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---
version: tip
layout: manpage_v2
title: nng_ctx_recv(3)
---
<h1>nng_ctx_recv(3)</h1>
<div class="sect1">
<h2 id="_name">NAME</h2>
<div class="sectionbody">
<div class="paragraph">
<p>nng_ctx_recv - receive message using context asynchronously</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_synopsis">SYNOPSIS</h2>
<div class="sectionbody">
<div class="listingblock">
<div class="content">
<pre class="pygments highlight"><code data-lang="c"><span></span><span class="tok-cp">#include</span><span class="tok-w"> </span><span class="tok-cpf"><nng/nng.h></span>
<span class="tok-kt">void</span><span class="tok-w"> </span><span class="tok-nf">nng_ctx_recv</span><span class="tok-p">(</span><span class="tok-n">nng_ctx</span><span class="tok-w"> </span><span class="tok-n">ctx</span><span class="tok-p">,</span><span class="tok-w"> </span><span class="tok-n">nng_aio</span><span class="tok-w"> </span><span class="tok-o">*</span><span class="tok-n">aio</span><span class="tok-p">);</span></code></pre>
</div>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_description">DESCRIPTION</h2>
<div class="sectionbody">
<div class="paragraph">
<p>The <code>nng_ctx_recv()</code> receives a <a href="nng_msg.5.html">message</a> using the
<a href="nng_ctx.5.html">context</a> <em>s</em> asynchronously.</p>
</div>
<div class="paragraph">
<p>When a message is successfully received by the context, it is
stored in the <em>aio</em> by an internal call equivalent to
<a href="nng_aio_set_msg.3.html"><code>nng_aio_set_msg()</code></a>, then the completion
callback on the <em>aio</em> is executed.
In this case, <a href="nng_aio_result.3.html"><code>nng_aio_result()</code></a> will
return zero.
The callback function is responsible for retrieving the message
and disposing of it appropriately.</p>
</div>
<div class="admonitionblock important">
<table>
<tr>
<td class="icon">
<i class="fa icon-important" title="Important"></i>
</td>
<td class="content">
Failing to accept and dispose of messages in this
case can lead to memory leaks.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>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 <a href="nng_aio_result.3.html"><code>nng_aio_result()</code></a> will be non-zero.</p>
</div>
<div class="admonitionblock note">
<table>
<tr>
<td class="icon">
<i class="fa icon-note" title="Note"></i>
</td>
<td class="content">
The semantics of what receiving a message means varies from protocol to
protocol, so examination of the protocol documentation is encouraged.
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_return_values">RETURN VALUES</h2>
<div class="sectionbody">
<div class="paragraph">
<p>None. (The operation completes asynchronously.)</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_errors">ERRORS</h2>
<div class="sectionbody">
<div class="hdlist">
<table>
<tr>
<td class="hdlist1">
<code>NNG_ECANCELED</code>
</td>
<td class="hdlist2">
<p>The operation was aborted.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ECLOSED</code>
</td>
<td class="hdlist2">
<p>The context <em>ctx</em> is not open.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ENOMEM</code>
</td>
<td class="hdlist2">
<p>Insufficient memory is available.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ENOTSUP</code>
</td>
<td class="hdlist2">
<p>The protocol for context <em>ctx</em> does not support receiving.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ESTATE</code>
</td>
<td class="hdlist2">
<p>The context <em>ctx</em> cannot receive data in this state.</p>
</td>
</tr>
<tr>
<td class="hdlist1">
<code>NNG_ETIMEDOUT</code>
</td>
<td class="hdlist2">
<p>The receive timeout expired.</p>
</td>
</tr>
</table>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_see_also">SEE ALSO</h2>
<div class="sectionbody">
<div class="paragraph text-left">
<p><a href="nng_aio_get_msg.3.html">nng_aio_get_msg(3)</a>,
<a href="nng_aio_set_msg.3.html">nng_aio_set_msg(3)</a>,
<a href="nng_msg_alloc.3.html">nng_msg_alloc(3)</a>,
<a href="nng_strerror.3.html">nng_strerror(3)</a>,
<a href="nng_aio.5.html">nng_aio(5)</a>,
<a href="nng_ctx.5.html">nng_ctx(5)</a>,
<a href="nng_msg.5.html">nng_msg(5)</a>,
<a href="nng.7.html">nng(7)</a></p>
</div>
</div>
</div>
|
