JChannelWrapper.java

/**
 * 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.activemq.artemis.api.core.jgroups;

import java.util.ArrayList;
import java.util.List;

import org.jboss.logging.Logger;
import org.jgroups.JChannel;
import org.jgroups.Message;
import org.jgroups.ReceiverAdapter;

/**
 * This class wraps a JChannel with a reference counter. The reference counter
 * controls the life of the JChannel. When reference count is zero, the channel
 * will be disconnected.
 */
public class JChannelWrapper {

   private static final Logger logger = Logger.getLogger(JChannelWrapper.class);

   private boolean connected = false;
   int refCount = 1;
   final JChannel channel;
   final String channelName;
   final List<JGroupsReceiver> receivers = new ArrayList<>();
   private final JChannelManager manager;

   public JChannelWrapper(JChannelManager manager, final String channelName, JChannel channel) throws Exception {
      this.refCount = 1;
      this.channelName = channelName;
      this.channel = channel;
      this.manager = manager;

      if (logger.isTraceEnabled() && channel.getReceiver() != null) {
         logger.trace(this + "The channel already had a receiver previously!!!! == " + channel.getReceiver(), new Exception("trace"));
      }

      //we always add this for the first ref count
      channel.setReceiver(new ReceiverAdapter() {

         @Override
         public String toString() {
            return "ReceiverAdapter::" + JChannelWrapper.this;
         }

         @Override
         public void receive(org.jgroups.Message msg) {
            if (logger.isTraceEnabled()) {
               logger.trace(this + ":: Wrapper received " + msg + " on channel " + channelName);
            }
            synchronized (receivers) {
               for (JGroupsReceiver r : receivers) {
                  r.receive(msg);
               }
            }
         }
      });
   }

   public JChannel getChannel() {
      return channel;
   }

   public String getChannelName() {
      return channelName;
   }

   public synchronized void close(boolean closeWrappedChannel) {
      refCount--;
      if (logger.isTraceEnabled())
         logger.trace(this + "::RefCount-- " + refCount + " on channel " + channelName, new Exception("Trace"));
      if (refCount == 0) {
         if (closeWrappedChannel) {
            closeChannel();
         }
         manager.removeChannel(channelName);
      }
   }

   public synchronized void closeChannel() {
      connected = false;
      channel.setReceiver(null);
      if (logger.isTraceEnabled()) {
         logger.trace(this + "::Closing Channel: " + channelName, new Exception("Trace"));
      }
      channel.close();
   }

   public void removeReceiver(JGroupsReceiver receiver) {
      if (logger.isTraceEnabled())
         logger.trace(this + "::removeReceiver: " + receiver + " on " + channelName, new Exception("Trace"));
      synchronized (receivers) {
         receivers.remove(receiver);
      }
   }

   public synchronized void connect() throws Exception {
      if (logger.isTraceEnabled()) {
         logger.trace(this + ":: Connecting " + channelName, new Exception("Trace"));
      }

      // It is important to check this otherwise we could reconnect an already connected channel
      if (connected) {
         return;
      }

      connected = true;

      if (!channel.isConnected()) {
         channel.connect(channelName);
      }
   }

   public void addReceiver(JGroupsReceiver jGroupsReceiver) {
      synchronized (receivers) {
         if (logger.isTraceEnabled())
            logger.trace(this + "::Add Receiver: " + jGroupsReceiver + " on " + channelName);
         receivers.add(jGroupsReceiver);
      }
   }

   public void send(org.jgroups.Message msg) throws Exception {
      if (logger.isTraceEnabled())
         logger.trace(this + "::Sending JGroups Message: Open=" + channel.isOpen() + " on channel " + channelName + " msg=" + msg);
      if (!manager.isLoopbackMessages()) {
         msg.setTransientFlag(Message.TransientFlag.DONT_LOOPBACK);
      }
      channel.send(msg);
   }

   public JChannelWrapper addRef() {
      this.refCount++;
      if (logger.isTraceEnabled())
         logger.trace(this + "::RefCount++ = " + refCount + " on channel " + channelName);
      return this;
   }

   @Override
   public String toString() {
      return super.toString() +
         "{refCount=" + refCount +
         ", channel=" + channel +
         ", channelName='" + channelName + '\'' +
         ", connected=" + connected +
         '}';
   }
}