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.argeo.api.cms.CmsLog;
  12 import org.argeo.eclipse.ui.EclipseUiException;
  13 import org.eclipse.swt.widgets.Display;
  14
  15 /**
  16  * {@link EventListener} which simplifies running actions within the UI thread.
  17  */
  18 public abstract class AsyncUiEventListener implements EventListener {
  19         // private final static Log logSuper = LogFactory
  20         // .getLog(AsyncUiEventListener.class);
  21         private final CmsLog logThis = CmsLog.getLog(getClass());
  22
  23         private final Display display;
  24
  25         public AsyncUiEventListener(Display display) {
  26                 super();
  27                 this.display = display;
  28         }
  29
  30         /** Called asynchronously in the UI thread. */
  31         protected abstract void onEventInUiThread(List<Event> events) 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) throws RepositoryException {
  38                 return true;
  39         }
  40
  41         protected CmsLog getLog() {
  42                 return logThis;
  43         }
  44
  45         public final void onEvent(final EventIterator eventIterator) {
  46                 final List<Event> events = new ArrayList<Event>();
  47                 while (eventIterator.hasNext())
  48                         events.add(eventIterator.nextEvent());
  49
  50                 if (logThis.isTraceEnabled())
  51                         logThis.trace("Received " + events.size() + " events");
  52
  53                 try {
  54                         if (!willProcessInUiThread(events))
  55                                 return;
  56                 } catch (RepositoryException e) {
  57                         throw new EclipseUiException("Cannot test skip events " + events, e);
  58                 }
  59
  60                 // Job job = new Job("JCR Events") {
  61                 // protected IStatus run(IProgressMonitor monitor) {
  62                 // if (display.isDisposed()) {
  63                 // logSuper.warn("Display is disposed cannot update UI");
  64                 // return Status.CANCEL_STATUS;
  65                 // }
  66
  67                 if (!display.isDisposed())
  68                         display.asyncExec(new Runnable() {
  69                                 public void run() {
  70                                         try {
  71                                                 onEventInUiThread(events);
  72                                         } catch (RepositoryException e) {
  73                                                 throw new EclipseUiException("Cannot process events " + events, e);
  74                                         }
  75                                 }
  76                         });
  77
  78                 // return Status.OK_STATUS;
  79                 // }
  80                 // };
  81                 // job.schedule();
  82         }
  83 }