Streaming: support streaming and a javascript test datasource (#16729)

packages/grafana-ui/src/components/Graph/Graph.tsx

@@ -105,7 +105,6 @@ export class Graph extends PureComponent<GraphProps> {
     };
 
     try {
-      console.log('Graph render');
       $.plot(this.element, series, flotOptions);
     } catch (err) {
       console.log('Graph rendering error', err, flotOptions, series);

packages/grafana-ui/src/types/data.ts

@@ -1,6 +1,7 @@
 export enum LoadingState {
   NotStarted = 'NotStarted',
   Loading = 'Loading',
+  Streaming = 'Streaming',
   Done = 'Done',
   Error = 'Error',
 }

packages/grafana-ui/src/types/datasource.ts

@@ -1,7 +1,7 @@
 import { ComponentClass } from 'react';
 import { TimeRange } from './time';
 import { PluginMeta } from './plugin';
-import { TableData, TimeSeries, SeriesData } from './data';
+import { TableData, TimeSeries, SeriesData, LoadingState } from './data';
 import { PanelData } from './panel';
 
 export interface DataSourcePluginOptionsEditorProps<TOptions> {
@@ -105,7 +105,7 @@ export interface DataSourceApi<TQuery extends DataQuery = DataQuery> {
   /**
    * Main metrics / data query action
    */
-  query(options: DataQueryRequest<TQuery>): Promise<DataQueryResponse>;
+  query(options: DataQueryRequest<TQuery>, observer?: DataStreamObserver): Promise<DataQueryResponse>;
 
   /**
    * Test & verify datasource settings & connection details
@@ -183,6 +183,47 @@ export type LegacyResponseData = TimeSeries | TableData | any;
 
 export type DataQueryResponseData = SeriesData | LegacyResponseData;
 
+export type DataStreamObserver = (event: DataStreamState) => void;
+
+export interface DataStreamState {
+  /**
+   * when Done or Error no more events will be processed
+   */
+  state: LoadingState;
+
+  /**
+   * Consistent key across events.
+   */
+  key: string;
+
+  /**
+   * The stream request.  The properties of this request will be examined
+   * to determine if the stream matches the original query.  If not, it
+   * will be unsubscribed.
+   */
+  request: DataQueryRequest;
+
+  /**
+   * Series data may not be known yet
+   */
+  series?: SeriesData[];
+
+  /**
+   * Error in stream (but may still be running)
+   */
+  error?: DataQueryError;
+
+  /**
+   * Optionally return only the rows that changed in this event
+   */
+  delta?: SeriesData[];
+
+  /**
+   * Stop listening to this stream
+   */
+  unsubscribe: () => void;
+}
+
 export interface DataQueryResponse {
   data: DataQueryResponseData[];
 }

pkg/tsdb/testdata/scenarios.go

@@ -225,6 +225,15 @@ func init() {
 		},
 	})
 
+	registerScenario(&Scenario{
+		Id:   "streaming_client",
+		Name: "Streaming Client",
+		Handler: func(query *tsdb.Query, context *tsdb.TsdbQuery) *tsdb.QueryResult {
+			// Real work is in javascript client
+			return tsdb.NewQueryResult()
+		},
+	})
+
 	registerScenario(&Scenario{
 		Id:   "table_static",
 		Name: "Table Static",

public/app/core/services/__mocks__/backend_srv.ts

@@ -4,6 +4,7 @@ const backendSrv = {
   getDashboardByUid: jest.fn(),
   getFolderByUid: jest.fn(),
   post: jest.fn(),
+  resolveCancelerIfExists: jest.fn(),
 };
 
 export function getBackendSrv() {

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

@@ -22,7 +22,7 @@ import { ScopedVars } from '@grafana/ui';
 
 import templateSrv from 'app/features/templating/template_srv';
 
-import { getProcessedSeriesData } from '../state/PanelQueryRunner';
+import { getProcessedSeriesData } from '../state/PanelQueryState';
 import { Unsubscribable } from 'rxjs';
 
 const DEFAULT_PLUGIN_ERROR = 'Error in plugin';
@@ -48,6 +48,7 @@ export interface State {
 export class PanelChrome extends PureComponent<Props, State> {
   timeSrv: TimeSrv = getTimeSrv();
   querySubscription: Unsubscribable;
+  delayedStateUpdate: Partial<State>;
 
   constructor(props: Props) {
     super(props);
@@ -118,7 +119,15 @@ export class PanelChrome extends PureComponent<Props, State> {
         }
       }
 
-      this.setState({ isFirstLoad, errorMessage, data });
+      const stateUpdate = { isFirstLoad, errorMessage, data };
+
+      if (this.isVisible) {
+        this.setState(stateUpdate);
+      } else {
+        // if we are getting data while another panel is in fullscreen / edit mode
+        // we need to store the data but not update state yet
+        this.delayedStateUpdate = stateUpdate;
+      }
     },
   };
 
@@ -162,9 +171,15 @@ export class PanelChrome extends PureComponent<Props, State> {
   };
 
   onRender = () => {
-    this.setState({
-      renderCounter: this.state.renderCounter + 1,
-    });
+    const stateUpdate = { renderCounter: this.state.renderCounter + 1 };
+
+    // If we have received a data update while hidden copy over that state as well
+    if (this.delayedStateUpdate) {
+      Object.assign(stateUpdate, this.delayedStateUpdate);
+      this.delayedStateUpdate = null;
+    }
+
+    this.setState(stateUpdate);
   };
 
   onOptionsChange = (options: any) => {

public/app/features/dashboard/state/PanelQueryRunner.test.ts

@@ -1,42 +1,15 @@
-import { getProcessedSeriesData, PanelQueryRunner } from './PanelQueryRunner';
-import { PanelData, DataQueryRequest } from '@grafana/ui/src/types';
+import { PanelQueryRunner } from './PanelQueryRunner';
+import {
+  PanelData,
+  DataQueryRequest,
+  DataStreamObserver,
+  DataStreamState,
+  LoadingState,
+  ScopedVars,
+} from '@grafana/ui/src/types';
 import moment from 'moment';
 
-describe('PanelQueryRunner', () => {
-  it('converts timeseries to table skipping nulls', () => {
-    const input1 = {
-      target: 'Field Name',
-      datapoints: [[100, 1], [200, 2]],
-    };
-    const input2 = {
-      // without target
-      target: '',
-      datapoints: [[100, 1], [200, 2]],
-    };
-    const data = getProcessedSeriesData([null, input1, input2, null, null]);
-    expect(data.length).toBe(2);
-    expect(data[0].fields[0].name).toBe(input1.target);
-    expect(data[0].rows).toBe(input1.datapoints);
-
-    // Default name
-    expect(data[1].fields[0].name).toEqual('Value');
-
-    // Every colun should have a name and a type
-    for (const table of data) {
-      for (const column of table.fields) {
-        expect(column.name).toBeDefined();
-        expect(column.type).toBeDefined();
-      }
-    }
-  });
-
-  it('supports null values from query OK', () => {
-    expect(getProcessedSeriesData([null, null, null, null])).toEqual([]);
-    expect(getProcessedSeriesData(undefined)).toEqual([]);
-    expect(getProcessedSeriesData((null as unknown) as any[])).toEqual([]);
-    expect(getProcessedSeriesData([])).toEqual([]);
-  });
-});
+jest.mock('app/core/services/backend_srv');
 
 interface ScenarioContext {
   setup: (fn: () => void) => void;
@@ -47,6 +20,9 @@ interface ScenarioContext {
   events?: PanelData[];
   res?: PanelData;
   queryCalledWith?: DataQueryRequest;
+  observer: DataStreamObserver;
+  runner: PanelQueryRunner;
+  scopedVars: ScopedVars;
 }
 
 type ScenarioFn = (ctx: ScenarioContext) => void;
@@ -57,12 +33,16 @@ function describeQueryRunnerScenario(description: string, scenarioFn: ScenarioFn
 
     const ctx: ScenarioContext = {
       widthPixels: 200,
+      scopedVars: {
+        server: { text: 'Server1', value: 'server-1' },
+      },
+      runner: new PanelQueryRunner(),
+      observer: (args: any) => {},
       setup: (fn: () => void) => {
         setupFn = fn;
       },
     };
 
-    let runner: PanelQueryRunner;
     const response: any = {
       data: [{ target: 'hello', datapoints: [] }],
     };
@@ -71,9 +51,11 @@ function describeQueryRunnerScenario(description: string, scenarioFn: ScenarioFn
       setupFn();
 
       const datasource: any = {
+        name: 'TestDB',
         interval: ctx.dsInterval,
-        query: (options: DataQueryRequest) => {
+        query: (options: DataQueryRequest, observer: DataStreamObserver) => {
           ctx.queryCalledWith = options;
+          ctx.observer = observer;
           return Promise.resolve(response);
         },
         testDatasource: jest.fn(),
@@ -81,6 +63,7 @@ function describeQueryRunnerScenario(description: string, scenarioFn: ScenarioFn
 
       const args: any = {
         datasource,
+        scopedVars: ctx.scopedVars,
         minInterval: ctx.minInterval,
         widthPixels: ctx.widthPixels,
         maxDataPoints: ctx.maxDataPoints,
@@ -93,15 +76,15 @@ function describeQueryRunnerScenario(description: string, scenarioFn: ScenarioFn
         queries: [{ refId: 'A', test: 1 }],
       };
 
-      runner = new PanelQueryRunner();
-      runner.subscribe({
+      ctx.runner = new PanelQueryRunner();
+      ctx.runner.subscribe({
         next: (data: PanelData) => {
           ctx.events.push(data);
         },
       });
 
       ctx.events = [];
-      ctx.res = await runner.run(args);
+      ctx.res = await ctx.runner.run(args);
     });
 
     scenarioFn(ctx);
@@ -109,6 +92,22 @@ function describeQueryRunnerScenario(description: string, scenarioFn: ScenarioFn
 }
 
 describe('PanelQueryRunner', () => {
+  describeQueryRunnerScenario('simple scenario', ctx => {
+    it('should set requestId on request', async () => {
+      expect(ctx.queryCalledWith.requestId).toBe('Q100');
+    });
+
+    it('should set datasource name on request', async () => {
+      expect(ctx.queryCalledWith.targets[0].datasource).toBe('TestDB');
+    });
+
+    it('should pass scopedVars to datasource with interval props', async () => {
+      expect(ctx.queryCalledWith.scopedVars.server.text).toBe('Server1');
+      expect(ctx.queryCalledWith.scopedVars.__interval.text).toBe('5m');
+      expect(ctx.queryCalledWith.scopedVars.__interval_ms.text).toBe('300000');
+    });
+  });
+
   describeQueryRunnerScenario('with no maxDataPoints or minInterval', ctx => {
     ctx.setup(() => {
       ctx.maxDataPoints = null;
@@ -165,4 +164,47 @@ describe('PanelQueryRunner', () => {
       expect(ctx.queryCalledWith.maxDataPoints).toBe(10);
     });
   });
+
+  describeQueryRunnerScenario('when datasource is streaming data', ctx => {
+    let streamState: DataStreamState;
+    let isUnsubbed = false;
+
+    beforeEach(() => {
+      streamState = {
+        state: LoadingState.Streaming,
+        key: 'test-stream-1',
+        series: [
+          {
+            rows: [],
+            fields: [],
+            name: 'I am a magic stream',
+          },
+        ],
+        request: {
+          requestId: ctx.queryCalledWith.requestId,
+        } as any,
+        unsubscribe: () => {
+          isUnsubbed = true;
+        },
+      };
+      ctx.observer(streamState);
+    });
+
+    it('should push another update to subscriber', async () => {
+      expect(ctx.events.length).toBe(2);
+    });
+
+    it('should set state to streaming', async () => {
+      expect(ctx.events[1].state).toBe(LoadingState.Streaming);
+    });
+
+    it('should not unsubscribe', async () => {
+      expect(isUnsubbed).toBe(false);
+    });
+
+    it('destroy should unsubscribe streams', async () => {
+      ctx.runner.destroy();
+      expect(isUnsubbed).toBe(true);
+    });
+  });
 });

public/app/features/dashboard/state/PanelQueryRunner.ts

@@ -1,27 +1,17 @@
 // Libraries
 import cloneDeep from 'lodash/cloneDeep';
+import throttle from 'lodash/throttle';
 import { Subject, Unsubscribable, PartialObserver } from 'rxjs';
 
 // Services & Utils
 import { getDatasourceSrv } from 'app/features/plugins/datasource_srv';
 import kbn from 'app/core/utils/kbn';
 import templateSrv from 'app/features/templating/template_srv';
-
-// Components & Types
-import {
-  guessFieldTypes,
-  toSeriesData,
-  PanelData,
-  LoadingState,
-  DataQuery,
-  TimeRange,
-  ScopedVars,
-  DataQueryRequest,
-  SeriesData,
-  DataSourceApi,
-} from '@grafana/ui';
 import { PanelQueryState } from './PanelQueryState';
 
+// Types
+import { PanelData, DataQuery, TimeRange, ScopedVars, DataQueryRequest, DataSourceApi } from '@grafana/ui';
+
 export interface QueryRunnerOptions<TQuery extends DataQuery = DataQuery> {
   datasource: string | DataSourceApi<TQuery>;
   queries: TQuery[];
@@ -54,6 +44,10 @@ export class PanelQueryRunner {
 
   private state = new PanelQueryState();
 
+  constructor() {
+    this.state.onStreamingDataUpdated = this.onStreamingDataUpdated;
+  }
+
   /**
    * Listen for updates to the PanelData.  If a query has already run for this panel,
    * the results will be immediatly passed to the observer
@@ -73,7 +67,7 @@ export class PanelQueryRunner {
     }
 
     // Send the last result
-    if (this.state.data.state !== LoadingState.NotStarted) {
+    if (this.state.isStarted()) {
       observer.next(this.state.getDataAfterCheckingFormats());
     }
 
@@ -103,6 +97,9 @@ export class PanelQueryRunner {
       delayStateNotification,
     } = options;
 
+    // filter out hidden queries & deep clone them
+    const clonedAndFilteredQueries = cloneDeep(queries.filter(q => !q.hide));
+
     const request: DataQueryRequest = {
       requestId: getNextRequestId(),
       timezone,
@@ -112,26 +109,20 @@ export class PanelQueryRunner {
       timeInfo,
       interval: '',
       intervalMs: 0,
-      targets: cloneDeep(
-        queries.filter(q => {
-          return !q.hide; // Skip any hidden queries
-        })
-      ),
+      targets: clonedAndFilteredQueries,
       maxDataPoints: maxDataPoints || widthPixels,
       scopedVars: scopedVars || {},
       cacheTimeout,
       startTime: Date.now(),
     };
-    // Deprecated
+
+    // Add deprecated property
     (request as any).rangeRaw = timeRange.raw;
 
     let loadingStateTimeoutId = 0;
 
     try {
-      const ds =
-        datasource && (datasource as any).query
-          ? (datasource as DataSourceApi)
-          : await getDatasourceSrv().get(datasource as string, request.scopedVars);
+      const ds = await getDataSource(datasource, request.scopedVars);
 
       // Attach the datasource name to each query
       request.targets = request.targets.map(query => {
@@ -148,17 +139,19 @@ export class PanelQueryRunner {
       // and add built in variables interval and interval_ms
       request.scopedVars = Object.assign({}, request.scopedVars, {
         __interval: { text: norm.interval, value: norm.interval },
-        __interval_ms: { text: norm.intervalMs, value: norm.intervalMs },
+        __interval_ms: { text: norm.intervalMs.toString(), value: norm.intervalMs },
       });
 
       request.interval = norm.interval;
       request.intervalMs = norm.intervalMs;
 
       // Check if we can reuse the already issued query
-      if (state.isRunning()) {
+      const active = state.getActiveRunner();
+      if (active) {
         if (state.isSameQuery(ds, request)) {
-          // TODO? maybe cancel if it has run too long?
-          return state.getCurrentExecutor();
+          // Maybe cancel if it has run too long?
+          console.log('Trying to execute query while last one has yet to complete, returning same promise');
+          return active;
         } else {
           state.cancel('Query Changed while running');
         }
@@ -166,8 +159,8 @@ export class PanelQueryRunner {
 
       // Send a loading status event on slower queries
       loadingStateTimeoutId = window.setTimeout(() => {
-        if (this.state.isRunning()) {
-          this.subject.next(this.state.data);
+        if (state.getActiveRunner()) {
+          this.subject.next(this.state.validateStreamsAndGetPanelData());
         }
       }, delayStateNotification || 500);
 
@@ -188,6 +181,18 @@ export class PanelQueryRunner {
     }
   }
 
+  /**
+   * Called after every streaming event.  This should be throttled so we
+   * avoid accidentally overwhelming the browser
+   */
+  onStreamingDataUpdated = throttle(
+    () => {
+      this.subject.next(this.state.validateStreamsAndGetPanelData());
+    },
+    50,
+    { trailing: true, leading: true }
+  );
+
   /**
    * Called when the panel is closed
    */
@@ -202,22 +207,12 @@ export class PanelQueryRunner {
   }
 }
 
-/**
- * All panels will be passed tables that have our best guess at colum type set
- *
- * This is also used by PanelChrome for snapshot support
- */
-export function getProcessedSeriesData(results?: any[]): SeriesData[] {
-  if (!results) {
-    return [];
-  }
-
-  const series: SeriesData[] = [];
-  for (const r of results) {
-    if (r) {
-      series.push(guessFieldTypes(toSeriesData(r)));
-    }
+async function getDataSource(
+  datasource: string | DataSourceApi | null,
+  scopedVars: ScopedVars
+): Promise<DataSourceApi> {
+  if (datasource && (datasource as any).query) {
+    return datasource as DataSourceApi;
   }
-
-  return series;
+  return await getDatasourceSrv().get(datasource as string, scopedVars);
 }

public/app/features/dashboard/state/PanelQueryState.test.ts

@@ -1,6 +1,6 @@
-import { toDataQueryError, PanelQueryState } from './PanelQueryState';
+import { toDataQueryError, PanelQueryState, getProcessedSeriesData } from './PanelQueryState';
 import { MockDataSourceApi } from 'test/mocks/datasource_srv';
-import { DataQueryResponse } from '@grafana/ui';
+import { DataQueryResponse, LoadingState } from '@grafana/ui';
 import { getQueryOptions } from 'test/helpers/getQueryOptions';
 
 describe('PanelQueryState', () => {
@@ -17,11 +17,11 @@ describe('PanelQueryState', () => {
 
   it('keeps track of running queries', async () => {
     const state = new PanelQueryState();
-    expect(state.isRunning()).toBeFalsy();
+    expect(state.getActiveRunner()).toBeFalsy();
     let hasRun = false;
     const dsRunner = new Promise<DataQueryResponse>((resolve, reject) => {
       // The status should be running when we get here
-      expect(state.isRunning()).toBeTruthy();
+      expect(state.getActiveRunner()).toBeTruthy();
       resolve({ data: ['x', 'y'] });
       hasRun = true;
     });
@@ -30,7 +30,7 @@ describe('PanelQueryState', () => {
 
     // should not actually run for an empty query
     let empty = await state.execute(ds, getQueryOptions({}));
-    expect(state.isRunning()).toBeFalsy();
+    expect(state.getActiveRunner()).toBeFalsy();
     expect(empty.series.length).toBe(0);
     expect(hasRun).toBeFalsy();
 
@@ -39,8 +39,162 @@ describe('PanelQueryState', () => {
       getQueryOptions({ targets: [{ hide: true, refId: 'X' }, { hide: true, refId: 'Y' }, { hide: true, refId: 'Z' }] })
     );
     // should not run any hidden queries'
-    expect(state.isRunning()).toBeFalsy();
+    expect(state.getActiveRunner()).toBeFalsy();
     expect(empty.series.length).toBe(0);
     expect(hasRun).toBeFalsy();
   });
 });
+
+describe('getProcessedSeriesData', () => {
+  it('converts timeseries to table skipping nulls', () => {
+    const input1 = {
+      target: 'Field Name',
+      datapoints: [[100, 1], [200, 2]],
+    };
+    const input2 = {
+      // without target
+      target: '',
+      datapoints: [[100, 1], [200, 2]],
+    };
+    const data = getProcessedSeriesData([null, input1, input2, null, null]);
+    expect(data.length).toBe(2);
+    expect(data[0].fields[0].name).toBe(input1.target);
+    expect(data[0].rows).toBe(input1.datapoints);
+
+    // Default name
+    expect(data[1].fields[0].name).toEqual('Value');
+
+    // Every colun should have a name and a type
+    for (const table of data) {
+      for (const column of table.fields) {
+        expect(column.name).toBeDefined();
+        expect(column.type).toBeDefined();
+      }
+    }
+  });
+
+  it('supports null values from query OK', () => {
+    expect(getProcessedSeriesData([null, null, null, null])).toEqual([]);
+    expect(getProcessedSeriesData(undefined)).toEqual([]);
+    expect(getProcessedSeriesData((null as unknown) as any[])).toEqual([]);
+    expect(getProcessedSeriesData([])).toEqual([]);
+  });
+});
+
+function makeSeriesStub(refId: string) {
+  return {
+    fields: [{ name: 'a' }],
+    rows: [],
+    refId,
+  };
+}
+
+describe('stream handling', () => {
+  const state = new PanelQueryState();
+  state.onStreamingDataUpdated = () => {
+    // nothing
+  };
+  state.request = {
+    requestId: '123',
+    range: {
+      raw: {
+        from: 123, // if string it gets revaluated
+      },
+    },
+  } as any;
+  state.response = {
+    state: LoadingState.Done,
+    series: [makeSeriesStub('A'), makeSeriesStub('B')],
+  };
+
+  it('gets the response', () => {
+    const data = state.validateStreamsAndGetPanelData();
+    expect(data.series.length).toBe(2);
+    expect(data.state).toBe(LoadingState.Done);
+    expect(data.series[0].refId).toBe('A');
+  });
+
+  it('adds a stream event', () => {
+    // Post a stream event
+    state.dataStreamObserver({
+      state: LoadingState.Loading,
+      key: 'C',
+      request: state.request, // From the same request
+      series: [makeSeriesStub('C')],
+      unsubscribe: () => {},
+    });
+    expect(state.streams.length).toBe(1);
+
+    const data = state.validateStreamsAndGetPanelData();
+    expect(data.series.length).toBe(3);
+    expect(data.state).toBe(LoadingState.Streaming);
+    expect(data.series[2].refId).toBe('C');
+  });
+
+  it('add another stream event (with a differnet key)', () => {
+    // Post a stream event
+    state.dataStreamObserver({
+      state: LoadingState.Loading,
+      key: 'D',
+      request: state.request, // From the same request
+      series: [makeSeriesStub('D')],
+      unsubscribe: () => {},
+    });
+    expect(state.streams.length).toBe(2);
+
+    const data = state.validateStreamsAndGetPanelData();
+    expect(data.series.length).toBe(4);
+    expect(data.state).toBe(LoadingState.Streaming);
+    expect(data.series[3].refId).toBe('D');
+  });
+
+  it('replace the first stream value, but keep the order', () => {
+    // Post a stream event
+    state.dataStreamObserver({
+      state: LoadingState.Loading,
+      key: 'C', // The key to replace previous index 2
+      request: state.request, // From the same request
+      series: [makeSeriesStub('X')],
+      unsubscribe: () => {},
+    });
+    expect(state.streams.length).toBe(2);
+
+    const data = state.validateStreamsAndGetPanelData();
+    expect(data.series[2].refId).toBe('X');
+  });
+
+  it('ignores streams from a differnet request', () => {
+    // Post a stream event
+    state.dataStreamObserver({
+      state: LoadingState.Loading,
+      key: 'Z', // Note with key 'A' it would still overwrite
+      request: {
+        ...state.request,
+        requestId: 'XXX', // Different request and id
+      } as any,
+      series: [makeSeriesStub('C')],
+      unsubscribe: () => {},
+    });
+
+    expect(state.streams.length).toBe(2); // no change
+    const data = state.validateStreamsAndGetPanelData();
+    expect(data.series.length).toBe(4);
+  });
+
+  it('removes streams when the query changes', () => {
+    state.request = {
+      ...state.request,
+      requestId: 'somethine else',
+    } as any;
+    state.response = {
+      state: LoadingState.Done,
+      series: [makeSeriesStub('F')],
+    };
+    expect(state.streams.length).toBe(2); // unchanged
+
+    const data = state.validateStreamsAndGetPanelData();
+    expect(data.series.length).toBe(1);
+    expect(data.series[0].refId).toBe('F');
+    expect(state.streams.length).toBe(0); // no streams
+  });
+});

public/app/features/dashboard/state/PanelQueryState.ts

@@ -1,16 +1,25 @@
+// Libraries
+import isString from 'lodash/isString';
+import isEqual from 'lodash/isEqual';
+
+// Utils & Services
+import { getBackendSrv } from 'app/core/services/backend_srv';
+import * as dateMath from 'app/core/utils/datemath';
+import { guessFieldTypes, toSeriesData, isSeriesData } from '@grafana/ui/src/utils';
+
+// Types
 import {
   DataSourceApi,
   DataQueryRequest,
   PanelData,
   LoadingState,
   toLegacyResponseData,
-  isSeriesData,
-  toSeriesData,
   DataQueryError,
+  DataStreamObserver,
+  DataStreamState,
+  SeriesData,
+  DataQueryResponseData,
 } from '@grafana/ui';
-import { getProcessedSeriesData } from './PanelQueryRunner';
-import { getBackendSrv } from 'app/core/services/backend_srv';
-import isEqual from 'lodash/isEqual';
 
 export class PanelQueryState {
   // The current/last running request
@@ -19,26 +28,33 @@ export class PanelQueryState {
     endTime: 1000, // Somethign not zero
   } as DataQueryRequest;
 
-  // The best known state of data
-  data = {
+  // The result back from the datasource query
+  response = {
     state: LoadingState.NotStarted,
     series: [],
   } as PanelData;
 
+  // Active stream results
+  streams: DataStreamState[] = [];
+
   sendSeries = false;
   sendLegacy = false;
 
   // A promise for the running query
-  private executor: Promise<PanelData> = {} as any;
+  private executor?: Promise<PanelData>;
   private rejector = (reason?: any) => {};
   private datasource: DataSourceApi = {} as any;
 
-  isRunning() {
-    return this.data.state === LoadingState.Loading; //
+  isFinished(state: LoadingState) {
+    return state === LoadingState.Done || state === LoadingState.Error;
+  }
+
+  isStarted() {
+    return this.response.state !== LoadingState.NotStarted;
   }
 
   isSameQuery(ds: DataSourceApi, req: DataQueryRequest) {
-    if (this.datasource !== this.datasource) {
+    if (ds !== this.datasource) {
       return false;
     }
 
@@ -46,16 +62,22 @@ export class PanelQueryState {
     return isEqual(this.request.targets, req.targets);
   }
 
-  getCurrentExecutor() {
+  /**
+   * Return the currently running query
+   */
+  getActiveRunner(): Promise<PanelData> | undefined {
     return this.executor;
   }
 
   cancel(reason: string) {
     const { request } = this;
+    this.executor = null;
+
     try {
+      // If no endTime the call to datasource.query did not complete
+      // call rejector to reject the executor promise
       if (!request.endTime) {
         request.endTime = Date.now();
-
         this.rejector('Canceled:' + reason);
       }
 
@@ -64,8 +86,11 @@ export class PanelQueryState {
         getBackendSrv().resolveCancelerIfExists(request.requestId);
       }
     } catch (err) {
-      console.log('Error canceling request');
+      console.log('Error canceling request', err);
     }
+
+    // Close any open streams
+    this.closeStreams(true);
   }
 
   execute(ds: DataSourceApi, req: DataQueryRequest): Promise<PanelData> {
@@ -75,85 +100,214 @@ export class PanelQueryState {
     if (!req.targets.length) {
       console.log('No queries, so return early');
       this.request.endTime = Date.now();
+      this.closeStreams();
       return Promise.resolve(
-        (this.data = {
+        (this.response = {
           state: LoadingState.Done,
           series: [], // Clear the data
           legacy: [],
-          request: req,
         })
       );
     }
 
     // Set the loading state immediatly
-    this.data.state = LoadingState.Loading;
-    return (this.executor = new Promise<PanelData>((resolve, reject) => {
+    this.response.state = LoadingState.Loading;
+    this.executor = new Promise<PanelData>((resolve, reject) => {
       this.rejector = reject;
 
       return ds
-        .query(this.request)
+        .query(this.request, this.dataStreamObserver)
         .then(resp => {
           this.request.endTime = Date.now();
+          this.executor = null;
 
           // Make sure we send something back -- called run() w/o subscribe!
           if (!(this.sendSeries || this.sendLegacy)) {
             this.sendSeries = true;
           }
 
-          // Make sure the response is in a supported format
-          const series = this.sendSeries ? getProcessedSeriesData(resp.data) : [];
-          const legacy = this.sendLegacy
-            ? resp.data.map(v => {
-                if (isSeriesData(v)) {
-                  return toLegacyResponseData(v);
-                }
-                return v;
-              })
-            : undefined;
-
-          resolve(
-            (this.data = {
-              state: LoadingState.Done,
-              request: this.request,
-              series,
-              legacy,
-            })
-          );
+          // Save the result state
+          this.response = {
+            state: LoadingState.Done,
+            request: this.request,
+            series: this.sendSeries ? getProcessedSeriesData(resp.data) : [],
+            legacy: this.sendLegacy ? translateToLegacyData(resp.data) : undefined,
+          };
+          resolve(this.validateStreamsAndGetPanelData());
         })
         .catch(err => {
+          this.executor = null;
           resolve(this.setError(err));
         });
-    }));
+    });
+
+    return this.executor;
+  }
+
+  // Send a notice when the stream has updated the current model
+  onStreamingDataUpdated: () => void;
+
+  // This gets all stream events and keeps track of them
+  // it will then delegate real changes to the PanelQueryRunner
+  dataStreamObserver: DataStreamObserver = (stream: DataStreamState) => {
+    // Streams only work with the 'series' format
+    this.sendSeries = true;
+
+    // Add the stream to our list
+    let found = false;
+    const active = this.streams.map(s => {
+      if (s.key === stream.key) {
+        found = true;
+        return stream;
+      }
+      return s;
+    });
+
+    if (!found) {
+      if (shouldDisconnect(this.request, stream)) {
+        console.log('Got stream update from old stream, unsubscribing');
+        stream.unsubscribe();
+        return;
+      }
+      active.push(stream);
+    }
+
+    this.streams = active;
+    this.onStreamingDataUpdated();
+  };
+
+  closeStreams(keepSeries = false) {
+    if (!this.streams.length) {
+      return;
+    }
+
+    const series: SeriesData[] = [];
+
+    for (const stream of this.streams) {
+      if (stream.series) {
+        series.push.apply(series, stream.series);
+      }
+
+      try {
+        stream.unsubscribe();
+      } catch {
+        console.log('Failed to unsubscribe to stream');
+      }
+    }
+
+    this.streams = [];
+
+    // Move the series from streams to the resposne
+    if (keepSeries) {
+      const { response } = this;
+      this.response = {
+        ...response,
+        series: [
+          ...response.series,
+          ...series, // Append the streamed series
+        ],
+      };
+    }
+  }
+
+  /**
+   * This is called before broadcasting data to listeners.  Given that
+   * stream events can happen at any point, we need to make sure to
+   * only return data from active streams.
+   */
+  validateStreamsAndGetPanelData(): PanelData {
+    const { response, streams, request } = this;
+
+    // When not streaming, return the response + request
+    if (!streams.length) {
+      return {
+        ...response,
+        request: request,
+      };
+    }
+
+    let done = this.isFinished(response.state);
+    const series = [...response.series];
+    const active: DataStreamState[] = [];
+
+    for (const stream of this.streams) {
+      if (shouldDisconnect(request, stream)) {
+        console.log('getPanelData() - shouldDisconnect true, unsubscribing to steam');
+        stream.unsubscribe();
+        continue;
+      }
+
+      active.push(stream);
+      series.push.apply(series, stream.series);
+
+      if (!this.isFinished(stream.state)) {
+        done = false;
+      }
+    }
+
+    this.streams = active;
+
+    // Update the time range
+    let timeRange = this.request.range;
+    if (isString(timeRange.raw.from)) {
+      timeRange = {
+        from: dateMath.parse(timeRange.raw.from, false),
+        to: dateMath.parse(timeRange.raw.to, true),
+        raw: timeRange.raw,
+      };
+    }
+
+    return {
+      state: done ? LoadingState.Done : LoadingState.Streaming,
+      series, // Union of series from response and all streams
+      legacy: this.sendLegacy ? translateToLegacyData(series) : undefined,
+      request: {
+        ...this.request,
+        range: timeRange, // update the time range
+      },
+    };
   }
 
   /**
    * Make sure all requested formats exist on the data
    */
   getDataAfterCheckingFormats(): PanelData {
-    const { data, sendLegacy, sendSeries } = this;
-    if (sendLegacy && (!data.legacy || !data.legacy.length)) {
-      data.legacy = data.series.map(v => toLegacyResponseData(v));
+    const { response, sendLegacy, sendSeries } = this;
+    if (sendLegacy && (!response.legacy || !response.legacy.length)) {
+      response.legacy = response.series.map(v => toLegacyResponseData(v));
     }
-    if (sendSeries && !data.series.length && data.legacy) {
-      data.series = data.legacy.map(v => toSeriesData(v));
+    if (sendSeries && !response.series.length && response.legacy) {
+      response.series = response.legacy.map(v => toSeriesData(v));
     }
-    return this.data;
+    return this.validateStreamsAndGetPanelData();
   }
 
   setError(err: any): PanelData {
     if (!this.request.endTime) {
       this.request.endTime = Date.now();
     }
-
-    return (this.data = {
-      ...this.data, // Keep any existing data
+    this.closeStreams(true);
+    this.response = {
+      ...this.response, // Keep any existing data
       state: LoadingState.Error,
       error: toDataQueryError(err),
-      request: this.request,
-    });
+    };
+    return this.validateStreamsAndGetPanelData();
   }
 }
 
+export function shouldDisconnect(source: DataQueryRequest, state: DataStreamState) {
+  // It came from the same the same request, so keep it
+  if (source === state.request || state.request.requestId.startsWith(source.requestId)) {
+    return false;
+  }
+
+  // We should be able to check that it is the same query regardless of
+  // if it came from the same request. This will be important for #16676
+
+  return true;
+}
+
 export function toDataQueryError(err: any): DataQueryError {
   const error = (err || {}) as DataQueryError;
   if (!error.message) {
@@ -175,3 +329,32 @@ export function toDataQueryError(err: any): DataQueryError {
   }
   return error;
 }
+
+function translateToLegacyData(data: DataQueryResponseData) {
+  return data.map(v => {
+    if (isSeriesData(v)) {
+      return toLegacyResponseData(v);
+    }
+    return v;
+  });
+}
+
+/**
+ * All panels will be passed tables that have our best guess at colum type set
+ *
+ * This is also used by PanelChrome for snapshot support
+ */
+export function getProcessedSeriesData(results?: any[]): SeriesData[] {
+  if (!results) {
+    return [];
+  }
+
+  const series: SeriesData[] = [];
+  for (const r of results) {
+    if (r) {
+      series.push(guessFieldTypes(toSeriesData(r)));
+    }
+  }
+
+  return series;
+}

public/app/plugins/datasource/testdata/StreamHandler.ts

@@ -0,0 +1,400 @@
+import defaults from 'lodash/defaults';
+import {
+  DataQueryRequest,
+  FieldType,
+  SeriesData,
+  DataQueryResponse,
+  DataQueryError,
+  DataStreamObserver,
+  DataStreamState,
+  LoadingState,
+} from '@grafana/ui';
+import { TestDataQuery, StreamingQuery } from './types';
+
+export const defaultQuery: StreamingQuery = {
+  type: 'signal',
+  speed: 250, // ms
+  spread: 3.5,
+  noise: 2.2,
+};
+
+type StreamWorkers = {
+  [key: string]: StreamWorker;
+};
+
+export class StreamHandler {
+  workers: StreamWorkers = {};
+
+  process(req: DataQueryRequest<TestDataQuery>, observer: DataStreamObserver): DataQueryResponse | undefined {
+    let resp: DataQueryResponse;
+
+    for (const query of req.targets) {
+      if ('streaming_client' !== query.scenarioId) {
+        continue;
+      }
+
+      if (!resp) {
+        resp = { data: [] };
+      }
+
+      // set stream option defaults
+      query.stream = defaults(query.stream, defaultQuery);
+      // create stream key
+      const key = req.dashboardId + '/' + req.panelId + '/' + query.refId;
+
+      if (this.workers[key]) {
+        const existing = this.workers[key];
+        if (existing.update(query, req)) {
+          continue;
+        }
+        existing.unsubscribe();
+        delete this.workers[key];
+      }
+
+      const type = query.stream.type;
+      if (type === 'signal') {
+        this.workers[key] = new SignalWorker(key, query, req, observer);
+      } else if (type === 'logs') {
+        this.workers[key] = new LogsWorker(key, query, req, observer);
+      } else {
+        throw {
+          message: 'Unknown Stream type: ' + type,
+          refId: query.refId,
+        } as DataQueryError;
+      }
+    }
+    return resp;
+  }
+}
+
+/**
+ * Manages a single stream request
+ */
+export class StreamWorker {
+  query: StreamingQuery;
+  stream: DataStreamState;
+  observer: DataStreamObserver;
+  last = -1;
+  timeoutId = 0;
+
+  constructor(key: string, query: TestDataQuery, request: DataQueryRequest, observer: DataStreamObserver) {
+    this.stream = {
+      key,
+      state: LoadingState.Streaming,
+      request,
+      unsubscribe: this.unsubscribe,
+    };
+    this.query = query.stream;
+    this.last = Date.now();
+    this.observer = observer;
+    console.log('Creating Test Stream: ', this);
+  }
+
+  unsubscribe = () => {
+    this.observer = null;
+    if (this.timeoutId) {
+      clearTimeout(this.timeoutId);
+      this.timeoutId = 0;
+    }
+  };
+
+  update(query: TestDataQuery, request: DataQueryRequest): boolean {
+    // Check if stream has been unsubscribed or query changed type
+    if (this.observer === null || this.query.type !== query.stream.type) {
+      return false;
+    }
+    this.query = query.stream;
+    this.stream.request = request; // OK?
+    console.log('Reuse Test Stream: ', this);
+    return true;
+  }
+
+  appendRows(append: any[][]) {
+    // Trim the maximum row count
+    const { query, stream } = this;
+    const maxRows = query.buffer ? query.buffer : stream.request.maxDataPoints;
+
+    // Edit the first series
+    const series = stream.series[0];
+    let rows = series.rows.concat(append);
+    const extra = maxRows - rows.length;
+    if (extra < 0) {
+      rows = rows.slice(extra * -1);
+    }
+    series.rows = rows;
+
+    // Tell the event about only the rows that changed (it may want to process them)
+    stream.delta = [{ ...series, rows: append }];
+
+    // Broadcast the changes
+    if (this.observer) {
+      this.observer(stream);
+    } else {
+      console.log('StreamWorker working without any observer');
+    }
+
+    this.last = Date.now();
+  }
+}
+
+export class SignalWorker extends StreamWorker {
+  value: number;
+
+  constructor(key: string, query: TestDataQuery, request: DataQueryRequest, observer: DataStreamObserver) {
+    super(key, query, request, observer);
+    setTimeout(() => {
+      this.stream.series = [this.initBuffer(query.refId)];
+      this.looper();
+    }, 10);
+  }
+
+  nextRow = (time: number) => {
+    const { spread, noise } = this.query;
+    this.value += (Math.random() - 0.5) * spread;
+    return [
+      time,
+      this.value, // Value
+      this.value - Math.random() * noise, // MIN
+      this.value + Math.random() * noise, // MAX
+    ];
+  };
+
+  initBuffer(refId: string): SeriesData {
+    const { speed, buffer } = this.query;
+    const data = {
+      fields: [
+        { name: 'Time', type: FieldType.time },
+        { name: 'Value', type: FieldType.number },
+        { name: 'Min', type: FieldType.number },
+        { name: 'Max', type: FieldType.number },
+      ],
+      rows: [],
+      refId,
+      name: 'Signal ' + refId,
+    } as SeriesData;
+
+    const request = this.stream.request;
+
+    this.value = Math.random() * 100;
+    const maxRows = buffer ? buffer : request.maxDataPoints;
+    let time = Date.now() - maxRows * speed;
+    for (let i = 0; i < maxRows; i++) {
+      data.rows.push(this.nextRow(time));
+      time += speed;
+    }
+    return data;
+  }
+
+  looper = () => {
+    if (!this.observer) {
+      const request = this.stream.request;
+      const elapsed = request.startTime - Date.now();
+      if (elapsed > 1000) {
+        console.log('Stop looping');
+        return;
+      }
+    }
+
+    // Make sure it has a minimum speed
+    const { query } = this;
+    if (query.speed < 5) {
+      query.speed = 5;
+    }
+
+    this.appendRows([this.nextRow(Date.now())]);
+    this.timeoutId = window.setTimeout(this.looper, query.speed);
+  };
+}
+
+export class LogsWorker extends StreamWorker {
+  index = 0;
+
+  constructor(key: string, query: TestDataQuery, request: DataQueryRequest, observer: DataStreamObserver) {
+    super(key, query, request, observer);
+
+    window.setTimeout(() => {
+      this.stream.series = [this.initBuffer(query.refId)];
+      this.looper();
+    }, 10);
+  }
+
+  getNextWord() {
+    this.index = (this.index + Math.floor(Math.random() * 5)) % words.length;
+    return words[this.index];
+  }
+
+  getRandomLine() {
+    let line = this.getNextWord();
+    while (line.length < 80) {
+      line += ' ' + this.getNextWord();
+    }
+    return line;
+  }
+
+  nextRow = (time: number) => {
+    return [time, this.getRandomLine()];
+  };
+
+  initBuffer(refId: string): SeriesData {
+    const { speed, buffer } = this.query;
+    const data = {
+      fields: [{ name: 'Time', type: FieldType.time }, { name: 'Line', type: FieldType.string }],
+      rows: [],
+      refId,
+      name: 'Logs ' + refId,
+    } as SeriesData;
+
+    const request = this.stream.request;
+
+    const maxRows = buffer ? buffer : request.maxDataPoints;
+    let time = Date.now() - maxRows * speed;
+    for (let i = 0; i < maxRows; i++) {
+      data.rows.push(this.nextRow(time));
+      time += speed;
+    }
+    return data;
+  }
+
+  looper = () => {
+    if (!this.observer) {
+      const request = this.stream.request;
+      const elapsed = request.startTime - Date.now();
+      if (elapsed > 1000) {
+        console.log('Stop looping');
+        return;
+      }
+    }
+
+    // Make sure it has a minimum speed
+    const { query } = this;
+    if (query.speed < 5) {
+      query.speed = 5;
+    }
+
+    this.appendRows([this.nextRow(Date.now())]);
+    this.timeoutId = window.setTimeout(this.looper, query.speed);
+  };
+}
+
+const words = [
+  'At',
+  'vero',
+  'eos',
+  'et',
+  'accusamus',
+  'et',
+  'iusto',
+  'odio',
+  'dignissimos',
+  'ducimus',
+  'qui',
+  'blanditiis',
+  'praesentium',
+  'voluptatum',
+  'deleniti',
+  'atque',
+  'corrupti',
+  'quos',
+  'dolores',
+  'et',
+  'quas',
+  'molestias',
+  'excepturi',
+  'sint',
+  'occaecati',
+  'cupiditate',
+  'non',
+  'provident',
+  'similique',
+  'sunt',
+  'in',
+  'culpa',
+  'qui',
+  'officia',
+  'deserunt',
+  'mollitia',
+  'animi',
+  'id',
+  'est',
+  'laborum',
+  'et',
+  'dolorum',
+  'fuga',
+  'Et',
+  'harum',
+  'quidem',
+  'rerum',
+  'facilis',
+  'est',
+  'et',
+  'expedita',
+  'distinctio',
+  'Nam',
+  'libero',
+  'tempore',
+  'cum',
+  'soluta',
+  'nobis',
+  'est',
+  'eligendi',
+  'optio',
+  'cumque',
+  'nihil',
+  'impedit',
+  'quo',
+  'minus',
+  'id',
+  'quod',
+  'maxime',
+  'placeat',
+  'facere',
+  'possimus',
+  'omnis',
+  'voluptas',
+  'assumenda',
+  'est',
+  'omnis',
+  'dolor',
+  'repellendus',
+  'Temporibus',
+  'autem',
+  'quibusdam',
+  'et',
+  'aut',
+  'officiis',
+  'debitis',
+  'aut',
+  'rerum',
+  'necessitatibus',
+  'saepe',
+  'eveniet',
+  'ut',
+  'et',
+  'voluptates',
+  'repudiandae',
+  'sint',
+  'et',
+  'molestiae',
+  'non',
+  'recusandae',
+  'Itaque',
+  'earum',
+  'rerum',
+  'hic',
+  'tenetur',
+  'a',
+  'sapiente',
+  'delectus',
+  'ut',
+  'aut',
+  'reiciendis',
+  'voluptatibus',
+  'maiores',
+  'alias',
+  'consequatur',
+  'aut',
+  'perferendis',
+  'doloribus',
+  'asperiores',
+  'repellat',
+];

public/app/plugins/datasource/testdata/datasource.ts

@@ -1,6 +1,15 @@
 import _ from 'lodash';
-import { DataSourceApi, DataQueryRequest, TableData, TimeSeries } from '@grafana/ui';
+import {
+  DataSourceApi,
+  DataQueryRequest,
+  TableData,
+  TimeSeries,
+  DataSourceInstanceSettings,
+  DataStreamObserver,
+} from '@grafana/ui';
 import { TestDataQuery, Scenario } from './types';
+import { getBackendSrv } from 'app/core/services/backend_srv';
+import { StreamHandler } from './StreamHandler';
 
 type TestData = TimeSeries | TableData;
 
@@ -10,16 +19,15 @@ export interface TestDataRegistry {
 
 export class TestDataDatasource implements DataSourceApi<TestDataQuery> {
   id: number;
+  streams = new StreamHandler();
 
   /** @ngInject */
-  constructor(instanceSettings, private backendSrv, private $q) {
+  constructor(instanceSettings: DataSourceInstanceSettings) {
     this.id = instanceSettings.id;
   }
 
-  query(options: DataQueryRequest<TestDataQuery>) {
-    const queries = _.filter(options.targets, item => {
-      return item.hide !== true;
-    }).map(item => {
+  query(options: DataQueryRequest<TestDataQuery>, observer: DataStreamObserver) {
+    const queries = options.targets.map(item => {
       return {
         refId: item.refId,
         scenarioId: item.scenarioId,
@@ -33,10 +41,16 @@ export class TestDataDatasource implements DataSourceApi<TestDataQuery> {
     });
 
     if (queries.length === 0) {
-      return this.$q.when({ data: [] });
+      return Promise.resolve({ data: [] });
     }
 
-    return this.backendSrv
+    // Currently we do not support mixed with client only streaming
+    const resp = this.streams.process(options, observer);
+    if (resp) {
+      return Promise.resolve(resp);
+    }
+
+    return getBackendSrv()
       .datasourceRequest({
         method: 'POST',
         url: '/api/tsdb/query',
@@ -76,7 +90,7 @@ export class TestDataDatasource implements DataSourceApi<TestDataQuery> {
       });
   }
 
-  annotationQuery(options) {
+  annotationQuery(options: any) {
     let timeWalker = options.range.from.valueOf();
     const to = options.range.to.valueOf();
     const events = [];
@@ -92,7 +106,7 @@ export class TestDataDatasource implements DataSourceApi<TestDataQuery> {
       });
       timeWalker += step;
     }
-    return this.$q.when(events);
+    return Promise.resolve(events);
   }
 
   getQueryDisplayText(query: TestDataQuery) {
@@ -110,6 +124,6 @@ export class TestDataDatasource implements DataSourceApi<TestDataQuery> {
   }
 
   getScenarios(): Promise<Scenario[]> {
-    return this.backendSrv.get('/api/tsdb/testdata/scenarios');
+    return getBackendSrv().get('/api/tsdb/testdata/scenarios');
   }
 }

public/app/plugins/datasource/testdata/partials/query.editor.html

@@ -36,4 +36,50 @@
 			<div class="gf-form-label gf-form-label--grow"></div>
 		</div>
 	</div>
+	<div class="gf-form-inline" ng-if="ctrl.scenario.id === 'streaming_client'">
+		<div class="gf-form gf-form">
+			<label class="gf-form-label query-keyword width-7">Type</label>
+			<div class="gf-form-select-wrapper">
+				<select 
+				  ng-model="ctrl.target.stream.type" 
+				  class="gf-form-input"
+					ng-options="type for type in ['signal','logs']"
+				  ng-change="ctrl.streamChanged()" />
+				</select>
+			</div>
+		</div>
+		<div class="gf-form">
+			<label class="gf-form-label query-keyword">Speed (ms)</label>
+			<input type="number" 
+				class="gf-form-input width-5" 
+				placeholder="value" 
+				ng-model="ctrl.target.stream.speed" 
+				min="10"
+				step="10"
+				ng-change="ctrl.streamChanged()" />
+		</div>
+		<div class="gf-form">
+			<label class="gf-form-label query-keyword">Spread</label>
+			<input type="number" 
+				class="gf-form-input width-5" 
+				placeholder="value" 
+				ng-model="ctrl.target.stream.spread" 
+				min="0.5"
+				step="0.1"
+				ng-change="ctrl.streamChanged()" />
+		</div>
+		<div class="gf-form">
+			<label class="gf-form-label query-keyword">Noise</label>
+			<input type="number" 
+				class="gf-form-input width-5" 
+				placeholder="value" 
+				ng-model="ctrl.target.stream.noise" 
+				min="0"
+				step="0.1"
+				ng-change="ctrl.streamChanged()" />
+		</div>
+		<div class="gf-form gf-form--grow">
+			<div class="gf-form-label gf-form-label--grow"></div>
+		</div>
+	</div>
 </query-editor-row>

public/app/plugins/datasource/testdata/query_ctrl.ts

@@ -2,6 +2,8 @@ import _ from 'lodash';
 
 import { QueryCtrl } from 'app/plugins/sdk';
 import moment from 'moment';
+import { defaultQuery } from './StreamHandler';
+import { getBackendSrv } from 'app/core/services/backend_srv';
 
 export class TestDataQueryCtrl extends QueryCtrl {
   static templateUrl = 'partials/query.editor.html';
@@ -13,7 +15,7 @@ export class TestDataQueryCtrl extends QueryCtrl {
   selectedPoint: any;
 
   /** @ngInject */
-  constructor($scope, $injector, private backendSrv) {
+  constructor($scope: any, $injector: any) {
     super($scope, $injector);
 
     this.target.scenarioId = this.target.scenarioId || 'random_walk';
@@ -49,10 +51,12 @@ export class TestDataQueryCtrl extends QueryCtrl {
   }
 
   $onInit() {
-    return this.backendSrv.get('/api/tsdb/testdata/scenarios').then(res => {
-      this.scenarioList = res;
-      this.scenario = _.find(this.scenarioList, { id: this.target.scenarioId });
-    });
+    return getBackendSrv()
+      .get('/api/tsdb/testdata/scenarios')
+      .then(res => {
+        this.scenarioList = res;
+        this.scenario = _.find(this.scenarioList, { id: this.target.scenarioId });
+      });
   }
 
   scenarioChanged() {
@@ -65,6 +69,16 @@ export class TestDataQueryCtrl extends QueryCtrl {
       delete this.target.points;
     }
 
+    if (this.target.scenarioId === 'streaming_client') {
+      this.target.stream = _.defaults(this.target.stream || {}, defaultQuery);
+    } else {
+      delete this.target.stream;
+    }
+
+    this.refresh();
+  }
+
+  streamChanged() {
     this.refresh();
   }
 }

public/app/plugins/datasource/testdata/types.ts

@@ -1,13 +1,22 @@
 import { DataQuery } from '@grafana/ui/src/types';
 
+export interface Scenario {
+  id: string;
+  name: string;
+}
+
 export interface TestDataQuery extends DataQuery {
   alias?: string;
   scenarioId: string;
   stringInput: string;
-  points: any;
+  points?: any[];
+  stream?: StreamingQuery;
 }
 
-export interface Scenario {
-  id: string;
-  name: string;
+export interface StreamingQuery {
+  type: 'signal' | 'logs';
+  speed: number;
+  spread: number;
+  noise: number; // wiggle around the signal for min/max
+  buffer?: number;
 }