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casacore::PrecTimer Class Reference

Precision timer to measure elapsed times in a cumulative way. More...

#include <PrecTimer.h>

Classes

struct  TimeStruct
 
union  Union1
 
struct  Union2
 

Public Member Functions

 PrecTimer ()
 Construct. More...
 
 ~PrecTimer ()
 Destruct. More...
 
void start ()
 Restart the timer. More...
 
void stop ()
 Stop the timer. More...
 
void reset ()
 Reset the timer to zero. More...
 
void show () const
 Show real time on cout or a user supplied stream. More...
 
void show (std::ostream &os) const
 
void show (const String &) const
 Show real time on cout or a user supplied stream preceeded by the string parameter. More...
 
void show (std::ostream &os, const String &prefix) const
 
double getReal () const
 Get the real time (in seconds). More...
 
unsigned long long getCount () const
 Get the total number of times start/stop is done. More...
 

Private Member Functions

void print_time (std::ostream &, double time) const
 

Static Private Member Functions

static double get_CPU_speed_in_MHz ()
 

Private Attributes

Union1 u1
 
Union2 u2
 

Static Private Attributes

static double CPU_speed_in_MHz
 

Detailed Description

Precision timer to measure elapsed times in a cumulative way.

Intended use:

Public interface

Review Status

Test programs:
tPrecTimer

Synopsis

The PrecTimer supplements the Timer class. If offers a low-overhead and high-resolution interval timer for use on i386, x86_64, ia64, and powerpc platforms, using the processor's timestamp counter that is incremented each cycle. Put timer.start() and timer.stop() calls around the piece of code to be timed. Because the timer is cumulative, the total time of a particular piece of code can be timed.
Caution: Make sure that start() and stop() calls alternate, otherwise very strange times will be the result;

A timer can be started and stopped multiple times; both the average and total time, as well as the number of iterations are printed. The measured time is real time (as opposed to user or system time). The timer can be used to measure from 10 nanosecond to a century interval.

Multiple timers can be used in a nested way as long as each of them has independent (matching) start and stop calls.

The class is more or less a copy of the original written by John Romein at ASTRON, Dwingeloo, the Netherlands.

Example

Here's how to create a timer, start it (the 'mark' member function) and display a breakdown.

PrecTimer ttimer; // the timer is reset at construction time
PrecTimer ctimer;
ttimer.reset(); // if you want to reset the timer (not needed here)
ttimer.start(); // start the total timer
for (int i=0; i<n; ++i) {
... do something..\.
ctimer.start(); // start the calc timer
...do some calculation which will be timed..\.
ctimer.stop(); // and stop it
}
ttimer.stop();
ttimer.show (cout, "Total ");
ctimer.show (cout, "Calculations");

Definition at line 101 of file PrecTimer.h.

Constructor & Destructor Documentation

casacore::PrecTimer::PrecTimer ( )
inline

Construct.

Definition at line 185 of file PrecTimer.h.

References reset().

casacore::PrecTimer::~PrecTimer ( )
inline

Destruct.

Definition at line 190 of file PrecTimer.h.

Member Function Documentation

static double casacore::PrecTimer::get_CPU_speed_in_MHz ( )
staticprivate
unsigned long long casacore::PrecTimer::getCount ( ) const
inline

Get the total number of times start/stop is done.

Definition at line 180 of file PrecTimer.h.

References casacore::PrecTimer::Union2::count, and u2.

double casacore::PrecTimer::getReal ( ) const

Get the real time (in seconds).

void casacore::PrecTimer::print_time ( std::ostream &  ,
double  time 
) const
private
void casacore::PrecTimer::reset ( )
inline

Reset the timer to zero.

Definition at line 174 of file PrecTimer.h.

References casacore::PrecTimer::Union2::count, casacore::PrecTimer::Union1::total_time, u1, and u2.

Referenced by PrecTimer().

void casacore::PrecTimer::show ( ) const

Show real time on cout or a user supplied stream.

void casacore::PrecTimer::show ( std::ostream &  os) const
void casacore::PrecTimer::show ( const String ) const

Show real time on cout or a user supplied stream preceeded by the string parameter.

void casacore::PrecTimer::show ( std::ostream &  os,
const String prefix 
) const
void casacore::PrecTimer::start ( )
inline
void casacore::PrecTimer::stop ( )
inline

Member Data Documentation

double casacore::PrecTimer::CPU_speed_in_MHz
staticprivate

Definition at line 168 of file PrecTimer.h.

Union1 casacore::PrecTimer::u1
private

Definition at line 165 of file PrecTimer.h.

Referenced by reset(), start(), and stop().

Union2 casacore::PrecTimer::u2
private

Definition at line 166 of file PrecTimer.h.

Referenced by getCount(), reset(), and stop().


The documentation for this class was generated from the following file: