limit experiments to first time users; fixes #14009

src/vs/platform/telemetry/common/telemetry.ts

@@ -18,7 +18,9 @@ export interface ITelemetryInfo {
 }
 
 export interface ITelemetryExperiments {
+	showDefaultViewlet: boolean;
 	showCommandsWatermark: boolean;
+	openUntitledFile: boolean;
 }
 
 export interface ITelemetryService {
@@ -39,7 +41,9 @@ export interface ITelemetryService {
 }
 
 export const defaultExperiments: ITelemetryExperiments = {
+	showDefaultViewlet: false,
 	showCommandsWatermark: false,
+	openUntitledFile: true
 };
 
 export const NullTelemetryService = {
@@ -62,15 +66,31 @@ export const NullTelemetryService = {
 };
 
 export function loadExperiments(storageService: IStorageService, configurationService: IConfigurationService): ITelemetryExperiments {
+
 	const key = 'experiments.randomness';
 	let valueString = storageService.get(key);
 	if (!valueString) {
 		valueString = Math.random().toString();
 		storageService.store(key, valueString);
 	}
-	const value = parseFloat(valueString);
+
+	const random0 = parseFloat(valueString);
+	let [random1, showDefaultViewlet] = splitRandom(random0);
+	const [random2, showCommandsWatermark] = splitRandom(random1);
+	let [, openUntitledFile] = splitRandom(random2);
+
+	// is the user a first time user?
+	let isNewSession = storageService.get('telemetry.lastSessionDate') ? false : true;
+	if (!isNewSession) {
+		// for returning users we fall back to the default configuration for the sidebar and the initially opened, empty editor
+		showDefaultViewlet = defaultExperiments.showDefaultViewlet;
+		openUntitledFile = defaultExperiments.openUntitledFile;
+	}
+
 	return applyOverrides(configurationService, {
-		showCommandsWatermark: value < 0.5
+		showDefaultViewlet,
+		showCommandsWatermark,
+		openUntitledFile
 	});
 }
 
@@ -85,6 +105,12 @@ export function applyOverrides(configurationService: IConfigurationService, expe
 	return experiments;
 }
 
+function splitRandom(random: number): [number, boolean] {
+	const scaled = random * 2;
+	const i = Math.floor(scaled);
+	return [scaled - i, i === 1];
+}
+
 export interface ITelemetryAppender {
 	log(eventName: string, data: any): void;
 }

src/vs/workbench/electron-browser/workbench.ts

@@ -326,7 +326,8 @@ export class Workbench implements IPartService {
 		}
 
 		// Empty workbench
-		else if (!this.workbenchParams.workspace) {
+		else if (!this.workbenchParams.workspace && this.telemetryService.getExperiments().openUntitledFile) {
+			// some first time users will not have an untiled file; returning users will always have one
 			return TPromise.as([{ input: this.untitledEditorService.createOrGet() }]);
 		}
 
@@ -428,7 +429,8 @@ export class Workbench implements IPartService {
 		// Sidebar visibility
 		this.sideBarHidden = this.storageService.getBoolean(Workbench.sidebarHiddenSettingKey, StorageScope.WORKSPACE, false);
 		if (!this.contextService.getWorkspace()) {
-			this.sideBarHidden = true; // we hide sidebar in single-file-mode
+			// some first time users will see a sidebar; returning users will not see the sidebar
+			this.sideBarHidden = !this.telemetryService.getExperiments().showDefaultViewlet;
 		}
 
 		const viewletRegistry = Registry.as<ViewletRegistry>(ViewletExtensions.Viewlets);