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package org.atmosphere.plugin.jgroups;
import org.atmosphere.cpr.Broadcaster;
import org.atmosphere.cpr.ClusterBroadcastFilter;
import org.jgroups.ChannelException;
import org.jgroups.JChannel;
import org.jgroups.Message;
import org.jgroups.ReceiverAdapter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.concurrent.ConcurrentLinkedQueue;
/**
* Clustering support based on JGroupsFilter (http://jgroups.org)
*
* @author Hubert Iwaniuk
*/
public class JGroupsFilter extends ReceiverAdapter implements ClusterBroadcastFilter {
private static final Logger logger = LoggerFactory.getLogger(JGroupsFilter.class);
private JChannel jchannel;
private String clusterName = "cluster-jgroups";
private Broadcaster bc;
private final ConcurrentLinkedQueue<String> receivedMessages = new ConcurrentLinkedQueue<String>();
public JGroupsFilter() {
this(null);
}
/**
* Create a JGroupsFilter based filter.
* @param bc the Broadcaster to use when receiving update from the cluster.
*/
public JGroupsFilter(Broadcaster bc) {
this(bc, "atmosphere-framework");
}
/**
* Create a JGroupsFilter based filter.
* @param bc the Broadcaster to use when receiving update from the cluster.
* @param containerName the current WebServer'name.
*/
public JGroupsFilter(Broadcaster bc, String containerName) {
this(bc, containerName, "cluster-atmosphere");
}
/**
* Create a JGroupsFilter based filter.
* @param bc the Broadcaster to use when receiving update from the cluster.
* @param containerName the current WebServer'name.
* @param clusterName the cluster's group name.
*/
public JGroupsFilter(Broadcaster bc, String containerName, String clusterName) {
this.bc = bc;
this.clusterName = clusterName;
}
public void setUri(String clusterName) {
this.clusterName = clusterName;
}
/**
* Prepare the cluster.
*/
public void init() {
try {
logger.info("Starting Atmosphere JGroups Clustering support");
//initialize jgroups channel
jchannel = new JChannel();
//register for Group Events
jchannel.setReceiver(this);
//join group
jchannel.connect(clusterName);
} catch (Throwable t) {
logger.warn("failed to connect to cluser", t);
}
}
/**
* Shutdown the cluster.
*/
public void destroy() {
jchannel.shutdown();
}
/** {@inheritDoc} */
@Override
public void receive(final Message message) {
final String msg = (String) message.getObject();
if (message.getSrc() != jchannel.getLocalAddress()){
if (msg != null) {
receivedMessages.offer(msg);
if (bc != null) {
bc.broadcast(msg);
}
}
}
}
/**
* Every time a message gets broadcasted, make sure we update the cluster.
* @param o the message to broadcast.
* @return The same message.
*/
public BroadcastAction filter(Object originalMessage, Object o) {
if (o instanceof String){
String message = (String)o;
// Avoid re-broadcasting
if (!receivedMessages.remove(message)) {
try {
jchannel.send(new Message(null, null, message));
} catch (ChannelException e) {
logger.warn("failed to send message", e);
}
}
return new BroadcastAction(message);
} else {
return new BroadcastAction(o);
}
}
/**
* Return the current {@link Broadcaster}
*/
public Broadcaster getBroadcaster() {
return bc;
}
/**
* Set the current {@link Broadcaster} to use when a cluster event happens.
* @param bc
*/
public void setBroadcaster(Broadcaster bc) {
this.bc = bc;
}
}