astrog::Timer Class Reference

#include <libastrog_timer.h>

List of all members.

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Detailed Description

Time operations with known accuracy.

A timer can only time one thing at once. To time multiple things that overlap, multiple timer objects should be used.

The timer is cumulative. That is, when you call stop it adds the amount of time passed since it was started to a total. Subsequent starts and stops add to this total. Calling start when it is already started, or stop when it is already stopped will have no effect.

A grain of a timer is the minimum amount of time that it can measure, which is determined by the underlying system time function.

When a timer is instanciated it will check to see if a previous timer has determined the grain of the system function it is using to get the current time. If it has not, it will determine it and set it so subsequent timers can simply look this value up. This means that the first timer you use in your code will cause a slight delay at construction of up to the grain of the system time function (usually a millisecond).

As well as keeping track of the time, the timer class also keeps track of the accuracy of the time measurement. Every start and stop call introduces an error of up to the grain of the system clock funtion. These are added together, and there are a range of accuracy funtions to display this in a variety of formats.

Definition at line 60 of file libastrog_timer.h.

Public Member Functions
	Timer ()
	Constructor for the Timer class.
	~Timer ()
	Deconstructor for the Timer class.
void	start ()
	Starts the timer.
void	stop ()
	Stops the timer.
void	reset ()
	Resets the timer.
double	get_time ()
	Returns the accumulated time in seconds.
double	get_error_absolute ()
	Returns the accumulated error in seconds.
double	get_error_relative ()
	Returns the error divided by the time.
double	get_error_percentage ()
	Returns the error divided by the time expressed as a percentage.
Static Public Member Functions
static double	get_grain ()
	Returns the grain of the system time call.
Static Private Member Functions
static void	set_grain ()
	Determines the grain of the system time function.
Private Attributes
int	timer_status
	The timer status, ie whether it is currently running.
double	time_elapsed
	Previously accumulated time.
int	error_grains
	Number of errors introduced by the start and stop calls.
timeb	latest_start
	Time of the last start call.
timeb	latest_stop
	Time of the last stop call.
Static Private Attributes
static double	grain = 0
	The grain of the system time function.

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Constructor & Destructor Documentation

astrog::Timer::Timer (   )

Constructor for the Timer class. Definition at line 35 of file timer.cpp. References error_grains, set_grain(), time_elapsed, and timer_status. { // get grain if it hasn't been determined already if (this->get_grain()==0.0) { this->set_grain(); } // timer starts off this->timer_status = 0; // accumulated time is zero this->time_elapsed = 0.0; // zero start/stops so far this->error_grains = 0; }

astrog::Timer::~Timer (   )

Deconstructor for the Timer class. Definition at line 52 of file timer.cpp. { }

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Member Function Documentation

double astrog::Timer::get_error_absolute (   )

Returns the accumulated error in seconds. Definition at line 89 of file timer.cpp. References error_grains, and grain. { return this->error_grains*Timer::grain; }

double astrog::Timer::get_error_percentage (   )

Returns the error divided by the time expressed as a percentage. Definition at line 99 of file timer.cpp. References get_error_relative(). { return 100*(this->get_error_relative()); }

double astrog::Timer::get_error_relative (   )

Returns the error divided by the time. Definition at line 94 of file timer.cpp. Referenced by get_error_percentage(). { return (this->get_error_absolute())/(this->get_time()); }

double astrog::Timer::get_grain (   )  [static]

Returns the grain of the system time call. Definition at line 104 of file timer.cpp. References grain. { return Timer::grain; }

double astrog::Timer::get_time (   )

Returns the accumulated time in seconds. Definition at line 83 of file timer.cpp. References time_elapsed. Referenced by astrog::PipelineTestTimer::execute(). { if (this->timer_status == 1) {} // TODO Throw error return this->time_elapsed; }

void astrog::Timer::reset (   )

Resets the timer. Definition at line 74 of file timer.cpp. References start(), stop(), and time_elapsed. { if (this->timer_status == 1) { this->stop(); this->start(); } this->time_elapsed = 0; }

void astrog::Timer::set_grain (   )  [static, private]

Determines the grain of the system time function. Definition at line 109 of file timer.cpp. References grain. Referenced by Timer(). { struct timeb start; struct timeb stop; ftime(&start); ftime(&stop); double time = 0; while (time<=0) { ftime(&stop); time = ((double)(stop.time-start.time)+(double)(stop.millitm-start.millitm)/1000.0f); } Timer::grain = time; }

void astrog::Timer::start (   )

Starts the timer. Calling this again once the timer is already started will have no effect on the timer object, and will cause an error event. Definition at line 56 of file timer.cpp. References error_grains, and timer_status. Referenced by astrog::PipelineTestTimer::execute(), and reset(). { if (this->timer_status == 1) {} // TODO throw error this->timer_status = 1; this->error_grains += 1; ftime(&this->latest_start); }

void astrog::Timer::stop (   )

Stops the timer. Calling this again once the timer is already stopped will have no effect on the timer object, and will cause an error event. Definition at line 64 of file timer.cpp. References error_grains, latest_start, latest_stop, time_elapsed, and timer_status. Referenced by astrog::PipelineTestTimer::execute(), and reset(). { if (this->timer_status == 0) {} // TODO throw error this->timer_status = 0; this->error_grains += 1; ftime(&this->latest_stop); time_elapsed += ((double)(latest_stop.time-latest_start.time) +((double)(latest_stop.millitm-latest_start.millitm))/1000.0f); }

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Member Data Documentation

int astrog::Timer::error_grains [private]

Number of errors introduced by the start and stop calls. See the class description for some more information. Multiply this value by the grain to get the absolute error of the timer. Should be incremented with every start or stop, and set to zero with reset. Definition at line 128 of file libastrog_timer.h. Referenced by get_error_absolute(), start(), stop(), and Timer().

double astrog::Timer::grain = 0 [static, private]

The grain of the system time function. Definition at line 104 of file libastrog_timer.h. Referenced by get_error_absolute(), get_grain(), and set_grain().

struct timeb astrog::Timer::latest_start [private]

Time of the last start call. Definition at line 132 of file libastrog_timer.h. Referenced by stop().

struct timeb astrog::Timer::latest_stop [private]

Time of the last stop call. Definition at line 136 of file libastrog_timer.h. Referenced by stop().

double astrog::Timer::time_elapsed [private]

Previously accumulated time. This is the time that previous consecutive start-stop calls have accumulated. If the timer is currently active, the time it has been active must be added to this variable to get the actual amount. Definition at line 119 of file libastrog_timer.h. Referenced by get_time(), reset(), stop(), and Timer().

int astrog::Timer::timer_status [private]

The timer status, ie whether it is currently running. 0 : not timing 1 : timing Definition at line 111 of file libastrog_timer.h. Referenced by start(), stop(), and Timer().

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

• inc/core/libastrog_timer.h (r26/r26)
• src/core/timer.cpp (r26/r26)

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