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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.ShutdownToken"></a><a class="link" href="ShutdownToken.html" title="SSL shutdown token requirements">SSL shutdown token requirements</a>
</h3></div></div></div>
<p>
A shutdown token is a <a class="link" href="../overview/model/completion_tokens.html" title="Completion Tokens">completion
token</a> for completion signature <code class="computeroutput"><span class="keyword">void</span><span class="special">(</span><span class="identifier">error_code</span><span class="special">)</span></code>.
</p>
<h5>
<a name="asio.reference.ShutdownToken.h0"></a>
<span><a name="asio.reference.ShutdownToken.examples"></a></span><a class="link" href="ShutdownToken.html#asio.reference.ShutdownToken.examples">Examples</a>
</h5>
<p>
A free function as a shutdown token:
</p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">shutdown_handler</span><span class="special">(</span>
<span class="keyword">const</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">ec</span><span class="special">)</span>
<span class="special">{</span>
<span class="special">...</span>
<span class="special">}</span>
</pre>
<p>
A shutdown token function object:
</p>
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">shutdown_handler</span>
<span class="special">{</span>
<span class="special">...</span>
<span class="keyword">void</span> <span class="keyword">operator</span><span class="special">()(</span>
<span class="keyword">const</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">ec</span><span class="special">)</span>
<span class="special">{</span>
<span class="special">...</span>
<span class="special">}</span>
<span class="special">...</span>
<span class="special">};</span>
</pre>
<p>
A lambda as a shutdown token:
</p>
<pre class="programlisting"><span class="identifier">ssl_stream</span><span class="special">.</span><span class="identifier">async_shutdown</span><span class="special">(...,</span>
<span class="special">[](</span><span class="keyword">const</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">ec</span><span class="special">)</span>
<span class="special">{</span>
<span class="special">...</span>
<span class="special">});</span>
</pre>
<p>
A non-static class member function adapted to a shutdown token using <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">bind</span><span class="special">()</span></code>:
</p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">my_class</span><span class="special">::</span><span class="identifier">shutdown_handler</span><span class="special">(</span>
<span class="keyword">const</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">ec</span><span class="special">)</span>
<span class="special">{</span>
<span class="special">...</span>
<span class="special">}</span>
<span class="special">...</span>
<span class="identifier">ssl_stream</span><span class="special">.</span><span class="identifier">async_shutdown</span><span class="special">(...,</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">bind</span><span class="special">(&</span><span class="identifier">my_class</span><span class="special">::</span><span class="identifier">shutdown_handler</span><span class="special">,</span>
<span class="keyword">this</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">placeholders</span><span class="special">::</span><span class="identifier">_1</span><span class="special">));</span>
</pre>
<p>
A non-static class member function adapted to a shutdown token using <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">bind</span><span class="special">()</span></code>:
</p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">my_class</span><span class="special">::</span><span class="identifier">shutdown_handler</span><span class="special">(</span>
<span class="keyword">const</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&</span> <span class="identifier">ec</span><span class="special">)</span>
<span class="special">{</span>
<span class="special">...</span>
<span class="special">}</span>
<span class="special">...</span>
<span class="identifier">ssl_stream</span><span class="special">.</span><span class="identifier">async_shutdown</span><span class="special">(...,</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">bind</span><span class="special">(&</span><span class="identifier">my_class</span><span class="special">::</span><span class="identifier">shutdown_handler</span><span class="special">,</span>
<span class="keyword">this</span><span class="special">,</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">placeholders</span><span class="special">::</span><span class="identifier">error</span><span class="special">));</span>
</pre>
<p>
Using <a class="link" href="use_future.html" title="use_future">use_future</a> as a shutdown
token:
</p>
<pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span class="identifier">future</span><span class="special"><</span><span class="keyword">void</span><span class="special">></span> <span class="identifier">f</span> <span class="special">=</span> <span class="identifier">ssl_stream</span><span class="special">.</span><span class="identifier">async_shutdown</span><span class="special">(...,</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">use_future</span><span class="special">);</span>
<span class="special">...</span>
<span class="keyword">try</span>
<span class="special">{</span>
<span class="identifier">f</span><span class="special">.</span><span class="identifier">get</span><span class="special">();</span>
<span class="special">}</span>
<span class="keyword">catch</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">system_error</span><span class="special">&</span> <span class="identifier">e</span><span class="special">)</span>
<span class="special">{</span>
<span class="special">...</span>
<span class="special">}</span>
</pre>
<p>
Using <a class="link" href="use_awaitable.html" title="use_awaitable">use_awaitable</a> as
a shutdown token:
</p>
<pre class="programlisting"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">awaitable</span><span class="special"><</span><span class="keyword">void</span><span class="special">></span> <span class="identifier">my_coroutine</span><span class="special">()</span>
<span class="special">{</span>
<span class="keyword">try</span>
<span class="special">{</span>
<span class="special">...</span>
<span class="identifier">co_await</span> <span class="identifier">ssl_stream</span><span class="special">.</span><span class="identifier">async_shutdown</span><span class="special">(...,</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">use_awaitable</span><span class="special">);</span>
<span class="special">...</span>
<span class="special">}</span>
<span class="keyword">catch</span> <span class="special">(</span><span class="keyword">const</span> <span class="identifier">system_error</span><span class="special">&</span> <span class="identifier">e</span><span class="special">)</span>
<span class="special">{</span>
<span class="special">...</span>
<span class="special">}</span>
<span class="special">}</span>
</pre>
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<div class="copyright-footer">Copyright © 2003-2023 Christopher M. Kohlhoff<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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