/* Copyright 2024 The TensorFlow Authors. All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
==============================================================================*/

#ifndef XLA_TSL_PROFILER_UTILS_NO_INIT_H_
#define XLA_TSL_PROFILER_UTILS_NO_INIT_H_

#include <utility>

namespace tsl {
namespace profiler {

// Wraps T into a union so that we can avoid the cost of automatic construction
// and destruction when tracing is disabled.
template <typename T>
union NoInit {
  // Ensure constructor and destructor do nothing.
  NoInit() {}
  ~NoInit() {}

  template <typename... Ts>
  void Emplace(Ts&&... args) {
    new (&value) T(std::forward<Ts>(args)...);
  }

  void Destroy() { value.~T(); }

  T Consume() && {
    T v = std::move(value);
    Destroy();
    return v;
  }

  T value;
};

}  // namespace profiler
}  // namespace tsl

#endif  // XLA_TSL_PROFILER_UTILS_NO_INIT_H_