rate.cpp

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 * Author: Eitan Marder-Eppstein
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#include <ros/rate.h>
 
namespace roswrap
{
 
        Rate::Rate(double frequency)
                : start_(Time::now())
                , expected_cycle_time_(1.0 / frequency)
                , actual_cycle_time_(0.0)
        { }
 
        Rate::Rate(const Duration& d)
                : start_(Time::now())
                , expected_cycle_time_(d.sec, d.nsec)
                , actual_cycle_time_(0.0)
        { }
 
 
 
        bool Rate::sleep()
        {
                Time expected_end = start_ + expected_cycle_time_;
 
                Time actual_end = Time::now();
 
                // detect backward jumps in time
                if (actual_end < start_)
                {
                        expected_end = actual_end + expected_cycle_time_;
                }
 
                //calculate the time we'll sleep for
                Duration sleep_time = expected_end - actual_end;
 
                //set the actual amount of time the loop took in case the user wants to know
                actual_cycle_time_ = actual_end - start_;
 
                //make sure to reset our start time
                start_ = expected_end;
 
                //if we've taken too much time we won't sleep
                if (sleep_time <= Duration(0.0))
                {
                        // if we've jumped forward in time, or the loop has taken more than a full extra
                        // cycle, reset our cycle
                        if (actual_end > expected_end + expected_cycle_time_)
                        {
                                start_ = actual_end;
                        }
                        // return false to show that the desired rate was not met
                        return false;
                }
 
                return sleep_time.sleep();
        }
 
        void Rate::reset()
        {
                start_ = Time::now();
        }
 
        Duration Rate::cycleTime() const
        {
                return actual_cycle_time_;
        }
 
        WallRate::WallRate(double frequency)
                : start_(WallTime::now())
                , expected_cycle_time_(1.0 / frequency)
                , actual_cycle_time_(0.0)
        {}
 
        WallRate::WallRate(const Duration& d)
                : start_(WallTime::now())
                , expected_cycle_time_(d.sec, d.nsec)
                , actual_cycle_time_(0.0)
        {}
 
        bool WallRate::sleep()
        {
                WallTime expected_end = start_ + expected_cycle_time_;
 
                WallTime actual_end = WallTime::now();
 
                // detect backward jumps in time
                if (actual_end < start_)
                {
                        expected_end = actual_end + expected_cycle_time_;
                }
 
                //calculate the time we'll sleep for
                WallDuration sleep_time = expected_end - actual_end;
 
                //set the actual amount of time the loop took in case the user wants to know
                actual_cycle_time_ = actual_end - start_;
 
                //make sure to reset our start time
                start_ = expected_end;
 
                //if we've taken too much time we won't sleep
                if (sleep_time <= WallDuration(0.0))
                {
                        // if we've jumped forward in time, or the loop has taken more than a full extra
                        // cycle, reset our cycle
                        if (actual_end > expected_end + expected_cycle_time_)
                        {
                                start_ = actual_end;
                        }
                        return false;
                }
 
                return sleep_time.sleep();
        }
 
        void WallRate::reset()
        {
                start_ = WallTime::now();
        }
 
        WallDuration WallRate::cycleTime() const
        {
                return actual_cycle_time_;
        }
 
 
}