perf - avoid IdleValue for a feature that is not enabled by default (microsoft#159469)

Author: bpasero

src/vs/workbench/contrib/localHistory/browser/localHistory.ts

@@ -8,22 +8,31 @@ import { Codicon } from 'vs/base/common/codicons';
 import { language } from 'vs/base/common/platform';
 import { ContextKeyExpr } from 'vs/platform/contextkey/common/contextkey';
 import { registerIcon } from 'vs/platform/theme/common/iconRegistry';
-import { IdleValue } from 'vs/base/common/async';
 
-export const LOCAL_HISTORY_DATE_FORMATTER: IdleValue<{ format: (timestamp: number) => string }> = new IdleValue(() => {
-	const options: Intl.DateTimeFormatOptions = { year: 'numeric', month: 'long', day: 'numeric', hour: 'numeric', minute: 'numeric' };
+interface ILocalHistoryDateFormatter {
+	format: (timestamp: number) => string;
+}
 
-	let formatter: Intl.DateTimeFormat;
-	try {
-		formatter = new Intl.DateTimeFormat(language, options);
-	} catch (error) {
-		formatter = new Intl.DateTimeFormat(undefined, options); // error can happen when language is invalid (https://github.com/microsoft/vscode/issues/147086)
+let localHistoryDateFormatter: ILocalHistoryDateFormatter | undefined = undefined;
+
+export function getLocalHistoryDateFormatter(): ILocalHistoryDateFormatter {
+	if (!localHistoryDateFormatter) {
+		const options: Intl.DateTimeFormatOptions = { year: 'numeric', month: 'long', day: 'numeric', hour: 'numeric', minute: 'numeric' };
+
+		let formatter: Intl.DateTimeFormat;
+		try {
+			formatter = new Intl.DateTimeFormat(language, options);
+		} catch (error) {
+			formatter = new Intl.DateTimeFormat(undefined, options); // error can happen when language is invalid (https://github.com/microsoft/vscode/issues/147086)
+		}
+
+		localHistoryDateFormatter = {
+			format: date => formatter.format(date)
+		};
 	}
 
-	return {
-		format: date => formatter.format(date)
-	};
-});
+	return localHistoryDateFormatter;
+}
 
 export const LOCAL_HISTORY_MENU_CONTEXT_VALUE = 'localHistory:item';
 export const LOCAL_HISTORY_MENU_CONTEXT_KEY = ContextKeyExpr.equals('timelineItem', LOCAL_HISTORY_MENU_CONTEXT_VALUE);

src/vs/workbench/contrib/localHistory/browser/localHistoryCommands.ts

@@ -30,7 +30,7 @@ import { IModelService } from 'vs/editor/common/services/model';
 import { ILanguageService } from 'vs/editor/common/languages/language';
 import { ILabelService } from 'vs/platform/label/common/label';
 import { firstOrDefault } from 'vs/base/common/arrays';
-import { LOCAL_HISTORY_DATE_FORMATTER, LOCAL_HISTORY_ICON_RESTORE, LOCAL_HISTORY_MENU_CONTEXT_KEY } from 'vs/workbench/contrib/localHistory/browser/localHistory';
+import { getLocalHistoryDateFormatter, LOCAL_HISTORY_ICON_RESTORE, LOCAL_HISTORY_MENU_CONTEXT_KEY } from 'vs/workbench/contrib/localHistory/browser/localHistory';
 import { IPathService } from 'vs/workbench/services/path/common/pathService';
 
 const LOCAL_HISTORY_CATEGORY = { value: localize('localHistory.category', "Local History"), original: 'Local History' };
@@ -646,7 +646,7 @@ export async function findLocalHistoryEntry(workingCopyHistoryService: IWorkingC
 
 const SEP = /\//g;
 function toLocalHistoryEntryDateLabel(timestamp: number): string {
-	return `${LOCAL_HISTORY_DATE_FORMATTER.value.format(timestamp).replace(SEP, '-')}`; // preserving `/` will break editor labels, so replace it with a non-path symbol
+	return `${getLocalHistoryDateFormatter().format(timestamp).replace(SEP, '-')}`; // preserving `/` will break editor labels, so replace it with a non-path symbol
 }
 
 //#endregion

src/vs/workbench/contrib/localHistory/browser/localHistoryTimeline.ts

@@ -20,7 +20,7 @@ import { SaveSourceRegistry } from 'vs/workbench/common/editor';
 import { IConfigurationService } from 'vs/platform/configuration/common/configuration';
 import { COMPARE_WITH_FILE_LABEL, toDiffEditorArguments } from 'vs/workbench/contrib/localHistory/browser/localHistoryCommands';
 import { MarkdownString } from 'vs/base/common/htmlContent';
-import { LOCAL_HISTORY_DATE_FORMATTER, LOCAL_HISTORY_ICON_ENTRY, LOCAL_HISTORY_MENU_CONTEXT_VALUE } from 'vs/workbench/contrib/localHistory/browser/localHistory';
+import { getLocalHistoryDateFormatter, LOCAL_HISTORY_ICON_ENTRY, LOCAL_HISTORY_MENU_CONTEXT_VALUE } from 'vs/workbench/contrib/localHistory/browser/localHistory';
 import { Schemas } from 'vs/base/common/network';
 import { IWorkspaceContextService } from 'vs/platform/workspace/common/workspace';
 import { getVirtualWorkspaceAuthority } from 'vs/platform/workspace/common/virtualWorkspace';
@@ -151,7 +151,7 @@ export class LocalHistoryTimeline extends Disposable implements IWorkbenchContri
 		return {
 			handle: entry.id,
 			label: SaveSourceRegistry.getSourceLabel(entry.source),
-			tooltip: new MarkdownString(`$(history) ${LOCAL_HISTORY_DATE_FORMATTER.value.format(entry.timestamp)}\n\n${SaveSourceRegistry.getSourceLabel(entry.source)}`, { supportThemeIcons: true }),
+			tooltip: new MarkdownString(`$(history) ${getLocalHistoryDateFormatter().format(entry.timestamp)}\n\n${SaveSourceRegistry.getSourceLabel(entry.source)}`, { supportThemeIcons: true }),
 			source: LocalHistoryTimeline.ID,
 			timestamp: entry.timestamp,
 			themeIcon: LOCAL_HISTORY_ICON_ENTRY,