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// Copyright (c) FIRST and other WPILib contributors.
// Open Source Software; you can modify and/or share it under the terms of
// the WPILib BSD license file in the root directory of this project.
#pragma once
#include <functional>
#include <units/time.h>
#include "frc/TimedRobot.h"
namespace frc {
/**
* TimesliceRobot extends the TimedRobot robot program framework to provide
* timeslice scheduling of periodic functions.
*
* The TimesliceRobot class is intended to be subclassed by a user creating a
* robot program.
*
* This class schedules robot operations serially in a timeslice format.
* TimedRobot's periodic functions are the first in the timeslice table with 0
* ms offset and 20 ms period. You can schedule additional controller periodic
* functions at a shorter period (5 ms by default). You give each one a
* timeslice duration, then they're run sequentially. The main benefit of this
* approach is consistent starting times for each controller periodic, which can
* make odometry and estimators more accurate and controller outputs change more
* consistently.
*
* Here's an example of measured subsystem durations and their timeslice
* allocations:
*
* <table>
* <tr>
* <td><b>Subsystem</b></td>
* <td><b>Duration (ms)</b></td>
* <td><b>Allocation (ms)</b></td>
* </tr>
* <tr>
* <td><b>Total</b></td>
* <td>5.0</td>
* <td>5.0</td>
* </tr>
* <tr>
* <td>TimedRobot</td>
* <td>?</td>
* <td>2.0</td>
* </tr>
* <tr>
* <td>Drivetrain</td>
* <td>1.32</td>
* <td>1.5</td>
* </tr>
* <tr>
* <td>Flywheel</td>
* <td>0.6</td>
* <td>0.7</td>
* </tr>
* <tr>
* <td>Turret</td>
* <td>0.6</td>
* <td>0.8</td>
* </tr>
* <tr>
* <td><b>Free</b></td>
* <td>0.0</td>
* <td>N/A</td>
* </tr>
* </table>
*
* Since TimedRobot periodic functions only run every 20ms, that leaves a 2 ms
* empty spot in the allocation table for three of the four 5 ms cycles
* comprising 20 ms. That's OK because the OS needs time to do other things.
*
* If the robot periodic functions and the controller periodic functions have a
* lot of scheduling jitter that cause them to occasionally overlap with later
* timeslices, consider giving the main robot thread a real-time priority using
* frc::SetCurrentThreadPriority(). An RT priority of 15 is a reasonable choice.
*
* If you do enable RT though, <i>make sure your periodic functions do not
* block</i>. If they do, the operating system will lock up, and you'll have to
* boot the roboRIO into safe mode and delete the robot program to recover.
*/
class TimesliceRobot : public TimedRobot {
public:
/**
* Constructor for TimesliceRobot.
*
* @param robotPeriodicAllocation The allocation to give the TimesliceRobot
* periodic functions.
* @param controllerPeriod The controller period. The sum of all scheduler
* allocations should be less than or equal to this
* value.
*/
explicit TimesliceRobot(units::second_t robotPeriodicAllocation,
units::second_t controllerPeriod);
/**
* Schedule a periodic function with the constructor's controller period and
* the given allocation. The function's runtime allocation will be placed
* after the end of the previous one's.
*
* If a call to this function makes the allocations exceed the controller
* period, an exception will be thrown since that means the TimesliceRobot
* periodic functions and the given function will have conflicting
* timeslices.
*
* @param func Function to schedule.
* @param allocation The function's runtime allocation out of the controller
* period.
*/
void Schedule(std::function<void()> func, units::second_t allocation);
private:
units::second_t m_nextOffset;
units::second_t m_controllerPeriod;
};
} // namespace frc