c – 如何从父插槽中删除子对象？可能会提升:: asio特定

我编写了一个网络服务器类来维护一组std ::网络客户端.网络客户端在断开连接时向网络服务器发出信号(通过boost :: bind).当网络客户端断开连接时,需要从Set中删除客户端实例并最终删除.我认为这是一种常见的模式,但我遇到的问题可能是,也可能不是ASIO特有的.

我试图减少相关代码：

/** NetworkServer.hpp **/
class NetworkServices : private boost::noncopyable
{
public:
    NetworkServices(void);
    ~NetworkServices(void);

private:
    void run();
    void onNetworkClientEvent(NetworkClientEvent&); 

private:
    std::set<boost::shared_ptr<const NetworkClient>> clients;
};


/** NetworkClient.cpp **/
void NetworkServices::run()
{
    running = true;

    boost::asio::io_service::work work(io_service); //keeps service running even if no operations

    // This creates just one thread for the boost::asio async network services
    boost::thread iot(boost::bind(&NetworkServices::run_io_service,this));

    while (running)
    {
        boost::system::error_code err;
        try
        {
            tcp::socket* socket = new tcp::socket(io_service);
            acceptor->accept(*socket,err);

            if (!err)
            {
                NetworkClient* networkClient = new NetworkClient(io_service,boost::shared_ptr<tcp::socket>(socket));
                networkClient->networkClientEventSignal.connect(boost::bind(&NetworkServices::onNetworkClientEvent,this,_1));

                clients.insert(boost::shared_ptr<NetworkClient>(networkClient));

                networkClient->init(); //kicks off 1st asynch_read call
            }
        }
        // etc...

    }
}

void NetworkServices::onNetworkClientEvent(NetworkClientEvent& evt)
{
    switch(evt.getType())
    {
        case NetworkClientEvent::CLIENT_ERROR :
        {
            boost::shared_ptr<const NetworkClient> clientPtr = evt.getClient().getSharedPtr();

            // ------ THIS IS THE MAGIC LINE -----
            // If I keep this,the io_service hangs. If I comment it out,// everything works fine (but I never delete the disconnected NetworkClient). 

            // If actually deleted the client here I might expect problems because it is the caller
            // of this method via boost::signal and bind.  However,The clientPtr is a shared ptr,and a
            // reference is being kept in the client itself while signaling,so
            // I would the object is not going to be deleted from the heap here. That seems to be the case.
            // Never-the-less,this line makes all the difference,most likely because it controls whether or not the NetworkClient ever gets deleted.
            clients.erase(clientPtr);

            //I should probably put this socket clean-up in NetworkClient destructor. Regardless by doing this,// I would expect the ASIO socket stuff to be adequately cleaned-up after this.

            tcp::socket& socket = clientPtr->getSocket();
            try {
                socket.shutdown(boost::asio::socket_base::shutdown_both);
                socket.close();
            }
            catch(...) {
                CommServerContext::error("Error while shutting down and closing socket.");
            }
            break;

        }
        default :
        {
            break;
        }
    }
}



/** NetworkClient.hpp **/
class NetworkClient : public boost::enable_shared_from_this<NetworkClient>,Client
{
    NetworkClient(boost::asio::io_service& io_service,boost::shared_ptr<tcp::socket> socket);
    virtual ~NetworkClient(void);

    inline boost::shared_ptr<const NetworkClient> getSharedPtr() const
    {
        return shared_from_this();
    };

    boost::signal <void (NetworkClientEvent&)>    networkClientEventSignal;

    void onAsyncReadHeader(const boost::system::error_code& error,size_t bytes_transferred);

};

/** NetworkClient.cpp - onAsyncReadHeader method called from io_service.run()
    thread as result of an async_read operation. Error condition usually 
    result of an unexpected client disconnect.**/
void NetworkClient::onAsyncReadHeader(  const boost::system::error_code& error,size_t bytes_transferred)
{
    if (error)
    {

        //Make sure this instance doesn't get deleted from parent/slot deferencing
        //Alternatively,somehow schedule for future delete?
        boost::shared_ptr<const NetworkClient> clientPtr = getSharedPtr();

        //Signal to service that this client is disconnecting
        NetworkClientEvent evt(*this,NetworkClientEvent::CLIENT_ERROR);
        networkClientEventSignal(evt);

        networkClientEventSignal.disconnect_all_slots();

        return;
    }

我认为从插槽处理程序中删除客户端是不安全的,因为函数返回将是… undefined？ (有趣的是,它似乎并没有让我感到沮丧.)所以我使用了boost：shared_ptr和shared_from_this来确保客户端不会被删除,直到所有插槽都被发出信号.但这似乎并不重要.

我相信这个问题并不是针对ASIO的,但问题在于使用ASIO时会以一种特殊的方式出现.我有一个执行io_service.run()的线程.所有ASIO读/写操作都是异步执行的.一切正常,多个客户端连接/断开连接除了我从上面的代码Set中删除我的客户端对象.如果我删除了我的客户端对象,io_service似乎在内部死锁,除非我启动另一个线程,否则不会执行进一步的异步操作.我试着/捕获io_service.run()调用并且无法检测到任何错误.

问题：

>是否有从父插槽中删除子对象(也是信号发射器)的最佳做法？
>当我删除我的网络客户端对象时,有关为什么io_service挂起的任何想法？