refactor(core): allow multiple DI profilers (angular#60562)

This commit changes the DI profiler infrastructure to
allow multiple profilers running at the same time.

PR Close angular#60562

Author: pkozlowski-opensource

packages/core/src/render3/debug/injector_profiler.ts

@@ -194,33 +194,55 @@ export function setInjectorProfilerContext(context: InjectorProfilerContext) {
   return previous;
 }
 
-let injectorProfilerCallback: InjectorProfiler | null = null;
+const injectorProfilerCallbacks: InjectorProfiler[] = [];
+
+const NOOP_PROFILER_REMOVAL = () => {};
+
+function removeProfiler(profiler: InjectorProfiler) {
+  const profilerIdx = injectorProfilerCallbacks.indexOf(profiler);
+  if (profilerIdx !== -1) {
+    injectorProfilerCallbacks.splice(profilerIdx, 1);
+  }
+}
 
 /**
- * Sets the callback function which will be invoked during certain DI events within the
- * runtime (for example: injecting services, creating injectable instances, configuring providers)
+ * Adds a callback function which will be invoked during certain DI events within the
+ * runtime (for example: injecting services, creating injectable instances, configuring providers).
+ * Multiple profiler callbacks can be set: in this case profiling events are
+ * reported to every registered callback.
  *
  * Warning: this function is *INTERNAL* and should not be relied upon in application's code.
  * The contract of the function might be changed in any release and/or the function can be removed
  * completely.
  *
  * @param profiler function provided by the caller or null value to disable profiling.
+ * @returns a cleanup function that, when invoked, removes a given profiler callback.
  */
-export const setInjectorProfiler = (injectorProfiler: InjectorProfiler | null) => {
+export function setInjectorProfiler(injectorProfiler: InjectorProfiler | null): () => void {
   !ngDevMode && throwError('setInjectorProfiler should never be called in production mode');
-  injectorProfilerCallback = injectorProfiler;
-};
+
+  if (injectorProfiler !== null) {
+    if (!injectorProfilerCallbacks.includes(injectorProfiler)) {
+      injectorProfilerCallbacks.push(injectorProfiler);
+    }
+    return () => removeProfiler(injectorProfiler);
+  } else {
+    injectorProfilerCallbacks.length = 0;
+    return NOOP_PROFILER_REMOVAL;
+  }
+}
 
 /**
  * Injector profiler function which emits on DI events executed by the runtime.
  *
  * @param event InjectorProfilerEvent corresponding to the DI event being emitted
  */
-function injectorProfiler(event: InjectorProfilerEvent): void {
+export function injectorProfiler(event: InjectorProfilerEvent): void {
   !ngDevMode && throwError('Injector profiler should never be called in production mode');
 
-  if (injectorProfilerCallback != null /* both `null` and `undefined` */) {
-    injectorProfilerCallback!(event);
+  for (let i = 0; i < injectorProfilerCallbacks.length; i++) {
+    const injectorProfilerCallback = injectorProfilerCallbacks[i];
+    injectorProfilerCallback(event);
   }
 }
 

packages/core/test/acceptance/injector_profiler_spec.ts

@@ -11,6 +11,7 @@ import {
   afterRender,
   ClassProvider,
   Component,
+  createEnvironmentInjector,
   Directive,
   ElementRef,
   inject,
@@ -43,6 +44,8 @@ import {
   InjectorProfilerEventType,
   ProviderConfiguredEvent,
   setInjectorProfiler,
+  injectorProfiler,
+  InjectorProfilerContext,
 } from '../../src/render3/debug/injector_profiler';
 import {getNodeInjectorLView, NodeInjector} from '../../src/render3/di';
 import {
@@ -103,7 +106,7 @@ describe('setProfiler', () => {
     });
   });
 
-  afterAll(() => setInjectorProfiler(null));
+  afterEach(() => setInjectorProfiler(null));
 
   it('should emit DI events when a component contains a provider and injects it', () => {
     class MyService {}
@@ -382,6 +385,70 @@ describe('setProfiler', () => {
   });
 });
 
+describe('profiler activation and removal', () => {
+  class SomeClass {}
+
+  const fakeContext: InjectorProfilerContext = {
+    injector: Injector.create({providers: []}),
+    token: SomeClass,
+  };
+
+  const fakeEvent: InjectorCreatedInstanceEvent = {
+    type: InjectorProfilerEventType.InstanceCreatedByInjector,
+    context: fakeContext,
+    instance: {value: new SomeClass()},
+  };
+
+  it('should allow adding and removing multiple profilers', () => {
+    const events: string[] = [];
+    const r1 = setInjectorProfiler((e) => events.push('P1: ' + e.type));
+    const r2 = setInjectorProfiler((e) => events.push('P2: ' + e.type));
+
+    injectorProfiler(fakeEvent);
+    expect(events).toEqual(['P1: 1', 'P2: 1']);
+
+    r1();
+    injectorProfiler(fakeEvent);
+    expect(events).toEqual(['P1: 1', 'P2: 1', 'P2: 1']);
+
+    r2();
+    injectorProfiler(fakeEvent);
+    expect(events).toEqual(['P1: 1', 'P2: 1', 'P2: 1']);
+  });
+
+  it('should not add / remove the same profiler twice', () => {
+    const events: string[] = [];
+    const p1 = (e: InjectorProfilerEvent) => events.push('P1: ' + e.type);
+    const r1 = setInjectorProfiler(p1);
+    const r2 = setInjectorProfiler(p1);
+
+    injectorProfiler(fakeEvent);
+    expect(events).toEqual(['P1: 1']);
+
+    r1();
+    injectorProfiler(fakeEvent);
+    expect(events).toEqual(['P1: 1']);
+
+    // subsequent removals should be noop
+    r1();
+    r2();
+  });
+
+  it('should clear all profilers when passing null', () => {
+    const events: string[] = [];
+    setInjectorProfiler((e) => events.push('P1: ' + e.type));
+    setInjectorProfiler((e) => events.push('P2: ' + e.type));
+
+    injectorProfiler(fakeEvent);
+    expect(events).toEqual(['P1: 1', 'P2: 1']);
+
+    // clear all profilers
+    setInjectorProfiler(null);
+    injectorProfiler(fakeEvent);
+    expect(events).toEqual(['P1: 1', 'P2: 1']);
+  });
+});
+
 describe('getInjectorMetadata', () => {
   it('should be able to determine injector type and name', fakeAsync(() => {
     class MyServiceA {}
@@ -487,7 +554,7 @@ describe('getInjectorMetadata', () => {
 
 describe('getInjectorProviders', () => {
   beforeEach(() => setupFrameworkInjectorProfiler());
-  afterAll(() => setInjectorProfiler(null));
+  afterEach(() => setInjectorProfiler(null));
 
   it('should be able to get the providers from a components injector', () => {
     class MyService {}
@@ -953,7 +1020,7 @@ describe('getInjectorProviders', () => {
 
 describe('getDependenciesFromInjectable', () => {
   beforeEach(() => setupFrameworkInjectorProfiler());
-  afterAll(() => setInjectorProfiler(null));
+  afterEach(() => setInjectorProfiler(null));
 
   it('should be able to determine which injector dependencies come from', fakeAsync(() => {
     class MyService {}
@@ -1244,7 +1311,7 @@ describe('getDependenciesFromInjectable', () => {
 
 describe('getInjectorResolutionPath', () => {
   beforeEach(() => setupFrameworkInjectorProfiler());
-  afterAll(() => setInjectorProfiler(null));
+  afterEach(() => setInjectorProfiler(null));
 
   it('should be able to inspect injector hierarchy structure', fakeAsync(() => {
     class MyServiceA {}