Class SmartPtrNoGIL

python/pyarrow/src/arrow/python/common.h:244–275

template <template <typename...> typename SmartPtr, typename... Ts>
class SmartPtrNoGIL : public SmartPtr<Ts...> {
  using Base = SmartPtr<Ts...>;

 public:
  template <typename... Args>
  SmartPtrNoGIL(Args&&... args) : Base(std::forward<Args>(args)...) {}

  ~SmartPtrNoGIL() { reset(); }

  template <typename... Args>
  void reset(Args&&... args) {
    auto release_guard = optional_gil_release();
    Base::reset(std::forward<Args>(args)...);
  }

  template <typename V>
  SmartPtrNoGIL& operator=(V&& v) {
    auto release_guard = optional_gil_release();
    Base::operator=(std::forward<V>(v));
    return *this;
  }

 private:
  // Only release the GIL if we own an object *and* the Python runtime is
  // valid *and* the GIL is held.
  std::optional<PyReleaseGIL> optional_gil_release() const {
    if (this->get() != nullptr && Py_IsInitialized() && PyGILState_Check()) {
      return PyReleaseGIL();
    }
    return {};
  }
};

/// \brief A std::shared_ptr<T, ...> subclass that releases the GIL when destroying T
template <typename... Ts>