boost::asio 连接管理9

这节先重构下代码，业务逻辑代码和通信基础设施代码需要解耦。业务逻辑代码处理通信过程中的协议，以及背后需要的应用逻辑。而通信基础设施代码专注于并发，TCP连接等特性。

首先把前面的代码Connection的一些成员函数纯虚函数，业务类可以继承之，根据需要重写虚函数。

Server类编程模板类，接受业务类作为模板参数，只要该类提供几个必须的公有成员函数即可。

因此目录结构调整如下：

├── CMakeLists.txt
├── include
│   ├── business
│   └── core
└── src
    ├── business
    ├── CMakeLists.txt
    ├── core
    └── main.cc

server类由于是模板类，删除.cc文件，只保留.h文件，并且放在core目录下。

connection类也放在core目录下,也变成模板类。core下的这两个类就是通信基础设施类。

新建一个business类，里面都放应用逻辑相关的代码。现在这里有一个Client类。

对应的src/CMakeLists.txt文件适当修改：

cmake_minimum_required(VERSION 2.8)
set(CMAKE_BUILD_TYPE Debug)
set(PROJECT_INCLUDE_DIR ../include)

find_package(Boost COMPONENTS system filesystem thread REQUIRED)
include_directories(${Boost_INCLUDE_DIR} ${PROJECT_INCLUDE_DIR})
AUX_SOURCE_DIRECTORY(${CMAKE_SOURCE_DIR}/src CPP_LIST1)
AUX_SOURCE_DIRECTORY(${CMAKE_SOURCE_DIR}/src/core CPP_LIST2)
AUX_SOURCE_DIRECTORY(${CMAKE_SOURCE_DIR}/src/business CPP_LIST3)

add_executable(service ${CPP_LIST1} ${CPP_LIST2} ${CPP_LIST3})
target_link_libraries(service ${Boost_LIBRARIES})

add_definitions(-Wall)

好。现在看一下main.cc的代码：

#include <iostream>
#include "core/server.h"
#include "business/client.h"

using namespace std;

int main(int argc,char ** argv) {
    try {
	io_service iosev;
	tcp::endpoint listen_endpoint(tcp::v4(), 8888);
        Server<Client> server(iosev, listen_endpoint, 10);
        server.Run();
    } catch(std::exception const& ex) {
      cout << "Exception: " << ex.what() << "";
    }
}

改动在于include client.h文件，并创建Server<Client>对象。

看一下core/server.h文件：

#ifndef CORE_SERVER_H_
#define CORE_SERVER_H_

#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <boost/thread/thread.hpp>
#include <vector>

using namespace std;
using namespace boost;
using boost::system::error_code;
using namespace boost::asio;
using ip::tcp;


// Crate a thread pool for io_service.
// Run the io_service to accept new incoming TCP connection and handle the I/O events
// You should provide your class as template argument here
// Your class must inherit from Connection class.
template<class T>
class Server {
 public:
  typedef T ClientType;
 Server(io_service& s, tcp::endpoint const& listen_endpoint, size_t threads_number)
   : io_(s),
    signals_(s),
    acceptor_(io_, listen_endpoint),
    thread_pool_size_(threads_number) {
      signals_.add(SIGINT);
      signals_.add(SIGTERM);
#if defined(SIGQUIT)
      signals_.add(SIGQUIT);
#endif
      signals_.async_wait(bind(&Server::Stop, this));
      shared_ptr<ClientType> c(new ClientType(io_));
          
      acceptor_.async_accept(c->socket, bind(&Server::AfterAccept, this, c, _1));
    }

  void AfterAccept(shared_ptr<ClientType>& c, error_code const& ec) {
    // Check whether the server was stopped by a signal before this completion
    // handler had a chance to run.
    if (!acceptor_.is_open()) {
      cout << "acceptor is closed" << endl;
      return;
    }
        
    if (!ec) {
      c->StartJob();
      shared_ptr<ClientType> c2(new ClientType(io_));
      acceptor_.async_accept(c2->socket, bind(&Server::AfterAccept, this, c2, _1));
    }
  }

  // Create a thread pool for io_service
  // Launch io_service
  void Run() {
    // Create a pool of threads to run all of the io_services.
    vector<shared_ptr<thread> > threads;
    for (size_t i = 0; i < thread_pool_size_; ++i) {
      shared_ptr<thread> t(new thread(bind(&io_service::run, &io_)));
      threads.push_back(t);
    }

    // Wait for all threads in the pool to exit.
    for (std::size_t i = 0; i < threads.size(); ++i) {
      threads[i]->join();
    }
  }

 private:

  void Stop() {
    cout << "stopping" << endl;
    acceptor_.close();
    io_.stop();
  }

 private:
  io_service& io_;
  boost::asio::signal_set signals_;
  tcp::acceptor acceptor_;
  size_t thread_pool_size_;
};

#endif

再看一下connection.h文件：

#ifndef CORE_CONNECTION_H_
#define	CORE_CONNECTION_H_

#include <boost/asio.hpp>
#include <boost/enable_shared_from_this.hpp>

using namespace boost::asio;
using ip::tcp;
using boost::system::error_code;

using namespace boost;
using namespace std;

template<class T>
class Connection: public boost::enable_shared_from_this<T> {
 public:

 Connection(io_service& s)
   : socket(s), strand_(s) {

  }

  ~Connection() {
  }

  // You must override it yourself
  // Default implementation closes the socket using shutdonw&cloes methods
  // You could override it if want change it
  // Or resue it with Connection::CloseSocket() format
  void CloseSocket() {
    socket.shutdown(tcp::socket::shutdown_both);
    socket.close();
  }
    
  // You must override it yourself
  virtual void StartJob() = 0;

  tcp::socket socket;
    
  // Strand to ensure the connection's handlers are not called concurrently.
  boost::asio::io_service::strand strand_;
};


#endif

改动有两处：

1.加了关键字virtual ... =0

2. enable_shared_from_this的模板参数是T而不再是Connection类。

现在看看business/client.h，这个类实现了具体服务器和一个客户端之间通信的逻辑。

#ifndef BUSINESS_CLIENT_H_
#define BUSINESS_CLIENT_H_

#include "core/connection.h"
#include <vector>

using namespace std;

class Client: public Connection<Client> {
 public:
  Client(io_service& s);

  void StartJob();

  void CloseSocket();

  void AfterReadChar(error_code const& ec);

 private:
  vector<char> read_buffer_;
};

#endif

client.cc文件代码：

#include "business/client.h"
#include <boost/bind.hpp>

using namespace boost;

Client::Client(io_service& s):
  Connection(s), read_buffer_(1, 0) {
}

void Client::StartJob() {
    async_read(socket, buffer(read_buffer_),
	       strand_.wrap(bind(&Client::AfterReadChar, shared_from_this(), _1)));
}

void Client::CloseSocket() {
  Connection::CloseSocket();
}


void Client::AfterReadChar(error_code const& ec) {
    if (ec) {
        cout << ec.message() << endl;
        return;
    }
    
    char x = read_buffer_[0];
    if (x == 'a') {
        cout << "correct data received" << endl;
        async_read(socket, buffer(read_buffer_),
		   strand_.wrap(bind(&Client::AfterReadChar, shared_from_this(), _1)));
    } else {
        cout << "wrong data received, char is:" << (int) x << endl;
        CloseSocket();
    }
}

好了，现在这个解耦够用了。下一节进行测试。