Method ReleaseConn

library/cpp/neh/tcp2.cpp:554–561

                }

                inline TConnectionRef ReleaseConn() noexcept {
                    TConnectionRef c;
                    {
                        auto g = Guard(AL_);
                        c.Swap(Conn_);
                    }
                    return c;
                }

                mutable TAdaptiveLock AL_; //guaranted calling notify() only once (prevent race between asio thread and current)
                THandleRef Hndl_;