apps/logstream/src/main/java/com/datatorrent/apps/logstream/SumItemFromMapOperator.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.apps.logstream;

import java.util.Map;

import javax.validation.constraints.NotNull;

import com.datatorrent.common.util.BaseOperator;
import com.datatorrent.api.DefaultInputPort;
import com.datatorrent.api.DefaultOutputPort;

/**
 * Sums the value of the selected dimension from the map over application window
 *
 * @param <K> dimension to select from map
 * @param <V> value to be summed
 * @since 0.9.4
 */
public class SumItemFromMapOperator<K, V> extends BaseOperator
{
  @NotNull
  private K sumDimension;
  private long sum = 0L;

  public void setSumDimension(K sumDimension)
  {
    this.sumDimension = sumDimension;
  }

  public final transient DefaultInputPort<Map<K, V>> mapInput = new DefaultInputPort<Map<K, V>>()
  {
    @Override
    public void process(Map<K, V> tuple)
    {
      V val = tuple.get(sumDimension);
      if (val != null) {
        sum += Long.valueOf((String)val);
      }
    }

  };
  public final transient DefaultOutputPort<String> output = new DefaultOutputPort<String>();

  @Override
  public void endWindow()
  {
    output.emit(String.valueOf(sum));
    sum = 0L;
  }

}