boost asio 异步实现tcp通讯

一、前言

boost asio可算是一个简单易用，功能又强大可跨平台的C++通讯库，效率也表现的不错，Linux环境是epoll实现的，而windows环境是iocp实现的。而tcp通讯是项目当中经常用到通讯方式之一，实现的方法有各式各样，因此总结一套适用于自己项目的方法是很有必要，很可能下一个项目直接套上去就可以用了。

二、实现思路

1.通讯包数据结构

Tag：检查数据包是否合法，具体会在下面讲解；

Length：描述Body的长度；

Command：表示数据包的类型，0表示心跳包（长连接需要心跳来检测连接是否正常），1表示注册包（客户端连接上服务器之后要将相关信息注册给服务器），2表示业务消息包；

business_type：业务消息包类型，服务器会根据业务消息包类型将数据路由到对应的客户端（客户端是有业务类型分类的）；

app_id：客户端唯一标识符；

Data：消息数据；

2.连接对象

客户端连接上服务器之后，双方都会产生一个socket连接对象，通过这个对象可以收发数据，因此我定义为socket_session。

//socket_session.h

 #pragma once
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include

 using boost::asio::ip::tcp;

 namespace firebird{
     enum command{ heartbeat = 0, regist, normal};

     const std::string tag = "KDS";

     class FIREBIRD_DECL socket_session;
     typedef boost::shared_ptr socket_session_ptr;

     class FIREBIRD_DECL socket_session:
         public boost::enable_shared_from_this,
         private boost::noncopyable
     {
     public:
         typedef boost::function<void(socket_session_ptr)> close_callback;
         typedef boost::function<void(
             const boost::system::error_code&,
             socket_session_ptr, message&)> read_data_callback;

         socket_session(boost::asio::io_service& io_service);
         ~socket_session(void);

         DWORD id() { return m_id; }
         WORD get_business_type(){ return m_business_type; }
         void set_business_type(WORD type) { m_business_type = type; }
         DWORD get_app_id(){ return m_app_id; }
         void set_app_id(DWORD app_id) { m_app_id = app_id; }
         std::string& get_remote_addr() { return m_name; }
         void set_remote_addr(std::string& name) { m_name = name; }
         tcp::socket& socket() { return m_socket; }

         void installCloseCallBack(close_callback cb){ close_cb = cb; }
         void installReadDataCallBack(read_data_callback cb) { read_data_cb = cb; }

         void start();
         void close();
         void async_write(const std::string& sMsg);
         void async_write(message& msg);

         bool is_timeout();
         void set_op_time(){std::time(&m_last_op_time);}

     private:
         static boost::detail::atomic_count m_last_id;

         DWORD m_id;
         WORD  m_business_type;
         DWORD m_app_id;
         std::string m_name;
         boost::array<char, 7> sHeader;
         std::string sBody;

         tcp::socket m_socket;
         boost::asio::io_service& m_io_service;

         std::time_t m_last_op_time;

         close_callback close_cb;
         read_data_callback read_data_cb;

         //发送消息
         void handle_write(const boost::system::error_code& e,
             std::size_t bytes_transferred, std::string* pmsg);

         //读消息头
         void handle_read_header(const boost::system::error_code& error);
         //读消息体
         void handle_read_body(const boost::system::error_code& error);

         void handle_close();
     };
 }

这里注意的是，定义了一个tag="KDS"，目的是为了检查收到的数据包是否有效，每一个数据包前3个字节不为“KDS”，那么就认为是非法的请求包，你也可以定义tag等于其它字符串，只要按协议发包就正常，当然这是比较简单的数据包检查方法了。比较严谨的方法是双方使用哈希算法来检查的，怎么做，这里先不做详解。

//socket_session.cpp

 #include "socket_session.h"

 namespace firebird{
     boost::detail::atomic_count socket_session::m_last_id(0);

     socket_session::socket_session(boost::asio::io_service& io_srv)
         :m_io_service(io_srv), m_socket(io_srv),
         m_business_type(0), m_app_id(0)
     {
         m_id = ++socket_session::m_last_id;
     }

     socket_session::~socket_session(void)
     {
         m_socket.close();
     }

     void socket_session::start()
     {
         m_socket.set_option(boost::asio::ip::tcp::acceptor::linger(true, 0));
         m_socket.set_option(boost::asio::socket_base::keep_alive(true));
         std::time(&m_last_op_time);
         const boost::system::error_code error;
         handle_read_header(error);
     }

     void socket_session::handle_close()
     {
         try{
             m_socket.close();
             close_cb(shared_from_this());
         }
         catch(std::exception& e)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << get_remote_addr() << "],socket异常:[" << e.what() << "]");
         }
         catch(...)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << get_remote_addr() << "],socket异常:[未知异常]");
         }
     }

     void socket_session::close()
     {
         //由于回调中有加锁的情况，必须提交到另外一个线程去做，不然会出现死锁
         m_io_service.post(boost::bind(&socket_session::handle_close, shared_from_this()));
     }

     static int connection_timeout = 60;

     bool socket_session::is_timeout()
     {
         std::time_t now;
         std::time(&now);
         return now - m_last_op_time > connection_timeout;
     }

     //读消息头
     void socket_session::handle_read_header(const boost::system::error_code& error)
     {
         LOG4CXX_DEBUG(firebird_log, KDS_CODE_INFO  << "enter.");

         try{
             if(error)
             {
                 LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO  << "连接远程地址:[" << get_remote_addr() << "],socket异常:[" << error.message().c_str() << "]");
                 close();
                 return;
             }

             std::string data;
             data.swap(sBody);
             boost::asio::async_read(m_socket,
                 boost::asio::buffer(sHeader),
                 boost::bind(&socket_session::handle_read_body, shared_from_this(),
                 boost::asio::placeholders::error));

             if (data.length() > 0 && data != "")
             {//读到数据回调注册的READ_DATA函数
                 message msg;
                 message_iarchive(msg, data);

                 read_data_cb(error, shared_from_this(), msg);
             }
         }
         catch(std::exception& e)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << get_remote_addr() << "],socket异常:[" << e.what() << "]");
             close();
         }
         catch(...)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << get_remote_addr() << "],socket异常:[未知异常]");
             close();
         }
     }

     //读消息体
     void socket_session::handle_read_body(const boost::system::error_code& error)
     {
         LOG4CXX_DEBUG(firebird_log, KDS_CODE_INFO << "enter.");

         try{
             if(error)
             {
                 LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << get_remote_addr() << "],socket异常:[" << error.message().c_str() << "]");
                 close();
                 return;
             }

             if (tag.compare(0, tag.length(), sHeader.data(), 0, tag.length()))
             {
                 LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO <<  "连接远程地址:[" << get_remote_addr() << "],socket异常:[这是个非法连接!]");
                 close();
                 return;
             }

             DWORD dwLength = 0;

             char* len = (char*)&dwLength;
             memcpy(len, &sHeader[tag.length()], sizeof(dwLength));

             sBody.resize(dwLength);
             char* pBody = &sBody[0];

             boost::asio::async_read(m_socket,
                 boost::asio::buffer(pBody, dwLength),
                 boost::bind(&socket_session::handle_read_header, shared_from_this(),
                 boost::asio::placeholders::error));
         }
         catch(std::exception& e)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << get_remote_addr() << "],socket异常:[" << e.what() << "]");
             close();
         }
         catch(...)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << get_remote_addr() << "],socket异常:[未知异常]");
             close();
         }
     }

     void socket_session::handle_write(const boost::system::error_code& error,
         std::size_t bytes_transferred, std::string* pmsg)
     {
         //数据发送成功就销毁
         if (pmsg != NULL)
         {
             delete pmsg;
         }

         if(error)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << get_remote_addr() << "],socket异常:[" << error.message().c_str() << "]");
             close();
             return;
         }
     }

     void socket_session::async_write(const std::string& sMsg)
     {
         LOG4CXX_DEBUG(firebird_log, KDS_CODE_INFO  << "enter.")

         try
         {
             DWORD dwLength = sMsg.size();
             char* pLen = (char*)&dwLength;

             //由于是异步发送，要保证数据发送完整时，才把数据销毁
             std::string* msg = new std::string();
             msg->append(tag);
             msg->append(pLen, sizeof(dwLength));
             msg->append(sMsg);

             boost::asio::async_write(m_socket,boost::asio::buffer(*msg, msg->size()),
                 boost::bind(&socket_session::handle_write, shared_from_this(),
                 boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred,
                 msg));

         }
         catch(std::exception& e)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << get_remote_addr() << "],socket异常:[" << e.what() << "]");
             close();
         }
         catch(...)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << get_remote_addr() << "],socket异常:[未知异常]");
             close();
         }
     }

     void socket_session::async_write(message& msg)
     {
         std::string data;
         message_oarchive(data, msg);

         async_write(data);
     }
 }

接受数据时，socket_session会先读取7个字节的head，比较前3个字节“KDS”，然后取得4个字节的Length，再读出Length长度的数据，最后将该数据传给read_data_cb回调函数处理，read_data_cb回调函数是在外部注册的。

3.连接管理器

对于服务器来说，它同时服务多个客户端，为了有效的管理，因此需要一个连接管理器，我定义为session_manager。session_manager主要是对socket_session的增删改查，和有效性检查。

//session_manager.h

 #pragma once
 #include "socket_session.h"
 #include "filter_container.h"
 #include
 #include
 #include
 #include
 #include
 #include
 #include

 namespace firebird{
     template<typename T>
     class var_gen_wraper
     {
     public:
         var_gen_wraper(): gen(boost::mt19937((boost::int32_t)std::time(0)),
             boost::uniform_smallint<>(1, 100)) {}
         typename T::result_type operator() () { return gen(); }
     private:
         T gen;
     };

     struct  session_stu
     {
         DWORD   id;
         WORD    business_type;
         std::string address;
         DWORD   app_id;
         socket_session_ptr session;
     };

     struct sid{};
     struct sbusiness_type{};
     struct saddress{};
     struct sapp_id{};

     enum session_idx_member{ session_id = 0, session_business_type, session_address, app_id};
 #define CLIENT 0
 #define SERVER 1

     typedef boost::multi_index::multi_index_container<
         session_stu,
         boost::multi_index::indexed_by<
         boost::multi_index::ordered_unique<
         boost::multi_index::tag, BOOST_MULTI_INDEX_MEMBER(session_stu, DWORD, id)>,
         boost::multi_index::ordered_non_unique<
         boost::multi_index::tag, BOOST_MULTI_INDEX_MEMBER(session_stu, WORD, business_type)>,
         boost::multi_index::ordered_non_unique<
         boost::multi_index::tag, BOOST_MULTI_INDEX_MEMBER(session_stu, std::string, address)>,
         boost::multi_index::ordered_non_unique<
         boost::multi_index::tag, BOOST_MULTI_INDEX_MEMBER(session_stu, DWORD, app_id)>
         >
     > session_set;

 #define MULTI_MEMBER_CON(Tag) boost::multi_index::index::type&
 #define MULTI_MEMBER_ITR(Tag) boost::multi_index::index::type::iterator

     struct is_business_type {
         is_business_type(WORD type)
             :m_type(type)
         {

         }
         bool operator()(const session_stu& s)
         {
             return (s.business_type == m_type);
         }

         WORD m_type;
     };

     class session_manager
     {
     public:
         typedef boost::shared_lock readLock;
         typedef boost:: unique_lock writeLock;

         session_manager(boost::asio::io_service& io_srv, int type, int expires_time);
         ~session_manager();

         void add_session(socket_session_ptr p);
         void update_session(socket_session_ptr p);

         template<typename Tag, typename Member>
         void del_session(Member m)
         {
             writeLock lock(m_mutex);
             if (m_sessions.empty())
             {
                 return ;
             }

             MULTI_MEMBER_CON(Tag) idx = boost::multi_index::get(m_sessions);
             //BOOST_AUTO(idx, boost::multi_index::get(m_sessions));
             BOOST_AUTO(iter, idx.find(m));

             if (iter != idx.end())
             {
                 idx.erase(iter);
             }
         }

         //获取容器中的第一个session
         template<typename Tag, typename Member>
         socket_session_ptr get_session(Member m)
         {
             readLock lock(m_mutex);

             if (m_sessions.empty())
             {
                 return socket_session_ptr();
             }

             MULTI_MEMBER_CON(Tag) idx = boost::multi_index::get(m_sessions);
             BOOST_AUTO(iter, idx.find(m));
             return iter != boost::end(idx) ? iter->session : socket_session_ptr();
         }

         //随机获取容器中的session
         template<typename Tag>
         socket_session_ptr get_session_by_business_type(WORD m)
         {
             typedef filter_container FilterContainer;
             readLock lock(m_mutex);

             if (m_sessions.empty())
             {
                 return socket_session_ptr();
             }

             MULTI_MEMBER_CON(Tag) idx = boost::multi_index::get(m_sessions);

             //对容器的元素条件过滤
             is_business_type predicate(m);
             FilterContainer fc(predicate, idx.begin(), idx.end());
             FilterContainer::FilterIter iter = fc.begin();

             if (fc.begin() == fc.end())
             {
                 return socket_session_ptr();
             }

             //typedef boost::variate_generator> var_gen;
             //typedef boost::details::pool::singleton_default> s_var_gen;
             ////根据随机数产生session
             //s_var_gen::object_type &gen = s_var_gen::instance();
             //int step = gen() % fc.szie();

             int step = m_next_session % fc.szie();
             ++m_next_session;

             for (int i = 0; i < step; ++i)
             {
                 iter++;
             }

             return iter != fc.end() ? iter->session : socket_session_ptr();
         }

         //根据类型和地址取session
         template<typename Tag>
         socket_session_ptr get_session_by_type_ip(WORD m, std::string& ip)
         {
             typedef filter_container FilterContainer;
             readLock lock(m_mutex);

             if (m_sessions.empty())
             {
                 return socket_session_ptr();
             }

             MULTI_MEMBER_CON(Tag) idx = boost::multi_index::get(m_sessions);

             //对容器的元素条件过滤
             is_business_type predicate(m);
             FilterContainer fc(predicate, idx.begin(), idx.end());
             FilterContainer::FilterIter iter = fc.begin();

             if (fc.begin() == fc.end())
             {
                 return socket_session_ptr();
             }

             while (iter != fc.end())
             {
                 if (iter->session->get_remote_addr().find(ip) != std::string::npos)
                 {
                     break;
                 }

                 iter++;
             }

             return iter != fc.end() ? iter->session : socket_session_ptr();
         }

         //根据类型和app_id取session
         template<typename Tag>
         socket_session_ptr get_session_by_type_appid(WORD m, DWORD app_id)
         {
             typedef filter_container FilterContainer;
             readLock lock(m_mutex);

             if (m_sessions.empty())
             {
                 return socket_session_ptr();
             }

             MULTI_MEMBER_CON(Tag) idx = boost::multi_index::get(m_sessions);

             //对容器的元素条件过滤
             is_business_type predicate(m);
             FilterContainer fc(predicate, idx.begin(), idx.end());
             FilterContainer::FilterIter iter = fc.begin();

             if (fc.begin() == fc.end())
             {
                 return socket_session_ptr();
             }

             while (iter != fc.end())
             {
                 if (iter->session->get_app_id() == app_id)
                 {
                     break;
                 }

                 iter++;
             }

             return iter != fc.end() ? iter->session : socket_session_ptr();
         }

     private:
         int m_type;
         int m_expires_time;
         boost::asio::io_service& m_io_srv;
         boost::asio::deadline_timer m_check_tick;
         boost::shared_mutex m_mutex;
         unsigned short m_next_session;

         session_set m_sessions;

         void check_connection();
     };
 }

这里主要用到了boost的multi_index容器，这是一个非常有用方便的容器，可实现容器的多列索引，具体的使用方法，在这里不多做详解。

//session_manager.cpp

 #include "session_manager.h"

 namespace firebird{
     session_manager::session_manager(boost::asio::io_service& io_srv, int type, int expires_time)
         :m_io_srv(io_srv), m_check_tick(io_srv), m_type(type), m_expires_time(expires_time),m_next_session(0)
     {
         check_connection();
     }

     session_manager::~session_manager()
     {

     }

     //检查服务器所有session的连接状态
     void session_manager::check_connection()
     {
         try{
             writeLock lock(m_mutex);

             session_set::iterator iter = m_sessions.begin();
             while (iter != m_sessions.end())
             {
                 LOG4CXX_DEBUG(firebird_log, "循环");
                 if (CLIENT == m_type)//客户端的方式
                 {
                     if (!iter->session->socket().is_open())//已断开，删除已断开的连接
                     {
                         LOG4CXX_INFO(firebird_log, "重新连接[" << iter->address << "]");
                         iter->session->close(); //通过关闭触发客户端重连
                     }
                     else{//连接中，发送心跳
                         message msg;
                         msg.command = heartbeat;
                         msg.business_type = iter->session->get_business_type();
                         msg.app_id = iter->session->get_app_id();
                         msg.data() = "H";

                         iter->session->async_write(msg);
                         iter->session->set_op_time();
                     }
                 }
                 else if (SERVER == m_type)//服务器的方式
                 {
                     if (!iter->session->socket().is_open())//已断开，删除已断开的连接
                     {
                         LOG4CXX_INFO(firebird_log, KDS_CODE_INFO << "删除已关闭的session:[" << iter->session->get_remote_addr() << "]");
                         iter = m_sessions.erase(iter);
                         continue;
                     }
                     else{//连接中，设定每30秒检查一次
                         if (iter->session->is_timeout()) //如果session已长时间没操作，则关闭
                         {
                             LOG4CXX_INFO(firebird_log, KDS_CODE_INFO << "删除已超时的session:[" << iter->session->get_remote_addr() << "]");
                             iter->session->close();//通过关闭触发删除session
                         }
                     }

                     iter->session->set_op_time();
                 }
                 else{
                     LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "unknown manager_type");
                 }
                 ++iter;
             }

             LOG4CXX_DEBUG(firebird_log, "定时检查");
             m_check_tick.expires_from_now(boost::posix_time::seconds(m_expires_time));
             m_check_tick.async_wait(boost::bind(&session_manager::check_connection, this));
         }
         catch(std::exception& e)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "[" << e.what() << "]");
         }
         catch(...)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "unknown exception.");
         }
     }

     void session_manager::add_session(socket_session_ptr p)
     {
         writeLock lock(m_mutex);
         session_stu stuSession;
         stuSession.id = p->id();
         stuSession.business_type = 0;
         stuSession.address = p->get_remote_addr();
         stuSession.app_id = p->get_app_id();
         stuSession.session = p;
         m_sessions.insert(stuSession);
     }

     void session_manager::update_session(socket_session_ptr p)
     {
         writeLock lock(m_mutex);
         if (m_sessions.empty())
         {
             return ;
         }

         MULTI_MEMBER_CON(sid) idx = boost::multi_index::get(m_sessions);
         BOOST_AUTO(iter, idx.find(p->id()));

         if (iter != idx.end())
         {
             const_cast(*iter).business_type = p->get_business_type();
             const_cast(*iter).app_id = p->get_app_id();
         }
     }
 }

这个时候，我就可以使用id、business_type、address、app_id当做key来索引socket_session了，单使用map容器是做不到的。

还有索引时，需要的一个条件过滤器

//filter_container.h

 #pragma once
 #include

 namespace firebird{
     template <class Predicate, class Iterator>
     class filter_container
     {
     public:
         typedef boost::filter_iterator FilterIter;

         filter_container(Predicate p, Iterator begin, Iterator end)
             :m_begin(p, begin, end),
             m_end(p, end, end)
         {

         }
         ~filter_container() {}

         FilterIter begin() { return m_begin; }
         FilterIter end()   { return m_end; }
         int szie() {
             int i = 0;
             FilterIter fi = m_begin;
             while(fi != m_end)
             {
                 ++i;
                 ++fi;
             }

             return i;
         }

     private:
         FilterIter m_begin;
         FilterIter m_end;
     };
 }

4.服务器端的实现

服务器我定义为server_socket_utils，拥有一个session_manager，每当accept成功得到一个socket_session时，都会将其增加到session_manager去管理，注册相关回调函数。

read_data_callback   接收到数据的回调函数

收到数据之后，也就是数据包的body部分，反序列化出command、business_type、app_id和data（我使用到了thrift），如果command==normal正常的业务包，会调用handle_read_data传入data。

close_callback 关闭socket_session触发的回调函数

根据id将该连接从session_manager中删除掉

//server_socket_utils.h

 #pragma once
 #include "socket_session.h"
 #include "session_manager.h"
 #include
 #include

 namespace firebird{
     using boost::asio::ip::tcp;

     class FIREBIRD_DECL server_socket_utils
     {
     private:
         boost::asio::io_service m_io_srv;
         boost::asio::io_service::work m_work;
         tcp::acceptor m_acceptor;

         void handle_accept(socket_session_ptr session, const boost::system::error_code& error);

         void close_callback(socket_session_ptr session);
         void read_data_callback(const boost::system::error_code& e,
             socket_session_ptr session, message& msg);

     protected:
         virtual void handle_read_data(message& msg, socket_session_ptr pSession) = 0;

     public:
         server_socket_utils(int port);
         ~server_socket_utils(void);

         void start();
         boost::asio::io_service& get_io_service() { return m_io_srv; }

         session_manager m_manager;
     };
 }

//server_socket_utils.cpp

 #include "server_socket_utils.h"

 namespace firebird{
     server_socket_utils::server_socket_utils(int port)
         :m_work(m_io_srv),
         m_acceptor(m_io_srv, tcp::endpoint(tcp::v4(), port)),
         m_manager(m_io_srv, SERVER, 3)
     {
         //m_acceptor.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
         //// 关闭连接前留0秒给客户接收数据
         //m_acceptor.set_option(boost::asio::ip::tcp::acceptor::linger(true, 0));
         //m_acceptor.set_option(boost::asio::ip::tcp::no_delay(true));
         //m_acceptor.set_option(boost::asio::socket_base::keep_alive(true));
         //m_acceptor.set_option(boost::asio::socket_base::receive_buffer_size(16384));
     }

     server_socket_utils::~server_socket_utils(void)
     {
     }

     void server_socket_utils::start()
     {
         try{
             socket_session_ptr new_session(new socket_session(m_io_srv));
             m_acceptor.async_accept(new_session->socket(),
                 boost::bind(&server_socket_utils::handle_accept, this, new_session,
                 boost::asio::placeholders::error));
         }
         catch(std::exception& e)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "socket异常:[" << e.what() << "]");
         }
         catch(...)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "socket异常:[未知异常]");
         }
     }

     void server_socket_utils::handle_accept(socket_session_ptr session, const boost::system::error_code& error)
     {
         if (!error)
         {
             try{
                 socket_session_ptr new_session(new socket_session(m_io_srv));
                 m_acceptor.async_accept(new_session->socket(),
                     boost::bind(&server_socket_utils::handle_accept, this, new_session,
                     boost::asio::placeholders::error));

                 if (session != NULL)
                 {
                     //注册关闭回调函数
                     session->installCloseCallBack(boost::bind(&server_socket_utils::close_callback, this, _1));
                     //注册读到数据回调函数
                     session->installReadDataCallBack(boost::bind(&server_socket_utils::read_data_callback, this, _1, _2, _3));

                     boost::format fmt("%1%:%2%");
                     fmt % session->socket().remote_endpoint().address().to_string();
                     fmt % session->socket().remote_endpoint().port();
                     session->set_remote_addr(fmt.str());

                     session->start();
                     m_manager.add_session(session);
                 }
             }
             catch(std::exception& e)
             {
                 LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "socket异常:[" << e.what() << "]");
             }
             catch(...)
             {
                 LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "socket异常:[未知异常]");
             }

         }
     }

     void server_socket_utils::close_callback(socket_session_ptr session)
     {
         LOG4CXX_DEBUG(firebird_log, "close_callback");
         try{
             m_manager.del_session(session->id());
         }
         catch(std::exception& e)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "socket异常:[" << e.what() << "]");
         }
         catch(...)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "socket异常:[未知异常]");
         }

     }

     void server_socket_utils::read_data_callback(const boost::system::error_code& e,
         socket_session_ptr session, message& msg)
     {
         try{
             LOG4CXX_DEBUG(firebird_log, "command =[" << msg.command << "],["
                 << msg.business_type << "],[" << msg.data() << "]");

             if (msg.command == heartbeat)
             {//心跳
                 session->async_write(msg);
             }
             else if (msg.command == regist)
             {//注册
                 session->set_business_type(msg.business_type);
                 session->set_app_id(msg.app_id);
                 m_manager.update_session(session);

                 session->async_write(msg);
                 LOG4CXX_FATAL(firebird_log, "远程地址:[" << session->get_remote_addr() << "],服务器类型:[" <<
                     session->get_business_type() << "],服务器ID:[" << session->get_app_id() << "]注册成功!");
             }
             else if (msg.command == normal)
             {//业务数据
                 handle_read_data(msg, session);
             }
             else
             {
                 LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "收到非法消息包!");
             }
         }
         catch(std::exception& e)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "socket异常:[" << e.what() << "]");
         }
         catch(...)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "socket异常:[未知异常]");
         }
     }
 }

5.客户端

客户端与服务器的逻辑也差不多，区别就是在于客户端通过connect得到socket_session，而服务器是通过accept得到socket_session。

//client_socket_utils.h

 #pragma once
 #include "socket_session.h"
 #include "session_manager.h"
 #include
 #include

 namespace firebird{
     class FIREBIRD_DECL client_socket_utils
     {
     public:
         client_socket_utils();
         ~client_socket_utils();

         void session_connect(std::vector& vSession);
         void session_connect(socket_session_ptr pSession);
         //socket_session_ptr get_session(std::string& addr);
         boost::asio::io_service& get_io_service() { return m_io_srv; }

     protected:
         virtual void handle_read_data(message& msg, socket_session_ptr pSession) = 0;

     private:
         boost::asio::io_service m_io_srv;
         boost::asio::io_service::work m_work;
         session_manager m_manager;

         void handle_connect(const boost::system::error_code& error,
             tcp::resolver::iterator endpoint_iterator, socket_session_ptr pSession);

         void close_callback(socket_session_ptr session);
         void read_data_callback(const boost::system::error_code& e,
             socket_session_ptr session, message& msg);
     };
 }

//client_socket_utils.cpp

 #include "client_socket_utils.h"

 namespace firebird{
     client_socket_utils::client_socket_utils()
         :m_work(m_io_srv), m_manager(m_io_srv, CLIENT, 3)
     {
     }

     client_socket_utils::~client_socket_utils()
     {
     }

     void client_socket_utils::session_connect(std::vector& vSession)
     {
         for (int i = 0; i < vSession.size(); ++i)
         {
             session_connect(vSession[i]);
         }
     }

     void client_socket_utils::session_connect(socket_session_ptr pSession)
     {
         std::string& addr = pSession->get_remote_addr();
         try{
             //注册关闭回调函数
             pSession->installCloseCallBack(boost::bind(&client_socket_utils::close_callback, this, _1));
             //注册读到数据回调函数
             pSession->installReadDataCallBack(boost::bind(&client_socket_utils::read_data_callback, this, _1, _2, _3));

             std::vector ip_port;
             boost::split(ip_port, addr, boost::is_any_of(":"));

             if (ip_port.size() < 2)
             {
                 //throw std::runtime_error("ip 格式不正确！");
                 LOG4CXX_ERROR(firebird_log, "[" << addr << "] ip 格式不正确!");
                 return;
             }

             tcp::resolver resolver(pSession->socket().get_io_service());
             tcp::resolver::query query(ip_port[0], ip_port[1]);
             tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);
             //pSession->set_begin_endpoint(endpoint_iterator);//设置起始地址，以便重连

             //由于客户端是不断重连的，即使还未连接也要保存该session
             m_manager.add_session(pSession);

             tcp::endpoint endpoint = *endpoint_iterator;
             pSession->socket().async_connect(endpoint,
                 boost::bind(&client_socket_utils::handle_connect, this,
                 boost::asio::placeholders::error, ++endpoint_iterator, pSession));
         }
         catch(std::exception& e)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << addr << "],socket异常:[" << e.what() << "]");
         }
         catch(...)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << addr << "],socket异常:[未知异常]");
         }
     }

     void client_socket_utils::handle_connect(const boost::system::error_code& error,
         tcp::resolver::iterator endpoint_iterator, socket_session_ptr pSession)
     {
         LOG4CXX_DEBUG(firebird_log, KDS_CODE_INFO << " enter.");
         std::string sLog;
         try{
             if (!error)
             {
                 LOG4CXX_FATAL(firebird_log, "服务器:[" << pSession->get_business_type() <<"],连接远程地址:[" << pSession->get_remote_addr().c_str() << "]成功!");
                 pSession->start();

                 //向服务器注册服务类型
                 message msg;
                 msg.command = regist;
                 msg.business_type = pSession->get_business_type();
                 msg.app_id = pSession->get_app_id();
                 msg.data() = "R";

                 pSession->async_write(msg);
             }
             else if (endpoint_iterator != tcp::resolver::iterator())
             {
                 LOG4CXX_ERROR(firebird_log, "连接远程地址:[" << pSession->get_remote_addr().c_str() << "]失败，试图重连下一个地址。");
                 pSession->socket().close();//此处用socket的close，不应用session的close触发连接，不然会导致一直重连
                 tcp::endpoint endpoint = *endpoint_iterator;
                 pSession->socket().async_connect(endpoint,
                     boost::bind(&client_socket_utils::handle_connect, this,
                     boost::asio::placeholders::error, ++endpoint_iterator, pSession));
             }
             else
             {
                 LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << pSession->get_remote_addr().c_str() << "]失败！");
                 pSession->socket().close();//此处用socket的close，不应用session的close触发连接，不然会导致一直重连
             }
         }
         catch(std::exception& e)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << pSession->get_remote_addr().c_str() <<"],socket异常:[" << e.what() << "]");
         }
         catch(...)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << pSession->get_remote_addr().c_str() <<"],socket异常:[未知异常]");
         }
     }

     void client_socket_utils::read_data_callback(const boost::system::error_code& e,
         socket_session_ptr session, message& msg)
     {
         LOG4CXX_DEBUG(firebird_log, "command =[" << msg.command << "],["
             << msg.business_type << "],[" << msg.data() << "]");

         if (msg.command == heartbeat)
         {//心跳
         }
         else if (msg.command == regist)
         {//注册
             LOG4CXX_FATAL(firebird_log, "服务器:[" << session->get_business_type() <<"]注册成功。");
         }
         else if (msg.command == normal)
         {//业务数据
             handle_read_data(msg, session);
         }
         else
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "收到非法消息包!");
         }
     }

     //关闭session就会重连
     void client_socket_utils::close_callback(socket_session_ptr session)
     {
         LOG4CXX_DEBUG(firebird_log, KDS_CODE_INFO << "enter.");

         try{
             //tcp::resolver::iterator endpoint_iterator = context.session->get_begin_endpoint();

             std::string& addr = session->get_remote_addr();

             std::vector ip_port;
             boost::split(ip_port, addr, boost::is_any_of(":"));

             if (ip_port.size() < 2)
             {
                 LOG4CXX_ERROR(firebird_log, "[" << addr << "] ip 格式不正确!");
                 return;
             }

             tcp::resolver resolver(session->socket().get_io_service());
             tcp::resolver::query query(ip_port[0], ip_port[1]);
             tcp::resolver::iterator endpoint_iterator = resolver.resolve(query);

             tcp::endpoint endpoint = *endpoint_iterator;
             session->socket().async_connect(endpoint,
                 boost::bind(&client_socket_utils::handle_connect, this,
                 boost::asio::placeholders::error, ++endpoint_iterator, session));
         }
         catch(std::exception& e)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << session->get_remote_addr().c_str() <<"],socket异常:[" << e.what() << "]");
         }
         catch(...)
         {
             LOG4CXX_ERROR(firebird_log, KDS_CODE_INFO << "连接远程地址:[" << session->get_remote_addr().c_str() <<"],socket异常:[未知异常]");
         }
     }
 }

5.对象串行化

socket_session发送和接收数据包的时候使用到了对象串行化，我这里是通过thrift实现的，其实boost的serialization库也提供了这样的功能，使用起来更为方便，但我在测试过程中，thrift相比之下性能会高很多，因此就坚持使用thrift了，感兴趣的话可以看我之前写的《使用thrift串行化对象》和《轻量级序列化库boost serialization》。

5.1字符串与thrift对象的相互转换

 #pragma once
 #include
 #include
 #include
 #include

 namespace firebird{
     using namespace apache::thrift;
     using namespace apache::thrift::transport;
     using namespace apache::thrift::protocol;

     template<typename T>
     void thrift_iserialize(T& stu, std::string& s)
     {
         boost::shared_ptr trans(new TMemoryBuffer((uint8_t*)&s[0], s.size()));
         boost::shared_ptr proto(new TBinaryProtocol(trans));
         stu.read(proto.get());
     }

     template<typename T>
     void thrift_oserialize(T& stu, std::string& s)
     {
         boost::shared_ptr trans(new TMemoryBuffer());
         boost::shared_ptr proto(new TBinaryProtocol(trans));
         stu.write(proto.get());
         s = trans->getBufferAsString();
     }
 }

5.2通过thrift对象，普通的对象与字符串的相互转换

 #pragma once

 #include "message_archive.hpp"
 #include
 #include

 namespace firebird
 {
     /*** message to ThriftMessage ***/
     void msg_to_tmsg(TMessage& tmsg, message& msg)
     {
         //设置
         tmsg.command = msg.command;
         tmsg.business_type = msg.business_type;
         tmsg.app_id = msg.app_id;
         //设置context
         tmsg.context.cmdVersion = msg.context().cmdVersion;
         tmsg.context.cpid.swap(msg.context().cpid);
         tmsg.context.remote_ip.swap(msg.context().remote_ip);
         tmsg.context.wSerialNumber = msg.context().wSerialNumber;
         tmsg.context.session_id = msg.context().session_id;

         //设置source
         for (int i = 0; i < msg.source().size(); ++i)
         {
             tmsg.source.push_back(msg.source()[i]);
         }

         //设置destination
         for (int i = 0; i < msg.destination().size(); ++i)
         {
             tmsg.destination.push_back(msg.destination()[i]);
         }

         //设置data
         tmsg.data = msg.data();
     }

     /*** ThriftMessage to message ***/
     void tmsg_to_msg(message& msg, TMessage& tmsg)
     {
         //设置
         msg.command = tmsg.command;
         msg.business_type = tmsg.business_type;
         msg.app_id = tmsg.app_id;

         //设置context
         msg.context().cmdVersion = tmsg.context.cmdVersion;
         msg.context().cpid = tmsg.context.cpid;
         msg.context().remote_ip = tmsg.context.remote_ip;
         msg.context().wSerialNumber = tmsg.context.wSerialNumber;
         msg.context().session_id = tmsg.context.session_id;

         //设置source
         for (int i = 0; i < tmsg.source.size(); ++i)
         {
             msg.source() << tmsg.source[i];
         }

         //设置destination
         for (int i = 0; i < tmsg.destination.size(); ++i)
         {
             msg.destination() << tmsg.destination[i];
         }

         //设置data
         msg.data() = tmsg.data;
     }

     void message_iarchive(message& msg, std::string& s)
     {
         TMessage tmsg;
         thrift_iserialize(tmsg, s);
         tmsg_to_msg(msg, tmsg);
     }

     void message_oarchive(std::string& s, message& msg)
     {
         TMessage tmsg;
         msg_to_tmsg(tmsg, msg);
         thrift_oserialize(tmsg, s);
     }
 }