Method is_closed

cpp/src/arrow/util/async_generator.h:926–934

Return whether the generator was closed or destroyed.

    /// Return whether the generator was closed or destroyed.
    bool is_closed() const {
      auto state = weak_state_.lock();
      if (!state) {
        // Generator was destroyed
        return true;
      }
      auto lock = state->mutex.Lock();
      return state->finished;
    }

   private:
    const std::weak_ptr<State> weak_state_;