/**
* This file Copyright (c) 2003-2012 Magnolia International
* Ltd. (http://www.magnolia-cms.com). All rights reserved.
*
*
* This file is dual-licensed under both the Magnolia
* Network Agreement and the GNU General Public License.
* You may elect to use one or the other of these licenses.
*
* This file is distributed in the hope that it will be
* useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
* implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
* Redistribution, except as permitted by whichever of the GPL
* or MNA you select, is prohibited.
*
* 1. For the GPL license (GPL), you can redistribute and/or
* modify this file under the terms of the GNU General
* Public License, Version 3, as published by the Free Software
* Foundation. You should have received a copy of the GNU
* General Public License, Version 3 along with this program;
* if not, write to the Free Software Foundation, Inc., 51
* Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* 2. For the Magnolia Network Agreement (MNA), this file
* and the accompanying materials are made available under the
* terms of the MNA which accompanies this distribution, and
* is available at http://www.magnolia-cms.com/mna.html
*
* Any modifications to this file must keep this entire header
* intact.
*
*/
package info.magnolia.cms.util;
import info.magnolia.context.LifeTimeJCRSessionUtil;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.jcr.RepositoryException;
import javax.jcr.Session;
import javax.jcr.Workspace;
import javax.jcr.observation.Event;
import javax.jcr.observation.EventIterator;
import javax.jcr.observation.EventListener;
import javax.jcr.observation.ObservationManager;
import org.apache.jackrabbit.core.observation.ObservationManagerImpl;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Util to register JCR observations. Supports delayed execution of the listener to handle event bursts.
*
* @version $Id$
*/
public class ObservationUtil {
private final static Logger log = LoggerFactory.getLogger(ObservationUtil.class);
private static final int ALL_EVENT_TYPES_MASK = Event.NODE_ADDED | Event.NODE_REMOVED | Event.NODE_MOVED | Event.PROPERTY_ADDED | Event.PROPERTY_CHANGED | Event.PROPERTY_REMOVED;
/**
* Unregisters all EventListeners for the given workspace.
*/
public static void dispose(String workspace) {
try {
ObservationManager om = getObservationManager(workspace);
if(om instanceof ObservationManagerImpl) {
((ObservationManagerImpl)om).dispose();
} else {
log.warn("Observation can not be disposed ");
}
} catch (RepositoryException e) {
log.error("Unable to Unregisters all EventListeners for the following workspace "+workspace, e);
}
}
/**
* Registers an EventListener for any node type.
*
* @see #registerChangeListener(String,String,boolean,String[],javax.jcr.observation.EventListener)
*/
public static void registerChangeListener(String workspace, String observationPath, EventListener listener) {
registerChangeListener(workspace, observationPath, true, listener);
}
/**
* Registers an EventListener for any node type.
*
* @see #registerChangeListener(String,String,boolean,String[],javax.jcr.observation.EventListener)
*/
public static void registerChangeListener(String workspace, String observationPath, boolean includeSubnodes, EventListener listener) {
registerChangeListener(workspace, observationPath, includeSubnodes, (String[]) null, listener);
}
/**
* Registers an EventListener for a specific node type.
*
* @see #registerChangeListener(String,String,boolean,String[],javax.jcr.observation.EventListener)
*/
public static void registerChangeListener(String workspace, String observationPath, boolean includeSubnodes, String nodeType, EventListener listener) {
registerChangeListener(workspace, observationPath, includeSubnodes, new String[] { nodeType }, listener);
}
/**
* Registers an EventListener for a specific node type and event types.
*
* @see #registerChangeListener(String,String,boolean,String[],int,javax.jcr.observation.EventListener)
*/
public static void registerChangeListener(String workspace, String observationPath, boolean includeSubnodes, String nodeType, int eventTypesMask, EventListener listener) {
if (nodeType == null) {
registerChangeListener(workspace, observationPath, includeSubnodes, (String[]) null, eventTypesMask, listener);
} else {
registerChangeListener(workspace, observationPath, includeSubnodes, new String[] { nodeType }, eventTypesMask, listener);
}
}
/**
* Registers an EventListener for a specific set of node types and event types.
*
* @see #registerChangeListener(String, String, boolean, String[], int, javax.jcr.observation.EventListener)
*/
public static void registerChangeListener(String workspace, String observationPath, boolean includeSubnodes, String[] nodeTypes, EventListener listener) {
registerChangeListener(workspace, observationPath, includeSubnodes, nodeTypes, ALL_EVENT_TYPES_MASK, listener);
}
/**
* Register a single event listener, bound to the given path. Be careful
* that if you observe "/", events are going to be generated for jcr:system,
* which is "shared" across all workspaces.
*
* @param workspace
* @param observationPath workspace path
* @param includeSubnodes the isDeep parameter of ObservationManager.addEventListener()
* @param nodeTypes the node types to filter events for
* @param eventTypesMask an ORed mask of even types (Event constants)
* @param listener event listener
* @see ObservationManager#addEventListener
* @see Event
*/
public static void registerChangeListener(String workspace, String observationPath, boolean includeSubnodes, String[] nodeTypes, int eventTypesMask, EventListener listener) {
log.debug("Registering event listener for path [{}]", observationPath); //$NON-NLS-1$
try {
ObservationManager observationManager = getObservationManager(workspace);
if (observationManager == null) {
log.error("Unable to add event listeners for " + observationPath); //$NON-NLS-1$
throw new IllegalStateException("Observation manager can't be obtained due to invalid session.");
}
observationManager.addEventListener(listener, eventTypesMask, observationPath, includeSubnodes, null, nodeTypes, false);
} catch (RepositoryException e) {
log.error("Unable to add event listeners for " + observationPath, e); //$NON-NLS-1$
}
}
public static void registerDeferredChangeListener(String workspace, String observationPath, EventListener listener, long delay, long maxDelay) {
registerDeferredChangeListener(workspace, observationPath, true, (String[]) null, listener, delay, maxDelay);
}
public static void registerDeferredChangeListener(String workspace, String observationPath, boolean includeSubnodes, EventListener listener, long delay, long maxDelay) {
registerDeferredChangeListener(workspace, observationPath, includeSubnodes, (String[]) null, listener, delay, maxDelay);
}
public static void registerDeferredChangeListener(String workspace, String observationPath, boolean includeSubnodes, String nodeType, EventListener listener, long delay, long maxDelay) {
registerDeferredChangeListener(workspace, observationPath, includeSubnodes, new String[] { nodeType }, listener, delay, maxDelay);
}
/**
* The event firing is deferred in case there is a series of fired events.
*
* @return the wrapped EventListener so that one can unregister it.
*/
public static void registerDeferredChangeListener(String workspace, String observationPath, boolean includeSubnodes, String[] nodeTypes, EventListener listener, long delay, long maxDelay) {
final EventListener deferredListener = instanciateDeferredEventListener(listener, delay, maxDelay);
registerChangeListener(workspace, observationPath, includeSubnodes, nodeTypes, deferredListener);
}
/**
* Use this and register the returned EventListener with the
* registerChangeListener() methods, if you need to be able to later
* unregister your EventListener.
*/
public static EventListener instanciateDeferredEventListener(EventListener listener, long delay, long maxDelay) {
return new DeferringEventListener(listener, delay, maxDelay);
}
public static void unregisterChangeListener(String workspace, EventListener listener) {
try {
ObservationManager om = getObservationManager(workspace);
if (om == null) {
// session have been invalidated and Observation manager is disconnected. Nothing to unregister. Bail out.
return;
}
om.removeEventListener(listener);
} catch (RepositoryException e) {
log.error("Unable to remove event listener [" + listener + "] from workspace " + workspace, e);
}
}
private static ObservationManager getObservationManager(String workspace) throws RepositoryException {
Workspace wks = getSession(workspace).getWorkspace();
return wks.getSession().isLive() ? wks.getObservationManager() : null;
}
private static Session getSession(String workspace) throws RepositoryException {
return LifeTimeJCRSessionUtil.getSession(workspace);
}
/**
* A listener using an {@link ObservationBasedDelayedExecutor}.
*/
public static class DeferringEventListener implements EventListener {
private ObservationBasedDelayedExecutor executor;
private EventListener listener;
public DeferringEventListener(EventListener listener, long delay, long maxDelay) {
this.listener = listener;
executor = new ObservationBasedDelayedExecutor(listener, delay, maxDelay);
}
@Override
public void onEvent(EventIterator events) {
this.executor.consume(events);
}
@Override
public String toString() {
return super.toString() + ":" + this.listener;
}
}
/**
* Deferred event handling. Uses the DelayedExecutor class.
*/
public static class ObservationBasedDelayedExecutor {
private final DelayedExecutor delayedExecutor;
private final List eventsBuffer = new ArrayList();
public ObservationBasedDelayedExecutor(final EventListener listener, long delay, long maxDelay) {
delayedExecutor = new DelayedExecutor(new Runnable() {
@Override
public void run() {
// during execution consume is blocked
synchronized (eventsBuffer) {
listener.onEvent(new ListBasedEventIterator(eventsBuffer));
eventsBuffer.clear();
}
}
}, delay, maxDelay);
}
protected void consume(EventIterator events) {
synchronized (this.eventsBuffer) {
while (events.hasNext()) {
this.eventsBuffer.add(events.next());
}
delayedExecutor.trigger();
}
}
}
/**
* List based event iterator. Used to collect events in a list which are
* later on passed to the listener.
*/
public static class ListBasedEventIterator implements EventIterator {
private Iterator iterator;
private List events;
private int pos = 0;
public ListBasedEventIterator(List events) {
this.events = events;
this.iterator = events.iterator();
}
@Override
public boolean hasNext() {
return this.iterator.hasNext();
}
@Override
public Object next() {
pos++;
return this.iterator.next();
}
@Override
public void remove() {
this.iterator.remove();
}
@Override
public Event nextEvent() {
return (Event) next();
}
@Override
public long getPosition() {
return pos;
}
@Override
public long getSize() {
return events.size();
}
@Override
public void skip(long skipNum) {
for (int i = 0; i < skipNum; i++) {
next();
}
}
}
}