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//
// double_buffered_echo_server.cpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2018 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/experimental/co_spawn.hpp>
#include <boost/asio/experimental/detached.hpp>
#include <boost/asio/io_context.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/signal_set.hpp>
#include <boost/asio/write.hpp>
#include <cstdio>
using boost::asio::ip::tcp;
using boost::asio::experimental::co_spawn;
using boost::asio::experimental::detached;
namespace this_coro = boost::asio::experimental::this_coro;
template <typename T>
using awaitable = boost::asio::experimental::awaitable<
T, boost::asio::io_context::executor_type>;
awaitable<void> echo(tcp::socket s)
{
auto token = co_await this_coro::token();
try
{
char data1[1024];
char data2[1024];
char* p1 = data1;
char* p2 = data2;
// Perform initial read into first buffer.
size_t n = co_await s.async_read_some(boost::asio::buffer(p1, 1024), token);
for (;;)
{
// Swap received data to other buffer and initiate write operation.
std::swap(p1, p2);
auto write_result = boost::asio::async_write(s, boost::asio::buffer(p2, n), token);
// Perform next read while write operation is in progress.
n = co_await s.async_read_some(boost::asio::buffer(p1, 1024), token);
// Wait for write operation to complete before proceeding.
co_await write_result;
}
}
catch (std::exception& e)
{
std::printf("echo Exception: %s\n", e.what());
}
}
awaitable<void> listener()
{
auto executor = co_await this_coro::executor();
auto token = co_await this_coro::token();
tcp::acceptor acceptor(executor.context(), {tcp::v4(), 55555});
for (;;)
{
tcp::socket socket = co_await acceptor.async_accept(token);
co_spawn(executor,
[socket = std::move(socket)]() mutable
{
return echo(std::move(socket));
},
detached);
}
}
int main()
{
try
{
boost::asio::io_context io_context(1);
boost::asio::signal_set signals(io_context, SIGINT, SIGTERM);
signals.async_wait([&](auto, auto){ io_context.stop(); });
co_spawn(io_context, listener, detached);
io_context.run();
}
catch (std::exception& e)
{
std::printf("Exception: %s\n", e.what());
}
}
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