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#include "base/singleton.h"

#include <array>

#include "absl/base/const_init.h"
#include "absl/base/thread_annotations.h"
#include "absl/log/log.h"
#include "absl/synchronization/mutex.h"

namespace mozc {
namespace internal {
namespace {

constinit absl::Mutex mu(absl::kConstInit);
constinit std::array<void (*)(), 256> finalizers ABSL_GUARDED_BY(mu) = {};
constinit int size ABSL_GUARDED_BY(mu) = 0;

}  // namespace

void AddSingletonFinalizer(void (*finalizer)()) ABSL_LOCKS_EXCLUDED(mu) {
  absl::MutexLock lock(mu);
  if (size >= finalizers.size()) {
    LOG(FATAL) << "Too many singletons";
  }
  finalizers[size++] = finalizer;
}

}  // namespace internal

void FinalizeSingletons() ABSL_LOCKS_EXCLUDED(internal::mu) {
  absl::MutexLock lock(internal::mu);
  // Run the finalizers in the reverse order of their registration for safer
  // destruction (e.g. in case one singleton depends on another).
  for (int i = internal::size - 1; i >= 0; --i) {
    internal::finalizers[i]();
  }
  internal::size = 0;
}

}  // namespace mozc
