package org.apache.helix.monitoring;
   
   /*
    * 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.
   */
  
  import org.apache.commons.math.stat.descriptive.DescriptiveStatistics;
  import org.apache.commons.math.stat.descriptive.SynchronizedDescriptiveStatistics;
  
  public class StatCollector
  {
    private static final int DEFAULT_WINDOW_SIZE = 100;
    private final DescriptiveStatistics _stats;
    private long _numDataPoints;
    private long _totalSum;
  
    public StatCollector()
    {
      _stats = new SynchronizedDescriptiveStatistics();
      _stats.setWindowSize(DEFAULT_WINDOW_SIZE);
    }
  
    public void addData(double data)
    {
      _numDataPoints++;
      _totalSum += data;
      _stats.addValue(data);
    }
  
    public long getTotalSum()
    {
      return _totalSum;
    }
  
    public DescriptiveStatistics getStatistics()
    {
      return _stats;
    }
  
    public long getNumDataPoints()
    {
      return _numDataPoints;
    }
  
    public void reset()
    {
      _numDataPoints = 0;
      _totalSum = 0;
      _stats.clear();
    }
  
    public double getMean()
    {
      if(_stats.getN() == 0)
      {
        return 0;
      }
      return _stats.getMean();
    }
  
    public double getMax()
    {
      return _stats.getMax();
    }
  
    public double getMin()
    {
      return _stats.getMin();
    }
  
    public double getPercentile(int percentage)
    {
      if(_stats.getN() == 0)
      {
        return 0;
      }
      return _stats.getPercentile(percentage*1.0);
    }
  }