wpilibc/sim/include/Notifier.h

/*----------------------------------------------------------------------------*/
/* Copyright (c) FIRST 2008-2017. All Rights Reserved.                        */
/* Open Source Software - may be modified and shared by FRC teams. The code   */
/* must be accompanied by the FIRST BSD license file in the root directory of */
/* the project.                                                               */
/*----------------------------------------------------------------------------*/

#pragma once

#include <atomic>
#include <functional>
#include <list>
#include <thread>
#include <utility>

#include "ErrorBase.h"
#include "HAL/cpp/priority_mutex.h"

namespace frc {

typedef std::function<void()> TimerEventHandler;

class Notifier : public ErrorBase {
 public:
  explicit Notifier(TimerEventHandler handler);

  template <typename Callable, typename Arg, typename... Args>
  Notifier(Callable&& f, Arg&& arg, Args&&... args)
      : Notifier(std::bind(std::forward<Callable>(f), std::forward<Arg>(arg),
                           std::forward<Args>(args)...)) {}
  virtual ~Notifier();

  Notifier(const Notifier&) = delete;
  Notifier& operator=(const Notifier&) = delete;

  void StartSingle(double delay);
  void StartPeriodic(double period);
  void Stop();

 private:
  static std::list<Notifier*> timerQueue;
  static priority_recursive_mutex queueMutex;
  static priority_mutex halMutex;
  static void* m_notifier;
  static std::atomic<int> refcount;

  // Process the timer queue on a timer event
  static void ProcessQueue(int mask, void* params);

  // Update the FPGA alarm since the queue has changed
  static void UpdateAlarm();

  // Insert the Notifier in the timer queue
  void InsertInQueue(bool reschedule);

  // Delete this Notifier from the timer queue
  void DeleteFromQueue();

  // Address of the handler
  TimerEventHandler m_handler;
  // The relative time (either periodic or single)
  double m_period = 0;
  // Absolute expiration time for the current event
  double m_expirationTime = 0;
  // True if this is a periodic event
  bool m_periodic = false;
  // Indicates if this entry is queued
  bool m_queued = false;
  // Held by interrupt manager task while handler call is in progress
  priority_mutex m_handlerMutex;
  static std::thread m_task;
  static std::atomic<bool> m_stopped;
  static void Run();
};

}  // namespace frc