feat: implement web-tracing-framework support

This includes implementation and minimal instrumentation

Closes #2610

modules/angular2/angular2.ts

@@ -15,3 +15,4 @@ export * from './directives';
 export * from './http';
 export * from './forms';
 export * from './render';
+export * from './profile';

modules/angular2/angular2_exports.ts

@@ -6,3 +6,4 @@ export * from './directives';
 export * from './http';
 export * from './forms';
 export * from './render';
+export * from './profile';

modules/angular2/profile.ts

@@ -0,0 +1,7 @@
+export {
+  wtfCreateScope,
+  wtfLeave,
+  wtfStartTimeRange,
+  wtfEndTimeRange,
+  WtfScopeFn
+} from './src/profile/profile';

modules/angular2/src/change_detection/abstract_change_detector.ts

@@ -14,6 +14,9 @@ import {BindingRecord} from './binding_record';
 import {Locals} from './parser/locals';
 import {Pipes} from './pipes/pipes';
 import {CHECK_ALWAYS, CHECK_ONCE, CHECKED, DETACHED, ON_PUSH} from './constants';
+import {wtfCreateScope, wtfLeave, WtfScopeFn} from '../profile/profile';
+
+var _scope_check: WtfScopeFn = wtfCreateScope(`ChangeDetector#check(ascii id, bool throwOnChange)`);
 
 class _Context {
   constructor(public element: any, public componentElement: any, public instance: any,
@@ -69,16 +72,13 @@ export class AbstractChangeDetector<T> implements ChangeDetector {
 
   runDetectChanges(throwOnChange: boolean): void {
     if (this.mode === DETACHED || this.mode === CHECKED) return;
-
+    var s = _scope_check(this.id, throwOnChange);
     this.detectChangesInRecords(throwOnChange);
-
     this._detectChangesInLightDomChildren(throwOnChange);
-
     if (throwOnChange === false) this.callOnAllChangesDone();
-
     this._detectChangesInShadowDomChildren(throwOnChange);
-
     if (this.mode === CHECK_ONCE) this.mode = CHECKED;
+    wtfLeave(s);
   }
 
   // This method is not intended to be overridden. Subclasses should instead provide an

modules/angular2/src/core/application_common.ts

@@ -71,6 +71,7 @@ import {
 } from 'angular2/src/render/dom/view/shared_styles_host';
 import {internalView} from 'angular2/src/core/compiler/view_ref';
 import {appComponentRefPromiseToken, appComponentTypeToken} from './application_tokens';
+import {wtfInit} from '../profile/wtf_init';
 
 var _rootInjector: Injector;
 
@@ -290,6 +291,7 @@ export function commonBootstrap(
     appComponentType: /*Type*/ any,
     componentInjectableBindings: List<Type | Binding | List<any>> = null): Promise<ApplicationRef> {
   BrowserDomAdapter.makeCurrent();
+  wtfInit();
   var bootstrapProcess = PromiseWrapper.completer();
   var zone = createNgZone(new ExceptionHandler(DOM, isDart ? false : true));
   zone.run(() => {

modules/angular2/src/core/compiler/compiler.ts

@@ -25,6 +25,7 @@ import {ProtoViewFactory} from './proto_view_factory';
 import {UrlResolver} from 'angular2/src/services/url_resolver';
 import {AppRootUrl} from 'angular2/src/services/app_root_url';
 import {ElementBinder} from './element_binder';
+import {wtfStartTimeRange, wtfEndTimeRange} from '../../profile/profile';
 
 import * as renderApi from 'angular2/src/render/api';
 
@@ -127,6 +128,7 @@ export class Compiler {
   compileInHost(componentTypeOrBinding: Type | Binding): Promise<ProtoViewRef> {
     var componentType = isType(componentTypeOrBinding) ? componentTypeOrBinding :
                                                          (<Binding>componentTypeOrBinding).token;
+    var r = wtfStartTimeRange('Compiler#compile()', stringify(componentType));
 
     var hostAppProtoView = this._compilerCache.getHost(componentType);
     var hostPvPromise;
@@ -149,7 +151,10 @@ export class Compiler {
                 return appProtoView;
               });
     }
-    return hostPvPromise.then(hostAppProtoView => hostAppProtoView.ref);
+    return hostPvPromise.then((hostAppProtoView) => {
+      wtfEndTimeRange(r);
+      return hostAppProtoView.ref;
+    });
   }
 
   private _compile(componentBinding: DirectiveBinding,

modules/angular2/src/core/compiler/view_manager.ts

@@ -15,6 +15,7 @@ import {
 import {AppViewManagerUtils} from './view_manager_utils';
 import {AppViewPool} from './view_pool';
 import {AppViewListener} from './view_listener';
+import {wtfCreateScope, wtfLeave, WtfScopeFn} from '../../profile/profile';
 
 /**
  * Entry point for creating, moving views in the view hierarchy and destroying views.
@@ -83,6 +84,7 @@ export class AppViewManager {
     return this._utils.getComponentInstance(hostView, boundElementIndex);
   }
 
+  _scope_createRootHostView: WtfScopeFn = wtfCreateScope('AppViewManager#createRootHostView()');
   /**
    * Load component view into existing element.
    *
@@ -139,6 +141,7 @@ export class AppViewManager {
    */
   createRootHostView(hostProtoViewRef: ProtoViewRef, overrideSelector: string,
                      injector: Injector): HostViewRef {
+    var s = this._scope_createRootHostView();
     var hostProtoView: viewModule.AppProtoView = internalProtoView(hostProtoViewRef);
     var hostElementSelector = overrideSelector;
     if (isBlank(hostElementSelector)) {
@@ -151,38 +154,45 @@ export class AppViewManager {
 
     this._renderer.hydrateView(hostView.render);
     this._utils.hydrateRootHostView(hostView, injector);
-
-    return hostView.ref;
+    return wtfLeave(s, hostView.ref);
   }
 
+  _scope_destroyRootHostView: WtfScopeFn = wtfCreateScope('AppViewManager#destroyRootHostView()');
   /**
    * Remove the View created with {@link AppViewManager#createRootHostView}.
    */
   destroyRootHostView(hostViewRef: HostViewRef) {
     // Note: Don't put the hostView into the view pool
     // as it is depending on the element for which it was created.
+    var s = this._scope_destroyRootHostView();
     var hostView = internalView(<ViewRef>hostViewRef);
     this._renderer.detachFragment(hostView.renderFragment);
     this._renderer.dehydrateView(hostView.render);
     this._viewDehydrateRecurse(hostView);
     this._viewListener.viewDestroyed(hostView);
     this._renderer.destroyView(hostView.render);
+    wtfLeave(s);
   }
 
+  _scope_createEmbeddedViewInContainer: WtfScopeFn =
+      wtfCreateScope('AppViewManager#createEmbeddedViewInContainer()');
   /**
    *
    * See {@link AppViewManager#destroyViewInContainer}.
    */
   createEmbeddedViewInContainer(viewContainerLocation: ElementRef, atIndex: number,
                                 templateRef: TemplateRef): ViewRef {
+    var s = this._scope_createEmbeddedViewInContainer();
     var protoView = internalProtoView(templateRef.protoViewRef);
     if (protoView.type !== ViewType.EMBEDDED) {
       throw new BaseException('This method can only be called with embedded ProtoViews!');
     }
-    return this._createViewInContainer(viewContainerLocation, atIndex, protoView,
-                                       templateRef.elementRef, null);
+    return wtfLeave(s, this._createViewInContainer(viewContainerLocation, atIndex, protoView,
+                                                   templateRef.elementRef, null));
   }
 
+  _scope_createHostViewInContainer: WtfScopeFn =
+      wtfCreateScope('AppViewManager#createHostViewInContainer()');
   /**
    *
    * See {@link AppViewManager#destroyViewInContainer}.
@@ -190,12 +200,14 @@ export class AppViewManager {
   createHostViewInContainer(viewContainerLocation: ElementRef, atIndex: number,
                             protoViewRef: ProtoViewRef,
                             imperativelyCreatedInjector: ResolvedBinding[]): HostViewRef {
+    var s = this._scope_createHostViewInContainer();
     var protoView = internalProtoView(protoViewRef);
     if (protoView.type !== ViewType.HOST) {
       throw new BaseException('This method can only be called with host ProtoViews!');
     }
-    return this._createViewInContainer(viewContainerLocation, atIndex, protoView,
-                                       viewContainerLocation, imperativelyCreatedInjector);
+    return wtfLeave(
+        s, this._createViewInContainer(viewContainerLocation, atIndex, protoView,
+                                       viewContainerLocation, imperativelyCreatedInjector));
   }
 
   /**
@@ -243,22 +255,27 @@ export class AppViewManager {
     }
   }
 
+  _scope_destroyViewInContainer = wtfCreateScope('AppViewMananger#destroyViewInContainer()');
   /**
    *
    * See {@link AppViewManager#createViewInContainer}.
    */
   destroyViewInContainer(viewContainerLocation: ElementRef, atIndex: number) {
+    var s = this._scope_destroyViewInContainer();
     var parentView = internalView(viewContainerLocation.parentView);
     var boundElementIndex = viewContainerLocation.boundElementIndex;
     this._destroyViewInContainer(parentView, boundElementIndex, atIndex);
+    wtfLeave(s);
   }
 
+  _scope_attachViewInContainer = wtfCreateScope('AppViewMananger#attachViewInContainer()');
   /**
    *
    * See {@link AppViewManager#detachViewInContainer}.
    */
   attachViewInContainer(viewContainerLocation: ElementRef, atIndex: number,
                         viewRef: ViewRef): ViewRef {
+    var s = this._scope_attachViewInContainer();
     var view = internalView(viewRef);
     var parentView = internalView(viewContainerLocation.parentView);
     var boundElementIndex = viewContainerLocation.boundElementIndex;
@@ -270,21 +287,23 @@ export class AppViewManager {
     // context view that might have been used.
     this._utils.attachViewInContainer(parentView, boundElementIndex, null, null, atIndex, view);
     this._attachRenderView(parentView, boundElementIndex, atIndex, view);
-    return viewRef;
+    return wtfLeave(s, viewRef);
   }
 
+  _scope_detachViewInContainer = wtfCreateScope('AppViewMananger#detachViewInContainer()');
   /**
    *
    * See {@link AppViewManager#attachViewInContainer}.
    */
   detachViewInContainer(viewContainerLocation: ElementRef, atIndex: number): ViewRef {
+    var s = this._scope_detachViewInContainer();
     var parentView = internalView(viewContainerLocation.parentView);
     var boundElementIndex = viewContainerLocation.boundElementIndex;
     var viewContainer = parentView.viewContainers[boundElementIndex];
     var view = viewContainer.views[atIndex];
     this._utils.detachViewInContainer(parentView, boundElementIndex, atIndex);
     this._renderer.detachFragment(view.renderFragment);
-    return view.ref;
+    return wtfLeave(s, view.ref);
   }
 
   _createMainView(protoView: viewModule.AppProtoView,

modules/angular2/src/core/life_cycle/life_cycle.ts

@@ -2,6 +2,7 @@ import {Injectable} from 'angular2/di';
 import {ChangeDetector} from 'angular2/src/change_detection/change_detection';
 import {NgZone} from 'angular2/src/core/zone/ng_zone';
 import {isPresent, BaseException} from 'angular2/src/facade/lang';
+import {wtfLeave, wtfCreateScope, WtfScopeFn} from '../../profile/profile';
 
 /**
  * Provides access to explicitly trigger change detection in an application.
@@ -31,6 +32,8 @@ import {isPresent, BaseException} from 'angular2/src/facade/lang';
  */
 @Injectable()
 export class LifeCycle {
+  static _scope_tick: WtfScopeFn = wtfCreateScope('LifeCycle#tick()');
+
   _changeDetector: ChangeDetector;
   _enforceNoNewChanges: boolean;
   _runningTick: boolean = false;
@@ -71,6 +74,7 @@ export class LifeCycle {
       throw new BaseException("LifeCycle.tick is called recursively");
     }
 
+    var s = LifeCycle._scope_tick();
     try {
       this._runningTick = true;
       this._changeDetector.detectChanges();
@@ -79,6 +83,7 @@ export class LifeCycle {
       }
     } finally {
       this._runningTick = false;
+      wtfLeave(s);
     }
   }
 }

modules/angular2/src/core/zone/ng_zone.ts

@@ -1,5 +1,7 @@
 import {List, ListWrapper, StringMapWrapper} from 'angular2/src/facade/collection';
 import {normalizeBlank, isPresent, global} from 'angular2/src/facade/lang';
+import {wtfLeave, wtfCreateScope, WtfScopeFn} from '../../profile/profile';
+
 
 export interface NgZoneZone extends Zone { _innerZone: boolean; }
 
@@ -13,6 +15,9 @@ export interface NgZoneZone extends Zone { _innerZone: boolean; }
  * `Zone`. The default `onTurnDone` runs the Angular change detection.
  */
 export class NgZone {
+  _zone_run_scope: WtfScopeFn = wtfCreateScope(`NgZone#run()`);
+  _zone_microtask: WtfScopeFn = wtfCreateScope(`NgZone#microtask()`);
+
   // Code executed in _mountZone does not trigger the onTurnDone.
   _mountZone;
   // _innerZone is the child of _mountZone. Any code executed in this zone will trigger the
@@ -134,7 +139,12 @@ export class NgZone {
    */
   run(fn: () => any): any {
     if (this._disabled) {
+      var s = this._zone_run_scope();
+      try {
         return fn();
+      } finally {
+        wtfLeave(s);
+      }
     } else {
       return this._innerZone.run(fn);
     }
@@ -165,6 +175,7 @@ export class NgZone {
   }
 
   _createInnerZone(zone, enableLongStackTrace) {
+    var _zone_microtask = this._zone_microtask;
     var ngZone = this;
     var errorHandling;
 
@@ -217,10 +228,12 @@ export class NgZone {
             return function(fn) {
               ngZone._pendingMicrotasks++;
               var microtask = function() {
+                var s = _zone_microtask();
                 try {
                   fn();
                 } finally {
                   ngZone._pendingMicrotasks--;
+                  wtfLeave(s);
                 }
               };
               parentScheduleMicrotask.call(this, microtask);

modules/angular2/src/profile/profile.ts

@@ -0,0 +1,80 @@
+export {WtfScopeFn} from './wtf_impl';
+
+import * as impl from "./wtf_impl";
+
+// Change exports to const once https://github.com/angular/ts2dart/issues/150
+
+/**
+ * True if WTF is enabled.
+ */
+export var wtfEnabled = impl.detectWTF();
+
+function noopScope(arg0?: any, arg1?: any): any {
+  return null;
+}
+
+/**
+ * Create trace scope.
+ *
+ * Scopes must be strictly nested and are analogous to stack frames, but
+ * do not have to follow the stack frames. Instead it is recommended that they follow logical
+ * nesting. You may want to use
+ * [Event
+ * Signatures](http://google.github.io/tracing-framework/instrumenting-code.html#custom-events)
+ * as they are defined in WTF.
+ *
+ * Used to mark scope entry. The return value is used to leave the scope.
+ *
+ *     final myScope = wtfCreateScope('MyClass#myMethod(ascii someVal)');
+ *
+ *     someMethod() {
+ *        var s = myScope('Foo'); // 'Foo' gets stored in tracing UI
+ *        // DO SOME WORK HERE
+ *        return wtfLeave(s, 123); // Return value 123
+ *     }
+ *
+ * Note, adding try-finally block around the work to ensure that `wtfLeave` gets called can
+ * negatively impact the performance of your application. For this reason we recommend that
+ * you don't add them to ensure that `wtfLeave` gets called. In production `wtfLeave` is a noop and
+ * so try-finally block has no value. When debugging perf issues, skipping `wtfLeave`, do to
+ * exception, will produce incorrect trace, but presence of exception signifies logic error which
+ * needs to be fixed before the app should be profiled. Add try-finally only when you expect that
+ * an exception is expected during normal execution while profiling.
+ *
+ */
+export var wtfCreateScope: (signature: string, flags?: any) => impl.WtfScopeFn =
+    wtfEnabled ? impl.createScope : (signature: string, flags?: any) => noopScope;
+
+/**
+ * Used to mark end of Scope.
+ *
+ * - `scope` to end.
+ * - `returnValue` (optional) to be passed to the WTF.
+ *
+ * Returns the `returnValue for easy chaining.
+ */
+export var wtfLeave:<T>(scope: any, returnValue?: T) => T =
+    wtfEnabled ? impl.leave : (s: any, r?: any) => r;
+
+/**
+ * Used to mark Async start. Async are similar to scope but they don't have to be strictly nested.
+ * The return value is used in the call to [endAsync]. Async ranges only work if WTF has been
+ * enabled.
+ *
+ *     someMethod() {
+ *        var s = wtfStartTimeRange('HTTP:GET', 'some.url');
+ *        var future = new Future.delay(5).then((_) {
+ *          wtfEndTimeRange(s);
+ *        });
+ *     }
+ */
+export var wtfStartTimeRange: (rangeType: string, action: string) => any =
+    wtfEnabled ? impl.startTimeRange : (rangeType: string, action: string) => null;
+
+/**
+ * Ends a async time range operation.
+ * [range] is the return value from [wtfStartTimeRange] Async ranges only work if WTF has been
+ * enabled.
+ */
+export var wtfEndTimeRange: (range: any) => void = wtfEnabled ? impl.endTimeRange : (r: any) =>
+                                                                                        null;

modules/angular2/src/profile/wtf_impl.dart

@@ -0,0 +1,96 @@
+/**
+ * Tracing for Dart applications.
+ *
+ * The tracing API hooks up to either [WTF](http://google.github.io/tracing-framework/) or
+ * [Dart Observatory](https://www.dartlang.org/tools/observatory/).
+ */
+library angular2.src.core.wtf_impl;
+
+typedef dynamic WtfScopeFn([arg0, arg1]);
+
+var context = null;
+var _trace;
+var _events;
+var _createScope;
+var   _leaveScope;
+var _beginTimeRange;
+var _endTimeRange;
+final List _arg1 = [null];
+final List _arg2 = [null, null];
+
+bool detectWTF() {
+  if (context != null && context.hasProperty('wtf')) {
+    var wtf = context['wtf'];
+    if (wtf.hasProperty('trace')) {
+      _trace = wtf['trace'];
+      _events = _trace['events'];
+      _createScope = _events['createScope'];
+      _leaveScope = _trace['leaveScope'];
+      _beginTimeRange = _trace['beginTimeRange'];
+      _endTimeRange = _trace['endTimeRange'];
+      return true;
+    }
+  }
+  return false;
+}
+
+int getArgSize(String signature) {
+  int start = signature.indexOf('(') + 1;
+  int end = signature.indexOf(')', start);
+  bool found = false;
+  int count = 0;
+  for(var i = start; i < end; i++) {
+    var ch = signature[i];
+    if (identical(ch, ',')) {
+      found = false;
+    }
+    if (!found) {
+      found = true;
+      count ++;
+    }
+  }
+  return count;
+}
+
+dynamic createScope(String signature, [flags]) {
+  _arg2[0] = signature;
+  _arg2[1] = flags;
+  var jsScope = _createScope.apply(_arg2, thisArg: _events);
+  switch(getArgSize(signature)) {
+    case 0:
+        return ([arg0, arg1]) {
+            return jsScope.apply(const []);
+        };
+    case 1:
+        return ([arg0, arg1]) {
+          _arg1[0] = arg0;
+          return jsScope.apply(_arg1);
+        };
+    case 2:
+        return ([arg0, arg1]) {
+          _arg2[0] = arg0;
+          _arg2[1] = arg1;
+          return jsScope.apply(_arg1);
+        };
+    default:
+        throw "Max 2 arguments are supported.";
+  }
+}
+
+void leave(scope, [returnValue]) {
+  _arg2[0] = scope;
+  _arg2[1] = returnValue;
+  _leaveScope.apply(_arg2, thisArg: _trace);
+  return returnValue;
+}
+
+dynamic startTimeRange(String rangeType, String action) {
+  _arg2[0] = rangeType;
+  _arg2[1] = action;
+  return _beginTimeRange.apply(_arg2, thisArg: _trace);
+}
+
+void endTimeRange(dynamic range) {
+  _arg1[0] = range;
+  _endTimeRange.apply(_arg1, thisArg: _trace);
+}

modules/angular2/src/profile/wtf_impl.ts

@@ -0,0 +1,56 @@
+import {global} from '../facade/lang';
+
+export interface WtfScopeFn { (arg0?: any, arg1?: any): any; }
+
+interface WTF {
+  trace: Trace;
+}
+
+interface Trace {
+  events: Events;
+  leaveScope(scope: Scope, returnValue: any);
+  beginTimeRange(rangeType: string, action: string): Range;
+  endTimeRange(range: Range);
+}
+
+interface Range {}
+
+interface Events {
+  createScope(signature: string, flags: any): Scope;
+}
+
+interface Scope {
+  (...args): any;
+}
+
+var trace: Trace;
+var events: Events;
+
+export function detectWTF(): boolean {
+  var wtf: WTF = global['wtf'];
+  if (wtf) {
+    trace = wtf['trace'];
+    if (trace) {
+      events = trace['events'];
+      return true;
+    }
+  }
+  return false;
+}
+
+export function createScope(signature: string, flags: any = null): any {
+  return events.createScope(signature, flags);
+}
+
+export function leave<T>(scope: Scope, returnValue?: T): T {
+  trace.leaveScope(scope, returnValue);
+  return returnValue;
+}
+
+export function startTimeRange(rangeType: string, action: string): Range {
+  return trace.beginTimeRange(rangeType, action);
+}
+
+export function endTimeRange(range: Range): void {
+  trace.endTimeRange(range);
+}

modules/angular2/src/profile/wtf_init.dart

@@ -0,0 +1,14 @@
+library angular2.src.core.wtf_init;
+
+import 'dart:js' as js;
+import 'wtf_impl.dart' as impl;
+
+/**
+ * Must be executed explicitly in Dart to set the JS Context.
+ *
+ * NOTE: this is done explicitly to allow WTF api not to depend on
+ * JS context and possible to run the noop WTF stubs outside the browser.
+ */
+wtfInit() {
+  impl.context = js.context;
+}

modules/angular2/src/profile/wtf_init.ts

@@ -0,0 +1,4 @@
+/**
+ * This is here because DART requires it. It is noop in JS.
+ */
+export function wtfInit() {}

modules/angular2/src/render/dom/compiler/view_loader.ts

@@ -16,6 +16,7 @@ import {XHR} from 'angular2/src/render/xhr';
 
 import {StyleInliner} from './style_inliner';
 import {StyleUrlResolver} from './style_url_resolver';
+import {wtfStartTimeRange, wtfEndTimeRange} from '../../../profile/profile';
 
 export class TemplateAndStyles {
   constructor(public template: string, public styles: string[]) {}
@@ -33,6 +34,7 @@ export class ViewLoader {
               private _styleUrlResolver: StyleUrlResolver) {}
 
   load(viewDef: ViewDefinition): Promise<TemplateAndStyles> {
+    var r = wtfStartTimeRange('ViewLoader#load()', stringify(viewDef.componentId));
     let tplAndStyles: List<Promise<TemplateAndStyles>| Promise<string>| string> =
         [this._loadHtml(viewDef.template, viewDef.templateAbsUrl)];
     if (isPresent(viewDef.styles)) {
@@ -56,8 +58,10 @@ export class ViewLoader {
           let loadedTplAndStyles = <TemplateAndStyles>res[0];
           let styles = <string[]>ListWrapper.slice(res, 1);
 
-          return new TemplateAndStyles(loadedTplAndStyles.template,
+          var templateAndStyles = new TemplateAndStyles(loadedTplAndStyles.template,
                                                         loadedTplAndStyles.styles.concat(styles));
+          wtfEndTimeRange(r);
+          return templateAndStyles;
         });
   }
 

modules/angular2/src/render/dom/dom_renderer.ts

@@ -22,6 +22,7 @@ import {
   cloneAndQueryProtoView,
   camelCaseToDashCase
 } from './util';
+import {WtfScopeFn, wtfLeave, wtfCreateScope} from '../../profile/profile';
 
 import {
   Renderer,
@@ -38,6 +39,7 @@ import {DOCUMENT_TOKEN, DOM_REFLECT_PROPERTIES_AS_ATTRIBUTES} from './dom_tokens
 
 const REFLECT_PREFIX: string = 'ng-reflect-';
 
+
 @Injectable()
 export class DomRenderer extends Renderer {
   _document;
@@ -53,19 +55,24 @@ export class DomRenderer extends Renderer {
     this._document = document;
   }
 
+  _scope_createRootHostView: WtfScopeFn = wtfCreateScope('DomRenderer#createRootHostView()');
   createRootHostView(hostProtoViewRef: RenderProtoViewRef, fragmentCount: number,
                      hostElementSelector: string): RenderViewWithFragments {
+    var s = this._scope_createRootHostView();
     var hostProtoView = resolveInternalDomProtoView(hostProtoViewRef);
     var element = DOM.querySelector(this._document, hostElementSelector);
     if (isBlank(element)) {
+      wtfLeave(s);
       throw new BaseException(`The selector "${hostElementSelector}" did not match any elements`);
     }
-    return this._createView(hostProtoView, element);
+    return wtfLeave(s, this._createView(hostProtoView, element));
   }
 
+  _scope_createView = wtfCreateScope('DomRenderer#createView()');
   createView(protoViewRef: RenderProtoViewRef, fragmentCount: number): RenderViewWithFragments {
+    var s = this._scope_createView();
     var protoView = resolveInternalDomProtoView(protoViewRef);
-    return this._createView(protoView, null);
+    return wtfLeave(s, this._createView(protoView, null));
   }
 
   destroyView(viewRef: RenderViewRef) {
@@ -109,11 +116,14 @@ export class DomRenderer extends Renderer {
     moveNodesAfterSibling(element, resolveInternalDomFragment(fragmentRef));
   }
 
+  _scope_detachFragment = wtfCreateScope('DomRenderer#detachFragment()');
   detachFragment(fragmentRef: RenderFragmentRef) {
+    var s = this._scope_detachFragment();
     var fragmentNodes = resolveInternalDomFragment(fragmentRef);
     for (var i = 0; i < fragmentNodes.length; i++) {
       DOM.remove(fragmentNodes[i]);
     }
+    wtfLeave(s);
   }
 
   hydrateView(viewRef: RenderViewRef) {
@@ -203,9 +213,12 @@ export class DomRenderer extends Renderer {
     DOM.setText(view.boundTextNodes[textNodeIndex], text);
   }
 
+  _scope_setEventDispatcher = wtfCreateScope('DomRenderer#setEventDispatcher()');
   setEventDispatcher(viewRef: RenderViewRef, dispatcher: any /*api.EventDispatcher*/): void {
+    var s = this._scope_setEventDispatcher();
     var view = resolveInternalDomView(viewRef);
     view.eventDispatcher = dispatcher;
+    wtfLeave(s);
   }
 
   _createView(protoView: DomProtoView, inplaceElement: HTMLElement): RenderViewWithFragments {

modules/angular2/test/profile/wtf_impl_spec.dart

@@ -0,0 +1,18 @@
+/// This file contains tests that make sense only in Dart
+library angular2.test.core.wtf_impl;
+
+import 'package:angular2/test_lib.dart';
+import 'package:angular2/src/profile/wtf_impl.dart' as impl;
+
+main() {
+  describe('WTF', () {
+    describe('getArgSize', () {
+      it("should parse args", () {
+        expect(impl.getArgSize('foo#bar')).toBe(0);
+        expect(impl.getArgSize('foo#bar()')).toBe(0);
+        expect(impl.getArgSize('foo#bar(foo bar)')).toBe(1);
+        expect(impl.getArgSize('foo#bar(foo bar, baz q)')).toBe(2);
+      });
+    });
+  });
+}