demo_example/async_echo_server.cpp

/*
 * Copyright (c) 2022, Alibaba Group Holding Limited;
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#include <cstdlib>
#include <iostream>
#include <thread>
#include "asio_coro_util.hpp"

using asio::ip::tcp;

async_simple::coro::Lazy<void> session(tcp::socket sock) {
    int msg_index = 0;
    for (;;) {
        const size_t max_length = 1024;
        char data[max_length];
        auto [error, length] =
            co_await async_read_some(sock, asio::buffer(data, max_length));
        msg_index++;
        if (error == asio::error::eof) {
            std::cout << "Remote client closed at message index: "
                      << msg_index - 1 << ".\n";
            break;
        } else if (error) {
            std::cout << error.message() << '\n';
            throw asio::system_error(error);
        }

        co_await async_write(sock, asio::buffer(data, length));
    }

    std::error_code ec;
    sock.shutdown(asio::ip::tcp::socket::shutdown_both, ec);
    sock.close(ec);

    std::cout << "Finished echo message, total: " << msg_index - 1 << ".\n";
}

async_simple::coro::Lazy<void> start_server(asio::io_context& io_context,
                                            unsigned short port,
                                            async_simple::Executor* E) {
    tcp::acceptor a(io_context, tcp::endpoint(tcp::v4(), port));
    std::cout << "Listen port " << port << " successfully.\n";
    for (;;) {
        tcp::socket socket(io_context);
        auto error = co_await async_accept(a, socket);
        if (error) {
            std::cout << "Accept failed, error: " << error.message() << '\n';
            continue;
        }
        std::cout << "New client coming.\n";
        session(std::move(socket)).via(E).detach();
    }
}

int main(int argc, char* argv[]) {
    try {
        asio::io_context io_context;
        std::thread thd([&io_context] {
            asio::io_context::work work(io_context);
            io_context.run();
        });
        AsioExecutor executor(io_context);
        async_simple::coro::syncAwait(
            start_server(io_context, 9980, &executor));
        thd.join();
    } catch (std::exception& e) {
        std::cerr << "Exception: " << e.what() << "\n";
    }

    return 0;
}