NAME

       nng_recv_aio - receive message asynchronously

SYNOPSIS

           #include <nng/nng.h>

           void nng_recv_aio(nng_socket s, nng_aio *aio);

DESCRIPTION

       The nng_recv_aio() receives a message using the socket s asynchronously.

       When a message is successfully received by the socket, it is stored in the aio by an internal call
       equivalent to nng_aio_set_msg(), then the completion callback on the aio is executed. In this case,
       nng_aio_result() will return zero. The callback function is responsible for retrieving the message and
       disposing of it appropriately.

           Important

           Failing to accept and dispose of messages in this case can lead to memory leaks.

       If for some reason the asynchronous receive cannot be completed successfully (including by being canceled
       or timing out), then the callback will still be executed, but nng_aio_result() will be non-zero.

           Note

           The semantics of what receiving a message means varies from protocol to protocol, so examination of
           the protocol documentation is encouraged. (For example, with a pub socket the data is broadcast, so
           that any peers who have a suitable subscription will be able to receive it using nng_recv() or a
           similar function.) Furthermore, some protocols may not support receiving (such as pub) or may require
           other conditions. (For example, req sockets cannot normally receive data, which are replies to
           requests, until they have first sent a request.)

RETURN VALUES

       None. (The operation completes asynchronously.)

ERRORS

       NNG_ECANCELED
           The operation was aborted.

       NNG_ECLOSED
           The socket s is not open.

       NNG_ENOMEM
           Insufficient memory is available.

       NNG_ENOTSUP
           The protocol for socket s does not support receiving.

       NNG_ESTATE
           The socket s cannot receive data in this state.

       NNG_ETIMEDOUT
           The receive timeout expired.

SEE ALSO

       nng_aio_get_msg(3), nng_aio_set_msg(3), nng_msg_alloc(3), nng_strerror(3), nng_aio(5), nng_msg(5),
       nng_socket(5), nng(7)

                                                   2025-04-20                                    NNG_RECV_AIO(3)