src/base/singleton.cc

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#include "base/singleton.h"

#ifdef OS_WIN
#include <Windows.h>
#else
#include <cstdlib>
#endif  // OS_WIN

#include "base/mutex.h"

namespace mozc {
namespace {

const size_t kMaxFinalizersSize = 256;
size_t g_finalizers_size = 0;

SingletonFinalizer::FinalizerFunc g_finalizers[kMaxFinalizersSize];

// We can't use CHECK logic for Singleton because CHECK (and LOG)
// obtains the singleton LogStream by calling Singleton::get().  If
// something goes wrong during Singleton::get of the LogStream, it
// recursively calls Singleton::get again to report errors, which
// leads an inifinite wait loop because the first Singleton::get locks
// everything.
// ExitWithError() exits the program without reporting errors, which
// is not good but better than an inifinite loop.
void ExitWithError() {
  // This logic is copied from logging.h
#ifdef OS_WIN
  ::RaiseException(::GetLastError(),
                   EXCEPTION_NONCONTINUABLE,
                   NULL, NULL);
#else
  exit(-1);
#endif
}
}  // namespace

void SingletonFinalizer::AddFinalizer(FinalizerFunc func) {
  // When g_finalizers_size is equal to kMaxFinalizersSize,
  // SingletonFinalizer::Finalize is called already.
  if (g_finalizers_size >= kMaxFinalizersSize) {
    ExitWithError();
  }
  // This part is not thread safe.
  // When two different classes are instantiated at the same time,
  // this code will raise an exception.
  g_finalizers[g_finalizers_size++] = func;
}

void SingletonFinalizer::Finalize() {
  // This part is not thread safe.
  // When two different classes are instantiated at the same time,
  // this code will raise an exception.
  for (int i = static_cast<int>(g_finalizers_size) - 1; i >= 0; --i) {
    (*g_finalizers[i])();
  }
  g_finalizers_size = 0;
}
}  // mozc