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/* -*- C++ -*- */
// $Id$
// ============================================================================
//
// = LIBRARY
// ace
//
// = FILENAME
// Stats.h
//
// = AUTHORS
// David L. Levine
//
// ============================================================================
#ifndef ACE_STATS_H
#define ACE_STATS_H
#include "ace/ACE.h"
#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */
#include "ace/Containers.h"
class ACE_Export ACE_Stats_Value
{
// = TITLE
// Helper class for ACE_Stats.
//
// = DESCRIPTION
// Container struct for 64-bit signed quantity and its
// precision. It would be nicer to use a fixed-point class, but
// this is sufficient. Users typically don't need to use this
// class directly; see ACE_Stats below.
public:
ACE_Stats_Value (const u_int precision);
// Constructor, which requires precision in terms of number of
// decimal digits. The more variation in the data, and the greater
// the data values, the smaller the precision must be to avoid
// overflow in the standard deviation calculation. 3 might be a
// good value, or maybe 4. 5 will probably be too large for
// non-trivial data sets.
u_int precision (void) const;
// Accessor for precision.
void whole (const ACE_UINT32);
// Set the whole_ field.
ACE_UINT32 whole (void) const;
// Accessor for the whole_ field.
void fractional (const ACE_UINT32);
// Set the fractional_ field.
ACE_UINT32 fractional (void) const;
// Accessor for the fractional_ field.
ACE_UINT32 fractional_field (void) const;
// Calculates the maximum value of the fractional portion, given its
// precision.
void scaled_value (ACE_UINT64 &) const;
// Access the value as an _unsigned_ 64 bit quantity. It scales the
// value up by <precision> decimal digits, so that no precision will
// be lost. It assumes that <whole_> is >= 0.
void dump (void) const;
// Print to stdout.
private:
ACE_UINT32 whole_;
// The integer portion of the value.
ACE_UINT32 fractional_;
// The fractional portion of the value.
u_int precision_;
// The number of decimal digits of precision represented by
// <fractional_>. Not declared const, so the only way to change it
// is via the assignment operator.
ACE_UNIMPLEMENTED_FUNC (ACE_Stats_Value (void))
};
class ACE_Export ACE_Stats
{
// = TITLE
// Provides simple statistical analysis.
//
// = DESCRIPTION
// Simple statistical analysis package. Prominent features are:
// 1) It does not use any floating point arithmetic.
// 2) It handles positive and/or negative sample values. The
// sample value type is ACE_INT32.
// 3) It uses 64 bit unsigned, but not 64 bit signed, quantities
// internally.
// 4) It checks for overflow of internal state.
// 5) It has no static variables of other than built-in types.
//
// Example usage:
// ACE_Stats stats;
// for (u_int i = 0; i < n; ++i)
// {
// const ACE_UINT32 sample = /* ... */;
// stats.sample (sample);
// }
// stats.print_summary (3);
public:
ACE_Stats (void);
// Default constructor.
int sample (const ACE_INT32 value);
// Provide a new sample. Returns 0 on success, -1 if it fails due
// to running out of memory, or to rolling over of the sample count.
ACE_UINT32 samples (void) const;
// Access the number of samples provided so far.
ACE_INT32 min_value (void) const;
// Value of the minimum sample provided so far.
ACE_INT32 max_value (void) const;
// Value of the maximum sample provided so far.
void mean (ACE_Stats_Value &mean,
const ACE_UINT32 scale_factor = 1);
// Access the mean of all samples provided so far. The fractional
// part is to the specified number of digits. E.g., 3 fractional
// digits specifies that the fractional part is in thousandths.
int std_dev (ACE_Stats_Value &std_dev,
const ACE_UINT32 scale_factor = 1);
// Access the standard deviation, whole and fractional parts. See
// description of <mean> method for argument descriptions.
int print_summary (const u_int precision,
const ACE_UINT32 scale_factor = 1,
FILE * = stdout) const;
// Print summary statistics. If scale_factor is not 1, then the
// results are divided by it, i.e., each of the samples is scaled
// down by it. If internal overflow is reached with the specified
// scale factor, it successively tries to reduce it. Returns -1 if
// there is overflow even with a 0 scale factor.
void reset ();
// Initialize internal state.
static void quotient (const ACE_UINT64 dividend,
const ACE_UINT32 divisor,
ACE_Stats_Value "ient);
// Utility division function, for ACE_UINT64 dividend.
static void quotient (const ACE_Stats_Value ÷nd,
const ACE_UINT32 divisor,
ACE_Stats_Value "ient);
// Utility division function, for ACE_Stats_Value dividend.
static void square_root (const ACE_UINT64 n,
ACE_Stats_Value &square_root);
// Sqrt function, which uses an oversimplified version of Newton's
// method. It's not fast, but it doesn't require floating point
// support.
void dump (void) const;
// Print summary statistics to stdout.
private:
u_int overflow_;
// Internal indication of whether there has been overflow. Contains
// the errno corresponding to the cause of overflow.
ACE_UINT32 number_of_samples_;
// Number of samples.
ACE_INT32 min_;
// Minimum sample value.
ACE_INT32 max_;
// Maximum sample value.
ACE_Unbounded_Queue <ACE_INT32> samples_;
// The samples.
};
#if defined (__ACE_INLINE__)
# include "ace/Stats.i"
#endif /* __ACE_INLINE__ */
#endif /* ! ACE_STATS_H */
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