template<typename T>
class cache_type
{
public:
    cache_type()
        : content_()
        , cache_lock_()
    {
    }

    cache_item<T>& get_element(int index)
    {
        std::lock_guard<std::mutex> lock(cache_lock_);

        if(static_cast<unsigned>(index) >= content_.size()) {
            content_.resize(index + 1);
        }

        return content_[index];
    }

    void flush()
    {
        std::lock_guard<std::mutex> lock(cache_lock_);
        content_.clear();
    }

private:
    std::vector<cache_item<T>> content_;
    std::mutex cache_lock_;
};