src/main/java/com/google/code/gossip/manager/impl/OnlyProcessReceivedPassiveGossipThread.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 com.google.code.gossip.manager.impl;

import java.util.List;

import com.google.code.gossip.GossipMember;
import com.google.code.gossip.GossipService;
import com.google.code.gossip.LocalGossipMember;
import com.google.code.gossip.RemoteGossipMember;
import com.google.code.gossip.manager.GossipManager;
import com.google.code.gossip.manager.PassiveGossipThread;

public class OnlyProcessReceivedPassiveGossipThread extends PassiveGossipThread {

  public OnlyProcessReceivedPassiveGossipThread(GossipManager gossipManager) {
    super(gossipManager);
  }

  /**
   * Merge remote list (received from peer), and our local member list. Simply, we must update the
   * heartbeats that the remote list has with our list. Also, some additional logic is needed to
   * make sure we have not timed out a member and then immediately received a list with that member.
   *
   * @param gossipManager
   * @param senderMember
   * @param remoteList
   */
  protected void mergeLists(GossipManager gossipManager, RemoteGossipMember senderMember,
          List<GossipMember> remoteList) {

    //if the person sending to us is in the dead list consider them up
    for (LocalGossipMember i : gossipManager.getDeadList()){
      if (i.getId().equals(senderMember.getId())){
        System.out.println(gossipManager.getMyself() +" caught a live one!");
        LocalGossipMember newLocalMember = new LocalGossipMember(senderMember.getHost(),
                senderMember.getPort(), senderMember.getId(), senderMember.getHeartbeat(),
                gossipManager, gossipManager.getSettings().getCleanupInterval());
        gossipManager.revivieMember(newLocalMember);
        newLocalMember.startTimeoutTimer();
      }
    }
    for (GossipMember remoteMember : remoteList) {
      if (remoteMember.getId().equals(gossipManager.getMyself().getId())) {
        continue;
      }  
      if (gossipManager.getMemberList().contains(remoteMember)) {
        LocalGossipMember localMember = gossipManager.getMemberList().get(
                gossipManager.getMemberList().indexOf(remoteMember));
        if (remoteMember.getHeartbeat() > localMember.getHeartbeat()) {
          localMember.setHeartbeat(remoteMember.getHeartbeat());
          localMember.resetTimeoutTimer();
        }
      } else if (!gossipManager.getMemberList().contains(remoteMember) 
              && !gossipManager.getDeadList().contains(remoteMember) ){
        LocalGossipMember newLocalMember = new LocalGossipMember(remoteMember.getHost(),
                remoteMember.getPort(), remoteMember.getId(), remoteMember.getHeartbeat(),
                gossipManager, gossipManager.getSettings().getCleanupInterval());
        gossipManager.createOrRevivieMember(newLocalMember);
        newLocalMember.startTimeoutTimer();
      } else {
        if (gossipManager.getDeadList().contains(remoteMember)) {
          LocalGossipMember localDeadMember = gossipManager.getDeadList().get(
                  gossipManager.getDeadList().indexOf(remoteMember));
          if (remoteMember.getHeartbeat() > localDeadMember.getHeartbeat()) {
            LocalGossipMember newLocalMember = new LocalGossipMember(remoteMember.getHost(),
                    remoteMember.getPort(), remoteMember.getId(), remoteMember.getHeartbeat(),
                    gossipManager, gossipManager.getSettings().getCleanupInterval());
            gossipManager.revivieMember(newLocalMember);
            newLocalMember.startTimeoutTimer();
            GossipService.LOGGER.debug("Removed remote member " + remoteMember.getAddress()
                    + " from dead list and added to local member list.");
          } else {
            GossipService.LOGGER.debug("me " + gossipManager.getMyself());
            GossipService.LOGGER.debug("sender " + senderMember);
            GossipService.LOGGER.debug("remote " + remoteList);
            GossipService.LOGGER.debug("live " + gossipManager.getMemberList());
            GossipService.LOGGER.debug("dead " + gossipManager.getDeadList());
          }
        } else {
          GossipService.LOGGER.debug("me " + gossipManager.getMyself());
          GossipService.LOGGER.debug("sender " + senderMember);
          GossipService.LOGGER.debug("remote " + remoteList);
          GossipService.LOGGER.debug("live " + gossipManager.getMemberList());
          GossipService.LOGGER.debug("dead " + gossipManager.getDeadList());
          //throw new IllegalArgumentException("wtf");
        }
      }
    }
  }

}

/**
old comment section:
// If a member is restarted the heartbeat will restart from 1, so we should check
// that here.
// So a member can become from the dead when it is either larger than a previous
// heartbeat (due to network failure)
// or when the heartbeat is 1 (after a restart of the service).
// TODO: What if the first message of a gossip service is sent to a dead node? The
// second member will receive a heartbeat of two.
// TODO: The above does happen. Maybe a special message for a revived member?
// TODO: Or maybe when a member is declared dead for more than
// _settings.getCleanupInterval() ms, reset the heartbeat to 0.
// It will then accept a revived member.
// The above is now handle by checking whether the heartbeat differs
// _settings.getCleanupInterval(), it must be restarted.
*/

/*
// The remote member is back from the dead.
// Remove it from the dead list.
// gossipManager.getDeadList().remove(localDeadMember);
// Add it as a new member and add it to the member list.
*/