pw_sync_stl/public/pw_sync_stl/mutex_native.h

// Copyright 2020 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
#pragma once

#include <mutex>

namespace pw::sync::backend {

// The NativeMutex class adds a flag that tracks whether the std::timed_mutex is
// locked. The C++ standard states that misusing a mutex is undefined behavior,
// so library implementations may simply ignore misuse. This ensures misuse hits
// a PW_CHECK.
struct NativeMutex {
  // The locked state is tracked in a variable. This function asserts if the
  // state is inconsistent (e.g. unlocking an unlocked mutex).
  void SetLockedState(bool new_state);

  std::timed_mutex mutex;
  bool locked = false;
};

using NativeMutexHandle = std::timed_mutex&;

}  // namespace pw::sync::backend