timer.h

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#pragma once
 
#include <atomic>
#include <chrono>
#include <mutex>
#include <thread>
 
#ifdef _WIN32
#include <windows.h>  // Must be included before mmsystem.h for Windows multimedia timer
#endif
#ifdef __linux__
#include <sys/timerfd.h>  // Linux timerfd
#include <unistd.h>       // read, close
#endif
 
#ifdef _WIN32
#include <mmsystem.h>  // Windows multimedia system for timeSetEvent
#endif
 
#include <condition_variable>
 
namespace mm::core::timer {

class MainTimer {
 public:
  static unsigned int DELAY_MS;

  static std::mutex listenerMx;

  static std::condition_variable listenerCv;

  static MainTimer& getInstance();

  static void notifyAllListeners();

  void wait();

  uint64_t getTickCount() const;

  uint64_t getCycleCount() const;

  uint64_t getCycleMissedTickCount() const;

  int64_t getElapsedTime() const;

  int64_t getWaitIntervalUs() const;
 
 private:
  std::mutex mx_;

  std::condition_variable cv_;

  unsigned int timerID_;

  bool timerTick_;

  std::atomic<uint64_t> tickCount_;

  std::atomic<uint64_t> cycleCount_;

  std::atomic<uint64_t> prevTickCount_;

  std::atomic<uint64_t> cycleMissedTickCount_;

  int64_t start_;

  std::chrono::steady_clock::time_point lastWaitTime_{};

  std::atomic<int64_t> waitIntervalUs_{0};

  MainTimer();

  ~MainTimer();

  MainTimer(const MainTimer&) = delete;

  MainTimer& operator=(const MainTimer&) = delete;
 
#ifdef _WIN32
  static void CALLBACK TimerCallback(unsigned int uID, unsigned int uMsg,
                                     DWORD_PTR dwUser, DWORD_PTR dw1,
                                     DWORD_PTR dw2);
#endif
#ifdef __linux__
  int timerfd_{-1};

  std::thread timerThread_;

  std::atomic<bool> timerRunning_{false};
#endif

  void onTimerTick();
};

class MainTimerListener {
 public:
  MainTimerListener();

  void wait();

  uint64_t getTickCount() const;

  uint64_t getCycleCount() const;

  int64_t getElapsedTime() const;
 
 private:
  std::atomic<uint64_t> tickCount_;

  std::atomic<uint64_t> refTickCount_;

  std::atomic<uint64_t> cycleCount_;

  int64_t start_;
};
 
}  // namespace mm::core::timer