Don't make VaadinSession serialize VaadinService (#10088)

* Refactor ApplicationRunnerServlet UIProvider to avoid indirect
reference through anonymous inner class

Change-Id: Ie4148e633192b1940ba82edbd26fbbc0cc2c4da3

server/src/com/vaadin/server/VaadinSession.java

@@ -27,6 +27,7 @@ import java.util.Locale;
 import java.util.Map;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
+import java.util.logging.Logger;
 
 import javax.portlet.PortletSession;
 import javax.servlet.http.HttpSession;
@@ -125,7 +126,7 @@ public class VaadinSession implements HttpSessionBindingListener, Serializable {
 
     private LinkedList<UIProvider> uiProviders = new LinkedList<UIProvider>();
 
-    private VaadinService service;
+    private transient VaadinService service;
 
     /**
      * Create a new service session tied to a Vaadin service
@@ -153,7 +154,15 @@ public class VaadinSession implements HttpSessionBindingListener, Serializable {
         // If we are going to be unbound from the session, the session must be
         // closing
         // Notify the service
-        service.fireSessionDestroy(this);
+        if (service == null) {
+            getLogger()
+                    .warning(
+                            "A VaadinSession instance not associated to any service is getting unbound. "
+                                    + "Session destroy events will not be fired and UIs in the session will not get detached. "
+                                    + "This might happen if a session is deserialized but never used before it expires.");
+        } else {
+            service.fireSessionDestroy(this);
+        }
         session = null;
     }
 
@@ -257,6 +266,7 @@ public class VaadinSession implements HttpSessionBindingListener, Serializable {
         if (attribute instanceof VaadinSession) {
             VaadinSession vaadinSession = (VaadinSession) attribute;
             vaadinSession.session = underlyingSession;
+            vaadinSession.service = service;
             return vaadinSession;
         }
 
@@ -896,4 +906,8 @@ public class VaadinSession implements HttpSessionBindingListener, Serializable {
     public boolean isClosing() {
         return closing;
     }
+
+    private static final Logger getLogger() {
+        return Logger.getLogger(VaadinSession.class.getName());
+    }
 }

uitest/src/com/vaadin/launcher/ApplicationRunnerServlet.java

@@ -139,13 +139,8 @@ public class ApplicationRunnerServlet extends LegacyVaadinServlet {
         try {
             final Class<?> classToRun = getClassToRun();
             if (UI.class.isAssignableFrom(classToRun)) {
-                session.addUIProvider(new UIProvider() {
-                    @Override
-                    public Class<? extends UI> getUIClass(
-                            UIClassSelectionEvent event) {
-                        return (Class<? extends UI>) classToRun;
-                    }
-                });
+                session.addUIProvider(new ApplicationRunnerUIProvider(
+                        classToRun));
             } else if (LegacyApplication.class.isAssignableFrom(classToRun)) {
                 // Avoid using own UIProvider for legacy Application
             } else if (UIProvider.class.isAssignableFrom(classToRun)) {
@@ -171,6 +166,19 @@ public class ApplicationRunnerServlet extends LegacyVaadinServlet {
         return getApplicationRunnerURIs(request).applicationClassname;
     }
 
+    private static final class ApplicationRunnerUIProvider extends UIProvider {
+        private final Class<?> classToRun;
+
+        private ApplicationRunnerUIProvider(Class<?> classToRun) {
+            this.classToRun = classToRun;
+        }
+
+        @Override
+        public Class<? extends UI> getUIClass(UIClassSelectionEvent event) {
+            return (Class<? extends UI>) classToRun;
+        }
+    }
+
     // TODO Don't need to use a data object now that there's only one field
     private static class URIS {
         // String staticFilesPath;