content: /**
   * 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 org.apache.apex.malhar.contrib.misc.algo;
  
  import java.util.HashMap;
  import java.util.Map;
  
  import org.apache.apex.malhar.lib.util.AbstractBaseNOperatorMap;
  import org.apache.commons.lang.mutable.MutableInt;
  
  import com.datatorrent.api.DefaultOutputPort;
  import com.datatorrent.api.annotation.OperatorAnnotation;
  
  /**
   * This operator filters the incoming stream of key value pairs by emitting the first N key value pairs with a specified key in each window.
   * <p>
   * Emits first N tuples of a particular key.
   * </p>
   * <p>
   * This module is a pass through module<br>
   * <br>
   * <b>StateFull : Yes, </b> tuple are compare across application window(s). <br>
   * <b>Partitions : No, </b> will yield wrong results. <br>
   * <br>
   * <b>Ports</b>:<br>
   * <b>data</b>: Input data port expects HashMap&lt;K,V&gt;<br>
   * <b>bottom</b>: Output data port, emits HashMap&lt;K,V&gt;<br>
   * <br>
   * <b>Properties</b>:<br>
   * <b>N</b>: The number of top values to be emitted per key<br>
   * <br>
   * <b>Specific compile time checks are</b>:<br>
   * N: Has to be >= 1<br>
   * <br>
   * <br>
   * </p>
   *
   * @displayName First N Keyval Pairs Matching Key
   * @category Rules and Alerts
   * @tags filter, key value
   * @deprecated
   * @since 0.3.2
   */
  @Deprecated
  @OperatorAnnotation(partitionable = false)
  public class FirstN<K,V> extends AbstractBaseNOperatorMap<K, V>
  {
    /**
     * key count map.
     */
    HashMap<K, MutableInt> keycount = new HashMap<K, MutableInt>();
  
    /**
     * Inserts tuples into the queue
     * @param tuple to insert in the queue
     */
    @Override
    public void processTuple(Map<K, V> tuple)
    {
      for (Map.Entry<K, V> e: tuple.entrySet()) {
        MutableInt count = keycount.get(e.getKey());
        if (count == null) {
          count = new MutableInt(0);
          keycount.put(e.getKey(), count);
        }
        count.increment();
        if (count.intValue() <= getN()) {
          first.emit(cloneTuple(e.getKey(), e.getValue()));
        }
      }
    }
  
    /**
     * The output port on which the first N key value pairs are emitted.
     */
    public final transient DefaultOutputPort<HashMap<K, V>> first = new DefaultOutputPort<HashMap<K, V>>();
  
    /**
     * Clears the cache to start anew in a new window
     */
    @Override
    public void endWindow()
    {
      keycount.clear();
    }
  
    /**
     * First N number of KeyValue pairs for each Key.
     *
     * @param val
     */
    public void setN(int val)
    {
      super.setN(val);
    }
  }
  