1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
|
//
// deferred_4.cpp
// ~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2023 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include <boost/asio.hpp>
#include <iostream>
using boost::asio::deferred;
template <typename CompletionToken>
auto async_wait_twice(boost::asio::steady_timer& timer, CompletionToken&& token)
{
return timer.async_wait(
deferred(
[&](boost::system::error_code ec)
{
std::cout << "first timer wait finished: " << ec.message() << "\n";
timer.expires_after(std::chrono::seconds(1));
return timer.async_wait(deferred);
}
)
)(
deferred(
[&](boost::system::error_code ec)
{
std::cout << "second timer wait finished: " << ec.message() << "\n";
return deferred.values(42);
}
)
)(
std::forward<CompletionToken>(token)
);
}
int main()
{
boost::asio::io_context ctx;
boost::asio::steady_timer timer(ctx);
timer.expires_after(std::chrono::seconds(1));
async_wait_twice(
timer,
[](int result)
{
std::cout << "result is " << result << "\n";
}
);
ctx.run();
return 0;
}
|
