// Traceable MUST only be used by a single thread. If a new thread is spawned in a sub-operation this thread MUST have its own Traceable copy.
class Traceable {
public:
    struct SpanContext {}
    Traceable(const Traceable& t) : _context(deep_copy(t._context)) {}
    // MUST be used by a single thread only.
    void setActiveContext(std::shared_ptr<BaseContext> context) {
        _context = std::move(context);
    }

    // MUST be used by a single thread only.
    std::shared_ptr<BaseContext> getActiveContext() const {
        return _context;
    }
private:
    std::shared_ptr<SpanContext> _context;
};