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.Random;
  
  import javax.validation.constraints.Max;
  import javax.validation.constraints.Min;
  
  import org.apache.apex.malhar.lib.util.BaseKeyOperator;
  
  import com.datatorrent.api.DefaultInputPort;
  import com.datatorrent.api.DefaultOutputPort;
  import com.datatorrent.api.annotation.OperatorAnnotation;
  import com.datatorrent.api.annotation.Stateless;
  
  /**
   * This operator takes a stream of tuples as input, and emits each tuple with a specified probability.
   * <p>
   * Emits the tuple as per probability of pass rate out of total rate. <br>
   * <br>
   * An efficient filter to allow sample analysis of a stream. Very useful is the incoming stream has high throughput.
   * </p>
   * <p>
   * <br>
   * <b> StateFull : No, </b> tuple is processed in current window. <br>
   * <b> Partitions : Yes. </b> No state dependency among input tuples. <br>
   * <b>Ports</b>:<br>
   * <b>data</b>: expects K<br>
   * <b>sample</b>: emits K<br>
   * <br>
   * <b>Properties</b>:<br>
   * <b>passrate</b>: Sample rate out of a total of totalrate. Default is 1<br>
   * <b>totalrate</b>: Total rate (divisor). Default is 100<br>
   * <br>
   * <b>Specific compile time checks are</b>: None<br>
   * passrate is positive integer<br>
   * totalrate is positive integer<br>
   * passrate and totalrate are not compared (i.e. passrate &lt; totalrate) check is not done to allow users to make this operator a passthrough (all) during testing<br>
   * <br>
   * <b>Specific run time checks are</b>: None<br>
   * <br>
   * </p>
   *
   * @displayName Sampler
   * @category Stats and Aggregations
   * @tags filter
   *
   * @since 0.3.2
   * @deprecated
   */
  @Deprecated
  @Stateless
  @OperatorAnnotation(partitionable = true)
  public class Sampler<K> extends BaseKeyOperator<K>
  {
    /**
     * This is the input port which receives tuples.
     */
    public final transient DefaultInputPort<K> data = new DefaultInputPort<K>()
    {
      /**
       * Emits tuples at a rate corresponding to the given samplingPercentage.
       */
      @Override
      public void process(K tuple)
      {
        double val = random.nextDouble();
        if (val > samplingPercentage) {
          return;
        }
        sample.emit(cloneKey(tuple));
      }
    };
  
    /**
     * This is the output port which emits the sampled tuples.
     */
    public final transient DefaultOutputPort<K> sample = new DefaultOutputPort<K>();
  
    @Min(0)
    @Max(1)
    private double samplingPercentage = 1.0;
  
    private transient Random random = new Random();
  
    /**
     * Gets the samplingPercentage.
     * @return the samplingPercentage
     */
    public double getSamplingPercentage()
    {
      return samplingPercentage;
    }
  
    /**
     * The percentage of tuples to allow to pass through this operator. This percentage should be
     * a number between 0 and 1 inclusive.
     * @param samplingPercentage the samplingPercentage to set
     */
    public void setSamplingPercentage(double samplingPercentage)
    {
      this.samplingPercentage = samplingPercentage;
    }
  }
  