nng_ctx_recv(3)

# nng_ctx_recv(3) Manual Page

## NAME

nng_ctx_recv - receive message using context asynchronously

## SYNOPSIS

    #include <nng/nng.h>

    void nng_ctx_recv(nng_ctx ctx, nng_aio *aio);

## DESCRIPTION

The `nng_ctx_recv()` receives a message using the context s asynchronously.

When a message is successfully received by the context, 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.

| 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.

| The semantics of what receiving a message means varies from protocol to protocol, so examination of the protocol documentation is encouraged.

## RETURN VALUES

None. (The operation completes asynchronously.)

## ERRORS

`NNG_ECANCELED` | The operation was aborted.
`NNG_ECLOSED` | The context ctx is not open.
`NNG_ENOMEM` | Insufficient memory is available.
`NNG_ENOTSUP` | The protocol for context ctx does not support receiving.
`NNG_ESTATE` | The context ctx 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_ctx(5), nng_msg(5), nng(7)