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.ArgeoException;
  14 import org.eclipse.swt.widgets.Display;
  15
  16 /** {@link EventListener} which simplifies running actions within the UI thread. */
  17 public abstract class AsyncUiEventListener implements EventListener {
  18 //      private final static Log logSuper = LogFactory
  19 //                      .getLog(AsyncUiEventListener.class);
  20         private final Log logThis = LogFactory.getLog(getClass());
  21
  22         private final Display display;
  23
  24         public AsyncUiEventListener(Display display) {
  25                 super();
  26                 this.display = display;
  27         }
  28
  29         /** Called asynchronously in the UI thread. */
  30         protected abstract void onEventInUiThread(List<Event> events)
  31                         throws RepositoryException;
  32
  33         /**
  34          * Whether these events should be processed in the UI or skipped with no UI
  35          * job created.
  36          */
  37         protected Boolean willProcessInUiThread(List<Event> events)
  38                         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 ArgeoException("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                                 display.asyncExec(new Runnable() {
  69                                         public void run() {
  70                                                 try {
  71                                                         onEventInUiThread(events);
  72                                                 } catch (RepositoryException e) {
  73                                                         throw new ArgeoException("Cannot process events "
  74                                                                         + events, e);
  75                                                 }
  76                                         }
  77                                 });
  78
  79 //                              return Status.OK_STATUS;
  80 //                      }
  81 //              };
  82 //              job.schedule();
  83         }
  84 }