React ui add query stats (#6190)

* Adds the query stats to UI

Adds the query load time, resolution and total number of time series,
as the current UI has

Signed-off-by: cstdev <pietomb00@hotmail.com>

* Implement unit test for QueryStats

Signed-off-by: cstdev <pietomb00@hotmail.com>

* Tidy Query Stats component

Rename it and expose a interface for the values it displays
Make it a functional component as it has no state or lifecycle
Better null/undefined checks
Only render if needed, decided by the panel
Remove old stats if the next errors

Signed-off-by: cstdev <pietomb00@hotmail.com>

web/ui/react-app/src/Panel.tsx

@@ -19,6 +19,7 @@ import GraphControls from './GraphControls';
 import Graph from './Graph';
 import DataTable from './DataTable';
 import TimeInput from './TimeInput';
+import QueryStatsView, { QueryStats } from './QueryStatsView';
 
 interface PanelProps {
   options: PanelOptions;
@@ -36,7 +37,7 @@ interface PanelState {
   } | null;
   loading: boolean;
   error: string | null;
-  stats: null; // TODO: Stats.
+  stats: QueryStats | null,
 }
 
 export interface PanelOptions {
@@ -100,6 +101,7 @@ class Panel extends Component<PanelProps, PanelState> {
   }
 
   executeQuery = (expr: string): void => {
+    const queryStart = Date.now();
     if (this.props.options.expr !== expr) {
       this.setOptions({expr: expr});
     }
@@ -119,7 +121,6 @@ class Panel extends Component<PanelProps, PanelState> {
     const endTime = this.getEndTime().valueOf() / 1000; // TODO: shouldn't valueof only work when it's a moment?
     const startTime = endTime - this.props.options.range;
     const resolution = this.props.options.resolution || Math.max(Math.floor(this.props.options.range / 250), 1);
-
     const url = new URL(window.location.href);
     const params: {[key: string]: string} = {
       'query': expr,
@@ -153,14 +154,29 @@ class Panel extends Component<PanelProps, PanelState> {
         throw new Error(json.error || 'invalid response JSON');
       }
 
+      let resultSeries = 0;
+      if (json.data) {
+        const { resultType, result } = json.data;
+        if (resultType === "scalar") {
+          resultSeries = 1;
+        } else if (result && result.length > 0) {
+          resultSeries = result.length;
+        }
+      }
+
       this.setState({
         error: null,
         data: json.data,
         lastQueryParams: {
-          startTime: startTime,
-          endTime: endTime,
-          resolution: resolution,
+          startTime,
+          endTime,
+          resolution,
         },
+        stats: {
+          loadTime: Date.now() - queryStart,
+          resolution,
+          resultSeries
+      },
         loading: false,
       });
       this.abortInFlightFetch = null;
@@ -246,6 +262,10 @@ class Panel extends Component<PanelProps, PanelState> {
                   Graph
                 </NavLink>
               </NavItem>
+              {
+                (!this.state.loading && !this.state.error && this.state.stats) && 
+                <QueryStatsView {...this.state.stats} />
+              }
             </Nav>
             <TabContent activeTab={this.props.options.type}>
               <TabPane tabId="table">

web/ui/react-app/src/QueryStatsView.css

@@ -0,0 +1,5 @@
+.query-stats{
+    flex-grow: 1;
+    font-size: 9px;
+    color: #999;
+}

web/ui/react-app/src/QueryStatsView.tsx

@@ -0,0 +1,20 @@
+import React, { FC } from 'react';
+import './QueryStatsView.css';
+
+export interface QueryStats {
+    loadTime: number;
+    resolution: number;
+    resultSeries: number;
+}
+
+const QueryStatsView: FC<QueryStats> = props => {
+    const {loadTime, resolution, resultSeries} = props;
+
+    return (
+        <div className="query-stats">
+            <span className="float-right">Load time: {loadTime}ms &ensp; Resolution: {resolution}s &ensp; Result series: {resultSeries}</span>
+        </div>
+    );
+}
+
+export default QueryStatsView;