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.ArgeoException;
  14 import org.eclipse.core.runtime.IProgressMonitor;
  15 import org.eclipse.core.runtime.IStatus;
  16 import org.eclipse.core.runtime.Status;
  17 import org.eclipse.core.runtime.jobs.Job;
  18 import org.eclipse.swt.widgets.Display;
  19
  20 /** {@link EventListener} which simplifies running actions within the UI thread. */
  21 public abstract class AsyncUiEventListener implements EventListener {
  22         private final static Log logSuper = LogFactory
  23                         .getLog(AsyncUiEventListener.class);
  24         private final Log logThis = LogFactory.getLog(getClass());
  25
  26         private final Display display;
  27
  28         public AsyncUiEventListener(Display display) {
  29                 super();
  30                 this.display = display;
  31         }
  32
  33         /** Called asynchronously in the UI thread. */
  34         protected abstract void onEventInUiThread(List<Event> events)
  35                         throws RepositoryException;
  36
  37         /**
  38          * Whether these events should be processed in the UI or skipped with no UI
  39          * job created.
  40          */
  41         protected Boolean willProcessInUiThread(List<Event> events)
  42                         throws RepositoryException {
  43                 return true;
  44         }
  45
  46         protected Log getLog() {
  47                 return logThis;
  48         }
  49
  50         public final void onEvent(final EventIterator eventIterator) {
  51                 final List<Event> events = new ArrayList<Event>();
  52                 while (eventIterator.hasNext())
  53                         events.add(eventIterator.nextEvent());
  54
  55                 if (logThis.isDebugEnabled())
  56                         logThis.debug("Received " + events.size() + " events");
  57
  58                 try {
  59                         if (!willProcessInUiThread(events))
  60                                 return;
  61                 } catch (RepositoryException e) {
  62                         throw new ArgeoException("Cannot test skip events " + events, e);
  63                 }
  64
  65 //              Job job = new Job("JCR Events") {
  66 //                      protected IStatus run(IProgressMonitor monitor) {
  67 //                              if (display.isDisposed()) {
  68 //                                      logSuper.warn("Display is disposed cannot update UI");
  69 //                                      return Status.CANCEL_STATUS;
  70 //                              }
  71
  72                                 display.asyncExec(new Runnable() {
  73                                         public void run() {
  74                                                 try {
  75                                                         onEventInUiThread(events);
  76                                                 } catch (RepositoryException e) {
  77                                                         throw new ArgeoException("Cannot process events "
  78                                                                         + events, e);
  79                                                 }
  80                                         }
  81                                 });
  82
  83 //                              return Status.OK_STATUS;
  84 //                      }
  85 //              };
  86 //              job.schedule();
  87         }
  88 }