EPOLLOUT 事件的意义 以及 处理示例

• 服务端准备好数据发往客户端

void Player::SendMsg(int seqid, a8::ReflectibleObject& msg)
{
    g_gglistener->SendToClient(socket_handle_, seqid, msg.metaclass->Tag(), msg);
}

• listener 找到对应的clientitem，并调用sendbuff

bool SendClientMsg(unsigned short sockhandle, const char *buff, int buffLen)
{
    mClientsMutex.lock();
    ClientSocketItem *p = GetClientSocket(sockhandle);
    if (p){
        p->SendBuff(buff, buffLen);
    }
    mClientsMutex.unlock();
}

• SendBuf

virtual void SendBuff(const char* buff, unsigned int bufflen)
{
    if (bufflen > 0){
        SendQueueNode* p = (SendQueueNode*)malloc(sizeof(SendQueueNode));
        memset(p, 0, sizeof(SendQueueNode));
        p->mBuff = (char*)malloc(bufflen);
        memmove(p->mBuff, buff, bufflen);
        p->mBuffLen = bufflen;
        mSendBufferMutex.lock();
        if(mWorkNode == NULL && mTopNode == NULL){
            mWorkNode = p;
            AsyncSend();   // 调用异步发送，开始进入发送流程
        }else{
            if (mBotNode){
                mBotNode->mNext = p;
                mBotNode = p;
            }else{
                mTopNode = p;
                mBotNode = p;
            }
        }
        mSendBufferMutex.unlock();
    }
}

• ASyncSend

void AsyncSend()
{
    while(mWorkNode){
        // 如果缓冲区已满，这里直接返回error，一般是EAGAIN，然后函数退出，待缓冲区满之后，会触发EPOLLOUT事件
        // 然后还会继续发送
        int sentbytes = ::send(mSocket,
                               mWorkNode->mBuff + mWorkNode->mSentBytes,
                               mWorkNode->mBuffLen - mWorkNode->mSentBytes,
                               0);
        if(sentbytes <= 0){
            break;
        }
        mWorkNode->mSentBytes += sentbytes;
        if(mWorkNode->mSentBytes >= mWorkNode->mBuffLen){
            ......
        }
    }
}

参考链接