measure the time it takes to execute parts of a program More...

#include <Timer.h>

Public Member Functions
	Timer ()
	Construct a timer and set the mark ("mark()"). More...

void	mark ()
	Set the timer mark – i.e., start the clock ticking. More...

double	user () const
	Get the user time (in seconds) since last "mark()". More...

double	system () const
	Get the system time (in seconds) since last "mark()". More...

double	all () const
	Get the user+system time (in seconds) since last "mark()". More...

double	real () const
	Get the real time (in seconds) since last "mark()". More...

void	show () const
	Show real, user, system time (in seconds) on cout or a user supplied stream. More...

void	show (ostream &os) const

void	show (const String &) const
	Show real, user, system time (in seconds) on cout or a user supplied stream preceeded by the string parameter. More...

void	show (ostream &os, const String &prefix) const

double	user_usec () const
	Get the user time (in microseconds) since last "mark()". More...

double	system_usec () const
	Get the system time (in microseconds) since last "mark()". More...

double	all_usec () const
	Get the user+system time (in microseconds) since last "mark()". More...

Private Attributes
rusage	usage0

timeb	real0

Detailed Description

measure the time it takes to execute parts of a program

Intended use:

Public interface

Review Status

Reviewed By:: Paul Shannon
Date Reviewed:: 1995/03/01/

Synopsis

The Timer class provides an interface to system timing. It allows a C++ program to record the time between a reference point (mark) and now. This class uses the system time(2) interface to provide time resolution at either millisecond or microsecond granularity, depending upon operating system support and features. Since the time duration is stored in a 32-bit word, the maximum time period before rollover occurs is about 71 minutes.

Due to operating system dependencies, the accuracy of all member function results may not be as documented. For example some operating systems do not support timers with microsecond resolution. In those cases, the values returned are provided to the nearest millisecond or other unit of time as appropriate. See the Timer header file for system- specific notes.

Tip: This Timer class is based on the TI COOL library Timer class

Example

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

realtime = user time + system time

 Timer timer;   // the mark is set at construction time
 timer.mark();  // if you want to restart the clock
...do some calculation..\.
 cout << "user:   " << timer.user () << endl; 
 cout << "system: " << timer.system () << endl;
 cout << "real:   " << timer.real () << endl; 

To Do

it might be useful to have a stop () member function: for really precise timing, the successive calls to user, system and real all happen at measurably different times
provide an enquiry function that reports the resolution of the timer
add 'start' member function, a synonym for 'mark' but more comprehensible

Definition at line 127 of file Timer.h.

Constructor & Destructor Documentation

casacore::Timer::Timer ( )

inline

Construct a timer and set the mark ("mark()").

Definition at line 132 of file Timer.h.

References mark().

Member Function Documentation

double casacore::Timer::all ( ) const

Get the user+system time (in seconds) since last "mark()".

double casacore::Timer::all_usec ( ) const

Get the user+system time (in microseconds) since last "mark()".

void casacore::Timer::mark ( )

Set the timer mark – i.e., start the clock ticking.

Referenced by Timer().

double casacore::Timer::real ( ) const

Get the real time (in seconds) since last "mark()".

void casacore::Timer::show ( ) const

Show real, user, system time (in seconds) on cout or a user supplied stream.

void casacore::Timer::show ( ostream & os ) const

void casacore::Timer::show ( const String & ) const

Show real, user, system time (in seconds) on cout or a user supplied stream preceeded by the string parameter.

void casacore::Timer::show	(	ostream &	os,
		const String &	prefix
	)		const

double casacore::Timer::system ( ) const

Get the system time (in seconds) since last "mark()".

double casacore::Timer::system_usec ( ) const

Get the system time (in microseconds) since last "mark()".

double casacore::Timer::user ( ) const

Get the user time (in seconds) since last "mark()".

double casacore::Timer::user_usec ( ) const

Get the user time (in microseconds) since last "mark()".

Member Data Documentation

timeb casacore::Timer::real0

private

Definition at line 203 of file Timer.h.

rusage casacore::Timer::usage0