noTargets = observable.pipe(
-        filter(({ datasourceRequest }) => datasourceRequest.targets.length === 0),
-        mergeMap(() => {
-          return of({ data: [] } as DataQueryResponse);
-        })
-      );
+          // all queries hidden return empty result for for this requestId
+          if (datasourceRequest.targets.length === 0) {
+            return of({ data: [], key: datasourceRequest.requestId });
+          }
+
+          runningSubRequests++;
+          let hasCountedAsDone = false;
 
-      const hasTargets = observable.pipe(
-        filter(({ datasourceRequest }) => datasourceRequest.targets.length > 0),
-        mergeMap(({ dataSourceApi, datasourceRequest }) => {
           return from(dataSourceApi.query(datasourceRequest)).pipe(
+            tap(
+              (response: DataQueryResponse) => {
+                if (
+                  hasCountedAsDone ||
+                  response.state === LoadingState.Streaming ||
+                  response.state === LoadingState.Loading
+                ) {
+                  return;
+                }
+                runningSubRequests--;
+                hasCountedAsDone = true;
+              },
+              () => {
+                if (hasCountedAsDone) {
+                  return;
+                }
+                hasCountedAsDone = true;
+                runningSubRequests--;
+              }
+            ),
             map((response: DataQueryResponse) => {
               return {
                 ...response,
                 data: response.data || [],
+                state: runningSubRequests === 0 ? LoadingState.Done : LoadingState.Loading,
                 key: `${dsName}${response.key || ''}`,
               } as DataQueryResponse;
             })
@@ -71,7 +87,7 @@ export class MixedDatasource extends DataSourceApi<DataQuery> {
         })
       );
 
-      observables.push(merge(noTargets, hasTargets));
+      observables.push(observable);
     }
 
     return merge(...observables);

public/test/mocks/datasource_srv.ts

@@ -40,7 +40,11 @@ export class MockDataSourceApi extends DataSourceApi {
     if (this.queryResolver) {
       return this.queryResolver;
     }
-    return Promise.resolve(this.result);
+    return new Promise(resolver => {
+      setTimeout(() => {
+        resolver(this.result);
+      });
+    });
   }
 
   testDatasource() {