FWD » Core Development » User Interface

I found the following stack trace in client log:

java.lang.IllegalStateException: There is no point to use incremental scroll for scrolling forward if the page is not full.
    at com.goldencode.p2j.ui.client.Browse.incrementalScroll(Browse.java:763)
    at com.goldencode.p2j.ui.client.Browse.incrementalScroll(Browse.java:730)
    at com.goldencode.p2j.ui.client.Browse.onKeyPressed(Browse.java:3673)
    at com.goldencode.p2j.ui.client.gui.BrowseGuiImpl.onKeyPressed(BrowseGuiImpl.java:3524)
    at com.goldencode.p2j.ui.client.Browse.processEvent(Browse.java:3863)
    at com.goldencode.p2j.ui.client.gui.BrowseGuiImpl.processEvent(BrowseGuiImpl.java:3561)
    at com.goldencode.p2j.ui.client.widget.TitledWindow.processEvent(TitledWindow.java:249)
    at com.goldencode.p2j.ui.client.gui.WindowGuiImpl.processEvent(WindowGuiImpl.java:1365)
    at com.goldencode.p2j.ui.chui.ThinClient.processEventsWorker(ThinClient.java:16667)
    at com.goldencode.p2j.ui.chui.ThinClient.pop(ThinClient.java:15453)
    at com.goldencode.p2j.ui.chui.ThinClient.eventBracket(ThinClient.java:15436)
    at com.goldencode.p2j.ui.chui.ThinClient.eventDrawingBracket(ThinClient.java:15360)
    at com.goldencode.p2j.ui.chui.ThinClient.applyWorker(ThinClient.java:15121)
    at com.goldencode.p2j.ui.chui.ThinClient.apply(ThinClient.java:3648)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.goldencode.p2j.util.MethodInvoker.invoke(MethodInvoker.java:124)
    at com.goldencode.p2j.net.Dispatcher.processInbound(Dispatcher.java:757)
    at com.goldencode.p2j.net.Conversation.block(Conversation.java:412)
    at com.goldencode.p2j.net.Conversation.waitMessage(Conversation.java:348)
    at com.goldencode.p2j.net.Queue.transactImpl(Queue.java:1170)
    at com.goldencode.p2j.net.Queue.transact(Queue.java:641)
    at com.goldencode.p2j.net.BaseSession.transact(BaseSession.java:271)
    at com.goldencode.p2j.net.HighLevelObject.transact(HighLevelObject.java:211)
    at com.goldencode.p2j.net.RemoteObject$RemoteAccess.invokeCore(RemoteObject.java:1473)
    at com.goldencode.p2j.net.InvocationStub.invoke(InvocationStub.java:145)
    at com.sun.proxy.$Proxy2.trigger(Unknown Source)
    at com.goldencode.p2j.ui.chui.ThinClient.trigger(ThinClient.java:12846)
    at com.goldencode.p2j.ui.chui.ThinClient.invokeTriggers(ThinClient.java:18334)
    at com.goldencode.p2j.ui.chui.ThinClient.invokeTriggers(ThinClient.java:18065)
    at com.goldencode.p2j.ui.chui.ThinClient.processProgressEvent(ThinClient.java:17177)
    at com.goldencode.p2j.ui.chui.ThinClient.processEventsWorker(ThinClient.java:16454)
    at com.goldencode.p2j.ui.chui.ThinClient.pop(ThinClient.java:15453)
    at com.goldencode.p2j.ui.chui.ThinClient.eventBracket(ThinClient.java:15436)
    at com.goldencode.p2j.ui.chui.ThinClient.eventDrawingBracket(ThinClient.java:15360)
    at com.goldencode.p2j.ui.chui.ThinClient.applyWorker(ThinClient.java:15121)
    at com.goldencode.p2j.ui.chui.ThinClient.waitForWorker(ThinClient.java:12193)
    at com.goldencode.p2j.ui.chui.ThinClient.waitForWorker(ThinClient.java:11677)
    at com.goldencode.p2j.ui.chui.ThinClient.waitFor(ThinClient.java:11620)
    at com.goldencode.p2j.ui.chui.ThinClient.waitFor(ThinClient.java:11574)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.goldencode.p2j.util.MethodInvoker.invoke(MethodInvoker.java:124)
    at com.goldencode.p2j.net.Dispatcher.processInbound(Dispatcher.java:757)
    at com.goldencode.p2j.net.Conversation.block(Conversation.java:412)
    at com.goldencode.p2j.net.Conversation.waitMessage(Conversation.java:348)
    at com.goldencode.p2j.net.Queue.transactImpl(Queue.java:1170)
    at com.goldencode.p2j.net.Queue.transact(Queue.java:641)
    at com.goldencode.p2j.net.BaseSession.transact(BaseSession.java:271)
    at com.goldencode.p2j.net.HighLevelObject.transact(HighLevelObject.java:211)
    at com.goldencode.p2j.net.RemoteObject$RemoteAccess.invokeCore(RemoteObject.java:1473)
    at com.goldencode.p2j.net.InvocationStub.invoke(InvocationStub.java:145)
    at com.sun.proxy.$Proxy4.standardEntry(Unknown Source)
    at com.goldencode.p2j.main.ClientCore.start(ClientCore.java:361)
    at com.goldencode.p2j.main.ClientCore.start(ClientCore.java:158)
    at com.goldencode.p2j.main.ClientDriver.start(ClientDriver.java:250)
    at com.goldencode.p2j.main.CommonDriver.process(CommonDriver.java:444)
    at com.goldencode.p2j.main.ClientDriver.process(ClientDriver.java:144)
    at com.goldencode.p2j.main.ClientDriver.main(ClientDriver.java:313)

This is a non-fatal event. There are no clues in the UI that something wrong happened, the client apparently continues to process messages from server. I am not able to pinpoint the exact cause and create a list of steps how to duplicate this.

The call to incrementalScroll is caused by an

APPLY "END":U TO BROWSE my-browse.

Throwing the exception is not fatal because the Exception is caught in processEventsWorker and just printed to System.err

I think throwing the exception in Browse:763 is not correct. The message should probably be logged as Warning instead.

That is the event which represents a programming error. The text can be changed to "Incremental scroll cannot be used for scrolling forward if the page is not full." However browse can continue its work without abending. The error probably should be raised using recordOrShowError.

Let me know if I should fix it (before/after deadline?).

Is there an error in the 4GL?

No, it's internal P2J error.

No, it's internal P2J error.

recordOrShowError() is only for "real" 4GL errors.

Is this a P2J bug?

Yes.

How much work is it to fix?

I'm not sure.
Ovidiu, how did you managed to create a 0 DOWN browse? (normally you can't create a browse with less than 2 DOWN)
Is there a testcase?

Stanislav Lomany wrote:

I'm not sure.
Ovidiu, how did you managed to create a 0 DOWN browse? (normally you can't create a browse with less than 2 DOWN)
Is there a testcase?

I am sending the instructions by mail because of sensitive information.

The issue occurs because the browse is not yet initialized at the point when "END" event is applied. So we must figure out the point where it is initialized in the original app.

How much work is it to fix?

I guess around a full day.

Greg, I'll fix it, but considering the amount of work for #3261 I'm not sure if I should fix it before or after Nov 30.

Ovidiu: Does this affect a user or is it just a report in the log?

I noticed that in the log, but throwing exceptions in this manner is dangerous. This time the incrementalScroll() was called from a event loop that caught it and logged it. If called from another place the client will crash. I thing we should log the event instead (UnimplementedFeature.TODO) as a reminder and return false because no rows were obtained from the server.

Agreed.

Stanislav: Please put that change in 3369a. Then you can fix this issue later.

I thing we should log the event instead (UnimplementedFeature.TODO) as a reminder and return false because no rows were obtained from the server.

It's a client-side error. Should I log it at server side (BTW how can I do that?) ?

It is OK to call UnimplementedFeature on the client. It will be logged there and that is OK.

Since 3369a is merged to trunk, at this point I hope you can just fix this issue properly.

The changes are included in task branch 3394a which has been merged to trunk as revision 11214.