package org.apache.helix.messaging.handling;
   
   /*
    * 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.
   */
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentLinkedQueue;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.apache.helix.PropertyKey;
  import org.apache.helix.model.CurrentState;
  import org.apache.helix.model.Message;
  import org.apache.helix.model.Message.Attributes;
  
  
  public class GroupMessageHandler
  {
    class CurrentStateUpdate
    {
      final PropertyKey  _key;
      final CurrentState _curStateDelta;
  
      public CurrentStateUpdate(PropertyKey key, CurrentState curStateDelta)
      {
        _key = key;
        _curStateDelta = curStateDelta;
      }
  
      public void merge(CurrentState curState)
      {
        _curStateDelta.getRecord().merge(curState.getRecord());
      }
    }
  
    static class GroupMessageInfo
    {
      final Message                                   _message;
      final AtomicInteger                             _countDown;
      final ConcurrentLinkedQueue<CurrentStateUpdate> _curStateUpdateList;
  
      public GroupMessageInfo(Message message)
      {
        _message = message;
        List<String> partitionNames = message.getPartitionNames();
        _countDown = new AtomicInteger(partitionNames.size());
        _curStateUpdateList = new ConcurrentLinkedQueue<CurrentStateUpdate>();
      }
      
      public Map<PropertyKey, CurrentState> merge()
      {
        Map<String, CurrentStateUpdate> curStateUpdateMap =
            new HashMap<String, CurrentStateUpdate>();
        for (CurrentStateUpdate update : _curStateUpdateList)
        {
          String path = update._key.getPath();
          if (!curStateUpdateMap.containsKey(path))
          {
            curStateUpdateMap.put(path, update);
          }
          else
          {
            curStateUpdateMap.get(path).merge(update._curStateDelta);
          }
        }
  
        Map<PropertyKey, CurrentState> ret = new HashMap<PropertyKey, CurrentState>();
        for (CurrentStateUpdate update : curStateUpdateMap.values())
        {
          ret.put(update._key, update._curStateDelta);
        }
  
        return ret;
      }
   
    }
  
    final ConcurrentHashMap<String, GroupMessageInfo> _groupMsgMap;
  
    public GroupMessageHandler()
    {
      _groupMsgMap = new ConcurrentHashMap<String, GroupMessageInfo>();
   }
 
   public void put(Message message)
   {
     _groupMsgMap.putIfAbsent(message.getId(), new GroupMessageInfo(message));
   }
 
   // return non-null if all sub-messages are completed
   public GroupMessageInfo onCompleteSubMessage(Message subMessage)
   {
     String parentMid = subMessage.getAttribute(Attributes.PARENT_MSG_ID);
     GroupMessageInfo info = _groupMsgMap.get(parentMid);
     if (info != null)
     {
       int val = info._countDown.decrementAndGet();
       if (val <= 0)
       {
         return _groupMsgMap.remove(parentMid);
       }
     }
 
     return null;
   }
 
   void addCurStateUpdate(Message subMessage, PropertyKey key, CurrentState delta)
   {
     String parentMid = subMessage.getAttribute(Attributes.PARENT_MSG_ID);
     GroupMessageInfo info = _groupMsgMap.get(parentMid);
     if (info != null)
     {
       info._curStateUpdateList.add(new CurrentStateUpdate(key, delta));
     }
 
   }
 }