ConnectionTrackingHandler.java

/*
 * Copyright (C) 2011 Google Inc.
 *
 * Licensed 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.ros.internal.transport;

import org.apache.commons.logging.Log;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ExceptionEvent;
import org.jboss.netty.channel.SimpleChannelHandler;
import org.jboss.netty.channel.group.ChannelGroup;
import org.ros.exception.RosRuntimeException;
import org.ros.log.RosLogFactory;

import java.io.IOException;
import java.nio.channels.Channels;

/**
 * Adds new {@link Channels} to the provided {@link ChannelGroup}.
 *
 * @author damonkohler@google.com (Damon Kohler)
 */
public class ConnectionTrackingHandler extends SimpleChannelHandler {

  private static final Log log = RosLogFactory.getLog(ConnectionTrackingHandler.class);

  /**
   * The channel group the connection is to be part of.
   */
  private final ChannelGroup channelGroup;

  public ConnectionTrackingHandler(ChannelGroup channelGroup) {
    this.channelGroup = channelGroup;
  }

  @Override
  public void channelOpen(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
    if (log.isDebugEnabled()) {
      log.debug("Channel opened: " + e.getChannel());
    }
    channelGroup.add(e.getChannel());
    super.channelOpen(ctx, e);
  }

  @Override
  public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
    if (log.isDebugEnabled()) {
      log.debug("Channel closed: " + e.getChannel());
    }
    super.channelClosed(ctx, e);
  }

  @Override
  public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception {
    ctx.getChannel().close();
    if (e.getCause() instanceof IOException) {
      // NOTE(damonkohler): We ignore exceptions here because they are common
      // (e.g. network failure, connection reset by peer, shutting down, etc.)
      // and should not be fatal. However, in all cases the channel should be
      // closed.
      log.error("Channel exception: " + ctx.getChannel(), e.getCause());
    } else {
      throw new RosRuntimeException(e.getCause());
    }
  }
}