library/src/main/java/com/datatorrent/lib/appdata/query/SimpleDoneQueueManager.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 java.util.concurrent.Semaphore;

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

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

/**
 * This is simple queue whose queue context is a {@link MutableBoolean} which determines whether or not to keep the query in the queue. If the
 * queue context is true, then the query is remove, if the queue context is false, then the query stays in the queue.
 * @param <QUERY_TYPE> The type of the queries that are enqueued in the queue.
 * @param <META_QUERY> The type of any meta data associated with the queries.
 * @since 3.0.0
 */
public class SimpleDoneQueueManager<QUERY_TYPE, META_QUERY>
    extends AbstractWindowEndQueueManager<QUERY_TYPE, META_QUERY, MutableBoolean>
{
  private QueueList<QueryBundle<QUERY_TYPE, META_QUERY, MutableBoolean>> queryQueue;
  private Semaphore semaphore = new Semaphore(1);

  public SimpleDoneQueueManager()
  {
  }

  @Override
  public boolean removeBundle(QueryBundle<QUERY_TYPE, META_QUERY, MutableBoolean> queryQueueable)
  {
    return queryQueueable.getQueueContext().booleanValue();
  }

  @Override
  public void addedNode(QueueListNode<QueryBundle<QUERY_TYPE, META_QUERY, MutableBoolean>> queryQueueable)
  {
    semaphore.release();
  }

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

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