perf(core): speed up retrieval of DestroyRef in EventEmitter (#54748

)

Speeds up the retrieval of `DestroyRef` in `EventEmitter` because
`try/catch` is expensive if there is no injection context.

We saw a script time regression in Cloud.

The goldens had to be updated because `getInjectImplementation` is now
referenced. `inject` also references the underlying field, but directly.
This is super minimal overhead of a function exposing the internal
field.

PR Close #54748

packages/core/src/di/contextual.ts

@@ -8,9 +8,10 @@
 
 import {RuntimeError, RuntimeErrorCode} from '../errors';
 import {InjectorProfilerContext, setInjectorProfilerContext} from '../render3/debug/injector_profiler';
+
+import {getInjectImplementation, setInjectImplementation} from './inject_switch';
 import type {Injector} from './injector';
 import {getCurrentInjector, setCurrentInjector} from './injector_compatibility';
-import {getInjectImplementation, setInjectImplementation} from './inject_switch';
 import {R3Injector} from './r3_injector';
 
 /**
@@ -47,6 +48,12 @@ export function runInInjectionContext<ReturnT>(injector: Injector, fn: () => Ret
   }
 }
 
+/**
+ * Whether the current stack frame is inside an injection context.
+ */
+export function isInInjectionContext(): boolean {
+  return getInjectImplementation() !== undefined || getCurrentInjector() != null;
+}
 /**
  * Asserts that the current stack frame is within an [injection
  * context](guide/dependency-injection-context) and has access to `inject`.
@@ -58,7 +65,7 @@ export function runInInjectionContext<ReturnT>(injector: Injector, fn: () => Ret
 export function assertInInjectionContext(debugFn: Function): void {
   // Taking a `Function` instead of a string name here prevents the unminified name of the function
   // from being retained in the bundle regardless of minification.
-  if (!getInjectImplementation() && !getCurrentInjector()) {
+  if (!isInInjectionContext()) {
     throw new RuntimeError(
         RuntimeErrorCode.MISSING_INJECTION_CONTEXT,
         ngDevMode &&

packages/core/src/event_emitter.ts

@@ -10,6 +10,7 @@ import {setActiveConsumer} from '@angular/core/primitives/signals';
 import {PartialObserver, Subject, Subscription} from 'rxjs';
 
 import {OutputRef} from './authoring/output/output_ref';
+import {isInInjectionContext} from './di/contextual';
 import {inject} from './di/injector_compatibility';
 import {DestroyRef} from './linker/destroy_ref';
 
@@ -107,18 +108,16 @@ export interface EventEmitter<T> extends Subject<T>, OutputRef<T> {
 
 class EventEmitter_ extends Subject<any> implements OutputRef<any> {
   __isAsync: boolean;  // tslint:disable-line
-  destroyRef: DestroyRef|undefined;
+  destroyRef: DestroyRef|undefined = undefined;
 
   constructor(isAsync: boolean = false) {
     super();
     this.__isAsync = isAsync;
 
     // Attempt to retrieve a `DestroyRef` optionally.
-    // For backwards compatibility reasons, this cannot be required.
-    try {
-      this.destroyRef = inject(DestroyRef);
-    } catch {
-      this.destroyRef = undefined;
+    // For backwards compatibility reasons, this cannot be required
+    if (isInInjectionContext()) {
+      this.destroyRef = inject(DestroyRef, {optional: true}) ?? undefined;
     }
   }
 

packages/core/test/bundling/animations-standalone/bundle.golden_symbols.json

@@ -914,6 +914,9 @@
   {
     "name": "getFirstLContainer"
   },
+  {
+    "name": "getInjectImplementation"
+  },
   {
     "name": "getInjectableDef"
   },

packages/core/test/bundling/animations/bundle.golden_symbols.json

@@ -980,6 +980,9 @@
   {
     "name": "getFirstLContainer"
   },
+  {
+    "name": "getInjectImplementation"
+  },
   {
     "name": "getInjectableDef"
   },

packages/core/test/bundling/cyclic_import/bundle.golden_symbols.json

@@ -752,6 +752,9 @@
   {
     "name": "getFirstLContainer"
   },
+  {
+    "name": "getInjectImplementation"
+  },
   {
     "name": "getInjectableDef"
   },

packages/core/test/bundling/defer/bundle.golden_symbols.json

@@ -857,6 +857,9 @@
   {
     "name": "getFirstNativeNode"
   },
+  {
+    "name": "getInjectImplementation"
+  },
   {
     "name": "getInjectableDef"
   },

packages/core/test/bundling/forms_reactive/bundle.golden_symbols.json

@@ -1052,6 +1052,9 @@
   {
     "name": "getFirstNativeNode"
   },
+  {
+    "name": "getInjectImplementation"
+  },
   {
     "name": "getInjectableDef"
   },

packages/core/test/bundling/forms_template_driven/bundle.golden_symbols.json

@@ -1016,6 +1016,9 @@
   {
     "name": "getFirstNativeNode"
   },
+  {
+    "name": "getInjectImplementation"
+  },
   {
     "name": "getInjectableDef"
   },

packages/core/test/bundling/hello_world/bundle.golden_symbols.json

@@ -587,6 +587,9 @@
   {
     "name": "getFirstLContainer"
   },
+  {
+    "name": "getInjectImplementation"
+  },
   {
     "name": "getInjectableDef"
   },

packages/core/test/bundling/hydration/bundle.golden_symbols.json

@@ -815,6 +815,9 @@
   {
     "name": "getFirstLContainer"
   },
+  {
+    "name": "getInjectImplementation"
+  },
   {
     "name": "getInjectableDef"
   },

packages/core/test/bundling/router/bundle.golden_symbols.json

@@ -1283,6 +1283,9 @@
   {
     "name": "getInherited"
   },
+  {
+    "name": "getInjectImplementation"
+  },
   {
     "name": "getInjectableDef"
   },

packages/core/test/bundling/standalone_bootstrap/bundle.golden_symbols.json

@@ -668,6 +668,9 @@
   {
     "name": "getFirstLContainer"
   },
+  {
+    "name": "getInjectImplementation"
+  },
   {
     "name": "getInjectableDef"
   },

packages/core/test/bundling/todo/bundle.golden_symbols.json

@@ -896,6 +896,9 @@
   {
     "name": "getFirstNativeNode"
   },
+  {
+    "name": "getInjectImplementation"
+  },
   {
     "name": "getInjectableDef"
   },