/*
* JBoss, Home of Professional Open Source.
* Copyright 2010, Red Hat, Inc., and individual contributors
* as indicated by the @author tags. See the copyright.txt file in the
* distribution for a full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.as.naming;
import java.security.AccessController;
import java.util.concurrent.ThreadFactory;
import org.jboss.as.naming.util.FastCopyHashMap;
import javax.naming.Binding;
import javax.naming.Name;
import javax.naming.event.EventContext;
import javax.naming.event.NamespaceChangeListener;
import javax.naming.event.NamingEvent;
import javax.naming.event.NamingListener;
import javax.naming.event.ObjectChangeListener;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import org.jboss.threads.JBossThreadFactory;
/**
* Coordinator responsible for passing @(code NamingEvent} instances to registered @{code NamingListener} instances. Two
* maps are used to managed a mapping between a listener and its configuration as well as a mapping from target name to a list
* of listener configurations. These maps are updated atomically on listener add and remove.
*
* @author John E. Bailey
*/
public class NamingEventCoordinator {
private volatile Map<TargetScope, List<ListenerHolder>> holdersByTarget = Collections.emptyMap();
private volatile Map<NamingListener, ListenerHolder> holdersByListener = Collections.emptyMap();
private final ThreadFactory threadFactory = new JBossThreadFactory(new ThreadGroup("NamingEventCoordinator-threads"), Boolean.FALSE, null, "%G - %t", null, null, AccessController.getContext());
private final Executor executor = Executors.newSingleThreadExecutor(threadFactory);
static final Integer[] DEFAULT_SCOPES = {EventContext.OBJECT_SCOPE, EventContext.ONELEVEL_SCOPE, EventContext.SUBTREE_SCOPE};
/**
* Add a listener to the coordinator with a given target name and event scope. This information is used when an
* event is fired to determine whether or not to fire this listener.
*
* @param target The target name to lister
* @param scope The event scope
* @param namingListener The listener
*/
synchronized void addListener(final String target, final int scope, final NamingListener namingListener) {
final TargetScope targetScope = new TargetScope(target, scope);
// Do we have a holder for this listener
ListenerHolder holder = holdersByListener.get(namingListener);
if (holder == null) {
holder = new ListenerHolder(namingListener, targetScope);
final Map<NamingListener, ListenerHolder> byListenerCopy = new FastCopyHashMap<NamingListener, ListenerHolder>(holdersByListener);
byListenerCopy.put(namingListener, holder);
holdersByListener = byListenerCopy;
} else {
holder.addTarget(targetScope);
}
List<ListenerHolder> holdersForTarget = holdersByTarget.get(targetScope);
if (holdersForTarget == null) {
holdersForTarget = new CopyOnWriteArrayList<ListenerHolder>();
final Map<TargetScope, List<ListenerHolder>> byTargetCopy = new FastCopyHashMap<TargetScope, List<ListenerHolder>>(holdersByTarget);
byTargetCopy.put(targetScope, holdersForTarget);
holdersByTarget = byTargetCopy;
}
holdersForTarget.add(holder);
}
/**
* Remove a listener. Will remove it from all target mappings. Once this method returns, the listener will no longer
* receive any events.
*
* @param namingListener The listener
*/
synchronized void removeListener(final NamingListener namingListener) {
// Do we have a holder for this listener
final ListenerHolder holder = holdersByListener.get(namingListener);
if (holder == null) {
return;
}
final Map<NamingListener, ListenerHolder> byListenerCopy = new FastCopyHashMap<NamingListener, ListenerHolder>(holdersByListener);
byListenerCopy.remove(namingListener);
holdersByListener = byListenerCopy;
final Map<TargetScope, List<ListenerHolder>> byTargetCopy = new FastCopyHashMap<TargetScope, List<ListenerHolder>>(holdersByTarget);
for (TargetScope targetScope : holder.targets) {
final List<ListenerHolder> holders = holdersByTarget.get(targetScope);
holders.remove(holder);
if (holders.isEmpty()) {
byTargetCopy.remove(targetScope);
}
}
holdersByTarget = byTargetCopy;
}
/**
* Fire a naming event. An event will be created with the provided information and sent to each listener that matches
* the target and scope information.
*
* @param context The event context generating the event.
* @param name The target name the event represents
* @param existingBinding The existing binding at the provided name
* @param newBinding The new binding at the provided name
* @param type The event type
* @param changeInfo The change info for the event
* @param scopes The scopes this event should be fired against
*/
void fireEvent(final EventContext context, final Name name, final Binding existingBinding, final Binding newBinding, int type, final String changeInfo, final Integer... scopes) {
final String target = name.toString();
final Set<Integer> scopeSet = new HashSet<Integer>(Arrays.asList(scopes));
final NamingEvent event = new NamingEvent(context, type, newBinding, existingBinding, changeInfo);
final Set<ListenerHolder> holdersToFire = new HashSet<ListenerHolder>();
// Check for OBJECT_SCOPE based listeners
if (scopeSet.contains(EventContext.OBJECT_SCOPE)) {
final TargetScope targetScope = new TargetScope(target, EventContext.OBJECT_SCOPE);
final List<ListenerHolder> holders = holdersByTarget.get(targetScope);
if (holders != null) {
for (ListenerHolder holder : holders) {
holdersToFire.add(holder);
}
}
}
// Check for ONELEVEL_SCOPE based listeners
if (scopeSet.contains(EventContext.ONELEVEL_SCOPE) && !name.isEmpty()) {
final TargetScope targetScope = new TargetScope(name.getPrefix(name.size() - 1).toString(), EventContext.ONELEVEL_SCOPE);
final List<ListenerHolder> holders = holdersByTarget.get(targetScope);
if (holders != null) {
for (ListenerHolder holder : holders) {
holdersToFire.add(holder);
}
}
}
// Check for SUBTREE_SCOPE based listeners
if (scopeSet.contains(EventContext.SUBTREE_SCOPE) && !name.isEmpty()) {
for (int i = 1; i < name.size(); i++) {
final Name parentName = name.getPrefix(i);
final TargetScope targetScope = new TargetScope(parentName.toString(), EventContext.SUBTREE_SCOPE);
final List<ListenerHolder> holders = holdersByTarget.get(targetScope);
if (holders != null) {
for (ListenerHolder holder : holders) {
holdersToFire.add(holder);
}
}
}
}
executor.execute(new FireEventTask(holdersToFire, event));
}
private class FireEventTask implements Runnable {
private final Set<ListenerHolder> listenerHolders;
private final NamingEvent event;
private FireEventTask(Set<ListenerHolder> listenerHolders, NamingEvent event) {
this.listenerHolders = listenerHolders;
this.event = event;
}
@Override
public void run() {
for (ListenerHolder holder : listenerHolders) {
final NamingListener listener = holder.listener;
switch (event.getType()) {
case NamingEvent.OBJECT_ADDED:
if (listener instanceof NamespaceChangeListener)
((NamespaceChangeListener) listener).objectAdded(event);
break;
case NamingEvent.OBJECT_REMOVED:
if (listener instanceof NamespaceChangeListener)
((NamespaceChangeListener) listener).objectRemoved(event);
break;
case NamingEvent.OBJECT_RENAMED:
if (listener instanceof NamespaceChangeListener)
((NamespaceChangeListener) listener).objectRenamed(event);
break;
case NamingEvent.OBJECT_CHANGED:
if (listener instanceof ObjectChangeListener)
((ObjectChangeListener) listener).objectChanged(event);
break;
}
}
}
}
private class ListenerHolder {
private volatile Set<TargetScope> targets = new HashSet<TargetScope>();
private final NamingListener listener;
private ListenerHolder(final NamingListener listener, final TargetScope initialTarget) {
this.listener = listener;
addTarget(initialTarget);
}
private synchronized void addTarget(final TargetScope targetScope) {
targets.add(targetScope);
}
}
private class TargetScope {
private final String target;
private final int scope;
private TargetScope(String target, int scope) {
this.target = target;
this.scope = scope;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
TargetScope that = (TargetScope) o;
if (scope != that.scope) return false;
if (target != null ? !target.equals(that.target) : that.target != null) return false;
return true;
}
@Override
public int hashCode() {
int result = target != null ? target.hashCode() : 0;
result = 31 * result + scope;
return result;
}
}
}