/** mutex to protect _state, _stable, _test and _emits */
mutable boost::mutex _data_mutex;
State _state;
boost::optional<std::string> _stable;
boost::optional<std::string> _test;
/** mutex to protect _state, _stable, _test and _emits */
mutable boost::mutex _data_mutex;
State _state;
boost::optional<std::string> _stable;
boost::optional<std::string> _test;