Vaadin - grid.getDataProvider().refreshAll(); Does not work after updating browser - grid

Question

how are you ? I have a detail with the push after updating the tab that contains my grid, I am using vaadin 8.0.4
,google chrome updated, and my example is based here https://github.com/vaadin/archetype-application-example
My application consists of data stored in mongodb, when I make a direct change in the db it is reflected in the grid every so often, 30 seconds, with push, it always works on a single tab, the problem appears when I update the tab or create a new one, the push seems to be disconnected and my grid is not updated anymore, the strange thing is that I added the #PreserveOnRefresh and in the first tab that accesses the application in that if the push works even after updating very strange.
This instance check changes in my db
private ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(5);
and
I use the grid update, with
grid.getDataProvider().refreshAll()
I even try to broadcast the tabs, by means of the pattern described in the book 12.16.4. Broadcasting to Other Users
because if the active notifications continue in all the tabs, but the grid does not, only in the original tab.
Update:
In this example application the problem is actually the login, when I remove it if everything works perfectly as it should be with push. But only when I remove the login
#Override
public void receiveBroadcast() {
access(() -> {
//Notification.show(message);
//grid.getDataProvider().refreshAll();
getNavigator().removeView(MonitorCrudView.VIEW_NAME);
getNavigator().addView(MonitorCrudView.VIEW_NAME,new MonitorCrudView(this));
getNavigator().navigateTo(MonitorCrudView.VIEW_NAME);
Notification.show("Grid updated", Notification.Type.TRAY_NOTIFICATION);
});
}
The detail is that when I have the AccessContro enabled, and I enter as admin by what you see, when executing the above method I get an exception of type "No request linked to the current thread"; Coming from the "CurrentUser" Class
https://github.com/vaadin/archetype-application-example/blob/master/mockapp-ui/src/main/java/org/vaadin/mockapp/samples/authentication/CurrentUser.java
But here in vaadin 8.0.4 changes a little
public final class CurrentUser {
/**
* The attribute key used to store the username in the session.
*/
public static final String CURRENT_USER_SESSION_ATTRIBUTE_KEY = CurrentUser.class
.getCanonicalName();
private CurrentUser() {
}
/**
* Returns the name of the current user stored in the current session, or an
* empty string if no user name is stored.
*
* #throws IllegalStateException
* if the current session cannot be accessed.
*/
public static String get() {
String currentUser = (String) getCurrentRequest().getWrappedSession()
.getAttribute(CURRENT_USER_SESSION_ATTRIBUTE_KEY);
if (currentUser == null) {
return "";
} else {
return currentUser;
}
}
/**
* Sets the name of the current user and stores it in the current session.
* Using a {#code null} username will remove the username from the session.
*
* #throws IllegalStateException
* if the current session cannot be accessed.
*/
public static void set(String currentUser) {
if (currentUser == null) {
getCurrentRequest().getWrappedSession().removeAttribute(
CURRENT_USER_SESSION_ATTRIBUTE_KEY);
} else {
getCurrentRequest().getWrappedSession().setAttribute(
CURRENT_USER_SESSION_ATTRIBUTE_KEY, currentUser);
}
}
private static VaadinRequest getCurrentRequest() {
VaadinRequest request = VaadinService.getCurrentRequest();
if (request == null) {
throw new IllegalStateException(
"No request bound to current thread");
}
return request;
}
}
UPDATE:
Https://github.com/rucko24/testView/blob/master/MyApp-ui/src/main/java/example/samples/crud/SampleCrudView.java
In this class I added the button that broadcast to all UI.
Log in as admin
Click on Update grid
Should give a type exception
java.util.concurrent.ExecutionException:
java.lang.IllegalStateException: No request bound to current thread
Does not continue to throw exeption after refreshing the UI
But when opening in an incognito tab it always throws the exception once before updating.
With the base project and mongo db plus the
private static ScheduledExecutorService scheduler =
Executors.newScheduledThreadPool (5);
I always get the same exception from above, and never change the view with push

Answer 1

Disclaimer: This is better suited as a comment but it does not fit the allocated space.
The VaadinService.getCurrentRequest() API doc states that:
The current response can not be used in e.g. background threads because of the way server implementations reuse response instances.
At the same time, the UI.access() javadoc is somewhat ambiguous stating that:
Please note that the runnable might be invoked on a different thread or later on the current thread, which means that custom thread locals might not have the expected values when the command is executed
The above statements kind of explain why VaadinService.getCurrentRequest() is null in your getCurrentRequest() method.
Nonetheless, it seems that UI.getCurrent() returns an instance when running in that background thread, also suggested by this vaadin forum post and vaadin book:
Your code is not thread safe as it does not lock the VaadinSession before accessing the UI. The preferred pattern is using the UI.access and VaadinSession.access methods as described in Book of Vaadin section 11.16.3. Inside an access block Vaadin automatically sets the relevant threadlocals in addition to properly handling session locking.
In conclusion, i'd suggest to replace all the calls to getCurrentRequest().getWrappedSession() with UI.getCurrent().getSession();, eg:
UI.getCurrent().getSession().getAttribute(CURRENT_USER_SESSI‌​ON_ATTRIBUTE_KEY);
or
UI.getCurrent().getSession().setAttribute(CURRENT_USER_SESSI‌​ON_ATTRIBUTE_KEY, currentUser);
I tested this with your sample and it worked fine.