Question

我正处于使用boost asio构建和测试TCP套接字客户端的早期阶段。我注意到，如果boost套接字与服务器建立连接，如果我连接服务器时关闭服务器（测试boost如何响应已关闭的连接），然后使用async_write向服务器写入消息，则没有任何反应一点都不永远不会调用异步写入处理程序方法（我原以为它会被调用并出现错误）。（如果套接字没有断开连接，则会正确调用异步写入处理程序方法。）

更新

添加deadline_timer以检查是否在异步写入处理程序之前超时我现在在写处理程序方法中遇到错误。它似乎以某种方式使deadline_timer也使用io_service的线程现在让错误冒泡到处理程序方法。我还不能解释这个......

代码如下所示：

comm_mgr(server_info& info, io_service& service): server_info_(info), io_service_(service), timer_(service) 
{
    DEBUG("comm_mgr.ctor()");           
}

void start(void)
{
    DEBUG("start(): starting connect() method call...");
    connect();
    DEBUG("start(): starting thread to run io_service::run()");
    t_ = new boost::thread(boost::bind(&io_service::run, &io_service_));

    timer_.async_wait(boost::bind(&comm_mgr::check_write_timeout, this));
}

void connect()
{

    tcp::resolver resolver(io_service_);
    tcp::resolver::query query(server_info_.host, server_info_.port);
    tcp::resolver::iterator iterator = resolver.resolve(query);

    INFO("connect(): resetting socket and calling async_connect with handle_connect callback. connecting to: " << server_info_.host << ":" << server_info_.port);
    socket.reset(new tcp::socket(io_service_));
    socket->async_connect(*iterator, boost::bind(&comm_mgr::handle_connect, this, boost::asio::placeholders::error, ++iterator));

}

void send(EZXMsg& msg)
{
    const char* encoded = msg.api_msg(0);
    size_t bytes = std::strlen(encoded);
    timer_.expires_from_now(boost::posix_time::seconds(30));
    boost::asio::async_write(*socket, boost::asio::buffer(encoded, bytes), boost::bind(&comm_mgr::handle_write, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred));     
}

void handle_write(const boost::system::error_code& error, std::size_t bytes_transferred)
{
    if (!error)
    {
       LOG4CXX_DEBUG(logger, "handle_write(): sent bytes" << bytes_transferred);
    } else {
       LOG4CXX_ERROR(logger, "handle_write(): error. ex=" << error);
    }
}

为什么写入方法在套接字关闭时写入时没有注册任何错误？

为什么不提升asio async写检测套接字已被关闭？

0 个答案: