From 91c2b00bab28523980a942a8b3b82deedd98451d Mon Sep 17 00:00:00 2001
From: Henning Dieterichs <hdieterichs@microsoft.com>
Date: Mon, 13 Nov 2023 12:23:58 +0100
Subject: [PATCH] Caches view model on input.

---
 .../browser/multiDiffEditor.ts                | 37 +++++--------------
 .../browser/multiDiffEditorInput.ts           | 35 +++++++++++++++++-
 2 files changed, 44 insertions(+), 28 deletions(-)

diff --git a/src/vs/workbench/contrib/multiDiffEditor/browser/multiDiffEditor.ts b/src/vs/workbench/contrib/multiDiffEditor/browser/multiDiffEditor.ts
index 6ca92292e4c8c..c30446f92f0a9 100644
--- a/src/vs/workbench/contrib/multiDiffEditor/browser/multiDiffEditor.ts
+++ b/src/vs/workbench/contrib/multiDiffEditor/browser/multiDiffEditor.ts
@@ -4,20 +4,17 @@
  *--------------------------------------------------------------------------------------------*/
 
 import * as DOM from 'vs/base/browser/dom';
-import { EditorPane } from 'vs/workbench/browser/parts/editor/editorPane';
-import { IEditorOpenContext } from 'vs/workbench/common/editor';
-import { ITelemetryService } from 'vs/platform/telemetry/common/telemetry';
-import { IThemeService } from 'vs/platform/theme/common/themeService';
-import { IStorageService } from 'vs/platform/storage/common/storage';
-import { InstantiationService } from 'vs/platform/instantiation/common/instantiationService';
-import { IInstantiationService } from 'vs/platform/instantiation/common/instantiation';
 import { CancellationToken } from 'vs/base/common/cancellation';
+import { MultiDiffEditorWidget } from 'vs/editor/browser/widget/multiDiffEditorWidget/multiDiffEditorWidget';
 import { IEditorOptions } from 'vs/platform/editor/common/editor';
-import { ITextModelService } from 'vs/editor/common/services/resolverService';
+import { IInstantiationService } from 'vs/platform/instantiation/common/instantiation';
+import { InstantiationService } from 'vs/platform/instantiation/common/instantiationService';
+import { IStorageService } from 'vs/platform/storage/common/storage';
+import { ITelemetryService } from 'vs/platform/telemetry/common/telemetry';
+import { IThemeService } from 'vs/platform/theme/common/themeService';
+import { EditorPane } from 'vs/workbench/browser/parts/editor/editorPane';
+import { IEditorOpenContext } from 'vs/workbench/common/editor';
 import { MultiDiffEditorInput } from 'vs/workbench/contrib/multiDiffEditor/browser/multiDiffEditorInput';
-import { MultiDiffEditorWidget } from 'vs/editor/browser/widget/multiDiffEditorWidget/multiDiffEditorWidget';
-import { toDisposable } from 'vs/base/common/lifecycle';
-import { ConstLazyPromise, IDiffEntry } from 'vs/editor/browser/widget/multiDiffEditorWidget/model';
 
 export class MultiDiffEditor extends EditorPane {
 	static readonly ID = 'multiDiffEditor';
@@ -27,7 +24,6 @@ export class MultiDiffEditor extends EditorPane {
 	constructor(
 		@IInstantiationService private readonly instantiationService: InstantiationService,
 		@ITelemetryService telemetryService: ITelemetryService,
-		@ITextModelService private readonly textModelService: ITextModelService,
 		@IThemeService themeService: IThemeService,
 		@IStorageService storageService: IStorageService
 	) {
@@ -40,21 +36,8 @@ export class MultiDiffEditor extends EditorPane {
 
 	override async setInput(input: MultiDiffEditorInput, options: IEditorOptions | undefined, context: IEditorOpenContext, token: CancellationToken): Promise<void> {
 		await super.setInput(input, options, context, token);
-
-		const rs = await Promise.all(input.resources.map(async r => ({
-			originalRef: await this.textModelService.createModelReference(r.original!),
-			modifiedRef: await this.textModelService.createModelReference(r.modified!),
-			title: r.resource.fsPath,
-		})));
-
-		this._multiDiffEditorWidget?.setModel({
-			onDidChange: () => toDisposable(() => { }),
-			diffs: rs.map(r => new ConstLazyPromise<IDiffEntry>({
-				original: r.originalRef.object.textEditorModel,
-				modified: r.modifiedRef.object.textEditorModel,
-				title: r.title,
-			})),
-		});
+		const vm = await input.getViewModel();
+		this._multiDiffEditorWidget?.setModel(vm);
 	}
 
 	layout(dimension: DOM.Dimension): void {
diff --git a/src/vs/workbench/contrib/multiDiffEditor/browser/multiDiffEditorInput.ts b/src/vs/workbench/contrib/multiDiffEditor/browser/multiDiffEditorInput.ts
index 59b39f6e7143f..dd4365ba554c0 100644
--- a/src/vs/workbench/contrib/multiDiffEditor/browser/multiDiffEditorInput.ts
+++ b/src/vs/workbench/contrib/multiDiffEditor/browser/multiDiffEditorInput.ts
@@ -7,6 +7,9 @@ import { localize } from 'vs/nls';
 import { URI } from 'vs/base/common/uri';
 import { DEFAULT_EDITOR_ASSOCIATION, EditorInputCapabilities } from 'vs/workbench/common/editor';
 import { EditorInput } from 'vs/workbench/common/editor/editorInput';
+import { ConstLazyPromise, IDiffEntry, IMultiDocumentDiffEditorModel } from 'vs/editor/browser/widget/multiDiffEditorWidget/model';
+import { ITextModelService } from 'vs/editor/common/services/resolverService';
+import { toDisposable } from 'vs/base/common/lifecycle';
 
 export class MultiDiffEditorInput extends EditorInput {
 	static readonly ID: string = 'workbench.input.multiDiffEditor';
@@ -31,9 +34,39 @@ export class MultiDiffEditorInput extends EditorInput {
 		return DEFAULT_EDITOR_ASSOCIATION.id;
 	}
 
-	constructor(readonly label: string | undefined, readonly resources: readonly MultiDiffEditorInputData[]) {
+	private _viewModel: IMultiDocumentDiffEditorModel | undefined;
+
+	constructor(
+		readonly label: string | undefined,
+		readonly resources: readonly MultiDiffEditorInputData[],
+		@ITextModelService private readonly _textModelService: ITextModelService,
+	) {
 		super();
 	}
+
+	async getViewModel(): Promise<IMultiDocumentDiffEditorModel> {
+		if (!this._viewModel) {
+			this._viewModel = await this._createViewModel();
+		}
+		return this._viewModel;
+	}
+
+	private async _createViewModel(): Promise<IMultiDocumentDiffEditorModel> {
+		const rs = await Promise.all(this.resources.map(async r => ({
+			originalRef: await this._textModelService.createModelReference(r.original!),
+			modifiedRef: await this._textModelService.createModelReference(r.modified!),
+			title: r.resource.fsPath,
+		})));
+
+		return {
+			onDidChange: () => toDisposable(() => { }),
+			diffs: rs.map(r => new ConstLazyPromise<IDiffEntry>({
+				original: r.originalRef.object.textEditorModel,
+				modified: r.modifiedRef.object.textEditorModel,
+				title: r.title,
+			})),
+		};
+	}
 }
 
 export class MultiDiffEditorInputData {