Boost.Asio学习之异步echo服务器实现

青旅半醒 2022-07-13 13:18 132阅读 0赞

代码见：[http://www.boost.org/doc/libs/1\_61\_0/doc/html/boost\_asio/examples/cpp11\_examples.html][http_www.boost.org_doc_libs_1_61_0_doc_html_boost_asio_examples_cpp11_examples.html]  
或者：[https://github.com/NearXdu/AsioLearn][https_github.com_NearXdu_AsioLearn]

当我们开始异步时，编码会变得稍微有点复杂。

每个异步操作启动了新的异步操作，以保持service.run()一直工作。

#include <cstdlib>
    #include <iostream>
    #include <memory>
    #include <utility>
    #include <boost/asio.hpp>
    
    using namespace boost::asio;
    using namespace boost::asio::ip;
    
    class session
      : public std::enable_shared_from_this<session>
    {
        public:
        session(tcp::socket socket):socket_(std::move(socket))
        {}
        void start()
        {
            do_read();
        }
        private:
        void do_read()
        {
            auto self(shared_from_this());
            socket_.async_read_some(boost::asio::buffer(data_,max_length),
                [self,this](boost::system::error_code ec, std::size_t length)
                {
                    if(!ec)
                do_write(length);
                });
        }
        void do_write(std::size_t length)
        {
            auto self(shared_from_this());
            boost::asio::async_write(socket_,boost::asio::buffer(data_,length),
                [this, self](boost::system::error_code ec, std::size_t /*length*/)
                {
                    if (!ec)
                    {
                        do_read();
                    }
                });
    
        }
        enum {max_length=1024};
        char data_[max_length];
        tcp::socket socket_;
    };
    class server
    {
        public:
        server(boost::asio::io_service & io_service,unsigned short port)
            :acceptor_(io_service,tcp::endpoint(tcp::v4(),port)),socket_(io_service)
        {
            do_accept();
        }
    
        private:
    
        void do_accept()
        {
            acceptor_.async_accept(socket_,
                [this](boost::system::error_code ec)
                {
                    if(!ec)
                    {
                        std::make_shared<session>(std::move(socket_))->start();
                    }
    
                    do_accept();
                });//异步接收连接
        }
    
        tcp::acceptor acceptor_;
        tcp::socket socket_;
    };//server
    
    
    int main(int argc, char* argv[])
    {
    
        try
        {
    #if 0
        if (argc != 2)
        {
            std::cerr << "Usage: async_tcp_echo_server <port>\n";
            return 1;
        }
    #endif
    
        boost::asio::io_service io_service;
    
        server s(io_service, 1024);
    
        io_service.run();
        }
        catch (std::exception& e)
        {
        std::cerr << "Exception: " << e.what() << "\n";
        }
        return 0;
    }

[http_www.boost.org_doc_libs_1_61_0_doc_html_boost_asio_examples_cpp11_examples.html]: http://www.boost.org/doc/libs/1_61_0/doc/html/boost_asio/examples/cpp11_examples.html
[https_github.com_NearXdu_AsioLearn]: https://github.com/NearXdu/AsioLearn