[maps] Revert "Revert of fix EMS vector file manifest is loaded in Discover (#190073)

Re-instate https://github.com/elastic/kibana/pull/189550. PR makes one
small clean-up in that getSuggestionsLazy promise will not reject when
modules fail to load.

https://github.com/elastic/kibana/pull/189984 confirmed that [the fix
did](https://github.com/elastic/kibana/pull/189550) had a large impact
on performance.

x-pack/plugins/maps/public/lens/choropleth_chart/region_key_editor.tsx

@@ -5,22 +5,50 @@
  * 2.0.
  */
 
-import React from 'react';
+import React, { useEffect, useMemo, useState } from 'react';
 import { i18n } from '@kbn/i18n';
-import { EuiComboBox, EuiComboBoxOptionOption, EuiFormRow } from '@elastic/eui';
+import { EuiComboBox, EuiComboBoxOptionOption, EuiFormRow, EuiSelect } from '@elastic/eui';
 import type { FileLayer } from '@elastic/ems-client';
 import { ChoroplethChartState } from './types';
 import { EMSFileSelect } from '../../components/ems_file_select';
+import { getEmsFileLayers } from '../../util';
 
 interface Props {
-  emsFileLayers: FileLayer[];
   state: ChoroplethChartState;
   setState: (state: ChoroplethChartState) => void;
 }
 
 export function RegionKeyEditor(props: Props) {
+  const [emsFileLayers, setEmsFileLayers] = useState<FileLayer[]>([]);
+  const [isLoading, setIsLoading] = useState(false);
+
+  useEffect(() => {
+    let ignore = false;
+    setIsLoading(true);
+    getEmsFileLayers()
+      .then((fileLayers) => {
+        if (!ignore) {
+          setEmsFileLayers(fileLayers);
+          setIsLoading(false);
+        }
+      })
+      .catch(() => {
+        if (!ignore) {
+          // eslint-disable-next-line no-console
+          console.warn(
+            `Lens region map is unable to access administrative boundaries from Elastic Maps Service (EMS). To avoid unnecessary EMS requests, set 'map.includeElasticMapsService: false' in 'kibana.yml'.`
+          );
+          setIsLoading(false);
+        }
+      });
+
+    return () => {
+      ignore = true;
+    };
+  }, []);
+
   function onEmsLayerSelect(emsLayerId: string) {
-    const emsFields = getEmsFields(props.emsFileLayers, emsLayerId);
+    const emsFields = getEmsFields(emsFileLayers, emsLayerId);
     props.setState({
       ...props.state,
       emsLayerId,
@@ -28,27 +56,30 @@ export function RegionKeyEditor(props: Props) {
     });
   }
 
-  function onEmsFieldSelect(selectedOptions: Array<EuiComboBoxOptionOption<string>>) {
-    if (selectedOptions.length === 0) {
-      return;
+  const emsFieldSelect = useMemo(() => {
+    const emsFields = getEmsFields(emsFileLayers, props.state.emsLayerId);
+    if (emsFields.length === 0) {
+      return null;
     }
 
-    props.setState({
-      ...props.state,
-      emsField: selectedOptions[0].value,
-    });
-  }
+    const selectedOption = props.state.emsField
+      ? emsFields.find((option: EuiComboBoxOptionOption<string>) => {
+          return props.state.emsField === option.value;
+        })
+      : undefined;
 
-  let emsFieldSelect;
-  const emsFields = getEmsFields(props.emsFileLayers, props.state.emsLayerId);
-  if (emsFields.length) {
-    let selectedOption;
-    if (props.state.emsField) {
-      selectedOption = emsFields.find((option: EuiComboBoxOptionOption<string>) => {
-        return props.state.emsField === option.value;
+    function onEmsFieldSelect(selectedOptions: Array<EuiComboBoxOptionOption<string>>) {
+      if (selectedOptions.length === 0) {
+        return;
+      }
+
+      props.setState({
+        ...props.state,
+        emsField: selectedOptions[0].value,
       });
     }
-    emsFieldSelect = (
+
+    return (
       <EuiFormRow
         label={i18n.translate('xpack.maps.choropleth.joinFieldLabel', {
           defaultMessage: 'Join field',
@@ -64,8 +95,11 @@ export function RegionKeyEditor(props: Props) {
         />
       </EuiFormRow>
     );
-  }
-  return (
+  }, [emsFileLayers, props]);
+
+  return isLoading ? (
+    <EuiSelect isLoading />
+  ) : (
     <>
       <EMSFileSelect
         isColumnCompressed

x-pack/plugins/maps/public/lens/choropleth_chart/setup.ts

@@ -8,7 +8,6 @@
 import type { ExpressionsSetup } from '@kbn/expressions-plugin/public';
 import type { CoreSetup, CoreStart } from '@kbn/core/public';
 import type { LensPublicSetup } from '@kbn/lens-plugin/public';
-import type { FileLayer } from '@elastic/ems-client';
 import type { MapsPluginStartDependencies } from '../../plugin';
 import { getExpressionFunction } from './expression_function';
 import { getExpressionRenderer } from './expression_renderer';
@@ -27,22 +26,10 @@ export function setupLensChoroplethChart(
   lens.registerVisualization(async () => {
     const [coreStart, plugins]: [CoreStart, MapsPluginStartDependencies, unknown] =
       await coreSetup.getStartServices();
-    const { getEmsFileLayers } = await import('../../util');
     const { getVisualization } = await import('./visualization');
 
-    let emsFileLayers: FileLayer[] = [];
-    try {
-      emsFileLayers = await getEmsFileLayers();
-    } catch (error) {
-      // eslint-disable-next-line no-console
-      console.warn(
-        `Lens region map setup is unable to access administrative boundaries from Elastic Maps Service (EMS). To avoid unnecessary EMS requests, set 'map.includeElasticMapsService: false' in 'kibana.yml'. For more details please visit ${coreStart.docLinks.links.maps.connectToEms}`
-      );
-    }
-
     return getVisualization({
       theme: coreStart.theme,
-      emsFileLayers,
       paletteService: await plugins.charts.palettes.getPalettes(),
     });
   });

x-pack/plugins/maps/public/lens/choropleth_chart/suggestions_lazy.ts

@@ -0,0 +1,53 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0; you may not use this file except in compliance with the Elastic License
+ * 2.0.
+ */
+
+import type { SuggestionRequest, VisualizationSuggestion } from '@kbn/lens-plugin/public';
+import type { FileLayer } from '@elastic/ems-client';
+import type { ChoroplethChartState } from './types';
+
+let emsFileLayers: FileLayer[] | undefined;
+let getSuggestionsActual:
+  | ((
+      suggestionRequest: SuggestionRequest<ChoroplethChartState>,
+      emsFileLayers: FileLayer[]
+    ) => Array<VisualizationSuggestion<ChoroplethChartState>>)
+  | undefined;
+let promise: undefined | Promise<void>;
+
+/**
+ * Avoid loading file layers during plugin setup
+ * Instead, load file layers when getSuggestions is called
+ * Since getSuggestions is sync, the trade off is that
+ * getSuggestions will return no suggestions until file layers load
+ */
+export function getSuggestionsLazy(
+  suggestionRequest: SuggestionRequest<ChoroplethChartState>
+): Array<VisualizationSuggestion<ChoroplethChartState>> {
+  if (!promise) {
+    promise = new Promise((resolve) => {
+      Promise.all([import('./suggestions'), import('../../util')])
+        .then(async ([{ getSuggestions }, { getEmsFileLayers }]) => {
+          getSuggestionsActual = getSuggestions;
+          try {
+            emsFileLayers = await getEmsFileLayers();
+          } catch (error) {
+            // eslint-disable-next-line no-console
+            console.warn(
+              `Lens region map is unable to access administrative boundaries from Elastic Maps Service (EMS). To avoid unnecessary EMS requests, set 'map.includeElasticMapsService: false' in 'kibana.yml'.`
+            );
+          }
+          resolve();
+        })
+        .catch(resolve);
+    });
+    return [];
+  }
+
+  return emsFileLayers && getSuggestionsActual
+    ? getSuggestionsActual(suggestionRequest, emsFileLayers)
+    : [];
+}

x-pack/plugins/maps/public/lens/choropleth_chart/visualization.tsx

@@ -7,15 +7,14 @@
 
 import React from 'react';
 import { i18n } from '@kbn/i18n';
-import type { FileLayer } from '@elastic/ems-client';
+import { dynamic } from '@kbn/shared-ux-utility';
 import type { PaletteRegistry } from '@kbn/coloring';
 import { ThemeServiceStart } from '@kbn/core/public';
 import { layerTypes } from '@kbn/lens-plugin/public';
 import type { OperationMetadata, SuggestionRequest, Visualization } from '@kbn/lens-plugin/public';
 import { IconRegionMap } from '@kbn/chart-icons';
-import { getSuggestions } from './suggestions';
+import { getSuggestionsLazy } from './suggestions_lazy';
 import type { ChoroplethChartState } from './types';
-import { RegionKeyEditor } from './region_key_editor';
 
 const REGION_KEY_GROUP_ID = 'region_key';
 const METRIC_GROUP_ID = 'metric';
@@ -27,11 +26,9 @@ const CHART_LABEL = i18n.translate('xpack.maps.lens.choropleth.label', {
 export const getVisualization = ({
   paletteService,
   theme,
-  emsFileLayers,
 }: {
   paletteService: PaletteRegistry;
   theme: ThemeServiceStart;
-  emsFileLayers: FileLayer[];
 }): Visualization<ChoroplethChartState> => ({
   id: 'lnsChoropleth',
 
@@ -73,7 +70,7 @@ export const getVisualization = ({
   },
 
   getSuggestions(suggestionRequest: SuggestionRequest<ChoroplethChartState>) {
-    return getSuggestions(suggestionRequest, emsFileLayers);
+    return getSuggestionsLazy(suggestionRequest);
   },
 
   initialize(addNewLayer, state) {
@@ -194,13 +191,13 @@ export const getVisualization = ({
 
   DimensionEditorComponent(props) {
     if (props.groupId === REGION_KEY_GROUP_ID) {
-      return (
-        <RegionKeyEditor
-          emsFileLayers={emsFileLayers}
-          state={props.state}
-          setState={props.setState}
-        />
-      );
+      const DimensionEditor = dynamic(async () => {
+        const { RegionKeyEditor } = await import('./region_key_editor');
+        return {
+          default: RegionKeyEditor,
+        };
+      });
+      return <DimensionEditor state={props.state} setState={props.setState} />;
     }
     return null;
   },