replaced watch with watchFile (#9873)

* replaced watch with watchFile

* testing debounce

* changed the beounce delay to 1500

extensions/notebook/src/book/bookTreeView.ts

@@ -8,7 +8,6 @@ import * as vscode from 'vscode';
 import * as path from 'path';
 import * as fs from 'fs-extra';
 import * as constants from '../common/constants';
-import * as fsw from 'fs';
 import { IPrompter, QuestionTypes, IQuestion } from '../prompts/question';
 import CodeAdapter from '../prompts/adapter';
 import { BookTreeItem, BookTreeItemType } from './bookTreeItem';
@@ -19,6 +18,7 @@ import * as loc from '../common/localizedConstants';
 import { ApiWrapper } from '../common/apiWrapper';
 import * as glob from 'fast-glob';
 import { isNullOrUndefined } from 'util';
+import { debounce } from '../common/utils';
 
 const Content = 'content';
 
@@ -126,13 +126,12 @@ export class BookTreeViewProvider implements vscode.TreeDataProvider<BookTreeIte
 
 			// add file watcher on toc file.
 			if (!isNotebook) {
-				fsw.watch(path.join(this.currentBook.bookPath, '_data', 'toc.yml'), async (event, filename) => {
-					if (event === 'change') {
-						let changedBook = this.books.find(book => book.bookPath === bookPath);
-						await changedBook.initializeContents().then(() => {
-							this._onDidChangeTreeData.fire(changedBook.bookItems[0]);
-						});
-						this._onDidChangeTreeData.fire();
+				fs.watchFile(path.join(bookPath, '_data', 'toc.yml'), async (curr, prev) => {
+					if (curr.mtime > prev.mtime) {
+						let book = this.books.find(book => book.bookPath === bookPath);
+						if (book) {
+							this.fireBookRefresh(book);
+						}
 					}
 				});
 			}
@@ -141,6 +140,13 @@ export class BookTreeViewProvider implements vscode.TreeDataProvider<BookTreeIte
 		}
 	}
 
+	@debounce(1500)
+	async fireBookRefresh(book: BookModel): Promise<void> {
+		await book.initializeContents().then(() => {
+			this._onDidChangeTreeData.fire();
+		});
+	}
+
 	async closeBook(book: BookTreeItem): Promise<void> {
 		// remove book from the saved books
 		let deletedBook: BookModel;
@@ -160,7 +166,7 @@ export class BookTreeViewProvider implements vscode.TreeDataProvider<BookTreeIte
 		} finally {
 			// remove watch on toc file.
 			if (deletedBook && !deletedBook.isNotebook) {
-				fsw.unwatchFile(path.join(deletedBook.bookPath, '_data', 'toc.yml'));
+				fs.unwatchFile(path.join(deletedBook.bookPath, '_data', 'toc.yml'));
 			}
 		}
 	}

extensions/notebook/src/common/utils.ts

@@ -262,3 +262,35 @@ export function getIgnoreSslVerificationConfigSetting(): boolean {
 	}
 	return true;
 }
+
+export function debounce(delay: number): Function {
+	return decorate((fn, key) => {
+		const timerKey = `$debounce$${key}`;
+
+		return function (this: any, ...args: any[]) {
+			clearTimeout(this[timerKey]);
+			this[timerKey] = setTimeout(() => fn.apply(this, args), delay);
+		};
+	});
+}
+
+function decorate(decorator: (fn: Function, key: string) => Function): Function {
+	return (_target: any, key: string, descriptor: any) => {
+		let fnKey: string | null = null;
+		let fn: Function | null = null;
+
+		if (typeof descriptor.value === 'function') {
+			fnKey = 'value';
+			fn = descriptor.value;
+		} else if (typeof descriptor.get === 'function') {
+			fnKey = 'get';
+			fn = descriptor.get;
+		}
+
+		if (!fn || !fnKey) {
+			throw new Error('not supported');
+		}
+
+		descriptor[fnKey] = decorator(fn, key);
+	};
+}

extensions/notebook/tsconfig.json

@@ -1,6 +1,7 @@
 {
 	"extends": "../shared.tsconfig.json",
 	"compilerOptions": {
+		"experimentalDecorators": true,
 		"lib": [
 			"dom"
 		],