cpp/platform/impl/windows/mutex.h

// Copyright 2021 Google LLC
//
// 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.
#ifndef PLATFORM_IMPL_WINDOWS_MUTEX_H_
#define PLATFORM_IMPL_WINDOWS_MUTEX_H_
#include <windows.h>
#include <stdio.h>
#include <synchapi.h>

#include <memory>
#include <mutex>  //  NOLINT

#include "absl/memory/memory.h"
#include "absl/synchronization/mutex.h"
#include "platform/api/mutex.h"
namespace location {
namespace nearby {
namespace windows {

// A lock is a tool for controlling access to a shared resource by multiple
// threads.
// https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/locks/Lock.html
class ABSL_LOCKABLE Mutex : public api::Mutex {
 public:
  explicit Mutex(Mode mode) : mode_(mode) {}
  ~Mutex() override = default;
  Mutex(Mutex&&) = delete;
  Mutex& operator=(Mutex&&) = delete;
  Mutex(const Mutex&) = delete;
  Mutex& operator=(const Mutex&) = delete;

  void Lock() ABSL_EXCLUSIVE_LOCK_FUNCTION() override {
    if (mode_ == Mode::kRegularNoCheck) mutex_.ForgetDeadlockInfo();
    if (mode_ == Mode::kRegular || mode_ == Mode::kRegularNoCheck) {
      mutex_.Lock();
    } else {
      recursive_mutex_.lock();
    }
  }

  void Unlock() ABSL_UNLOCK_FUNCTION() override {
    if (mode_ == Mode::kRegular || mode_ == Mode::kRegularNoCheck) {
      mutex_.Unlock();
    } else {
      recursive_mutex_.unlock();
    }
  }

 private:
  friend class ConditionVariable;
  absl::Mutex mutex_;
  std::recursive_mutex recursive_mutex_;  //  The actual mutex allocation
  Mode mode_;
};

}  // namespace windows
}  // namespace nearby
}  // namespace location
#endif  // PLATFORM_IMPL_WINDOWS_MUTEX_H_