StateGuard.hpp

#pragma once
#include <atomic>
#include <thread>
 
namespace YSFX
{
class StateGuard
{
public:
  [[nodiscard]] bool try_enter() noexcept
  {
    return !m_busy.exchange(true, std::memory_order_acquire);
  }
 
  void enter() noexcept
  {
    while(m_busy.exchange(true, std::memory_order_acquire))
      std::this_thread::yield();
  }
 
  void leave() noexcept { m_busy.store(false, std::memory_order_release); }
 
private:
  std::atomic_bool m_busy{false};
};
 
class StateLock
{
public:
  explicit StateLock(StateGuard& g) noexcept
      : m_guard{g}
  {
    m_guard.enter();
  }
  ~StateLock() { m_guard.leave(); }
  StateLock(const StateLock&) = delete;
  StateLock& operator=(const StateLock&) = delete;
 
private:
  StateGuard& m_guard;
};
}