library/src/main/java/org/apache/apex/malhar/lib/appdata/query/WindowEndQueueManager.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.datatorrent.lib.appdata.query;

import org.apache.commons.lang3.mutable.MutableLong;

import com.datatorrent.lib.appdata.query.QueueList.QueueListNode;

/**
 * The WindowEndQueueManager keeps a countdown representing the number of application windows a query should stay alive for. If
 * a query's countdown reaches 0 it is removed from the queue.
 * @param <QUERY_TYPE> The type of queries to be queued.
 * @param <META_QUERY> The type of metadata to be associated with queued queries.
 * @since 3.0.0
 */
public class WindowEndQueueManager<QUERY_TYPE, META_QUERY>
    extends AbstractWindowEndQueueManager<QUERY_TYPE, META_QUERY, MutableLong>
{
  public WindowEndQueueManager()
  {
  }

  @Override
  public boolean removeBundle(QueryBundle<QUERY_TYPE, META_QUERY, MutableLong> queryQueueable)
  {
    return queryQueueable.getQueueContext().longValue() <= 0L;
  }

  @Override
  public void endWindow()
  {
    for (QueueListNode<QueryBundle<QUERY_TYPE, META_QUERY, MutableLong>> tempNode = queryQueue.getHead();
        tempNode != null; tempNode = tempNode.getNext()) {
      MutableLong qc = tempNode.getPayload().getQueueContext();
      qc.decrement();
    }
  }

  @Override
  public void addedNode(QueueListNode<QueryBundle<QUERY_TYPE, META_QUERY, MutableLong>> queryQueueable)
  {
    //Do nothing
  }

  @Override
  public void removedNode(QueueListNode<QueryBundle<QUERY_TYPE, META_QUERY, MutableLong>> queryQueueable)
  {
    //Do nothing
  }

  @Override
  public boolean addingFilter(QueryBundle<QUERY_TYPE, META_QUERY, MutableLong> queryBundle)
  {
    return true;
  }
}