Merge from vscode merge-base (#22780)

* Revert "Revert "Merge from vscode merge-base (#22769)" (#22779)"

This reverts commit 47a1745180.

* Fix notebook download task

* Remove done call from extensions-ci

extensions/markdown-language-features/src/logging.ts

@@ -0,0 +1,88 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the Source EULA. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as vscode from 'vscode';
+import { Disposable } from './util/dispose';
+import { lazy } from './util/lazy';
+
+enum Trace {
+	Off,
+	Verbose
+}
+
+namespace Trace {
+	export function fromString(value: string): Trace {
+		value = value.toLowerCase();
+		switch (value) {
+			case 'off':
+				return Trace.Off;
+			case 'verbose':
+				return Trace.Verbose;
+			default:
+				return Trace.Off;
+		}
+	}
+}
+
+export interface ILogger {
+	verbose(title: string, message: string, data?: any): void;
+}
+
+export class VsCodeOutputLogger extends Disposable implements ILogger {
+	private trace?: Trace;
+
+	private readonly outputChannel = lazy(() => this._register(vscode.window.createOutputChannel('Markdown')));
+
+	constructor() {
+		super();
+
+		this._register(vscode.workspace.onDidChangeConfiguration(() => {
+			this.updateConfiguration();
+		}));
+
+		this.updateConfiguration();
+	}
+
+	public verbose(title: string, message: string, data?: any): void {
+		if (this.trace === Trace.Verbose) {
+			this.appendLine(`[Verbose ${this.now()}] ${title}: ${message}`);
+			if (data) {
+				this.appendLine(VsCodeOutputLogger.data2String(data));
+			}
+		}
+	}
+
+	private now(): string {
+		const now = new Date();
+		return String(now.getUTCHours()).padStart(2, '0')
+			+ ':' + String(now.getMinutes()).padStart(2, '0')
+			+ ':' + String(now.getUTCSeconds()).padStart(2, '0') + '.' + String(now.getMilliseconds()).padStart(3, '0');
+	}
+
+	private updateConfiguration(): void {
+		this.trace = this.readTrace();
+	}
+
+	private appendLine(value: string): void {
+		this.outputChannel.value.appendLine(value);
+	}
+
+	private readTrace(): Trace {
+		return Trace.fromString(vscode.workspace.getConfiguration().get<string>('markdown.trace.extension', 'off'));
+	}
+
+	private static data2String(data: any): string {
+		if (data instanceof Error) {
+			if (typeof data.stack === 'string') {
+				return data.stack;
+			}
+			return data.message;
+		}
+		if (typeof data === 'string') {
+			return data;
+		}
+		return JSON.stringify(data, undefined, 2);
+	}
+}