Defers the WorkingCopyService.onDidContentChange event

Previously dealing with working copies was taking about 1.5% of the total
runtime for the keypress function, this reduces it to around 0.2% by
deferring all handling of the event until the text has rendered. Since the
onDidContentChange event is not used, this should be a low risk change.

Part of #161622

src/vs/base/common/event.ts

@@ -53,6 +53,18 @@ export namespace Event {
 		}
 	}
 
+	/**
+	 * Given an event, returns another event which debounces calls and defers the listeners to a
+	 * later task via a shared `setTimeout`. The event is converted into a signal (`Event<void>`) to
+	 * avoid additional object creation as a result of merging events and to try prevent race
+	 * conditions that could arise when using related deferred and non-deferred events.
+	 *
+	 * This is useful for deferring non-critical work (eg. general UI updates) to ensure it does not
+	 * block critical work (eg. latency of keypress to text rendered).
+	 */
+	export function defer(event: Event<unknown>): Event<void> {
+		return debounce<unknown, void>(event, () => void 0, 0);
+	}
 
 	/**
 	 * Given an event, returns another event which only fires once.

src/vs/workbench/api/browser/mainThreadCustomEditors.ts

@@ -437,6 +437,7 @@ class MainThreadCustomEditorModel extends ResourceWorkingCopy implements ICustom
 
 	private readonly _onDidChangeContent: Emitter<void> = this._register(new Emitter<void>());
 	readonly onDidChangeContent: Event<void> = this._onDidChangeContent.event;
+	readonly onDidChangeContentDeferred: Event<void> = Event.defer(this._onDidChangeContent.event);
 
 	private readonly _onDidSave: Emitter<IWorkingCopySaveEvent> = this._register(new Emitter<IWorkingCopySaveEvent>());
 	readonly onDidSave: Event<IWorkingCopySaveEvent> = this._onDidSave.event;

src/vs/workbench/contrib/notebook/common/notebookEditorModel.ts

@@ -91,6 +91,7 @@ export class ComplexNotebookEditorModel extends EditorModel implements INotebook
 			readonly capabilities = that._isUntitled() ? WorkingCopyCapabilities.Untitled : WorkingCopyCapabilities.None;
 			readonly onDidChangeDirty = that.onDidChangeDirty;
 			readonly onDidChangeContent = that._onDidChangeContent.event;
+			readonly onDidChangeContentDeferred = Event.defer(that._onDidChangeContent.event);
 			readonly onDidSave = that.onDidSave;
 			isDirty(): boolean { return that.isDirty(); }
 			backup(token: CancellationToken): Promise<IWorkingCopyBackup> { return that.backup(token); }

src/vs/workbench/contrib/searchEditor/browser/searchEditorInput.ts

@@ -123,6 +123,7 @@ export class SearchEditorInput extends EditorInput {
 			readonly capabilities = input.hasCapability(EditorInputCapabilities.Untitled) ? WorkingCopyCapabilities.Untitled : WorkingCopyCapabilities.None;
 			readonly onDidChangeDirty = input.onDidChangeDirty;
 			readonly onDidChangeContent = input.onDidChangeContent;
+			readonly onDidChangeContentDeferred = Event.defer(input.onDidChangeContent);
 			readonly onDidSave = input.onDidSave;
 			isDirty(): boolean { return input.isDirty(); }
 			backup(token: CancellationToken): Promise<IWorkingCopyBackup> { return input.backup(token); }

src/vs/workbench/services/textfile/common/textFileEditorModel.ts

@@ -4,7 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { localize } from 'vs/nls';
-import { Emitter } from 'vs/base/common/event';
+import { Emitter, Event } from 'vs/base/common/event';
 import { URI } from 'vs/base/common/uri';
 import { assertIsDefined, withNullAsUndefined } from 'vs/base/common/types';
 import { EncodingMode, ITextFileService, TextFileEditorModelState, ITextFileEditorModel, ITextFileStreamContent, ITextFileResolveOptions, IResolvedTextFileEditorModel, ITextFileSaveOptions, TextFileResolveReason, ITextFileEditorModelSaveEvent } from 'vs/workbench/services/textfile/common/textfiles';
@@ -51,6 +51,7 @@ export class TextFileEditorModel extends BaseTextEditorModel implements ITextFil
 
 	private readonly _onDidChangeContent = this._register(new Emitter<void>());
 	readonly onDidChangeContent = this._onDidChangeContent.event;
+	readonly onDidChangeContentDeferred = Event.defer(this._onDidChangeContent.event);
 
 	private readonly _onDidResolve = this._register(new Emitter<TextFileResolveReason>());
 	readonly onDidResolve = this._onDidResolve.event;

src/vs/workbench/services/untitled/common/untitledTextEditorModel.ts

@@ -83,6 +83,7 @@ export class UntitledTextEditorModel extends BaseTextEditorModel implements IUnt
 
 	private readonly _onDidChangeContent = this._register(new Emitter<void>());
 	readonly onDidChangeContent = this._onDidChangeContent.event;
+	readonly onDidChangeContentDeferred = Event.defer(this._onDidChangeContent.event);
 
 	private readonly _onDidChangeName = this._register(new Emitter<void>());
 	readonly onDidChangeName = this._onDidChangeName.event;

src/vs/workbench/services/workingCopy/common/resourceWorkingCopy.ts

@@ -152,6 +152,7 @@ export abstract class ResourceWorkingCopy extends Disposable implements IResourc
 
 	abstract onDidChangeDirty: Event<void>;
 	abstract onDidChangeContent: Event<void>;
+	abstract onDidChangeContentDeferred: Event<void>;
 	abstract onDidSave: Event<IWorkingCopySaveEvent>;
 
 	abstract isDirty(): boolean;

src/vs/workbench/services/workingCopy/common/storedFileWorkingCopy.ts

@@ -290,6 +290,7 @@ export class StoredFileWorkingCopy<M extends IStoredFileWorkingCopyModel> extend
 
 	private readonly _onDidChangeContent = this._register(new Emitter<void>());
 	readonly onDidChangeContent = this._onDidChangeContent.event;
+	readonly onDidChangeContentDeferred = Event.defer(this._onDidChangeContent.event);
 
 	private readonly _onDidResolve = this._register(new Emitter<void>());
 	readonly onDidResolve = this._onDidResolve.event;

src/vs/workbench/services/workingCopy/common/untitledFileWorkingCopy.ts

@@ -101,6 +101,7 @@ export class UntitledFileWorkingCopy<M extends IUntitledFileWorkingCopyModel> ex
 
 	private readonly _onDidChangeContent = this._register(new Emitter<void>());
 	readonly onDidChangeContent = this._onDidChangeContent.event;
+	readonly onDidChangeContentDeferred = Event.defer(this._onDidChangeContent.event);
 
 	private readonly _onDidChangeDirty = this._register(new Emitter<void>());
 	readonly onDidChangeDirty = this._onDidChangeDirty.event;

src/vs/workbench/services/workingCopy/common/workingCopy.ts

@@ -145,6 +145,12 @@ export interface IWorkingCopy extends IWorkingCopyIdentifier {
 	 */
 	readonly onDidChangeContent: Event<void>;
 
+	/**
+	 * Used by the workbench e.g. to trigger auto-save
+	 * (unless this working copy is untitled) and backups.
+	 */
+	readonly onDidChangeContentDeferred: Event<void>;
+
 	/**
 	 * Used by the workbench e.g. to track local history
 	 * (unless this working copy is untitled).

src/vs/workbench/services/workingCopy/common/workingCopyService.ts

@@ -174,7 +174,7 @@ export class WorkingCopyService extends Disposable implements IWorkingCopyServic
 
 		// Wire in Events
 		const disposables = new DisposableStore();
-		disposables.add(workingCopy.onDidChangeContent(() => this._onDidChangeContent.fire(workingCopy)));
+		disposables.add(workingCopy.onDidChangeContentDeferred(() => this._onDidChangeContent.fire(workingCopy)));
 		disposables.add(workingCopy.onDidChangeDirty(() => this._onDidChangeDirty.fire(workingCopy)));
 		disposables.add(workingCopy.onDidSave(e => this._onDidSave.fire({ workingCopy, ...e })));
 

src/vs/workbench/services/workingCopy/test/browser/resourceWorkingCopy.test.ts

@@ -24,6 +24,7 @@ suite('ResourceWorkingCopy', function () {
 		capabilities = WorkingCopyCapabilities.None;
 		onDidChangeDirty = Event.None;
 		onDidChangeContent = Event.None;
+		onDidChangeContentDeferred = Event.None;
 		onDidSave = Event.None;
 		isDirty(): boolean { return false; }
 		async backup(token: CancellationToken): Promise<IWorkingCopyBackup> { throw new Error('Method not implemented.'); }

src/vs/workbench/test/common/workbenchTestServices.ts

@@ -139,6 +139,7 @@ export class TestWorkingCopy extends Disposable implements IWorkingCopy {
 
 	private readonly _onDidChangeContent = this._register(new Emitter<void>());
 	readonly onDidChangeContent = this._onDidChangeContent.event;
+	readonly onDidChangeContentDeferred = Event.defer(this._onDidChangeContent.event);
 
 	private readonly _onDidSave = this._register(new Emitter<IStoredFileWorkingCopySaveEvent>());
 	readonly onDidSave = this._onDidSave.event;