trinitycore 魔兽服务器源码分析(二) 网络

书接上文 继续分析Socket.h SocketMgr.h

template<class T>
class Socket : public std::enable_shared_from_this<T>

根据智能指针的使用规则 类中有使用本类自己的指针 必须继承自enable_shared_from_this<> 防止自引用 不能释放的BUG

class Socket封装了asio中的socket类 获取远端ip 端口等功能， 并且额外提供异步读写的功能

类中的两个原子变量 _closed _closing标记该socket的关闭开启状态

bool Update()函数根据socket是否是同步异步标记进行写入队列的处理。 同步则进行处理 异步则暂缓

void AsyncRead()  void AsyncReadWithCallback(void (T::*callback)(boost::system::error_code, std::size_t))

则采取异步读取socket 调用默认函数ReadHandlerInternal() 或者输入函数T::*callback()

由于AsyncReadWithCallback 函数中bind 需要 T类的指针 所以才有开头的继承std::enable_shared_from_this<T>

但是使用比较怪异  std::enable_shared_from_this<>用法一般是继承自己本身 

class self :: public std::enable_shared_from_this<self>{
public:

　　void test(){

　　// only for test 
　　std::bind(&self ::test, shared_from_this());

　　}
}

异步写write类似  ,由bool AsyncProcessQueue()函数发起

使用asio的async_write_some函数异步读取连接内容 并调用回调函数WriteHandler()或者WriteHandlerWrapper()

不过需要结合MessageBuffer 一起跟进流程

类代码如下

/*
 * Copyright (C) 2008-2017 TrinityCore <http://www.trinitycore.org/>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef __SOCKET_H__
#define __SOCKET_H__

#include "MessageBuffer.h"
#include "Log.h"
#include <atomic>
#include <queue>
#include <memory>
#include <functional>
#include <type_traits>
#include <boost/asio/ip/tcp.hpp>

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

#define READ_BLOCK_SIZE 4096
#ifdef BOOST_ASIO_HAS_IOCP
#define TC_SOCKET_USE_IOCP
#endif

template<class T>
class Socket : public std::enable_shared_from_this<T>
{
public:
    explicit Socket(tcp::socket&& socket) : _socket(std::move(socket)), _remoteAddress(_socket.remote_endpoint().address()),
        _remotePort(_socket.remote_endpoint().port()), _readBuffer(), _closed(false), _closing(false), _isWritingAsync(false)
    {
        _readBuffer.Resize(READ_BLOCK_SIZE);
    }

    virtual ~Socket()
    {
        _closed = true;
        boost::system::error_code error;
        _socket.close(error);
    }

    virtual void Start() = 0;

    virtual bool Update()
    {
        if (_closed)
            return false;

#ifndef TC_SOCKET_USE_IOCP
        if (_isWritingAsync || (_writeQueue.empty() && !_closing))
            return true;

        for (; HandleQueue();)
            ;
#endif

        return true;
    }

    boost::asio::ip::address GetRemoteIpAddress() const
    {
        return _remoteAddress;
    }

    uint16 GetRemotePort() const
    {
        return _remotePort;
    }

    void AsyncRead()
    {
        if (!IsOpen())
            return;

        _readBuffer.Normalize();
        _readBuffer.EnsureFreeSpace();
        _socket.async_read_some(boost::asio::buffer(_readBuffer.GetWritePointer(), _readBuffer.GetRemainingSpace()),
            std::bind(&Socket<T>::ReadHandlerInternal, this->shared_from_this(), std::placeholders::_1, std::placeholders::_2));
    }

    void AsyncReadWithCallback(void (T::*callback)(boost::system::error_code, std::size_t))
    {
        if (!IsOpen())
            return;

        _readBuffer.Normalize();
        _readBuffer.EnsureFreeSpace();
        _socket.async_read_some(boost::asio::buffer(_readBuffer.GetWritePointer(), _readBuffer.GetRemainingSpace()),
            std::bind(callback, this->shared_from_this(), std::placeholders::_1, std::placeholders::_2));
    }

    void QueuePacket(MessageBuffer&& buffer)
    {
        _writeQueue.push(std::move(buffer));

#ifdef TC_SOCKET_USE_IOCP
        AsyncProcessQueue();
#endif
    }

    bool IsOpen() const { return !_closed && !_closing; }

    void CloseSocket()
    {
        if (_closed.exchange(true))
            return;

        boost::system::error_code shutdownError;
        _socket.shutdown(boost::asio::socket_base::shutdown_send, shutdownError);
        if (shutdownError)
            TC_LOG_DEBUG("network", "Socket::CloseSocket: %s errored when shutting down socket: %i (%s)", GetRemoteIpAddress().to_string().c_str(),
                shutdownError.value(), shutdownError.message().c_str());

        OnClose();
    }

    /// Marks the socket for closing after write buffer becomes empty
    void DelayedCloseSocket() { _closing = true; }

    MessageBuffer& GetReadBuffer() { return _readBuffer; }

protected:
    virtual void OnClose() { }

    virtual void ReadHandler() = 0;

    bool AsyncProcessQueue()
    {
        if (_isWritingAsync)
            return false;

        _isWritingAsync = true;

#ifdef TC_SOCKET_USE_IOCP
        MessageBuffer& buffer = _writeQueue.front();
        _socket.async_write_some(boost::asio::buffer(buffer.GetReadPointer(), buffer.GetActiveSize()), std::bind(&Socket<T>::WriteHandler,
            this->shared_from_this(), std::placeholders::_1, std::placeholders::_2));
#else
        _socket.async_write_some(boost::asio::null_buffers(), std::bind(&Socket<T>::WriteHandlerWrapper,
            this->shared_from_this(), std::placeholders::_1, std::placeholders::_2));
#endif

        return false;
    }

    void SetNoDelay(bool enable)
    {
        boost::system::error_code err;
        _socket.set_option(tcp::no_delay(enable), err);
        if (err)
            TC_LOG_DEBUG("network", "Socket::SetNoDelay: failed to set_option(boost::asio::ip::tcp::no_delay) for %s - %d (%s)",
                GetRemoteIpAddress().to_string().c_str(), err.value(), err.message().c_str());
    }

private:
    void ReadHandlerInternal(boost::system::error_code error, size_t transferredBytes)
    {
        if (error)
        {
            CloseSocket();
            return;
        }

        _readBuffer.WriteCompleted(transferredBytes);
        ReadHandler();
    }

#ifdef TC_SOCKET_USE_IOCP

    void WriteHandler(boost::system::error_code error, std::size_t transferedBytes)
    {
        if (!error)
        {
            _isWritingAsync = false;
            _writeQueue.front().ReadCompleted(transferedBytes);
            if (!_writeQueue.front().GetActiveSize())
                _writeQueue.pop();

            if (!_writeQueue.empty())
                AsyncProcessQueue();
            else if (_closing)
                CloseSocket();
        }
        else
            CloseSocket();
    }

#else

    void WriteHandlerWrapper(boost::system::error_code /*error*/, std::size_t /*transferedBytes*/)
    {
        _isWritingAsync = false;
        HandleQueue();
    }

    bool HandleQueue()
    {
        if (_writeQueue.empty())
            return false;

        MessageBuffer& queuedMessage = _writeQueue.front();

        std::size_t bytesToSend = queuedMessage.GetActiveSize();

        boost::system::error_code error;
        std::size_t bytesSent = _socket.write_some(boost::asio::buffer(queuedMessage.GetReadPointer(), bytesToSend), error);

        if (error)
        {
            if (error == boost::asio::error::would_block || error == boost::asio::error::try_again)
                return AsyncProcessQueue();

            _writeQueue.pop();
            if (_closing && _writeQueue.empty())
                CloseSocket();
            return false;
        }
        else if (bytesSent == 0)
        {
            _writeQueue.pop();
            if (_closing && _writeQueue.empty())
                CloseSocket();
            return false;
        }
        else if (bytesSent < bytesToSend) // now n > 0
        {
            queuedMessage.ReadCompleted(bytesSent);
            return AsyncProcessQueue();
        }

        _writeQueue.pop();
        if (_closing && _writeQueue.empty())
            CloseSocket();
        return !_writeQueue.empty();
    }

#endif

    tcp::socket _socket;

    boost::asio::ip::address _remoteAddress;
    uint16 _remotePort;

    MessageBuffer _readBuffer;
    std::queue<MessageBuffer> _writeQueue;

    std::atomic<bool> _closed;
    std::atomic<bool> _closing;

    bool _isWritingAsync;
};

#endif // __SOCKET_H__

 //======================================================

template<class SocketType>
class SocketMgr

将之前的Socket NetworkThread AsyncAcceptor

整合了起来

virtual bool StartNetwork(boost::asio::io_service& service, std::string const& bindIp, uint16 port, int threadCount)函数

开启threadCount个NetworkThread 

创建一个AsyncAcceptor 异步ACCEPT连接

 uint32 SelectThreadWithMinConnections() 函数会返回连接数目最少的NetworkThread 的线程索引

std::pair<tcp::socket*, uint32> GetSocketForAccept()则返回连接数目最少的线程索引和 该线程用于异步连接Socket指针

其余的start stop 就没什么了

值得关注的是virtual void OnSocketOpen(tcp::socket&& sock, uint32 threadIndex)

当继承SocketMgr的服务器在accept的时候会调用该函数

函数功能是运行accept的Socket的run函数

并且讲Socket加入到NetworkThread 的Socket容器中(AddSocket函数)

整个类的代码如下

/*
 * Copyright (C) 2008-2017 TrinityCore <http://www.trinitycore.org/>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef SocketMgr_h__
#define SocketMgr_h__

#include "AsyncAcceptor.h"
#include "Errors.h"
#include "NetworkThread.h"
#include <boost/asio/ip/tcp.hpp>
#include <memory>

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

template<class SocketType>
class SocketMgr
{
public:
    virtual ~SocketMgr()
    {
        ASSERT(!_threads && !_acceptor && !_threadCount, "StopNetwork must be called prior to SocketMgr destruction");
    }

    virtual bool StartNetwork(boost::asio::io_service& service, std::string const& bindIp, uint16 port, int threadCount)
    {
        ASSERT(threadCount > 0);

        AsyncAcceptor* acceptor = nullptr;
        try
        {
            acceptor = new AsyncAcceptor(service, bindIp, port);
        }
        catch (boost::system::system_error const& err)
        {
            TC_LOG_ERROR("network", "Exception caught in SocketMgr.StartNetwork (%s:%u): %s", bindIp.c_str(), port, err.what());
            return false;
        }

        if (!acceptor->Bind())
        {
            TC_LOG_ERROR("network", "StartNetwork failed to bind socket acceptor");
            return false;
        }

        _acceptor = acceptor;
        _threadCount = threadCount;
        _threads = CreateThreads();

        ASSERT(_threads);

        for (int32 i = 0; i < _threadCount; ++i)
            _threads[i].Start();

        return true;
    }

    virtual void StopNetwork()
    {
        _acceptor->Close();

        if (_threadCount != 0)
            for (int32 i = 0; i < _threadCount; ++i)
                _threads[i].Stop();

        Wait();

        delete _acceptor;
        _acceptor = nullptr;
        delete[] _threads;
        _threads = nullptr;
        _threadCount = 0;
    }

    void Wait()
    {
        if (_threadCount != 0)
            for (int32 i = 0; i < _threadCount; ++i)
                _threads[i].Wait();
    }

    virtual void OnSocketOpen(tcp::socket&& sock, uint32 threadIndex)
    {
        try
        {
            std::shared_ptr<SocketType> newSocket = std::make_shared<SocketType>(std::move(sock));
            newSocket->Start();

            _threads[threadIndex].AddSocket(newSocket);
        }
        catch (boost::system::system_error const& err)
        {
            TC_LOG_WARN("network", "Failed to retrieve client's remote address %s", err.what());
        }
    }

    int32 GetNetworkThreadCount() const { return _threadCount; }

    uint32 SelectThreadWithMinConnections() const
    {
        uint32 min = 0;

        for (int32 i = 1; i < _threadCount; ++i)
            if (_threads[i].GetConnectionCount() < _threads[min].GetConnectionCount())
                min = i;

        return min;
    }

    std::pair<tcp::socket*, uint32> GetSocketForAccept()
    {
        uint32 threadIndex = SelectThreadWithMinConnections();
        return std::make_pair(_threads[threadIndex].GetSocketForAccept(), threadIndex);
    }

protected:
    SocketMgr() : _acceptor(nullptr), _threads(nullptr), _threadCount(0)
    {
    }

    virtual NetworkThread<SocketType>* CreateThreads() const = 0;

    AsyncAcceptor* _acceptor;
    NetworkThread<SocketType>* _threads;
    int32 _threadCount;
};

#endif // SocketMgr_h__