common/native/tcutils/scopeguard.h

/*
 * Copyright (C) 2022 The Android Open Source Project
 *
 * 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.
 */

// -----------------------------------------------------------------------------
// TODO: figure out a way to use libbase_ndk. This is currently not working
// because of missing apex availability. For now, we can use a copy of
// ScopeGuard which is very lean compared to unique_fd. This code has been
// copied verbatim from:
// https://cs.android.com/android/platform/superproject/+/master:system/libbase/include/android-base/scopeguard.h

#pragma once

#include <utility> // for std::move, std::forward

namespace android {
namespace base {

// ScopeGuard ensures that the specified functor is executed no matter how the
// current scope exits.
template <typename F> class ScopeGuard {
public:
  ScopeGuard(F &&f) : f_(std::forward<F>(f)), active_(true) {}

  ScopeGuard(ScopeGuard &&that) noexcept
      : f_(std::move(that.f_)), active_(that.active_) {
    that.active_ = false;
  }

  template <typename Functor>
  ScopeGuard(ScopeGuard<Functor> &&that)
      : f_(std::move(that.f_)), active_(that.active_) {
    that.active_ = false;
  }

  ~ScopeGuard() {
    if (active_)
      f_();
  }

  ScopeGuard() = delete;
  ScopeGuard(const ScopeGuard &) = delete;
  void operator=(const ScopeGuard &) = delete;
  void operator=(ScopeGuard &&that) = delete;

  void Disable() { active_ = false; }

  bool active() const { return active_; }

private:
  template <typename Functor> friend class ScopeGuard;

  F f_;
  bool active_;
};

template <typename F> ScopeGuard<F> make_scope_guard(F &&f) {
  return ScopeGuard<F>(std::forward<F>(f));
}

} // namespace base
} // namespace android