library/src/main/java/com/datatorrent/lib/db/AbstractBatchTransactionableStoreOutputOperator.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.db;

import java.util.Collection;
import com.google.common.collect.Lists;

/**
 * This is the base implementation for an aggregate output operator,
 * which writes to a transactionable store. 
 * All the writes to the store over an application window are sent in one batch.
 * <p></p>
 * @displayName Abstract Batch Transactionable Store Output
 * @category Output
 * @tags transactional, output operator
 *
 * @param <T> The tuple type.
 * @param <S> The store type.
 * @since 1.0.2
 */
@org.apache.hadoop.classification.InterfaceStability.Evolving
public abstract class AbstractBatchTransactionableStoreOutputOperator<T, S extends TransactionableStore>
    extends AbstractAggregateTransactionableStoreOutputOperator<T, S>
{

  private Collection<T> tuples;
  public AbstractBatchTransactionableStoreOutputOperator()
  {
    tuples = Lists.newArrayList();
  }

  @Override
  public void processTuple(T tuple)
  {
    tuples.add(tuple);
  }

  @Override
  public void endWindow()
  {
    super.endWindow();
    tuples.clear();
  }

  /**
   * Processes the whole batch at the end window and writes to the store.
   *
   */
  public abstract void processBatch(Collection<T> tuples);

  @Override
  public void storeAggregate()
  {
    processBatch(tuples);
  }
}