First cut of file service based user data service

src/vs/workbench/services/userData/common/fileUserDataService.ts

+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import { Event, Emitter } from 'vs/base/common/event';
+import { Disposable } from 'vs/base/common/lifecycle';
+import { IUserDataService, IUserDataChangesEvent } from './userDataService';
+import { IFileService, FileChangesEvent } from 'vs/platform/files/common/files';
+import { URI } from 'vs/base/common/uri';
+import * as resources from 'vs/base/common/resources';
+import { TernarySearchTree } from 'vs/base/common/map';
+import { VSBuffer } from 'vs/base/common/buffer';
+import { IEnvironmentService } from 'vs/platform/environment/common/environment';
+
+export class FileUserDataService extends Disposable implements IUserDataService {
+	_serviceBrand: any;
+
+	private readonly settingsHome: URI;
+
+	private _onDidChange: Emitter<IUserDataChangesEvent> = this._register(new Emitter<IUserDataChangesEvent>());
+	readonly onDidChange: Event<IUserDataChangesEvent> = this._onDidChange.event;
+
+	constructor(
+		@IEnvironmentService environmentService: IEnvironmentService,
+		@IFileService private readonly fileService: IFileService
+	) {
+		super();
+		// Assumption: This path always exists
+		this.settingsHome = environmentService.appSettingsHome;
+		this.fileService.watch(this.settingsHome);
+
+		this._register(this.fileService.onFileChanges(e => this.handleFileChanges(e)));
+	}
+
+	private handleFileChanges(event: FileChangesEvent): void {
+		const changedKeys: string[] = [];
+		for (const change of event.changes) {
+			const key = resources.relativePath(this.settingsHome, change.resource);
+			if (key) {
+				changedKeys.push(key);
+			}
+		}
+		if (changedKeys.length) {
+			this._onDidChange.fire(new UserDataChangesEvent(changedKeys));
+		}
+	}
+
+	read(key: string): Promise<string> {
+		return this.fileService.readFile(this.toResource(key)).then(content => content.value.toString());
+	}
+
+	write(key: string, value: string): Promise<void> {
+		return this.fileService.writeFile(this.toResource(key), VSBuffer.fromString(value)).then(() => undefined);
+	}
+
+	private toResource(key: string): URI {
+		return resources.joinPath(this.settingsHome, ...key.split('/'));
+	}
+
+}
+
+class UserDataChangesEvent implements IUserDataChangesEvent {
+
+	private _keysTree: TernarySearchTree<string> | undefined = undefined;
+
+	constructor(readonly keys: string[]) { }
+
+	private get keysTree(): TernarySearchTree<string> {
+		if (!this._keysTree) {
+			this._keysTree = TernarySearchTree.forPaths<string>();
+			for (const key of this.keys) {
+				this._keysTree.set(key, key);
+			}
+		}
+		return this._keysTree;
+	}
+
+	contains(keyOrSegment: string): boolean {
+		return this.keysTree.findSubstr(keyOrSegment) !== undefined;
+	}
+
+}
\ No newline at end of file

src/vs/workbench/services/userData/common/userDataService.ts

@@ -8,10 +8,15 @@ import { Event } from 'vs/base/common/event';
 
 export const IUserDataService = createDecorator<IUserDataService>('userDataService');
 
+export interface IUserDataChangesEvent {
+	keys: string[];
+	contains(keyOrSegment: string): boolean;
+}
+
 export interface IUserDataService {
 	_serviceBrand: any;
 
-	onDidChange: Event<string>;
+	onDidChange: Event<IUserDataChangesEvent>;
 
 	read(key: string): Promise<string>;