1 //
2 // refactored_echo_server.cpp
3 // ~~~~~~~~~~~~~~~~~~~~~~~~~~
4 //
5 // Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6 //
7 // Distributed under the Boost Software License, Version 1.0. (See accompanying
8 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9 //
10
11 #include <boost/asio/co_spawn.hpp>
12 #include <boost/asio/detached.hpp>
13 #include <boost/asio/io_context.hpp>
14 #include <boost/asio/ip/tcp.hpp>
15 #include <boost/asio/signal_set.hpp>
16 #include <boost/asio/write.hpp>
17 #include <cstdio>
18
19 using boost::asio::ip::tcp;
20 using boost::asio::awaitable;
21 using boost::asio::co_spawn;
22 using boost::asio::detached;
23 using boost::asio::use_awaitable;
24 namespace this_coro = boost::asio::this_coro;
25
echo_once(tcp::socket & socket)26 awaitable<void> echo_once(tcp::socket& socket)
27 {
28 char data[128];
29 std::size_t n = co_await socket.async_read_some(boost::asio::buffer(data), use_awaitable);
30 co_await async_write(socket, boost::asio::buffer(data, n), use_awaitable);
31 }
32
echo(tcp::socket socket)33 awaitable<void> echo(tcp::socket socket)
34 {
35 try
36 {
37 for (;;)
38 {
39 // The asynchronous operations to echo a single chunk of data have been
40 // refactored into a separate function. When this function is called, the
41 // operations are still performed in the context of the current
42 // coroutine, and the behaviour is functionally equivalent.
43 co_await echo_once(socket);
44 }
45 }
46 catch (std::exception& e)
47 {
48 std::printf("echo Exception: %s\n", e.what());
49 }
50 }
51
listener()52 awaitable<void> listener()
53 {
54 auto executor = co_await this_coro::executor;
55 tcp::acceptor acceptor(executor, {tcp::v4(), 55555});
56 for (;;)
57 {
58 tcp::socket socket = co_await acceptor.async_accept(use_awaitable);
59 co_spawn(executor, echo(std::move(socket)), detached);
60 }
61 }
62
main()63 int main()
64 {
65 try
66 {
67 boost::asio::io_context io_context(1);
68
69 boost::asio::signal_set signals(io_context, SIGINT, SIGTERM);
70 signals.async_wait([&](auto, auto){ io_context.stop(); });
71
72 co_spawn(io_context, listener(), detached);
73
74 io_context.run();
75 }
76 catch (std::exception& e)
77 {
78 std::printf("Exception: %s\n", e.what());
79 }
80 }
81