/*
* RHQ Management Platform
* Copyright (C) 2005-2008 Red Hat, Inc.
* All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation version 2 of the License.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
package org.rhq.enterprise.communications;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import javax.management.Notification;
import javax.management.NotificationListener;
import mazz.i18n.Logger;
import org.jboss.remoting.InvokerLocator;
import org.jboss.remoting.ident.Identity;
import org.jboss.remoting.network.NetworkNotification;
import org.rhq.enterprise.communications.command.server.discovery.AutoDiscoveryListener;
import org.rhq.enterprise.communications.i18n.CommI18NFactory;
import org.rhq.enterprise.communications.i18n.CommI18NResourceKeys;
/**
* This is the listener that, on behalf of the Service Container, will listen and process notifications indicating new
* servers have come online and gone offline.
*
* @author John Mazzitelli
*/
class ServiceContainerNetworkNotificationListener implements NotificationListener {
/**
* Logger
*/
private static final Logger LOG = CommI18NFactory.getLogger(ServiceContainerNetworkNotificationListener.class);
/**
* The list of listeners that will receive notifications when new servers are discovered or old servers have died.
*/
private List<AutoDiscoveryListener> m_discoveryListeners = new ArrayList<AutoDiscoveryListener>();
/**
* The map of all the servers and their connectors that have been discovered. By "server" it is meant a server VM
* that hosts one or more Connectors. The key is the {@link Identity} that identifies the "server" and the values
* are a <code>List</code> of {@link InvokerLocator} objects.
*/
private Map<Identity, List<InvokerLocator>> m_discoveredServers = new HashMap<Identity, List<InvokerLocator>>();
/**
* Used for its monitor lock to limit access to the other data fields.
*/
private Object m_lock = new Object();
/**
* Enables the given listener to receive notifications when servers come online and go offline.
*
* @param listener
*/
public void add(AutoDiscoveryListener listener) {
synchronized (m_lock) {
m_discoveryListeners.add(listener);
}
}
/**
* Removes the given listener from the list of listeners this object will send notifications to. The given listener
* will no longer receive notifications when servers come online and go offline.
*
* @param listener
*/
public void remove(AutoDiscoveryListener listener) {
synchronized (m_lock) {
m_discoveryListeners.remove(listener);
}
}
/**
* Removes all listeners from this object. Once this returns, this object will not notify any object when servers
* come online and go offline.
*/
public void removeAll() {
synchronized (m_lock) {
m_discoveryListeners.clear();
}
}
/**
* When a new server is detected or an old server goes away, this method will be notified. This method notifies all
* listeners when added/removed/updated notifications are received.
*
* @see NotificationListener#handleNotification(Notification, Object)
*/
public void handleNotification(Notification notification, Object handback) {
// check to see if its a network notification
if (notification instanceof NetworkNotification) {
LOG.debug(CommI18NResourceKeys.GOT_NOTIF, notification.getType());
NetworkNotification networkNotification = (NetworkNotification) notification;
if (NetworkNotification.SERVER_ADDED.equals(networkNotification.getType())) {
serverAddedNotification(networkNotification);
} else if (NetworkNotification.SERVER_REMOVED.equals(networkNotification.getType())) {
serverRemovedNotification(networkNotification);
} else if (NetworkNotification.SERVER_UPDATED.equals(networkNotification.getType())) {
serverUpdatedNotification(networkNotification);
}
}
return;
}
/**
* Processes the {@link NetworkNotification#SERVER_ADDED} notification. This notification means a new "server VM"
* has come online and has one or more remote endpoints in it (the remote endpoints are specified by their
* {@link InvokerLocator} objects).
*
* @param networkNotification the notification
*/
private void serverAddedNotification(NetworkNotification networkNotification) {
List<AutoDiscoveryListener> listeners_copy;
InvokerLocator[] notif_locators = networkNotification.getLocator();
synchronized (m_lock) {
// add the new server to the map of discovered servers (we shouldn't have seen this before, but assume we might have)
List<InvokerLocator> server_invokers = m_discoveredServers.get(networkNotification.getIdentity());
if (server_invokers == null) {
// add the new server to our map of known servers and give it an empty list of invokers that we will fill
server_invokers = new ArrayList<InvokerLocator>(networkNotification.getLocator().length);
m_discoveredServers.put(networkNotification.getIdentity(), server_invokers);
}
// go through each locator in the notification and add it to the known invokers for our new server
for (int x = 0; x < notif_locators.length; x++) {
server_invokers.add(notif_locators[x]);
}
// make a copy while we are synchronized - then release the lock so we let other notifications to get processed
listeners_copy = new ArrayList<AutoDiscoveryListener>(m_discoveryListeners);
}
// notify all of our listeners of the new invoker locators
for (int x = 0; x < notif_locators.length; x++) {
notifyListenersOnline(listeners_copy, notif_locators[x]);
}
return;
}
/**
* Processes the {@link NetworkNotification#SERVER_REMOVED} notification. This notification means a previously known
* "server VM" has gone offline and has taken all of its remote endpoints with it.
*
* @param networkNotification the notification
*/
private void serverRemovedNotification(NetworkNotification networkNotification) {
List<AutoDiscoveryListener> listeners_copy;
InvokerLocator[] notif_locators = networkNotification.getLocator();
synchronized (m_lock) {
// the server has gone down, remove it from our map of known servers
m_discoveredServers.remove(networkNotification.getIdentity());
// make a copy while we are synchronized - then release the lock so we let other notifications to get processed
listeners_copy = new ArrayList<AutoDiscoveryListener>(m_discoveryListeners);
}
// notify all of our listeners of the invoker locators that have gone down
for (int x = 0; x < notif_locators.length; x++) {
notifyListenersOffline(listeners_copy, notif_locators[x]);
}
return;
}
/**
* Processes the {@link NetworkNotification#SERVER_UPDATED} notification. This notification means a previously known
* "server VM" has either added a new remote endpoint or removed an old remote endpoint.
*
* @param networkNotification the notification
*/
private void serverUpdatedNotification(NetworkNotification networkNotification) {
List<AutoDiscoveryListener> listeners_copy;
List<InvokerLocator> new_invokers = new ArrayList<InvokerLocator>();
List<InvokerLocator> dead_invokers = new ArrayList<InvokerLocator>();
InvokerLocator[] notif_locators = networkNotification.getLocator();
synchronized (m_lock) {
// get the updated server's list of currently known invokers
// we should have seen this server before, but assume we might not have
List<InvokerLocator> server_invokers = m_discoveredServers.get(networkNotification.getIdentity());
// compare the known list of invokers with the updated invokers in the notification.
// any found in the notification that aren't known yet are to be considered having gone online
for (int i = 0; i < notif_locators.length; i++) {
InvokerLocator cur_notif_locator = notif_locators[i];
if (!server_invokers.contains(cur_notif_locator)) {
// haven't see this invoker before, its new so let's add it to our list
new_invokers.add(cur_notif_locator);
server_invokers.add(cur_notif_locator);
}
}
// compare the known list of invokers with the updated invokers in the notification.
// any not found in the notification that are known are to be considered having gone offline
List notif_locators_list = Arrays.asList(notif_locators);
for (Iterator iter = server_invokers.iterator(); iter.hasNext();) {
InvokerLocator cur_server_invoker = (InvokerLocator) iter.next();
if (!notif_locators_list.contains(cur_server_invoker)) {
dead_invokers.add(cur_server_invoker); // this invoker that used to be online is now down
}
}
// since we can't modify the server_invokers list while we were iterating, we have to do it here
// in a separate loop iterating the dead invokers list
for (Iterator iter = dead_invokers.iterator(); iter.hasNext();) {
InvokerLocator dead_invoker = (InvokerLocator) iter.next();
server_invokers.remove(dead_invoker);
}
// make a copy while we are synchronized - then release the lock so we let other notifications to get processed
listeners_copy = new ArrayList<AutoDiscoveryListener>(m_discoveryListeners);
}
// notify our listeners of those servers that have come online and gone offline
for (Iterator iter = new_invokers.iterator(); iter.hasNext();) {
InvokerLocator new_invoker = (InvokerLocator) iter.next();
notifyListenersOnline(listeners_copy, new_invoker);
}
for (Iterator iter = dead_invokers.iterator(); iter.hasNext();) {
InvokerLocator dead_invoker = (InvokerLocator) iter.next();
notifyListenersOffline(listeners_copy, dead_invoker);
}
return;
}
/**
* Notifies the list of listeners that a new server invoker is online. This is given a local copy of our listeners
* (i.e. this is a list of all the listeners that will be notified, but is a copy of the
* {@link #m_discoveryListeners} so we will not need to synchronize on its access)
*
* @param listeners_copy
* @param new_server_invoker_locator
*/
private void notifyListenersOnline(List listeners_copy, InvokerLocator new_server_invoker_locator) {
LOG.debug(CommI18NResourceKeys.SERVICE_CONTAINER_NETWORK_NOTIF_LISTENER_SERVER_ONLINE,
new_server_invoker_locator);
// notify each of our listeners that a new invoker is now online
for (Iterator iter = listeners_copy.iterator(); iter.hasNext();) {
AutoDiscoveryListener listener = (AutoDiscoveryListener) iter.next();
try {
listener.serverOnline(new_server_invoker_locator);
} catch (Throwable t) {
LOG.error(t, CommI18NResourceKeys.SERVICE_CONTAINER_NETWORK_NOTIF_LISTENER_ONLINE_PROCESSING_FAILURE,
new_server_invoker_locator);
}
}
return;
}
/**
* Notifies the list of listeners that a known server invoker has gone offline. This is given a local copy of our
* listeners (i.e. this is a list of all the listeners that will be notified, but is a copy of the
* {@link #m_discoveryListeners} so we will not need to synchronize on its access)
*
* @param listeners_copy
* @param dead_server_invoker_locator
*/
private void notifyListenersOffline(List listeners_copy, InvokerLocator dead_server_invoker_locator) {
LOG.debug(CommI18NResourceKeys.SERVICE_CONTAINER_NETWORK_NOTIF_LISTENER_SERVER_OFFLINE,
dead_server_invoker_locator);
// notify each of our listeners that an invoker is now offline
for (Iterator iter = listeners_copy.iterator(); iter.hasNext();) {
AutoDiscoveryListener listener = (AutoDiscoveryListener) iter.next();
try {
listener.serverOffline(dead_server_invoker_locator);
} catch (Throwable t) {
LOG.error(t, CommI18NResourceKeys.SERVICE_CONTAINER_NETWORK_NOTIF_LISTENER_OFFLINE_PROCESSING_FAILURE,
dead_server_invoker_locator);
}
}
return;
}
}