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The consign completion token adapter can be used to attach additional
values to a completion handler. This is typically used to keep at least
one copy of an object, such as a smart pointer, alive until the
completion handler is called.
For example:
auto timer1 = std::make_shared<boost::asio::steady_timer>(my_io_context);
timer1->expires_after(std::chrono::seconds(1));
timer1->async_wait(
boost::asio::consign(
[](boost::system::error_code ec)
{
// ...
},
timer1
)
);
auto timer2 = std::make_shared<boost::asio::steady_timer>(my_io_context);
timer2->expires_after(std::chrono::seconds(30));
std::future<void> f =
timer2->async_wait(
boost::asio::consign(
boost::asio::use_future,
timer2
)
);
61 lines
1.4 KiB
C++
61 lines
1.4 KiB
C++
//
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// consign.cpp
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// ~~~~~~~~~~
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//
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// Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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// Disable autolinking for unit tests.
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#if !defined(BOOST_ALL_NO_LIB)
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#define BOOST_ALL_NO_LIB 1
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#endif // !defined(BOOST_ALL_NO_LIB)
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// Test that header file is self-contained.
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#include <boost/asio/consign.hpp>
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#include <boost/asio/bind_executor.hpp>
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#include <boost/asio/io_context.hpp>
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#include <boost/asio/post.hpp>
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#include <boost/asio/system_timer.hpp>
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#include "unit_test.hpp"
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void consign_test()
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{
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#if defined(BOOST_ASIO_HAS_STD_TUPLE) \
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&& defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
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boost::asio::io_context io1;
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boost::asio::io_context io2;
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boost::asio::system_timer timer1(io1);
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int count = 0;
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timer1.expires_after(boost::asio::chrono::seconds(0));
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timer1.async_wait(
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boost::asio::consign(
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boost::asio::bind_executor(io2.get_executor(),
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[&count](boost::system::error_code)
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{
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++count;
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}), 123, 321));
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BOOST_ASIO_CHECK(count == 0);
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io1.run();
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BOOST_ASIO_CHECK(count == 0);
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io2.run();
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BOOST_ASIO_CHECK(count == 1);
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#endif // defined(BOOST_ASIO_HAS_STD_TUPLE)
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// && defined(BOOST_ASIO_HAS_VARIADIC_TEMPLATES)
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}
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BOOST_ASIO_TEST_SUITE
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(
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"consign",
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BOOST_ASIO_TEST_CASE(consign_test)
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)
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