library/src/main/java/org/apache/apex/malhar/lib/stream/DevNullCounter.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.stream;

import javax.validation.constraints.Min;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.datatorrent.api.Context.OperatorContext;
import com.datatorrent.api.DefaultInputPort;
import com.datatorrent.common.util.BaseOperator;

/**
 * An implementation of BaseOperator that is used for logging by counting the tuple and then drops it.
 * <p>
 * Increments a count and writes the net number (rate) to console. Useful to benchmark other
 * modules.<br>
 * This operator is neither pass through nor windowed as far as data tuples are
 * concerned. The logging is done during end of window call.<br>
 * <br>
 * <b>Port</b>:<br>
 * <b>data</b>: expects K<br>
 * <br>
 * <b>Properties</b>: rollingwindowcount: Number of windows to average over.
 * Results are written to the log<br>
 * <br>
 * @displayName Dev Null Counter
 * @category Stream Manipulators
 * @tags count
 * @since 0.3.3
 */
public class DevNullCounter<K> extends BaseOperator
{
        /**
   * Input port that takes objects to be counted in each window.
   */
  public final transient DefaultInputPort<K> data = new DefaultInputPort<K>()
  {
    /**
     * Process each tuple. Expects upstream node to compute number of tuples in
     * that window and send it as an int<br>
     *
     * @param tuple
     */
    @Override
    public void process(K tuple)
    {
      tuple_count++;
    }
  };
  private static Logger log = LoggerFactory.getLogger(DevNullCounter.class);
  private long windowStartTime = 0;
  long[] tuple_numbers = null;
  long[] time_numbers = null;
  int tuple_index = 0;
  int count_denominator = 1;
  long count_windowid = 0;
  long tuple_count = 1; // so that the first begin window starts the count down

  private boolean debug = true;

  /**
   * getter function for debug state
   *
   * @return debug state
   */
  public boolean getDebug()
  {
    return debug;
  }

  /**
   * setter function for debug state
   *
   * @param i
   *          sets debug to i
   */
  public void setDebug(boolean i)
  {
    debug = i;
  }

  @Min(1)
  private int rollingwindowcount = 1;

  public void setRollingwindowcount(int val)
  {
    rollingwindowcount = val;
  }

  /**
   * Sets up all the config parameters. Assumes checking is done and has passed
   *
   * @param context
   */
  @Override
  public void setup(OperatorContext context)
  {
    windowStartTime = 0;
    if (rollingwindowcount != 1) { // Initialized the tuple_numbers
      tuple_numbers = new long[rollingwindowcount];
      time_numbers = new long[rollingwindowcount];
      for (int i = tuple_numbers.length; i > 0; i--) {
        tuple_numbers[i - 1] = 0;
        time_numbers[i - 1] = 0;
      }
      tuple_index = 0;
    }
  }

  @Override
  public void beginWindow(long windowId)
  {
    if (tuple_count != 0) { // Do not restart time if no tuples were sent
      windowStartTime = System.currentTimeMillis();
      tuple_count = 0;
    }
  }

  /**
   * convenient method for not sending more than configured number of windows.
   */
  @Override
  public void endWindow()
  {
    if (!debug) {
      return;
    }
    if (tuple_count == 0) {
      return;
    }
    long elapsedTime = System.currentTimeMillis() - windowStartTime;
    if (elapsedTime == 0) {
      elapsedTime = 1; // prevent from / zero
    }

    long average;
    long tuples_per_sec = (tuple_count * 1000) / elapsedTime; // * 1000 as
                                                              // elapsedTime is
                                                              // in millis
    if (rollingwindowcount == 1) {
      average = tuples_per_sec;
    } else { // use tuple_numbers
      long slots;
      if (count_denominator == rollingwindowcount) {
        tuple_numbers[tuple_index] = tuple_count;
        time_numbers[tuple_index] = elapsedTime;
        slots = rollingwindowcount;
        tuple_index++;
        if (tuple_index == rollingwindowcount) {
          tuple_index = 0;
        }
      } else {
        tuple_numbers[count_denominator - 1] = tuple_count;
        time_numbers[count_denominator - 1] = elapsedTime;
        slots = count_denominator;
        count_denominator++;
      }
      long time_slot = 0;
      long numtuples = 0;
      for (int i = 0; i < slots; i++) {
        numtuples += tuple_numbers[i];
        time_slot += time_numbers[i];
      }
      average = (numtuples * 1000) / time_slot;
    }
    log.debug(String.format(
        "\nWindowid (%d), Time (%d ms): The rate for %d tuples is %d. This window had %d tuples_per_sec ",
        count_windowid++, elapsedTime, tuple_count, average, tuples_per_sec));
  }
}