EchoServer(EventLoop *loop,
           const InetAddress &addr, 
           const std::string &name)
    : server_(loop, addr, name)
        , loop_(loop)
    {
        // 注冊回調(diào)函數(shù)
        server_.setConnectionCallback(
            std::bind(&EchoServer::onConnection, this, std::placeholders::_1)
        );

        server_.setMessageCallback(
            std::bind(&EchoServer::onMessage, this,
                      std::placeholders::_1, std::placeholders::_2, std::placeholders::_3)
        // 設(shè)置合適的loop線程數(shù)量 loopthread 不包括baseloop
        server_.setThreadNum(3);
    }

TcpServer::TcpServer(EventLoop *loop,
                const InetAddress &listenAddr,
                const std::string &nameArg,
                Option option)
                : loop_(CheckLoopNotNull(loop))
                , ipPort_(listenAddr.toIpPort())
                , name_(nameArg)
                , acceptor_(new Acceptor(loop, listenAddr, option == kReusePort))
                , threadPool_(new EventLoopThreadPool(loop, name_))
                , connectionCallback_()
                , messageCallback_()
                , nextConnId_(1)
                , started_(0)
{
    // 當(dāng)有新用戶連接時(shí)候，會(huì)執(zhí)行該回調(diào)函數(shù)
    acceptor_->setNewConnectionCallback(std::bind(&TcpServer::newConnection, this, 
        std::placeholders::_1, std::placeholders::_2));
}

Acceptor::Acceptor(EventLoop *loop, const InetAddress &listenAddr, bool reuseport)
    : loop_(loop), acceptSocket_(createNonblocking()) // socket
      ,
      acceptChannel_(loop, acceptSocket_.fd()), listenning_(false)
{
    acceptSocket_.setReuseAddr(true);
    acceptSocket_.setReusePort(true);
    acceptSocket_.bindAddress(listenAddr); // 綁定套接字
    // 有新用戶的連接，執(zhí)行一個(gè)回調(diào)（打包為channel）
    acceptChannel_.setReadCallback(std::bind(&Acceptor::handleRead, this));
}

// 開啟服務(wù)器監(jiān)聽
void TcpServer::start()
{
	// 防止一個(gè)TcpServer被start多次
    if (started_++ == 0) 
    {
        threadPool_->start(threadInitCallback_); // 啟動(dòng)底層的loop線程池,這里會(huì)按照設(shè)定了threadnum設(shè)置pool的數(shù)量
        loop_->runInLoop(std::bind(&Acceptor::listen, acceptor_.get()));
    }
}

void Acceptor::listen()
{
    listenning_ = true;
    acceptSocket_.listen();         // listen
    acceptChannel_.enableReading(); // acceptChannel_ => Poller
}

// listenfd有事件發(fā)生了，就是有新用戶連接了
void Acceptor::handleRead()
{
    InetAddress peerAddr;
    int connfd = acceptSocket_.accept(&peerAddr);
    if (connfd >= 0)
    {
        // 若用戶實(shí)現(xiàn)定義了，則執(zhí)行，否則說明用戶對新到來的連接沒有需要執(zhí)行的，所以直接關(guān)閉
        if (newConnectionCallback_)
        {
            newConnectionCallback_(connfd, peerAddr); // 輪詢找到subLoop，喚醒，分發(fā)當(dāng)前的新客戶端的Channel
        }
        else
        {
            ::close(connfd);
        }
    }
    ...
}

void TcpServer::newConnection(int sockfd, const InetAddress &peerAddr)
{
    // 輪詢算法選擇一個(gè)subloop來管理對應(yīng)的這個(gè)新連接
    EventLoop *ioLoop = threadPool_->getNextLoop(); 
    char buf[64] = {0};
    snprintf(buf, sizeof buf, "-%s#%d", ipPort_.c_str(), nextConnId_);
    ++nextConnId_;
    std::string connName = name_ + buf;

    LOG_INFO("TcpServer::newConnection [%s] - new connection [%s] from %s \n",
        name_.c_str(), connName.c_str(), peerAddr.toIpPort().c_str());
    // 通過sockfd獲取其綁定的本地ip和端口
    sockaddr_in local;
    ::bzero(&local, sizeof local);
    socklen_t addrlen = sizeof local;
    if (::getsockname(sockfd, (sockaddr*)&local, &addrlen) < 0)
    {
        LOG_ERROR("sockets::getLocalAddr");
    }
    InetAddress localAddr(local);
    // 根據(jù)連接成功的sockfd,創(chuàng)建TcpConnection
    TcpConnectionPtr conn(new TcpConnection(
                            ioLoop,
                            connName,
                            sockfd,   // Socket Channel
                            localAddr,
                            peerAddr));
    connections_[connName] = conn;
	// 下面的回調(diào)時(shí)用戶設(shè)置給TcpServer，TcpServer又設(shè)置給TcpConnection，TcpConnetion又設(shè)置給Channel，Channel又設(shè)置給Poller，Poller通知channel調(diào)用這個(gè)回調(diào)
    conn->setConnectionCallback(connectionCallback_);
    conn->setMessageCallback(messageCallback_);
    conn->setWriteCompleteCallback(writeCompleteCallback_);
    // 設(shè)置了如何關(guān)閉連接的回調(diào)
    conn->setCloseCallback(
        std::bind(&TcpServer::removeConnection, this, std::placeholders::_1)
    );
    // 直接調(diào)用connectEstablished
    ioLoop->runInLoop(std::bind(&TcpConnection::connectEstablished, conn));
}