org.argeo.cms.ui/src/org/argeo/eclipse/ui/jcr/AsyncUiEventListener.java

   1 package org.argeo.eclipse.ui.jcr;
   2
   3 import java.util.ArrayList;
   4 import java.util.List;
   5
   6 import javax.jcr.RepositoryException;
   7 import javax.jcr.observation.Event;
   8 import javax.jcr.observation.EventIterator;
   9 import javax.jcr.observation.EventListener;
  10
  11 import org.apache.commons.logging.Log;
  12 import org.apache.commons.logging.LogFactory;
  13 import org.argeo.eclipse.ui.EclipseUiException;
  14 import org.eclipse.swt.widgets.Display;
  15
  16 /**
  17  * {@link EventListener} which simplifies running actions within the UI thread.
  18  */
  19 public abstract class AsyncUiEventListener implements EventListener {
  20         // private final static Log logSuper = LogFactory
  21         // .getLog(AsyncUiEventListener.class);
  22         private final Log logThis = LogFactory.getLog(getClass());
  23
  24         private final Display display;
  25
  26         public AsyncUiEventListener(Display display) {
  27                 super();
  28                 this.display = display;
  29         }
  30
  31         /** Called asynchronously in the UI thread. */
  32         protected abstract void onEventInUiThread(List<Event> events) throws RepositoryException;
  33
  34         /**
  35          * Whether these events should be processed in the UI or skipped with no UI
  36          * job created.
  37          */
  38         protected Boolean willProcessInUiThread(List<Event> events) throws RepositoryException {
  39                 return true;
  40         }
  41
  42         protected Log getLog() {
  43                 return logThis;
  44         }
  45
  46         public final void onEvent(final EventIterator eventIterator) {
  47                 final List<Event> events = new ArrayList<Event>();
  48                 while (eventIterator.hasNext())
  49                         events.add(eventIterator.nextEvent());
  50
  51                 if (logThis.isTraceEnabled())
  52                         logThis.trace("Received " + events.size() + " events");
  53
  54                 try {
  55                         if (!willProcessInUiThread(events))
  56                                 return;
  57                 } catch (RepositoryException e) {
  58                         throw new EclipseUiException("Cannot test skip events " + events, e);
  59                 }
  60
  61                 // Job job = new Job("JCR Events") {
  62                 // protected IStatus run(IProgressMonitor monitor) {
  63                 // if (display.isDisposed()) {
  64                 // logSuper.warn("Display is disposed cannot update UI");
  65                 // return Status.CANCEL_STATUS;
  66                 // }
  67
  68                 if (!display.isDisposed())
  69                         display.asyncExec(new Runnable() {
  70                                 public void run() {
  71                                         try {
  72                                                 onEventInUiThread(events);
  73                                         } catch (RepositoryException e) {
  74                                                 throw new EclipseUiException("Cannot process events " + events, e);
  75                                         }
  76                                 }
  77                         });
  78
  79                 // return Status.OK_STATUS;
  80                 // }
  81                 // };
  82                 // job.schedule();
  83         }
  84 }