The nng_socket_close() function closes the supplied socket, s. Messages that have been submitted for
sending may be flushed or delivered, depending upon the transport.
The nng_close() function also does this, and is the old name for this function. The nng_close() function
is considered deprecated and may be removed in the next major release.
Further attempts to use the socket after this call returns will result in NNG_ECLOSED. Threads waiting
for operations on the socket when this call is executed may also return with an NNG_ECLOSED result.
Note
Closing the socket while data is in transmission will likely lead to loss of that data. There is no
automatic linger or flush to ensure that the socket send buffers have completely transmitted. It is
recommended to wait a brief period after calling nng_send() or similar functions, before calling this
function.