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

   1 /*
   2  * Copyright (C) 2007-2012 Argeo GmbH
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *         http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 package org.argeo.eclipse.ui.jcr;
  17
  18 import java.util.ArrayList;
  19 import java.util.List;
  20
  21 import javax.jcr.RepositoryException;
  22 import javax.jcr.observation.Event;
  23 import javax.jcr.observation.EventIterator;
  24 import javax.jcr.observation.EventListener;
  25
  26 import org.apache.commons.logging.Log;
  27 import org.apache.commons.logging.LogFactory;
  28 import org.argeo.ArgeoException;
  29 import org.eclipse.swt.widgets.Display;
  30
  31 /** {@link EventListener} which simplifies running actions within the UI thread. */
  32 public abstract class AsyncUiEventListener implements EventListener {
  33 //      private final static Log logSuper = LogFactory
  34 //                      .getLog(AsyncUiEventListener.class);
  35         private final Log logThis = LogFactory.getLog(getClass());
  36
  37         private final Display display;
  38
  39         public AsyncUiEventListener(Display display) {
  40                 super();
  41                 this.display = display;
  42         }
  43
  44         /** Called asynchronously in the UI thread. */
  45         protected abstract void onEventInUiThread(List<Event> events)
  46                         throws RepositoryException;
  47
  48         /**
  49          * Whether these events should be processed in the UI or skipped with no UI
  50          * job created.
  51          */
  52         protected Boolean willProcessInUiThread(List<Event> events)
  53                         throws RepositoryException {
  54                 return true;
  55         }
  56
  57         protected Log getLog() {
  58                 return logThis;
  59         }
  60
  61         public final void onEvent(final EventIterator eventIterator) {
  62                 final List<Event> events = new ArrayList<Event>();
  63                 while (eventIterator.hasNext())
  64                         events.add(eventIterator.nextEvent());
  65
  66                 if (logThis.isTraceEnabled())
  67                         logThis.trace("Received " + events.size() + " events");
  68
  69                 try {
  70                         if (!willProcessInUiThread(events))
  71                                 return;
  72                 } catch (RepositoryException e) {
  73                         throw new ArgeoException("Cannot test skip events " + events, e);
  74                 }
  75
  76 //              Job job = new Job("JCR Events") {
  77 //                      protected IStatus run(IProgressMonitor monitor) {
  78 //                              if (display.isDisposed()) {
  79 //                                      logSuper.warn("Display is disposed cannot update UI");
  80 //                                      return Status.CANCEL_STATUS;
  81 //                              }
  82
  83                                 display.asyncExec(new Runnable() {
  84                                         public void run() {
  85                                                 try {
  86                                                         onEventInUiThread(events);
  87                                                 } catch (RepositoryException e) {
  88                                                         throw new ArgeoException("Cannot process events "
  89                                                                         + events, e);
  90                                                 }
  91                                         }
  92                                 });
  93
  94 //                              return Status.OK_STATUS;
  95 //                      }
  96 //              };
  97 //              job.schedule();
  98         }
  99 }