feat(signal-slice): optimize subscription management

libs/ngxtension/signal-slice/src/signal-slice.spec.ts

@@ -1,3 +1,4 @@
+import { DestroyRef } from '@angular/core';
 import { toSignal } from '@angular/core/rxjs-interop';
 import { TestBed, fakeAsync, flush, tick } from '@angular/core/testing';
 import { Observable, Subject, of, timer } from 'rxjs';
@@ -245,6 +246,32 @@ describe(signalSlice.name, () => {
 			});
 		});
 
+		it('should not register a new permanent subscription teardown on every call with a plain value', () => {
+			TestBed.runInInjectionContext(() => {
+				const destroyRef = TestBed.inject(DestroyRef);
+				const onDestroySpy = jest.spyOn(destroyRef, 'onDestroy');
+
+				const state = signalSlice({
+					initialState,
+					actionSources: {
+						increaseAge: (state, $: Observable<number>) =>
+							$.pipe(map((amount) => ({ age: state().age + amount }))),
+					},
+				});
+
+				// one permanent subscription is made at slice-creation time by
+				// the internal `connect(state, sharedObservable)` call
+				const baseline = onDestroySpy.mock.calls.length;
+				expect(baseline).toBeGreaterThan(0);
+
+				state.increaseAge(1);
+				state.increaseAge(1);
+				state.increaseAge(1);
+
+				expect(onDestroySpy.mock.calls.length).toEqual(baseline);
+			});
+		});
+
 		it('should resolve the updated state as a promise after reducer is invoked', (done) => {
 			TestBed.runInInjectionContext(() => {
 				const state = signalSlice({

libs/ngxtension/signal-slice/src/signal-slice.ts

@@ -209,7 +209,6 @@ export function signalSlice<
 				destroyRef,
 				subject,
 				subs,
-				sharedObservable,
 			);
 		}
 	}
@@ -293,7 +292,6 @@ function addReducerProperties(
 	destroyRef: DestroyRef,
 	subject: Subject<unknown>,
 	subs: Subject<unknown>[],
-	observableFromActionSource?: Observable<any>,
 ) {
 	const version = createNotifier();
 	Object.defineProperties(readonlyState, {
@@ -319,12 +317,6 @@ function addReducerProperties(
 					});
 				}
 
-				if (observableFromActionSource) {
-					observableFromActionSource
-						.pipe(takeUntilDestroyed(destroyRef))
-						.subscribe();
-				}
-
 				return new Promise((res) => {
 					state$.pipe(take(1)).subscribe((val) => {
 						res(val);