// Copyright (c) 2006, Google Inc.

// All rights reserved.

//

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are

// met:

//

//     * Redistributions of source code must retain the above copyright

// notice, this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above

// copyright notice, this list of conditions and the following disclaimer

// in the documentation and/or other materials provided with the

// distribution.

//     * Neither the name of Google Inc. nor the names of its

// contributors may be used to endorse or promote products derived from

// this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#ifndef GOOGLE_PROTOBUF_STUBS_MUTEX_H_

#define GOOGLE_PROTOBUF_STUBS_MUTEX_H_

#include <mutex>

#ifdef GOOGLE_PROTOBUF_SUPPORT_WINDOWS_XP

#include <windows.h>

// GetMessage conflicts with GeneratedMessageReflection::GetMessage().

#ifdef GetMessage

#undef GetMessage

#endif

#endif

#include <google/protobuf/stubs/macros.h>

// Define thread-safety annotations for use below, if we are building with

// Clang.

#if defined(__clang__) && !defined(SWIG)

#define GOOGLE_PROTOBUF_ACQUIRE(...) \

  __attribute__((acquire_capability(__VA_ARGS__)))

#define GOOGLE_PROTOBUF_RELEASE(...) \

  __attribute__((release_capability(__VA_ARGS__)))

#define GOOGLE_PROTOBUF_SCOPED_CAPABILITY __attribute__((scoped_lockable))

#define GOOGLE_PROTOBUF_CAPABILITY(x) __attribute__((capability(x)))

#else

#define GOOGLE_PROTOBUF_ACQUIRE(...)

#define GOOGLE_PROTOBUF_RELEASE(...)

#define GOOGLE_PROTOBUF_SCOPED_CAPABILITY

#define GOOGLE_PROTOBUF_CAPABILITY(x)

#endif

#include <google/protobuf/port_def.inc>

// ===================================================================

// emulates google3/base/mutex.h

namespace google {

namespace protobuf {

namespace internal {

#define GOOGLE_PROTOBUF_LINKER_INITIALIZED

#ifdef GOOGLE_PROTOBUF_SUPPORT_WINDOWS_XP

// This class is a lightweight replacement for std::mutex on Windows platforms.

// std::mutex does not work on Windows XP SP2 with the latest VC++ libraries,

// because it utilizes the Concurrency Runtime that is only supported on Windows

// XP SP3 and above.

class PROTOBUF_EXPORT CriticalSectionLock {

 public:

  CriticalSectionLock() { InitializeCriticalSection(&critical_section_); }

  ~CriticalSectionLock() { DeleteCriticalSection(&critical_section_); }

  void lock() { EnterCriticalSection(&critical_section_); }

  void unlock() { LeaveCriticalSection(&critical_section_); }

 private:

  CRITICAL_SECTION critical_section_;

  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(CriticalSectionLock);

};

#endif

// In MSVC std::mutex does not have a constexpr constructor.

// This wrapper makes the constructor constexpr.

template <typename T>

class CallOnceInitializedMutex {

 public:

  constexpr CallOnceInitializedMutex() : flag_{}, buf_{} {}

  ~CallOnceInitializedMutex() { get().~T(); }

  void lock() { get().lock(); }

  void unlock() { get().unlock(); }

 private:

  T& get() {

    std::call_once(flag_, [&] { ::new (static_cast<void*>(&buf_)) T(); });

    return reinterpret_cast<T&>(buf_);

  }

  std::once_flag flag_;

  alignas(T) char buf_[sizeof(T)];

};

// Mutex is a natural type to wrap. As both google and other organization have

// specialized mutexes. gRPC also provides an injection mechanism for custom

// mutexes.

class GOOGLE_PROTOBUF_CAPABILITY("mutex") PROTOBUF_EXPORT WrappedMutex {

 public:

#if defined(__QNX__)

  constexpr WrappedMutex() = default;

#else

  constexpr WrappedMutex() {}

#endif

  void Lock() GOOGLE_PROTOBUF_ACQUIRE() { mu_.lock(); }

  void Unlock() GOOGLE_PROTOBUF_RELEASE() { mu_.unlock(); }

  // Crash if this Mutex is not held exclusively by this thread.

  // May fail to crash when it should; will never crash when it should not.

  void AssertHeld() const {}

 private:

#if defined(GOOGLE_PROTOBUF_SUPPORT_WINDOWS_XP)

  CallOnceInitializedMutex<CriticalSectionLock> mu_{};

#elif defined(_WIN32)

  CallOnceInitializedMutex<std::mutex> mu_{};

#else

  std::mutex mu_{};

#endif

};

using Mutex = WrappedMutex;

// MutexLock(mu) acquires mu when constructed and releases it when destroyed.

class GOOGLE_PROTOBUF_SCOPED_CAPABILITY PROTOBUF_EXPORT MutexLock {

 public:

  explicit MutexLock(Mutex* mu) GOOGLE_PROTOBUF_ACQUIRE(mu) : mu_(mu) {

    this->mu_->Lock();

  }

  ~MutexLock() GOOGLE_PROTOBUF_RELEASE() { this->mu_->Unlock(); }

 private:

  Mutex *const mu_;

  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MutexLock);

};

// TODO(kenton):  Implement these?  Hard to implement portably.

typedef MutexLock ReaderMutexLock;

typedef MutexLock WriterMutexLock;

// MutexLockMaybe is like MutexLock, but is a no-op when mu is nullptr.

class PROTOBUF_EXPORT MutexLockMaybe {

 public:

  explicit MutexLockMaybe(Mutex *mu) :

    mu_(mu) { if (this->mu_ != nullptr) { this->mu_->Lock(); } }

  ~MutexLockMaybe() { if (this->mu_ != nullptr) { this->mu_->Unlock(); } }

 private:

  Mutex *const mu_;

  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MutexLockMaybe);

};

#if defined(GOOGLE_PROTOBUF_NO_THREADLOCAL)

template<typename T>

class ThreadLocalStorage {

 public:

  ThreadLocalStorage() {

    pthread_key_create(&key_, &ThreadLocalStorage::Delete);

  }

  ~ThreadLocalStorage() {

    pthread_key_delete(key_);

  }

  T* Get() {

    T* result = static_cast<T*>(pthread_getspecific(key_));

    if (result == nullptr) {

      result = new T();

      pthread_setspecific(key_, result);

    }

    return result;

  }

 private:

  static void Delete(void* value) {

    delete static_cast<T*>(value);

  }

  pthread_key_t key_;

  GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(ThreadLocalStorage);

};

#endif

}  // namespace internal

// We made these internal so that they would show up as such in the docs,

// but we don't want to stick "internal::" in front of them everywhere.

using internal::Mutex;

using internal::MutexLock;

using internal::ReaderMutexLock;

using internal::WriterMutexLock;

using internal::MutexLockMaybe;

}  // namespace protobuf

}  // namespace google

#undef GOOGLE_PROTOBUF_ACQUIRE

#undef GOOGLE_PROTOBUF_RELEASE

#include <google/protobuf/port_undef.inc>

#endif  // GOOGLE_PROTOBUF_STUBS_MUTEX_H_