<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>co_spawn (1 of 6 overloads)</title> <link rel="stylesheet" href="../../../boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.75.2"> <link rel="home" href="../../../index.html" title="Asio"> <link rel="up" href="../co_spawn.html" title="co_spawn"> <link rel="prev" href="../co_spawn.html" title="co_spawn"> <link rel="next" href="overload2.html" title="co_spawn (2 of 6 overloads)"> <meta name="viewport" content="width=device-width, initial-scale=1"> </head> <body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> <table cellpadding="2" width="100%"><tr><td valign="top"><img alt="asio C++ library" width="250" height="60" src="../../../asio.png"></td></tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="../co_spawn.html"><img src="../../../prev.png" alt="Prev"></a><a accesskey="u" href="../co_spawn.html"><img src="../../../up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../home.png" alt="Home"></a><a accesskey="n" href="overload2.html"><img src="../../../next.png" alt="Next"></a> </div> <div class="section"> <div class="titlepage"><div><div><h4 class="title"> <a name="asio.reference.co_spawn.overload1"></a><a class="link" href="overload1.html" title="co_spawn (1 of 6 overloads)">co_spawn (1 of 6 overloads)</a> </h4></div></div></div> <p> Spawn a new coroutined-based thread of execution. </p> <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span> <span class="keyword">typename</span> <a class="link" href="../Executor1.html" title="Executor requirements">Executor</a><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <a class="link" href="../Executor1.html" title="Executor requirements">AwaitableExecutor</a><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">CompletionToken</span> <span class="special">=</span> <a class="link" href="../asynchronous_operations.html#asio.reference.asynchronous_operations.default_completion_tokens"><span class="emphasis"><em>DEFAULT</em></span></a><span class="special">></span> <a class="link" href="../asynchronous_operations.html#asio.reference.asynchronous_operations.automatic_deduction_of_initiating_function_return_type"><span class="emphasis"><em>DEDUCED</em></span></a> <span class="identifier">co_spawn</span><span class="special">(</span> <span class="keyword">const</span> <span class="identifier">Executor</span> <span class="special">&</span> <span class="identifier">ex</span><span class="special">,</span> <span class="identifier">awaitable</span><span class="special"><</span> <span class="identifier">T</span><span class="special">,</span> <span class="identifier">AwaitableExecutor</span> <span class="special">></span> <span class="identifier">a</span><span class="special">,</span> <span class="identifier">CompletionToken</span> <span class="special">&&</span> <span class="identifier">token</span> <span class="special">=</span> <a class="link" href="../asynchronous_operations.html#asio.reference.asynchronous_operations.default_completion_tokens"><span class="emphasis"><em>DEFAULT</em></span></a><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">constraint</span><span class="special"><</span> <span class="special">(</span><span class="identifier">is_executor</span><span class="special"><</span> <span class="identifier">Executor</span> <span class="special">>::</span><span class="identifier">value</span><span class="special">||</span><span class="identifier">execution</span><span class="special">::</span><span class="identifier">is_executor</span><span class="special"><</span> <span class="identifier">Executor</span> <span class="special">>::</span><span class="identifier">value</span><span class="special">)&&</span><span class="identifier">is_convertible</span><span class="special"><</span> <span class="identifier">Executor</span><span class="special">,</span> <span class="identifier">AwaitableExecutor</span> <span class="special">>::</span><span class="identifier">value</span> <span class="special">>::</span><span class="identifier">type</span> <span class="special">=</span> <span class="number">0</span><span class="special">);</span> </pre> <h6> <a name="asio.reference.co_spawn.overload1.h0"></a> <span><a name="asio.reference.co_spawn.overload1.parameters"></a></span><a class="link" href="overload1.html#asio.reference.co_spawn.overload1.parameters">Parameters</a> </h6> <div class="variablelist"> <p class="title"><b></b></p> <dl> <dt><span class="term">ex</span></dt> <dd><p> The executor that will be used to schedule the new thread of execution. </p></dd> <dt><span class="term">a</span></dt> <dd><p> The <a class="link" href="../awaitable.html" title="awaitable"><code class="computeroutput"><span class="identifier">awaitable</span></code></a> object that is the result of calling the coroutine's entry point function. </p></dd> <dt><span class="term">token</span></dt> <dd> <p> The <a class="link" href="../../overview/model/completion_tokens.html" title="Completion Tokens">completion token</a> that will handle the notification that the thread of execution has completed. The function signature of the completion handler must be: </p> <pre class="programlisting"><span class="keyword">void</span> <span class="identifier">handler</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span><span class="special">,</span> <span class="identifier">T</span><span class="special">);</span> </pre> </dd> </dl> </div> <h6> <a name="asio.reference.co_spawn.overload1.h1"></a> <span><a name="asio.reference.co_spawn.overload1.completion_signature"></a></span><a class="link" href="overload1.html#asio.reference.co_spawn.overload1.completion_signature">Completion Signature</a> </h6> <pre class="programlisting"><span class="keyword">void</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span><span class="special">,</span> <span class="identifier">T</span><span class="special">)</span> </pre> <h6> <a name="asio.reference.co_spawn.overload1.h2"></a> <span><a name="asio.reference.co_spawn.overload1.example"></a></span><a class="link" href="overload1.html#asio.reference.co_spawn.overload1.example">Example</a> </h6> <pre class="programlisting"><span class="identifier">asio</span><span class="special">::</span><span class="identifier">awaitable</span><span class="special"><</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">></span> <span class="identifier">echo</span><span class="special">(</span><span class="identifier">tcp</span><span class="special">::</span><span class="identifier">socket</span> <span class="identifier">socket</span><span class="special">)</span> <span class="special">{</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">bytes_transferred</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="keyword">try</span> <span class="special">{</span> <span class="keyword">char</span> <span class="identifier">data</span><span class="special">[</span><span class="number">1024</span><span class="special">];</span> <span class="keyword">for</span> <span class="special">(;;)</span> <span class="special">{</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">n</span> <span class="special">=</span> <span class="identifier">co_await</span> <span class="identifier">socket</span><span class="special">.</span><span class="identifier">async_read_some</span><span class="special">(</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">data</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="identifier">co_await</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">async_write</span><span class="special">(</span><span class="identifier">socket</span><span class="special">,</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">buffer</span><span class="special">(</span><span class="identifier">data</span><span class="special">,</span> <span class="identifier">n</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="identifier">bytes_transferred</span> <span class="special">+=</span> <span class="identifier">n</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">std</span><span class="special">::</span><span class="identifier">exception</span><span class="special">&)</span> <span class="special">{</span> <span class="special">}</span> <span class="identifier">co_return</span> <span class="identifier">bytes_transferred</span><span class="special">;</span> <span class="special">}</span> <span class="comment">// ...</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">co_spawn</span><span class="special">(</span><span class="identifier">my_executor</span><span class="special">,</span> <span class="identifier">echo</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">my_tcp_socket</span><span class="special">)),</span> <span class="special">[](</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">exception_ptr</span> <span class="identifier">e</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">n</span><span class="special">)</span> <span class="special">{</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"transferred "</span> <span class="special"><<</span> <span class="identifier">n</span> <span class="special"><<</span> <span class="string">"\n"</span><span class="special">;</span> <span class="special">});</span> </pre> <h6> <a name="asio.reference.co_spawn.overload1.h3"></a> <span><a name="asio.reference.co_spawn.overload1.per_operation_cancellation"></a></span><a class="link" href="overload1.html#asio.reference.co_spawn.overload1.per_operation_cancellation">Per-Operation Cancellation</a> </h6> <p> The new thread of execution is created with a cancellation state that supports <code class="computeroutput"><span class="identifier">cancellation_type</span><span class="special">::</span><span class="identifier">terminal</span></code> values only. To change the cancellation state, call <a class="link" href="../this_coro__reset_cancellation_state.html" title="this_coro::reset_cancellation_state"><code class="computeroutput"><span class="identifier">this_coro</span><span class="special">::</span><span class="identifier">reset_cancellation_state</span></code></a>. </p> </div> <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>) </p> </div> <hr> <div class="spirit-nav"> <a accesskey="p" href="../co_spawn.html"><img src="../../../prev.png" alt="Prev"></a><a accesskey="u" href="../co_spawn.html"><img src="../../../up.png" alt="Up"></a><a accesskey="h" href="../../../index.html"><img src="../../../home.png" alt="Home"></a><a accesskey="n" href="overload2.html"><img src="../../../next.png" alt="Next"></a> </div> </body> </html>