NetBeans' HintsController and EventQueue

Question

We are building an application based on the Netbeans Platform, and one part of it is an editor for a specific language we use.

We have the following class to highlight errors in the syntax:

class SyntaxErrorsHighlightingTask extends org.netbeans.modules.parsing.spi.ParserResultTask {

public SyntaxErrorsHighlightingTask () {
}

@Override
public void run (org.netbeans.modules.parsing.spi.Parser.Result result, org.netbeans.modules.parsing.spi.SchedulerEvent event) {
    try {
        final javax.swing.text.Document document = result.getSnapshot().getSource ().getDocument(false);
        final List<ErrorDescription> errors = new ArrayList<ErrorDescription> ();
        // finds errors on the document and add them to 'errors' list
        }

        /***
        OFFENDING CODE GOES HERE
        ***/

    } catch (javax.swing.text.BadLocationException ex1) {
        org.openide.util.Exceptions.printStackTrace (ex1);
    } catch (org.netbeans.modules.parsing.spi.ParseException ex1) {
        Exceptions.printStackTrace (ex1);
    }
}

@Override
public int getPriority () {
    return 100;
}

@Override
public Class<? extends Scheduler> getSchedulerClass () {
    return Scheduler.EDITOR_SENSITIVE_TASK_SCHEDULER;
}

@Override
public void cancel () {
}

}

The offending code, that throws an exception, is this:

org.netbeans.spi.editor.hints.HintsController.setErrors (document, "testsequence", errors);

Based on searching results, it was changed to the following:

SwingUtilities.invokeLater(new Runnable() {

                @Override
                public void run() {
                     System.err.println("is EDT? " + SwingUtilities.isEventDispatchThread());
                     HintsController.setErrors (document, "testsequence", errors);
                }
           });

The following is what happens when a syntax error is introduced in the editor:

is EDT? true
SEVERE [org.openide.util.RequestProcessor]: Error in RequestProcessor org.netbeans.spi.editor.hints.HintsController$1
java.lang.IllegalStateException: Must be run in EQ
    at org.netbeans.editor.Annotations.addAnnotation(Annotations.java:195)
    at org.netbeans.modules.editor.NbEditorDocument.addAnnotation(NbEditorDocument.java:251)
    at org.openide.text.NbDocument.addAnnotation(NbDocument.java:504)
    at org.netbeans.modules.editor.hints.AnnotationHolder$NbDocumentAttacher.attachAnnotation(AnnotationHolder.java:235)
    at org.netbeans.modules.editor.hints.AnnotationHolder.attachAnnotation(AnnotationHolder.java:208)
    at org.netbeans.modules.editor.hints.AnnotationHolder.updateAnnotationOnLine(AnnotationHolder.java:674)
    at org.netbeans.modules.editor.hints.AnnotationHolder.setErrorDescriptionsImpl(AnnotationHolder.java:899)
    at org.netbeans.modules.editor.hints.AnnotationHolder.access$1300(AnnotationHolder.java:113)
    at org.netbeans.modules.editor.hints.AnnotationHolder$4.run(AnnotationHolder.java:812)
    at org.netbeans.editor.BaseDocument.render(BaseDocument.java:1409)
    at org.netbeans.modules.editor.hints.AnnotationHolder.setErrorDescriptions(AnnotationHolder.java:809)
    at org.netbeans.modules.editor.hints.HintsControllerImpl.setErrorsImpl(HintsControllerImpl.java:111)
    at org.netbeans.modules.editor.hints.HintsControllerImpl.setErrors(HintsControllerImpl.java:93)
    at org.netbeans.spi.editor.hints.HintsController$1.run(HintsController.java:79)
    at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1424)
    at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1968)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to
    at org.openide.util.RequestProcessor.post(RequestProcessor.java:425)
    at org.netbeans.spi.editor.hints.HintsController.setErrors(HintsController.java:77)
    at com.#.#.#.editor.parser.SyntaxErrorsHighlightingTask$1.run(SyntaxErrorsHighlightingTask.java:74)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:641)
    at java.awt.EventQueue.access$000(EventQueue.java:84)
    at java.awt.EventQueue$1.run(EventQueue.java:602)
    at java.awt.EventQueue$1.run(EventQueue.java:600)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:611)
    at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:148)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
[catch] at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

What happens is, the call is to HintsController is being made in the EDT (EventDispatch Thread). However, Annotations.addAnnotation() is being run in another thread - sometimes in the "System clipboard synchronizer" thread, sometimes in the "Inactive RequestProcessor" thread. Since it checks if its being run on the EDT, it always throws an IllegalStateException.

I'm no expert in using the Netbeans Platform, and I'm pretty new to this specific application on the company - so I might be missing something really obvious. Google didn't help much. Anyone has any advice?

Answer 1

Turns out, it was not a problem with the code after all.

As pointed on the NetBeans-dev list:

HintsController.setErrors can be called from any thread - it uses its own worker thread, and reschedules to AWT thread when necessary.

The requirement to invoke Annotations.addAnnotation in AWT thread has been removed quite some time ago by: http://hg.netbeans.org/main-silver/rev/db82e4e0fbcc

The same changeset also removed automatic rescheduling into AWT thread in NbDocument.addAnnotation. So it seems that the build you are using has the second part of the changeset, but not the first part (...)

After a careful review of maven's pom.xml files, I realized that the application was loading newer versions of the libs while the module was loading older versions, so it would run the wrong code. Related SO question about that here.

Answer 2

Maybe you should try to update your errors with a method like this one :

private void updateError(javax.swing.text.Document document, List<ErrorDescription> errors) {
    if(javax.swing.SwingUtilities.isEventDispatchThread()) {
        HintsController.setErrors (document, "testsequence", errors);
    }
    else {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                 HintsController.setErrors (document, "testsequence", errors);
            }
       });
    }    
}