Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
ok, thx thomas it begins to become clearer,
my code attached don't use scheduler, thats right. meanwhile (thx to you
thomas) i played with Scheduler and Timer. The current code looks like:
public void start() {
Timer timer = new Timer() {
@Override
public void run() {
if (ttReady auReady) {
continueStart();
this.cancel();
}
else {
System.out.println(waiting: + ttReady + +
auReady);
}
}
};
timer.scheduleRepeating(1000);
}
but the feeling about this code is not better than the feeling with my
infinite loop. i think the problem is, that i don't really understand the
backgrounds - especially the scheduler. could you please show me some
sample code for my special problem (how should start() look like?) or give
some reference to docs explaining the scheduler/the model behind it?
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Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
i found a bit of info about scheduler
herehttp://stackoverflow.com/questions/5131086/using-the-gwt-scheduler.
now i got:
private boolean tryToContinue() {
if (ttReady auReady) {
continueStart();
return false;
} else
return true;
}
public void start() {
Scheduler.get().scheduleEntry(new RepeatingCommand() {
@Override
public boolean execute() {
return tryToContinue();
}
});
i used scheduleEntry because of Javadoc: This type of command is
appropriate for instrumentation or code that needs to know when something
happens.
But i am unsure about my implementation/ my understanding about scheduler -
is the code above correct?
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Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
Using SimpleEventBus the following does not behave like you expect:
eventBus.addHandler(FirstEvent.TYPE, new FirstHandler() {
void onFirstEvent(FirstEvent e) {
//will be enqueued to be added. So handler is not fully registered
eventBus.addHandler(SecondEvent.TYPE, new SecondHandler() {
void onSecondEvent(SecondEvent e) {
sysout(second event)
}
}
//wont trigger handler from above
eventBus.fire(new SecondEvent());
sysout(first event done);
}
});
The output would be first event done and you wont see second event on
the console. As Thomas said handlers that you add to the event bus while an
event is actually dispatched (in this case FirstEvent) will cause the
SimpleEventBus to put the new handler into a queue. After all events are
dispatched the contents of this queue is added to the list of known
handlers ready to be executed. But as all events are already dispatched
these new handlers wont get executed.
And thats exactly what happens with your original code. Once your
DataReceiver has finished loading your data you fire an event
OnSometimeEvent. The handler of this event calls continueStart() which in
turn adds a handler to the event bus via historyHandler.register(...) and
then fires a second event via historyHandler.handleCurrentHistory().
Because you register the history handler while your OnSometimeEvent gets
dispatched this handler will be stored in a queue in SimpleEventBus. Then
the second event will be dispatched (fired by
historyHandler.handleCurrentHistory()) and after this event has been
executed the handler in the queue will be added to the list of known
handlers.
To solve this you either have to refactor your code in a way that all
handlers are registered to the event bus before OnSometimeEvent is fired or
you have to break your code execution flow by taking the continueStart()
method and defer it until OnSometimeEvent has been dispatched.
So:
public void start() {
if(dataReady) {
Scheduler.get().scheduleFinally(
//
continueStart();
);
} else { //wait }
}
should do the trick. If scheduleFinally does not work try scheduleDeferred
which executes the code even later. If you want to understand the Scheduler
class you should read something about the browser event loop.
-- J.
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Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
THX for this explanation Jens! the problem i have with the code you suggested is: how to implement //wait as stated before my first implementation with an (infinite) while loop could block the whole browser. So whats about the other kinds of scheduleXXX? Whats about the code i showed above - using scheduleEntry? According do Javadoc scheduleEntry is exactly what i need, but i am unsure how to use it. -- You received this message because you are subscribed to the Google Groups Google Web Toolkit group. To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/lyGmS_rDSU0J. To post to this group, send email to google-web-toolkit@googlegroups.com. To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
the problem i have with the code you suggested is: how to implement //wait Put the label into your RootPanel like in the original code. I was a bit lazy and didn't want to retype it. as stated before my first implementation with an (infinite) while loop could block the whole browser. As javascript is executed on a single thread you never want an infinite while loop. This will always block the browser. You just want to react to events. -- You received this message because you are subscribed to the Google Groups Google Web Toolkit group. To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/jvSPrZEFDkwJ. To post to this group, send email to google-web-toolkit@googlegroups.com. To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
Grrr.
onModuleLoad() {
// launch task 1
// launch task 2
// display wait message, or whatever
}
onTask1Finished() {
task1Finished = true;
maybeContinue();
}
onTask2Finished() {
task2Finished = true;
maybeContinue();
}
maybeContinue() {
if (task1Finished task2Finished) {
// we're running from an event dispatch so handlers we add to the
EventBus are deferred, and firing an event synchronously wouldn't trigger
them, so we defer the whole thing
Scheduler.get().scheduleFinally(new ScheduledCommand() {
@Override
public void execute() {
// create your activity handlers, then:
historyHandler.handleCurrentHistory();
}
});
}
}
The first 3 methods you already have, the last one too, just missing that
damn Scheduler bit; i.e. 5 damn lines.
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Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
Thank YOU Thomas, i guess now i got it - i don't have to schedule the data-loading but all the other stuff that need to be properly initialized, right? Thanks for your patience (i is probably not the first time i say thx for your patience :-)). i just wanted jens to ask what happens if dataReady is not ready - i guess nothing? but for interest: my code above (using scheduleEntry) would work, wouldn't it? i'll will refactor my code -- You received this message because you are subscribed to the Google Groups Google Web Toolkit group. To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/ZIU6mIG7AVMJ. To post to this group, send email to google-web-toolkit@googlegroups.com. To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
At the moment i read your last post/ understood the problem i knew that you
tried it several times - i saw all your vehement efforts to get it into my
brain (but some times brains don't want to see :-) ).
i just refactored my code - in fact i haven't changed much (i already had
some scheduler stuff in my code). Because all my tasks are done on
construction time (gin injected stuff, ApplicationManager registers himself
to onTaskDoneEvents in constructor) i got rid of the public start()
method. Now i only have a private start called in the way you suggested it:
...
@Override
public void onTopicTreeLoadedEvent(TopicTreeLoadedEvent event) {
ttReady = true;
start();
}
..
@Override
public void onAdminUnitsLoaded(AdminUnitsLoadedEvent event) {
auReady = true;
start();
}
...
private void start() {
if (ttReady auReady) {
Scheduler.get().scheduleFinally(new ScheduledCommand() {
@Override
public void execute() {
// set up activity managers
sidePanelAreaManager.setDisplay(contentArea.getWestSideArea());
breadCrumbAreaManager.setDisplay(contentArea.getBreadcrumArea());
contentMenuAreaManager.setDisplay(contentArea.getContentMenuArea());
contentAreaManager.setDisplay(contentArea.getContentArea());
// insert dynamic layout in static layout
staticView.getContentArea().setWidget(contentArea);
contentArea.setDefaultLayout();
historyHandler.register(placeController, eventBus,
startPlace);
historyHandler.handleCurrentHistory();
currentPlace = placeController.getWhere();
}
});
}
}
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Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
so at the moment i delay it (the whole continueStart()) untill some events
occur. And you propose not to delay it with scheduleDeferred (until 2
events occurred) but with scheduleFinally? Or how the code shoul look like?
at the moment it is:
...
new SchedulerImpl().scheduleDeferred(new ScheduledCommand() {
@Override
public void execute() {
while (!(ttReady auReady)) {
//bad i know
}
continueStart();
}
...
private void continueStart() {
// set up activity managers
sidePanelAreaManager.setDisplay(contentArea.getWestSideArea());
breadCrumbAreaManager.setDisplay(contentArea.getBreadcrumArea());
contentMenuAreaManager.setDisplay(contentArea.getContentMenuArea());
contentAreaManager.setDisplay(contentArea.getContentArea());
// insert dynamic layout in static layout
staticView.getContentArea().setWidget(contentArea);
contentArea.setDefaultLayout();
currentPlace = placeController.getWhere();
eventBus.addHandler(PlaceChangeEvent.TYPE, this);
historyHandler.register(placeController, eventBus, startPlace);
historyHandler.handleCurrentHistory();
// currentPlace = placeController.getWhere();
// eventBus.addHandler(PlaceChangeEvent.TYPE, this);
}
so please tell me what lines to move where or what lines to change
thx in advance
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Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
I didn't see an Scheduler being used in the code you attached. Whichever scheduledXxx method, the idea is to get out of the event dispatching, so the above is fine (except that your while loop in the ScheduledCommand can cause an infinite loop: JS is single-threaded; Also, I'd have put the test outside the ScheduledCommand: if everything's loaded and I can continueStart, then launch continueStart, but slightly deferred, to make sure it's not executed while an event is being dispatched). -- You received this message because you are subscribed to the Google Groups Google Web Toolkit group. To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/Qx9leowD2_oJ. To post to this group, send email to google-web-toolkit@googlegroups.com. To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
i made an (nearly)minimal example showing this problem. it is a simple
sandbox app where i made some experiments with RequestFactory and
Activities and Places (no DI, no Gin). The crux is now, that onModuleLoad
is starting an AppManager.start(). The AppManager shows only wait until
data is received and event is fired. I f event is received all the
activities/places machinery is started - but here is the problem: no
activity is started but PlaceChangeEvent is fired. But all later
PalceChangeEvents are handled correctly. So what to do to reproduce:
Start the app see wait, wait see received data (the data sending
service waits 10seconds) - no activities started.
Change id in url from 1 to 2 or vice versa - activities are started
correctly.
or change start() in AppManager and run continueStart() directly:
public void start() {
//if (dataReady) {
continueStart();
//} else {
//appLayout.add(new Label(wait!));
//}
}
So why the activities are not started on first load? what happens here?
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Sandkasten.7z
Description: application/7z-compressed
Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
I think that's because the code now runs from within an event, so handlers addition/removal is done after the event is processed; but handleCurrentHistory() fires events synchronously, so the event handlers are not yet registered. As a workaround, defer continueStart() a bit more so it executes outside the event handling logic, within a Scheduler.scheduleFinally() for instance. -- You received this message because you are subscribed to the Google Groups Google Web Toolkit group. To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/ijSNu_E7QVsJ. To post to this group, send email to google-web-toolkit@googlegroups.com. To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
that was my first guess but i debugged into ActivityManager's- register event code. all activity managers are instatiated and have themselve registered on placechange events before the deferred handleCurrentHistory() occurs. Or the other way around: if i do not defer the start all is working fine. it seem only to work if all stuff happens inside onModuleLoad(). and it seem that problem only occur if handleCurrentHistory() happens after onModuleLoad and all the binding and instantiation in onModuleLoad. (but i am not sure about all that) -- You received this message because you are subscribed to the Google Groups Google Web Toolkit group. To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/6kYPVfzYDCEJ. To post to this group, send email to google-web-toolkit@googlegroups.com. To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
What I meant is that, assuming you're using a SimpleEventBus, the PlaceChangeRequestHandler-s and PlaceChangeHandler-s are in the deferredDeltas list, they're not yet fully registered: http://code.google.com/p/google-web-toolkit/source/browse/trunk/user/src/com/google/web/bindery/event/shared/SimpleEventBus.java You need to defer the handleCurrentHistory() call outside the event dispatching; but you can actually defer the whole continueStart if you prefer (the handlers would then be registered right away, with no queuing in the deferredDeltas) -- You received this message because you are subscribed to the Google Groups Google Web Toolkit group. To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/3nGq2Eo_aHkJ. To post to this group, send email to google-web-toolkit@googlegroups.com. To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
at the moment the whole continueStart is deferred at the end of this
continueStart handleCurrentHistory() is called, after instantiating
activity mappers and managers. Before that (on construction time of
AppManager) EventBus and PlaceController are instantiated.
you could look in the code i attached in 2nd post. which lines of code
should be moved where?
(i still don't understand why it works with out the delay but fails with
delay)
in my real code i tried also to delay the start with a Timer - no matter
how long the start is deferred it works fine. but as soon as continueStart
is run after onModuleLoad() - eventBased delay it fails. in meantime
deferred it synchronously by implementing start() like this:
new SchedulerImpl().scheduleDeferred(new ScheduledCommand() {
@Override
public void execute() {
while (!(ttReady auReady)) {
System.out.println(waiting);
}
continueStart();
}
});
This is working fine. The time of delaying is the same as before: as soon
as tt and are become ready. but for interest i want to know/understand what
is happening here.
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Re: problems with loading stuff/bootstrapping onModuleLoad triggered by an event
As I said: handleCurrentHistory() is called from within onAdminUnitSelected, i.e. an event dispatch. Delay it (either just handleCurrentHistory() or the whole continueStart()) with Scheduler#scheduleFinally to make it execute *outside* the event dispatching, so that the place change handlers are *effectively* registered (on not kept on hold by the SimpleEventBus until the end of the current dispatch). -- You received this message because you are subscribed to the Google Groups Google Web Toolkit group. To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/SsSWpg5inGsJ. To post to this group, send email to google-web-toolkit@googlegroups.com. To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
problems with loading stuff/bootstrapping onModuleLoad triggered by an event
the scenario is as follows (i use gin): - onModuleLoad instantiates a ApplicationManager and runs start() on it. - ApplicationManager sets up all activitymanagers and the layout, gives every manager some display area, sets up history handler and start history (historyHandler.handleCurrentHistory();) all is running fine but i want the application manager to defer the loading until an event (data-loaded-event). so i make the manager listen to it and all the setup-stuff is done in a new method continueStart(); called on this event. the former start() (called in onModuleLoad) just displays a loading widget. but now no activity is started. i debugged into the code. it seems that with this deferred loading the ActivityManagers don't hear the PlaceChangeEvent fired by historyHandler.handleCurrentHistory(); (The Eventbus emitting this event is the same the ActivityManager registered on) So what's going on here? my only explanation at the moment is, that this could be related to the fact that all the application setup stuff happens after onModuleLoad has finished (it only calls start(), and in background applicationManager is waiting for an event and does the reals setup after onModulLoad()) so what to do - thx in advance -- You received this message because you are subscribed to the Google Groups Google Web Toolkit group. To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/7mOwGd4TlfgJ. To post to this group, send email to google-web-toolkit@googlegroups.com. To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
