Merge pull request #744 from NativeScript/pete/fix-gc-issue-no-weakref

Fix #720 GC issue - No weak ref found

Author: petekanev

runtime/src/main/jni/ObjectManager.cpp

@@ -460,6 +460,10 @@ void ObjectManager::MarkReachableObjects(Isolate* isolate, const Local<Object>&
             NativeScriptExtension::ReleaseClosureObjects(closureObjects);
         }
 
+        if (o->IsArray()) {
+            MarkReachableArrayElements(o, s);
+        }
+
         auto proto = o->GetPrototype();
         if (!proto.IsEmpty() && !proto->IsNull() && !proto->IsUndefined() && proto->IsObject()) {
             s.push(proto);
@@ -518,6 +522,19 @@ void ObjectManager::MarkReachableObjects(Isolate* isolate, const Local<Object>&
     } // while
 }
 
+void ObjectManager::MarkReachableArrayElements(Local<Object> &o, stack<Local<Value>> &s) {
+    auto arr = o.As<Array>();
+
+    int arrEnclosedObjectsLength = arr->Length();
+    for (int i = 0; i < arrEnclosedObjectsLength; i++) {
+        auto enclosedElement = arr->Get(i);
+
+        if (!enclosedElement.IsEmpty() && enclosedElement->IsObject()) {
+            s.push(enclosedElement);
+        }
+    }
+}
+
 void ObjectManager::OnGcStartedStatic(Isolate* isolate, GCType type, GCCallbackFlags flags) {
     try {
         auto runtime = Runtime::GetRuntime(isolate);

runtime/src/main/jni/ObjectManager.h

@@ -49,12 +49,15 @@ class ObjectManager {
 
         v8::Local<v8::Object> GetEmptyObject(v8::Isolate* isolate);
 
+        static void MarkReachableArrayElements(v8::Local<v8::Object> &o, std::stack<v8::Local<v8::Value>> &s);
+
         enum class MetadataNodeKeys {
             JsInfo,
             CallSuper,
             END
         };
 
+
     private:
 
         struct JSInstanceInfo {

test-app/app/src/main/assets/app/tests/testGC.js

@@ -264,6 +264,29 @@ describe("Tests garbage collection", function () {
 		gc();
 		java.lang.System.gc();
 	});
+
+	it("should keep array-enclosed objects alive after GC", function () {
+        function createObjects(name) {
+            var arr = new Array();
+            arr.push(new com.tns.tests.Class1());
+
+            var cb1 = new com.tns.tests.Class1.Callback1(name, {
+                getMessage: function() {
+                    var msg = arr[0].getMessage();
+                    return msg;
+                }
+            });
+
+            return com.tns.tests.Class1.Class2.printMessageWithDelay(cb1, 2 * 1000);
+        }
+
+        expect(createObjects("Callback1")).toBe(true);
+        expect(createObjects("Callback2")).toBe(true);
+        expect(createObjects("Callback3")).toBe(true);
+
+        gc();
+        java.lang.System.gc();
+    })
 
 	it("should properly reintroduce Java object back in a callback", function () {
 		function getTestObject() {