chromium/third_party/protobuf/src/google/protobuf/stubs/mutex.h

// 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 …
#define GOOGLE_PROTOBUF_RELEASE …
#define GOOGLE_PROTOBUF_SCOPED_CAPABILITY …
#define GOOGLE_PROTOBUF_CAPABILITY(x) …
#else
#define GOOGLE_PROTOBUF_ACQUIRE …
#define GOOGLE_PROTOBUF_RELEASE …
#define GOOGLE_PROTOBUF_SCOPED_CAPABILITY
#define GOOGLE_PROTOBUF_CAPABILITY …
#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 { … };

// 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 { … };

Mutex;

// MutexLock(mu) acquires mu when constructed and releases it when destroyed.
class GOOGLE_PROTOBUF_SCOPED_CAPABILITY PROTOBUF_EXPORT MutexLock { … };

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

// MutexLockMaybe is like MutexLock, but is a no-op when mu is nullptr.
class PROTOBUF_EXPORT 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.
Mutex;
MutexLock;
ReaderMutexLock;
WriterMutexLock;
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_