Method try_lock

extern/boost/boost/thread/v2/shared_mutex.hpp:283–292

    }

    inline bool shared_mutex::try_lock()
    {
      boost::unique_lock<mutex_t> lk(mut_);
      if (!no_writer_no_readers())
      {
        return false;
      }
      state_ = write_entered_;
      return true;
    }

#ifdef BOOST_THREAD_USES_CHRONO
    template <class Clock, class Duration>