third_party/protobuf/src/google/protobuf/stubs/once.cc

// Protocol Buffers - Google's data interchange format
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// http://code.google.com/p/protobuf/
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// Author: kenton@google.com (Kenton Varda)
//
// emulates google3/base/once.h
//
// This header is intended to be included only by internal .cc files and
// generated .pb.cc files.  Users should not use this directly.

#ifdef _WIN32
#include <windows.h>
#endif

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

namespace google {
namespace protobuf {

#ifdef _WIN32

struct ProtobufOnceInternal {
  ProtobufOnceInternal() {
    InitializeCriticalSection(&critical_section);
  }
  ~ProtobufOnceInternal() {
    DeleteCriticalSection(&critical_section);
  }
  CRITICAL_SECTION critical_section;
};

ProtobufOnceType::~ProtobufOnceType()
{
  delete internal_;
  internal_ = NULL;
}

ProtobufOnceType::ProtobufOnceType() {
  // internal_ may be non-NULL if Init() was already called.
  if (internal_ == NULL) internal_ = new ProtobufOnceInternal;
}

void ProtobufOnceType::Init(void (*init_func)()) {
  // internal_ may be NULL if we're still in dynamic initialization and the
  // constructor has not been called yet.  As mentioned in once.h, we assume
  // that the program is still single-threaded at this time, and therefore it
  // should be safe to initialize internal_ like so.
  if (internal_ == NULL) internal_ = new ProtobufOnceInternal;

  EnterCriticalSection(&internal_->critical_section);
  if (!initialized_) {
    init_func();
    initialized_ = true;
  }
  LeaveCriticalSection(&internal_->critical_section);
}

#endif

}  // namespace protobuf
}  // namespace google