libs/beast/example/websocket/server/stackless/websocket_server_stackless.cpp
//
// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail 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)
//
// Official repository: https://github.com/boostorg/beast
//
//------------------------------------------------------------------------------
//
// Example: WebSocket server, stackless coroutine
//
//------------------------------------------------------------------------------
#include <boost/beast/core.hpp>
#include <boost/beast/websocket.hpp>
#include <boost/asio/coroutine.hpp>
#include <boost/asio/strand.hpp>
#include <algorithm>
#include <cstdlib>
#include <functional>
#include <iostream>
#include <memory>
#include <string>
#include <thread>
#include <vector>
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>
//------------------------------------------------------------------------------
// Report a failure
void
fail(beast::error_code ec, char const* what)
{
std::cerr << what << ": " << ec.message() << "\n";
}
// Echoes back all received WebSocket messages
class session
: public boost::asio::coroutine
, public std::enable_shared_from_this<session>
{
websocket::stream<beast::tcp_stream> ws_;
beast::flat_buffer buffer_;
public:
// Take ownership of the socket
explicit
session(tcp::socket socket)
: ws_(std::move(socket))
{
}
// Start the asynchronous operation
void
run()
{
loop({}, 0);
}
#include <boost/asio/yield.hpp>
void
loop(
beast::error_code ec,
std::size_t bytes_transferred)
{
boost::ignore_unused(bytes_transferred);
reenter(*this)
{
// 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-stackless");
}));
// Accept the websocket handshake
yield ws_.async_accept(
std::bind(
&session::loop,
shared_from_this(),
std::placeholders::_1,
0));
if(ec)
return fail(ec, "accept");
for(;;)
{
// Read a message into our buffer
yield ws_.async_read(
buffer_,
std::bind(
&session::loop,
shared_from_this(),
std::placeholders::_1,
std::placeholders::_2));
if(ec == websocket::error::closed)
{
// This indicates that the session was closed
return;
}
if(ec)
fail(ec, "read");
// Echo the message
ws_.text(ws_.got_text());
yield ws_.async_write(
buffer_.data(),
std::bind(
&session::loop,
shared_from_this(),
std::placeholders::_1,
std::placeholders::_2));
if(ec)
return fail(ec, "write");
// Clear the buffer
buffer_.consume(buffer_.size());
}
}
}
#include <boost/asio/unyield.hpp>
};
//------------------------------------------------------------------------------
// Accepts incoming connections and launches the sessions
class listener
: public boost::asio::coroutine
, public std::enable_shared_from_this<listener>
{
net::io_context& ioc_;
tcp::acceptor acceptor_;
tcp::socket socket_;
public:
listener(
net::io_context& ioc,
tcp::endpoint endpoint)
: ioc_(ioc)
, acceptor_(net::make_strand(ioc))
, socket_(net::make_strand(ioc))
{
beast::error_code ec;
// Open the acceptor
acceptor_.open(endpoint.protocol(), ec);
if(ec)
{
fail(ec, "open");
return;
}
// Allow address reuse
acceptor_.set_option(net::socket_base::reuse_address(true), ec);
if(ec)
{
fail(ec, "set_option");
return;
}
// Bind to the server address
acceptor_.bind(endpoint, ec);
if(ec)
{
fail(ec, "bind");
return;
}
// Start listening for connections
acceptor_.listen(
net::socket_base::max_listen_connections, ec);
if(ec)
{
fail(ec, "listen");
return;
}
}
// Start accepting incoming connections
void
run()
{
loop();
}
private:
#include <boost/asio/yield.hpp>
void
loop(beast::error_code ec = {})
{
reenter(*this)
{
for(;;)
{
yield acceptor_.async_accept(
socket_,
std::bind(
&listener::loop,
shared_from_this(),
std::placeholders::_1));
if(ec)
{
fail(ec, "accept");
}
else
{
// Create the session and run it
std::make_shared<session>(std::move(socket_))->run();
}
// Make sure each session gets its own strand
socket_ = tcp::socket(net::make_strand(ioc_));
}
}
}
#include <boost/asio/unyield.hpp>
};
//------------------------------------------------------------------------------
int main(int argc, char* argv[])
{
// Check command line arguments.
if (argc != 4)
{
std::cerr <<
"Usage: websocket-server-stackless <address> <port> <threads>\n" <<
"Example:\n" <<
" websocket-server-stackless 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};
// Create and launch a listening port
std::make_shared<listener>(ioc, tcp::endpoint{address, port})->run();
// 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;
}