/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.sling.replication.trigger.impl;
import javax.annotation.Nonnull;
import javax.jcr.RepositoryException;
import javax.jcr.Session;
import javax.jcr.observation.Event;
import javax.jcr.observation.EventIterator;
import javax.jcr.observation.EventListener;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import org.apache.sling.jcr.api.SlingRepository;
import org.apache.sling.replication.communication.ReplicationRequest;
import org.apache.sling.replication.trigger.ReplicationRequestHandler;
import org.apache.sling.replication.trigger.ReplicationTrigger;
import org.apache.sling.replication.trigger.ReplicationTriggerException;
import org.apache.sling.replication.util.ReplicationJcrUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Abstract implementation of a {@link org.apache.sling.replication.trigger.ReplicationTrigger} that listens for 'safe'
* events and triggers a {@link org.apache.sling.replication.communication.ReplicationRequest} from that.
*/
public abstract class AbstractJcrEventTrigger implements ReplicationTrigger {
private final Logger log = LoggerFactory.getLogger(getClass());
private final Map<String, JcrEventReplicationTriggerListener> registeredListeners = new ConcurrentHashMap<String, JcrEventReplicationTriggerListener>();
private final String path;
private final String serviceUser;
protected final SlingRepository repository;
public AbstractJcrEventTrigger(SlingRepository repository, String path, String serviceUser) {
this.repository = repository;
this.path = path;
this.serviceUser = serviceUser;
}
public void register(@Nonnull ReplicationRequestHandler requestHandler) throws ReplicationTriggerException {
Session session = null;
try {
session = getSession();
JcrEventReplicationTriggerListener listener = new JcrEventReplicationTriggerListener(requestHandler);
registeredListeners.put(requestHandler.toString(), listener);
session.getWorkspace().getObservationManager().addEventListener(
listener, getEventTypes(), path, true, null, null, false);
} catch (RepositoryException e) {
throw new ReplicationTriggerException("unable to register handler " + requestHandler, e);
} finally {
if (session != null) {
session.logout();
}
}
}
public void unregister(@Nonnull ReplicationRequestHandler requestHandler) throws ReplicationTriggerException {
JcrEventReplicationTriggerListener listener = registeredListeners.get(requestHandler.toString());
if (listener != null) {
Session session = null;
try {
session = getSession();
session.getWorkspace().getObservationManager().removeEventListener(listener);
} catch (RepositoryException e) {
throw new ReplicationTriggerException("unable to unregister handler " + requestHandler, e);
} finally {
if (session != null) {
session.logout();
}
}
}
}
private class JcrEventReplicationTriggerListener implements EventListener {
private final ReplicationRequestHandler requestHandler;
public JcrEventReplicationTriggerListener(ReplicationRequestHandler requestHandler) {
this.requestHandler = requestHandler;
}
public void onEvent(EventIterator eventIterator) {
while (eventIterator.hasNext()) {
Event event = eventIterator.nextEvent();
try {
if (ReplicationJcrUtils.isSafe(event)) {
ReplicationRequest request = processEvent(event);
if (request != null) {
requestHandler.handle(request);
}
}
} catch (RepositoryException e) {
log.error("Error while handling event {}", event, e);
}
}
}
}
/**
* process the received event and generates a replication request
*
* @param event an {@link javax.jcr.observation.Event} to be processed
* @return the {@link org.apache.sling.replication.communication.ReplicationRequest} originated by processing the event,
* or <code>null</code> if no request could be generated
* @throws RepositoryException
*/
protected abstract ReplicationRequest processEvent(Event event) throws RepositoryException;
/**
* get the binary int event types to be handled by this JCR event listener
*
* @return a <code>int</code> as generated by e.g. <code>Event.NODE_ADDED | Event.NODE_MOVED</code>
*/
protected int getEventTypes() {
return Event.NODE_ADDED | Event.NODE_MOVED | Event.NODE_REMOVED | Event.PROPERTY_CHANGED |
Event.PROPERTY_ADDED | Event.PROPERTY_REMOVED;
}
/**
* return a newly initiated JCR session to register the {@link javax.jcr.observation.EventListener}
*
* @return a {@link javax.jcr.Session}
* @throws RepositoryException
*/
protected Session getSession() throws RepositoryException {
return repository.loginService(serviceUser, null);
}
}