nb diff perf improvements by comparing hash values (microsoft#227145)

* nb diff perf improvements by comparing hash values

* More efficient

Author: DonJayamanne

src/vs/workbench/contrib/notebook/browser/diff/diffComponents.ts

@@ -1644,7 +1644,7 @@ export class ModifiedElement extends AbstractElementRenderer {
 			{
 				updateInfoRendering: () => renderSourceEditor(),
 				checkIfModified: (cell) => {
-					return cell.modified?.textModel.getValue() !== cell.original?.textModel.getValue() ? { reason: undefined } : false;
+					return cell.modified?.textModel.getTextBufferHash() !== cell.original?.textModel.getTextBufferHash() ? { reason: undefined } : false;
 				},
 				getFoldingState: (cell) => cell.cellFoldingState,
 				updateFoldingState: (cell, state) => cell.cellFoldingState = state,
@@ -1660,7 +1660,7 @@ export class ModifiedElement extends AbstractElementRenderer {
 		const scopedContextKeyService = this.contextKeyService.createScoped(this.templateData.inputToolbarContainer);
 		this._register(scopedContextKeyService);
 		const inputChanged = NOTEBOOK_DIFF_CELL_INPUT.bindTo(scopedContextKeyService);
-		inputChanged.set(this.cell.modified.textModel.getValue() !== this.cell.original.textModel.getValue());
+		inputChanged.set(this.cell.modified.textModel.getTextBufferHash() !== this.cell.original.textModel.getTextBufferHash());
 
 		const ignoreWhitespace = NOTEBOOK_DIFF_CELL_IGNORE_WHITESPACE.bindTo(scopedContextKeyService);
 		const ignore = this.textConfigurationService.getValue<boolean>(this.cell.modified.uri, 'diffEditor.ignoreTrimWhitespace');
@@ -1675,7 +1675,7 @@ export class ModifiedElement extends AbstractElementRenderer {
 		const refreshToolbar = () => {
 			const ignore = this.textConfigurationService.getValue<boolean>(this.cell.modified.uri, 'diffEditor.ignoreTrimWhitespace');
 			ignoreWhitespace.set(ignore);
-			const hasChanges = this.cell.modified.textModel.getValue() !== this.cell.original.textModel.getValue();
+			const hasChanges = this.cell.modified.textModel.getTextBufferHash() !== this.cell.original.textModel.getTextBufferHash();
 			inputChanged.set(hasChanges);
 
 			if (hasChanges) {

src/vs/workbench/contrib/notebook/browser/diff/notebookDiffViewModel.ts

@@ -443,7 +443,7 @@ function createDiffViewModels(instantiationService: IInstantiationService, confi
 			case 'unchanged': {
 				const originalCell = originalModel.cells[diff.originalCellIndex];
 				const modifiedCell = modifiedModel.cells[diff.modifiedCellIndex];
-				const type = (originalCell.textModel?.getValue() !== modifiedCell.textModel?.getValue()) ? 'modified' : 'unchanged';
+				const type = originalCell.equal(modifiedCell) ? 'unchanged' : 'modified';
 				return new SideBySideDiffElementViewModel(
 					model.modified.notebook,
 					model.original.notebook,

src/vs/workbench/contrib/notebook/common/model/notebookCellTextModel.ts

@@ -419,6 +419,10 @@ export class NotebookCellTextModel extends Disposable implements ICell {
 			return false;
 		}
 
+		if (this.outputs.length !== b.outputs.length) {
+			return false;
+		}
+
 		if (this.getTextLength() !== b.getTextLength()) {
 			return false;
 		}