C++ Boost.Asio异步编程

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donnytab
     广东
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    头图

    Boost.Asio是Boost库中非常著名的I/O组件，是用于网络和低层IO编程的跨平台C++库，为开发者提供了C++环境下稳定的异步模型。本文将介绍Boost库中Asio的结构及相关异步编程。

    Asio三大组件

    io_object

    I/O对象的集合，其中包含大家所熟悉的socket、deadline_timer等对象，主要功能是提供接口给用户使用。

    services服务

    逻辑功能的实现者，其中包含提供定时功能的deadline_timer_service、提供socket相关功能的win_iocp_socket_service(windows平台)/reactive_socket_service(其他平台)、作为io_service功能的真正实现者win_iocp_io_service(windows平台)/task_io_service(其他平台)等等服务。

    Asio核心组件

    在这一层中可以理解为就是io_service，它通过关联的类service_registry将实现具体功能所需的服务组合起来，再由io_object提供接口给用户使用。

    编程实例

    TCP异步连接

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

// 异步连接回调函数
void on_connect(boost::system::error_code ec)
{
     if (ec)  // 连接失败, 输出错误码
         std::cout << "async connect error:" << ec.message() << std::endl;
     else  // 连接成功
         std::cout << "async connect ok!" << std::endl;
 }
 
int main() {
     boost::asio::io_service ios;  // 创建io_service对象
     boost::asio::ip::tcp::endpoint addr(
     boost::asio::ip::address::from_string("127.0.0.1"), 12345);  // server端地址
     boost::asio::ip::tcp::socket conn_socket(ios);  // 创建tcp协议的socket对象
     conn_socket.async_connect(addr, &on_connect);  // 发起异步连接请求
     ios.run();  // 调用io_service::run, 等待异步操作结果
 
     std::cin.get();
     return 0;
}

    TCP异步接受连接

    #include <iostream>
#include <boost/asio.hpp>
#include <boost/bind.hpp>

// 异步连接回调函数
void on_accept(boost::system::error_code ec, boost::asio::ip::tcp::socket * socket_ptr)
{
     if (ec)  // 连接失败, 输出错误码
         std::cout << "async accept error:" << ec.message() << std::endl;
     else  // 连接成功
         std::cout << "async accept from (" << socket_ptr->remote_endpoint() << ")" << std::endl;
 
     // 断开连接, 释放资源.
     socket_ptr->close(), delete socket_ptr;
}
 
int main() {
     boost::asio::io_service ios;  // 创建io_service对象
     boost::asio::ip::tcp::endpoint addr(
     boost::asio::ip::address::from_string("0.0.0.0"), 12345);  // server端地址
     boost::asio::ip::tcp::acceptor acceptor(ios, addr, false);  // 创建acceptor对象
     boost::asio::ip::tcp::socket * socket_ptr = new boost::asio::ip::tcp::socket(ios);
     acceptor.async_accept(*socket_ptr
         , boost::bind(&on_accept, boost::asio::placeholders::error, socket_ptr));  // 调用异步accept请求
     ios.run();  // 调用io_service::run, 等待异步操作结果
 
     std::cin.get();
     return 0;
}

    TCP异步读写数据

    #include <iostream>
#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/array.hpp>
 
typedef boost::shared_ptr<boost::asio::ip::tcp::socket> socket_ptr_t;
typedef boost::array<char, 128> buffer_t;
typedef boost::shared_ptr<buffer_t> buffer_ptr_t;
 
// 异步读数据回调函数
void on_read(boost::system::error_code ec
     , std::size_t len, socket_ptr_t socket_ptr, buffer_ptr_t buffer_ptr)
{
     if (ec)
         std::cout << "async write error:" << ec.message() << std::endl;
     else
     {
         std::cout << "async read size:" << len;
         std::cout << " info:" << std::string((char*)buffer_ptr->begin(), len) << std::endl;
 
         // auto release socket and buffer.
     }
}
 
// 异步写数据回调函数
void on_write(boost::system::error_code ec
     , std::size_t len, socket_ptr_t socket_ptr, buffer_ptr_t buffer_ptr)
{
     if (ec)
         std::cout << "async write error:" << ec.message() << std::endl;
     else
     {
         std::cout << "async write size:" << len << std::endl;
         socket_ptr->async_read_some(boost::asio::buffer(buffer_ptr.get(), buffer_t::size())
             , boost::bind(&on_read, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred
                 , socket_ptr, buffer_ptr));
     }
}
 
// 异步连接回调函数
void on_accept(boost::system::error_code ec, socket_ptr_t socket_ptr)
{
     if (ec)  // 连接失败, 输出错误码
     {
         std::cout << "async accept error:" << ec.message() << std::endl;
     }
     else  // 连接成功
     {
         std::cout << "async accept from (" << socket_ptr->remote_endpoint() << ")" << std::endl;
         buffer_ptr_t buffer_ptr(new buffer_t);
         strcpy_s((char*)buffer_ptr->begin(), buffer_t::size(), "abcdefg");
         socket_ptr->async_write_some(boost::asio::buffer(buffer_ptr.get(), strlen((char*)buffer_ptr->begin()))
             , boost::bind(&on_write, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred
                 , socket_ptr, buffer_ptr));
     }
}
 
int main() {
     boost::asio::io_service ios;  // 创建io_service对象
     boost::asio::ip::tcp::endpoint addr(
         boost::asio::ip::address::from_string("0.0.0.0"), 12345);  // server端地址
     boost::asio::ip::tcp::acceptor acceptor(ios, addr, false);  // 创建acceptor对象
     socket_ptr_t socket_ptr(new boost::asio::ip::tcp::socket(ios));
     acceptor.async_accept(*socket_ptr
         , boost::bind(&on_accept, boost::asio::placeholders::error, socket_ptr));  // 调用异步accept请求
     ios.run();  // 调用io_service::run, 等待异步操作结果
 
     std::cout << "press enter key...";
     std::cin.get();
     return 0;
}

    TCP强制关闭连接

    #include <iostream>
#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/array.hpp>

typedef boost::shared_ptr<boost::asio::ip::tcp::socket> socket_ptr_t;
typedef boost::array<char, 128> buffer_t;
typedef boost::shared_ptr<buffer_t> buffer_ptr_t;
 
// 异步读数据回调函数
void on_read(boost::system::error_code ec
     , std::size_t len, socket_ptr_t socket_ptr, buffer_ptr_t buffer_ptr)
{
     if (ec)  // 连接失败, 输出错误码
     {
         std::cout << "async read error:" << ec.message() << std::endl;
     }
}
 
// 异步写数据回调函数
void on_write(boost::system::error_code ec
     , std::size_t len, socket_ptr_t socket_ptr, buffer_ptr_t buffer_ptr)
{
     if (ec)  // 连接失败, 输出错误码
     {
         std::cout << "async write error:" << ec.message() << std::endl;
     }
}
 
// 异步连接回调函数
void on_accept(boost::system::error_code ec, socket_ptr_t socket_ptr)
{
     if (ec)  // 连接失败, 输出错误码
     {
         std::cout << "async accept error:" << ec.message() << std::endl;
     }
     else  // 连接成功
     {
         std::cout << "async accept from (" << socket_ptr->remote_endpoint() << ")" << std::endl;
 
         {
             buffer_ptr_t buffer_ptr(new buffer_t);
             strcpy_s((char*)buffer_ptr->begin(), buffer_t::size(), "abcdefg");
             socket_ptr->async_write_some(boost::asio::buffer(buffer_ptr.get(), strlen((char*)buffer_ptr->begin()))
                 , boost::bind(&on_write, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred
                 , socket_ptr, buffer_ptr));
         } 
         {
             buffer_ptr_t buffer_ptr(new buffer_t);
             socket_ptr->async_read_some(boost::asio::buffer(buffer_ptr.get(), buffer_t::size())
                 , boost::bind(&on_read, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred
                 , socket_ptr, buffer_ptr));
         }
 
         /// 强制关闭连接
         socket_ptr->close(ec);
         if (ec)
             std::cout << "close error:" << ec.message() << std::endl;
     }
}
 
int main()
{
     boost::asio::io_service ios;  // 创建io_service对象
     boost::asio::ip::tcp::endpoint addr(
         boost::asio::ip::address::from_string("0.0.0.0"), 12345);  // server端地址
     boost::asio::ip::tcp::acceptor acceptor(ios, addr, false);  // 创建acceptor对象
     socket_ptr_t socket_ptr(new boost::asio::ip::tcp::socket(ios));
     acceptor.async_accept(*socket_ptr
         , boost::bind(&on_accept, boost::asio::placeholders::error, socket_ptr));  // 调用异步accept请求
     socket_ptr.reset();
     ios.run();  // 调用io_service::run, 等待异步操作结果
 
     std::cout << "press enter key...";
     std::cin.get();
     return 0;
}

    TCP优雅地关闭连接

    #include <iostream>
#include <boost/asio.hpp>
#include <boost/bind.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/array.hpp>
 
typedef boost::shared_ptr<boost::asio::ip::tcp::socket> socket_ptr_t;
typedef boost::array<char, 32> buffer_t;
typedef boost::shared_ptr<buffer_t> buffer_ptr_t;
  
// 异步读数据回调函数
 void on_read(boost::system::error_code ec
     , std::size_t len, socket_ptr_t socket_ptr, buffer_ptr_t buffer_ptr)
 {
     static int si = 0;
     if (ec)  // 连接失败, 输出错误码
     {
         std::cout << "async read(" << si++ << ") error:" << ec.message() << std::endl;
         socket_ptr->shutdown(boost::asio::socket_base::shutdown_receive, ec);
         socket_ptr->close(ec);
         if (ec)
             std::cout << "close error:" << ec.message() << std::endl;
     }
     else
     {
         std::cout << "read(" << si++ << ") len:" << len << std::endl;
 
         socket_ptr->async_read_some(boost::asio::buffer(buffer_ptr.get(), buffer_t::size())
             , boost::bind(&on_read, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred
             , socket_ptr, buffer_ptr));
     }
 }
 
 // 异步写数据回调函数
 void on_write(boost::system::error_code ec
     , std::size_t len, socket_ptr_t socket_ptr, buffer_ptr_t buffer_ptr)
 {
     if (ec)  // 连接失败, 输出错误码
     {
         std::cout << "async write error:" << ec.message() << std::endl;
     }
     else
     {
         /// 优雅地关闭连接
         socket_ptr->shutdown(boost::asio::ip::tcp::socket::shutdown_send, ec);
         if (ec)
             std::cout << "shutdown send error:" << ec.message() << std::endl;
     }
 }
 
 // 异步连接回调函数
 void on_accept(boost::system::error_code ec, socket_ptr_t socket_ptr)
 {
     if (ec)  // 连接失败, 输出错误码
     {
         std::cout << "async accept error:" << ec.message() << std::endl;
     }
     else  // 连接成功
     {
         std::cout << "async accept from (" << socket_ptr->remote_endpoint() << ")" << std::endl;
 
        {
             buffer_ptr_t buffer_ptr(new buffer_t);
             socket_ptr->async_read_some(boost::asio::buffer(buffer_ptr.get(), buffer_t::size())
                 , boost::bind(&on_read, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred
                 , socket_ptr, buffer_ptr));
         }
 
         {
             buffer_ptr_t buffer_ptr(new buffer_t);
             strcpy_s((char*)buffer_ptr->begin(), buffer_t::size(), "abcdefg");
             socket_ptr->async_write_some(boost::asio::buffer(buffer_ptr.get(), strlen((char*)buffer_ptr->begin()))
                 , boost::bind(&on_write, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred
                 , socket_ptr, buffer_ptr));
         }
     }
}

int main()
{ 
     boost::asio::io_service ios;  // 创建io_service对象
     boost::asio::ip::tcp::endpoint addr(
         boost::asio::ip::address::from_string("0.0.0.0"), 12345);  // server端地址
     boost::asio::ip::tcp::acceptor acceptor(ios, addr, false);  // 创建acceptor对象
     socket_ptr_t socket_ptr(new boost::asio::ip::tcp::socket(ios));
     acceptor.async_accept(*socket_ptr
         , boost::bind(&on_accept, boost::asio::placeholders::error, socket_ptr));  // 调用异步accept请求
     socket_ptr.reset();
     ios.run();  // 调用io_service::run, 等待异步操作结果
 
     std::cout << "press enter key...";
     std::cin.get();
     return 0;
}
    c++boost异步编程io
    donnytab
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