//-----------------------------------------------------------------------------

// Copyright 2022 Google LLC

//

// 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

//

//     https://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 SRC_COMMON_UTILS_REF_COUNTER_H_

#define SRC_COMMON_UTILS_REF_COUNTER_H_

#include <cstddef>

#include "src/common/logging/logging.h"

namespace raksha {

// Note that this is not a thread-safe class.

class RefCounter {

 public:

  RefCounter() : count_(0) {}

  RefCounter(size_t init) : count_(init) {}

  operator size_t() const { return count_; }

  // Adds the given increment and returns the old value.

  size_t FetchAdd(size_t increment) {

    size_t old = count_;

    count_ += increment;

    return old;

  }

  // Subtracts the given increment and returns the old value.

  size_t FetchSub(size_t decrement) {

    CHECK(count_ >= decrement) << "FetchSub can decrement below zero.";

    size_t old = count_;

    count_ -= decrement;

    return old;

  }

 private:

  size_t count_;

};

}  // namespace raksha

#endif  // SRC_COMMON_UTILS_REF_COUNTER_H_