ndbt_stats.hpp

mysql-5.0.22.tar.gz源码包

/* Copyright (C) 2003 MySQL AB

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

#ifndef NDBT_STATS_HPP
#define NDBT_STATS_HPP

#include <ndb_global.h>

class NDBT_Stats {
public:
  NDBT_Stats() { reset(); }
  
  void reset() { sum = sum2 = 0.0; max = DBL_MIN; ; min = DBL_MAX; n = 0;}
  
  void addObservation(double t) { 
    sum+= t; 
    sum2 += (t*t); 
    n++; 
    if(min > t) min = t;
    if(max < t) max = t;
  }
  
  double getMean() const { return sum/n;}
  double getStddev() const { return sqrt(getVariance()); }
  double getVariance() const { return (n*sum2 - (sum*sum))/(n*n);}
  double getMin() const { return min;}
  double getMax() const { return max;}
  int    getCount() const { return n;}

  NDBT_Stats & operator+=(const NDBT_Stats & c){
    sum += c.sum;
    sum2 += c.sum2;
    n += c.n;
    if(min > c.min) min = c.min;
    if(max < c.max) max = c.max;
    return * this;
  }
private:
  double sum;
  double sum2;
  int n;
  double min, max;
};

inline
double
NDB_SQRT(double x){
  assert(x >= 0);

  double y = 0;
  double s = 1;
  double r = 0;
  while(y <= x){
    y += s;
    s += 2;
    r += 1;
  }
  return r - 1;
}

#endif