libs/beast/example/websocket/server/awaitable/websocket_server_awaitable.cpp
//
// Copyright (c) 2022 Klemens D. Morgenstern (klemens dot morgenstern at gmx dot net)
//
// 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)
//
// Official repository: https://github.com/boostorg/beast
//
//------------------------------------------------------------------------------
//
// Example: WebSocket server, coroutine
//
//------------------------------------------------------------------------------
#include <boost/beast/core.hpp>
#include <boost/beast/websocket.hpp>
#include <boost/asio/awaitable.hpp>
#include <boost/asio/co_spawn.hpp>
#include <boost/asio/detached.hpp>
#include <boost/asio/use_awaitable.hpp>
#include <algorithm>
#include <cstdlib>
#include <functional>
#include <iostream>
#include <memory>
#include <string>
#include <thread>
#include <vector>
#if defined(BOOST_ASIO_HAS_CO_AWAIT)
namespace beast = boost::beast; // from <boost/beast.hpp>
namespace http = beast::http; // from <boost/beast/http.hpp>
namespace websocket = beast::websocket; // from <boost/beast/websocket.hpp>
namespace net = boost::asio; // from <boost/asio.hpp>
using tcp = boost::asio::ip::tcp; // from <boost/asio/ip/tcp.hpp>
using stream = websocket::stream<
typename beast::tcp_stream::rebind_executor<
typename net::use_awaitable_t<>::executor_with_default<net::any_io_executor>>::other>;
//------------------------------------------------------------------------------
// Echoes back all received WebSocket messages
net::awaitable<void>
do_session(stream ws)
{
// Set suggested timeout settings for the websocket
ws.set_option(
websocket::stream_base::timeout::suggested(
beast::role_type::server));
// Set a decorator to change the Server of the handshake
ws.set_option(websocket::stream_base::decorator(
[](websocket::response_type& res)
{
res.set(http::field::server,
std::string(BOOST_BEAST_VERSION_STRING) +
" websocket-server-coro");
}));
// Accept the websocket handshake
co_await ws.async_accept();
for(;;)
try {
// This buffer will hold the incoming message
beast::flat_buffer buffer;
// Read a message
co_await ws.async_read(buffer);
// Echo the message back
ws.text(ws.got_text());
co_await ws.async_write(buffer.data());
}
catch(boost::system::system_error & se)
{
if (se.code() != websocket::error::closed)
throw;
}
}
//------------------------------------------------------------------------------
// Accepts incoming connections and launches the sessions
net::awaitable<void>
do_listen(
tcp::endpoint endpoint)
{
// Open the acceptor
auto acceptor = net::use_awaitable.as_default_on(tcp::acceptor(co_await net::this_coro::executor));
acceptor.open(endpoint.protocol());
// Allow address reuse
acceptor.set_option(net::socket_base::reuse_address(true));
// Bind to the server address
acceptor.bind(endpoint);
// Start listening for connections
acceptor.listen(net::socket_base::max_listen_connections);
for(;;)
boost::asio::co_spawn(
acceptor.get_executor(),
do_session(stream(co_await acceptor.async_accept())),
[](std::exception_ptr e)
{
try
{
std::rethrow_exception(e);
}
catch (std::exception &e) {
std::cerr << "Error in session: " << e.what() << "\n";
}
});
}
int main(int argc, char* argv[])
{
// Check command line arguments.
if (argc != 4)
{
std::cerr <<
"Usage: websocket-server-awaitable <address> <port> <threads>\n" <<
"Example:\n" <<
" websocket-server-awaitable 0.0.0.0 8080 1\n";
return EXIT_FAILURE;
}
auto const address = net::ip::make_address(argv[1]);
auto const port = static_cast<unsigned short>(std::atoi(argv[2]));
auto const threads = std::max<int>(1, std::atoi(argv[3]));
// The io_context is required for all I/O
net::io_context ioc(threads);
// Spawn a listening port
boost::asio::co_spawn(
ioc,
do_listen(tcp::endpoint{address, port}),
[](std::exception_ptr e)
{
if (e)
try
{
std::rethrow_exception(e);
}
catch(std::exception & e)
{
std::cerr << "Error: " << e.what() << "\n";
}
});
// Run the I/O service on the requested number of threads
std::vector<std::thread> v;
v.reserve(threads - 1);
for(auto i = threads - 1; i > 0; --i)
v.emplace_back(
[&ioc]
{
ioc.run();
});
ioc.run();
return EXIT_SUCCESS;
}
#else
int main(int, char * [])
{
std::printf("awaitables require C++20\n");
return 1;
}
#endif