// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0

#pragma once

#include <atomic>
#include <memory>
#include <mutex>

#include "opentelemetry/version.h"

OPENTELEMETRY_BEGIN_NAMESPACE
namespace sdk
{
namespace common
{
/**
 * A wrapper to provide atomic shared pointers.
 *
 * This wrapper relies on a mutex for gcc 4.8, and specializations of
 * std::atomic_store and std::atomic_load for all other instances.
 */
#if (__GNUC__ == 4 && (__GNUC_MINOR__ >= 8))
template <class T>
class AtomicSharedPtr
{
public:
  explicit AtomicSharedPtr(std::shared_ptr<T> ptr) noexcept : ptr_{std::move(ptr)} {}

  void store(const std::shared_ptr<T> &other) noexcept
  {
    std::lock_guard<std::mutex> lock_guard{mu_};
    ptr_ = other;
  }

  std::shared_ptr<T> load() const noexcept
  {
    std::lock_guard<std::mutex> lock_guard{mu_};
    return ptr_;
  }

private:
  std::shared_ptr<T> ptr_;
  mutable std::mutex mu_;
};
#else
template <class T>
class AtomicSharedPtr
{
public:
  explicit AtomicSharedPtr(std::shared_ptr<T> ptr) noexcept : ptr_{std::move(ptr)} {}

  void store(const std::shared_ptr<T> &other) noexcept { std::atomic_store(&ptr_, other); }

  std::shared_ptr<T> load() const noexcept { return std::atomic_load(&ptr_); }

private:
  std::shared_ptr<T> ptr_;
};
#endif
}  // namespace common
}  // namespace sdk
OPENTELEMETRY_END_NAMESPACE