lib: settle signals when controller's signal is GCed

lib/internal/abort_controller.js

@@ -95,8 +95,25 @@ const dependantSignalsCleanupRegistry = new SafeFinalizationRegistry((signalWeak
     }
   });
 });
+
 const gcPersistentSignals = new SafeSet();
 
+const finalizer = new SafeFinalizationRegistry(({ sourceSignalRef, composedSignalRef }) => {
+  // TODO: remove ref from source signal
+  // TODO: remove composed signal from gcPersistentSignals
+  const composedSignal = composedSignalRef.deref();
+  if (composedSignal !== undefined) {
+    composedSignal[kSourceSignals].delete(sourceSignalRef);
+    gcPersistentSignals.delete(composedSignal);
+  }
+
+  // TODO: remove ref from dependant signal
+  const sourceSignal = sourceSignalRef.deref();
+  if (sourceSignal !== undefined) {
+    sourceSignal[kDependantSignals].delete(composedSignalRef);
+  }
+});
+
 const kAborted = Symbol('kAborted');
 const kReason = Symbol('kReason');
 const kCloneData = Symbol('kCloneData');
@@ -258,6 +275,9 @@ class AbortSignal extends EventTarget {
         resultSignal[kSourceSignals].add(signalWeakRef);
         signal[kDependantSignals].add(resultSignalWeakRef);
         dependantSignalsCleanupRegistry.register(resultSignal, signalWeakRef);
+        // when the source signal - coming from the controller - is gced, we need to remove it from the dependant
+        // signals of the composite signal
+        finalizer.register(signal, { sourceSignalRef: signalWeakRef, composedSignalRef: resultSignalWeakRef});
       } else if (!signal[kSourceSignals]) {
         continue;
       } else {
@@ -293,6 +313,7 @@ class AbortSignal extends EventTarget {
       // listener, then we don't want it to be gc'd while the listener
       // is attached and the timer still hasn't fired. So, we retain a
       // strong ref that is held for as long as the listener is registered.
+
       gcPersistentSignals.add(this);
     }
   }
@@ -434,6 +455,7 @@ class AbortController {
    */
   get signal() {
     this.#signal ??= new AbortSignal(kDontThrowSymbol);
+
     return this.#signal;
   }