oxmox
17f68cf8fe
git-subtree-dir: external/nng git-subtree-split: 169221da8d53b2ca4fda76f894bee8505887a7c6
81 lines
2.8 KiB
Text
81 lines
2.8 KiB
Text
= nng_recv_aio(3)
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//
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// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
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// Copyright 2018 Capitar IT Group BV <info@capitar.com>
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//
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// This document is supplied under the terms of the MIT License, a
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// copy of which should be located in the distribution where this
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// file was obtained (LICENSE.txt). A copy of the license may also be
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// found online at https://opensource.org/licenses/MIT.
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//
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== NAME
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nng_recv_aio - receive message asynchronously
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== SYNOPSIS
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[source, c]
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----
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#include <nng/nng.h>
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void nng_recv_aio(nng_socket s, nng_aio *aio);
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----
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== DESCRIPTION
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The `nng_recv_aio()` receives a xref:nng_msg.5.adoc[message] using the
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xref:nng_socket.5.adoc[socket] _s_ asynchronously.
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When a message is successfully received by the socket, it is
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stored in the _aio_ by an internal call equivalent to
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xref:nng_aio_set_msg.3.adoc[`nng_aio_set_msg()`], then the completion
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callback on the _aio_ is executed.
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In this case, xref:nng_aio_result.3.adoc[`nng_aio_result()`] will
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return zero.
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The callback function is responsible for retrieving the message
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and disposing of it appropriately.
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IMPORTANT: Failing to accept and dispose of messages in this
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case can lead to memory leaks.
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If for some reason the asynchronous receive cannot be completed
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successfully (including by being canceled or timing out), then
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the callback will still be executed,
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but xref:nng_aio_result.3.adoc[`nng_aio_result()`] will be non-zero.
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NOTE: The semantics of what receiving a message means varies from protocol to
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protocol, so examination of the protocol documentation is encouraged.
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(For example, with a xref:nng_pub.7.adoc[_pub_] socket the data is broadcast, so that
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any peers who have a suitable subscription will be able to receive it using
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xref:nng_recv.3.adoc[`nng_recv()`] or a similar function.)
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Furthermore, some protocols may not support receiving (such as
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xref:nng_pub.7.adoc[_pub_]) or may require other conditions.
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(For example, xref:nng_req.7.adoc[_req_] sockets cannot normally receive data, which
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are replies to requests, until they have first sent a request.)
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== RETURN VALUES
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None. (The operation completes asynchronously.)
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== ERRORS
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[horizontal]
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`NNG_ECANCELED`:: The operation was aborted.
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`NNG_ECLOSED`:: The socket _s_ is not open.
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`NNG_ENOMEM`:: Insufficient memory is available.
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`NNG_ENOTSUP`:: The protocol for socket _s_ does not support receiving.
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`NNG_ESTATE`:: The socket _s_ cannot receive data in this state.
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`NNG_ETIMEDOUT`:: The receive timeout expired.
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== SEE ALSO
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[.text-left]
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xref:nng_aio_get_msg.3.adoc[nng_aio_get_msg(3)],
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xref:nng_aio_set_msg.3.adoc[nng_aio_set_msg(3)],
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xref:nng_msg_alloc.3.adoc[nng_msg_alloc(3)],
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xref:nng_strerror.3.adoc[nng_strerror(3)],
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xref:nng_aio.5.adoc[nng_aio(5)],
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xref:nng_msg.5.adoc[nng_msg(5)],
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xref:nng_socket.5.adoc[nng_socket(5)],
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xref:nng.7.adoc[nng(7)]
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