/*
* 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.jackrabbit.oak.plugins.observation;
import static com.google.common.base.Preconditions.checkState;
import java.util.Iterator;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.jcr.observation.Event;
import javax.jcr.observation.EventListener;
import com.google.common.util.concurrent.Monitor;
import com.google.common.util.concurrent.Monitor.Guard;
import org.apache.jackrabbit.api.jmx.EventListenerMBean;
import org.apache.jackrabbit.commons.iterator.EventIteratorAdapter;
import org.apache.jackrabbit.commons.observation.ListenerTracker;
import org.apache.jackrabbit.oak.api.ContentSession;
import org.apache.jackrabbit.oak.core.ImmutableRoot;
import org.apache.jackrabbit.oak.core.ImmutableTree;
import org.apache.jackrabbit.oak.namepath.NamePathMapper;
import org.apache.jackrabbit.oak.plugins.observation.filter.ACFilter;
import org.apache.jackrabbit.oak.plugins.observation.filter.EventFilter;
import org.apache.jackrabbit.oak.plugins.observation.filter.FilterProvider;
import org.apache.jackrabbit.oak.plugins.observation.filter.Filters;
import org.apache.jackrabbit.oak.spi.commit.CommitInfo;
import org.apache.jackrabbit.oak.spi.commit.Observer;
import org.apache.jackrabbit.oak.spi.security.authorization.permission.PermissionProvider;
import org.apache.jackrabbit.oak.spi.state.NodeState;
import org.apache.jackrabbit.oak.spi.whiteboard.Registration;
import org.apache.jackrabbit.oak.spi.whiteboard.Whiteboard;
import org.apache.jackrabbit.oak.spi.whiteboard.WhiteboardUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A {@code ChangeProcessor} generates observation {@link javax.jcr.observation.Event}s
* based on a {@link FilterProvider filter} and delivers them to an {@link EventListener}.
* <p>
* After instantiation a {@code ChangeProcessor} must be started in order to start
* delivering observation events and stopped to stop doing so.
*/
public class ChangeProcessor implements Observer {
private static final Logger log = LoggerFactory.getLogger(ChangeProcessor.class);
private final ContentSession contentSession;
private final NamePathMapper namePathMapper;
private final PermissionProvider permissionProvider;
private final ListenerTracker tracker;
private final EventListener eventListener;
private final AtomicReference<FilterProvider> filterProvider;
private Registration observerSubscription;
private Registration mBeanSubscription;
private NodeState previousRoot;
public ChangeProcessor(
ContentSession contentSession,
NamePathMapper namePathMapper,
PermissionProvider permissionProvider,
ListenerTracker tracker, FilterProvider filter) {
this.contentSession = contentSession;
this.namePathMapper = namePathMapper;
this.permissionProvider = permissionProvider;
this.tracker = tracker;
eventListener = tracker.getTrackedListener();
filterProvider = new AtomicReference<FilterProvider>(filter);
}
/**
* Set the filter for the events this change processor will generate.
* @param filter
*/
public void setFilterProvider(FilterProvider filter) {
filterProvider.set(filter);
}
/**
* Start this change processor
* @param whiteboard the whiteboard instance to used for scheduling individual
* runs of this change processor.
* @throws IllegalStateException if started already
*/
public synchronized void start(Whiteboard whiteboard) {
checkState(observerSubscription == null, "Change processor started already");
observerSubscription = WhiteboardUtils.registerObserver(whiteboard, this);
mBeanSubscription = WhiteboardUtils.registerMBean(whiteboard, EventListenerMBean.class,
tracker.getListenerMBean(), "EventListener", tracker.toString());
}
private final Monitor runningMonitor = new Monitor();
private final RunningGuard running = new RunningGuard(runningMonitor);
/**
* Try to stop this change processor if running. This method will wait
* the specified time for a pending event listener to complete. If
* no timeout occurred no further events will be delivered after this
* method returns.
*
* @param timeOut time this method will wait for an executing event
* listener to complete.
* @param unit time unit for {@code timeOut}
* @return {@code true} if no time out occurred and this change processor
* could be stopped, {@code false} otherwise.
* @throws IllegalStateException if not yet started or stopped already
*/
public synchronized boolean stopAndWait(int timeOut, TimeUnit unit) {
checkState(observerSubscription != null, "Change processor not started");
running.stop();
if (runningMonitor.enter(timeOut, unit)) {
mBeanSubscription.unregister();
observerSubscription.unregister();
runningMonitor.leave();
return true;
} else {
return false;
}
}
/**
* Stop this change processor after all pending events have been
* delivered. In contrast to {@link #stopAndWait(int, java.util.concurrent.TimeUnit)}
* this method returns immediately without waiting for pending listeners to
* complete.
*/
public synchronized void stop() {
checkState(observerSubscription != null, "Change processor not started");
running.stop();
mBeanSubscription.unregister();
observerSubscription.unregister();
runningMonitor.leave();
}
@Override
public void contentChanged(@Nonnull NodeState root, @Nullable CommitInfo info) {
if (previousRoot != null) {
try {
FilterProvider provider = filterProvider.get();
// FIXME don't rely on toString for session id
if (provider.includeCommit(contentSession.toString(), info)) {
String basePath = provider.getPath();
EventFilter userFilter = provider.getFilter(previousRoot, root);
EventFilter acFilter = new ACFilter(previousRoot, root, permissionProvider, basePath);
ImmutableTree beforeTree = getTree(previousRoot, basePath);
ImmutableTree afterTree = getTree(root, basePath);
EventIterable<Event> events = new EventIterable<Event>(
beforeTree.getNodeState(), afterTree.getNodeState(),
Filters.all(userFilter, acFilter),
new JcrListener(beforeTree, afterTree, namePathMapper, info));
Iterator<Event> iterator = events.iterator();
if (iterator.hasNext() && runningMonitor.enterIf(running)) {
try {
eventListener.onEvent(new EventIteratorAdapter(iterator));
} finally {
runningMonitor.leave();
}
}
}
} catch (Exception e) {
log.warn("Error while dispatching observation events", e);
}
}
previousRoot = root;
}
private static ImmutableTree getTree(NodeState nodeState, String path) {
return new ImmutableRoot(nodeState).getTree(path);
}
private static class RunningGuard extends Guard {
private boolean stopped;
public RunningGuard(Monitor monitor) {
super(monitor);
}
@Override
public boolean isSatisfied() {
return !stopped;
}
public void stop() {
checkState(!stopped, "Change processor already stopped");
stopped = true;
}
}
}