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

Restart the timer.

Definition at line 194 of file PrecTimer.h.

References casacore::PrecTimer::Union1::s1, casacore::time(), casacore::PrecTimer::Union1::total_time, casacore::PrecTimer::TimeStruct::total_time_high, casacore::PrecTimer::TimeStruct::total_time_low, and u1.

void casacore::PrecTimer::stop ( )

inline

Stop the timer.

Definition at line 268 of file PrecTimer.h.

References casacore::PrecTimer::Union2::count, casacore::PrecTimer::Union1::s1, casacore::time(), casacore::PrecTimer::Union1::total_time, casacore::PrecTimer::TimeStruct::total_time_high, casacore::PrecTimer::TimeStruct::total_time_low, u1, and u2.

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().

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

• casa/OS/PrecTimer.h