Package at.bestsolution.efxclipse.runtime.events

Source Code of at.bestsolution.efxclipse.runtime.events.EventBroker

/*******************************************************************************
* Copyright (c) 2009, 2010 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
*     IBM Corporation - initial API and implementation
*******************************************************************************/
package at.bestsolution.efxclipse.runtime.events;

import java.util.Collection;
import java.util.Dictionary;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;

import javax.annotation.PreDestroy;
import javax.inject.Inject;

import org.eclipse.e4.core.di.annotations.Optional;
import org.eclipse.e4.core.services.events.IEventBroker;
import org.eclipse.e4.ui.di.UISynchronize;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.BundleException;
import org.osgi.framework.ServiceRegistration;
import org.osgi.service.event.Event;
import org.osgi.service.event.EventAdmin;
import org.osgi.service.event.EventConstants;
import org.osgi.service.event.EventHandler;

import at.bestsolution.efxclipse.runtime.core.log.Log;
import at.bestsolution.efxclipse.runtime.core.log.Logger;

@SuppressWarnings("restriction")
public class EventBroker implements IEventBroker {
 
  // TBD synchronization
  private Map<EventHandler, ServiceRegistration> registrations = new HashMap<EventHandler, ServiceRegistration>();

  @Inject
  @Optional
  UISynchronize uiSync;
 
  @Inject
  @Log
  Logger logger;
 
  // This is a temporary code to ensure that bundle containing
  // EventAdmin implementation is started. This code it to be removed once
  // the proper method to start EventAdmin is added.
  static {
    EventAdmin eventAdmin = Activator.getEventAdmin();
    if (eventAdmin == null) {
      Bundle[] bundles = Activator.getContext().getBundles();
      for (Bundle bundle : bundles) {
        if (!"org.eclipse.equinox.event".equals(bundle.getSymbolicName()))
          continue;
        try {
          bundle.start(Bundle.START_TRANSIENT);
        } catch (BundleException e) {
          e.printStackTrace();
        }
        break;
      }
    }
  }
 
  public EventBroker() {
    // placeholder
  }

  public boolean send(String topic, Object data) {
    Event event = constructEvent(topic, data);
    EventAdmin eventAdmin = Activator.getEventAdmin();
    if (eventAdmin == null) {
      logger.error("No event admin found");
      return false;
    }
    eventAdmin.sendEvent(event);
    return true;
  }

  public boolean post(String topic, Object data) {
    Event event = constructEvent(topic, data);
    EventAdmin eventAdmin = Activator.getEventAdmin();
    if (eventAdmin == null) {
      logger.error("No event admin found");
      return false;
    }
    eventAdmin.postEvent(event);
    return true;
  }

  @SuppressWarnings("unchecked")
  private Event constructEvent(String topic, Object data) {
    Event event;
    if (data instanceof Dictionary<?,?>) {
      event = new Event(topic, (Dictionary<String,?>)data);
    } else if (data instanceof Map<?,?>) {
      event = new Event(topic, (Map<String,?>)data);
    } else {
      Dictionary<String, Object> d = new Hashtable<String, Object>(2);
      d.put(EventConstants.EVENT_TOPIC, topic);
      if (data != null)
        d.put(IEventBroker.DATA, data);
      event = new Event(topic, d);
    }
    return event;
  }

  public boolean subscribe(String topic, EventHandler eventHandler) {
    return subscribe(topic, null, eventHandler, false);
  }
 
  public boolean subscribe(String topic, String filter, EventHandler eventHandler, boolean headless) {
    BundleContext bundleContext = Activator.getContext();
    if (bundleContext == null) {
      logger.error("No bundle context");
      return false;
    }
    String[] topics = new String[] {topic};
    Dictionary<String, Object> d = new Hashtable<String, Object>();
    d.put(EventConstants.EVENT_TOPIC, topics);
    if (filter != null)
      d.put(EventConstants.EVENT_FILTER, filter);
    EventHandler wrappedHandler = new UIEventHandler(eventHandler, headless ? null : uiSync);
    ServiceRegistration registration = bundleContext.registerService(EventHandler.class.getName(), wrappedHandler, d);
    registrations.put(eventHandler, registration);
    return true;
  }

  public boolean unsubscribe(EventHandler eventHandler) {
    ServiceRegistration registration = (ServiceRegistration) registrations.remove(eventHandler);
    if (registration == null)
      return false;
    registration.unregister();
    return true;
  }
 
  @PreDestroy
  void dispose() {
    Collection<ServiceRegistration> values = registrations.values();
    ServiceRegistration[] array = values.toArray(new ServiceRegistration[values.size()]);
    registrations.clear();
    for (int i = 0; i < array.length; i++) {
      array[i].unregister();
    }
  }
}
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