handy源码阅读（六）：tcp类

首先是tcpconn和tcpserver类：

struct TcpConn : public std::enable_shared_from_this<TcpConn>, private noncopyable {
  enum State {
    Invalid = 1,
    Handshaking,
    Connected,
    Closed,
    Failed,
  };
  TcpConn();
  virtual ~TcpConn();
  template <class C = TcpConn>
  static TcpConnPtr createConnection(EventBase* base, const std::string& host, unsigned short port, int timeout = 0, const std::string& localip = "") {
    TcpConnPtr con(new C);
    con->connect(base, host, port, timeout, localip);
    return con;
  }
  template <class C = TcpConn>
  static TcpConnPtr createConnection(EventBase* base, int fd, Ip4Addr local, Ip4Addr peer) {
    TcpConnPtr con(new C);
    con->attach(base, fd, local, peer);
    return con;
  }
  bool isClient() {
    return destPort_ > 0;
  }
  template <class T>
  T& context() {
    return ctx_.context<T>();
  }
  EventBase* getBase() {
    return base_;
  }
  State getState() {
    return state_;
  }
  Buffer& getInput() {
    return input_;
  }
  Buffer& getOutput() {
    return output_;
  }
  Channel* getChannel() {
    return channel_;
  }
  bool writable() {
    return channel_ ? channel_->writeEnabled() : false;
  }
  void sendOutput() {
    send(output_);
  }
  void send(Buffer& msg);
  void send(const char* buf, size_t len);
  void send(const std::string& s) {
    send(s.data(), s.size());
  }
  void send(const char* s) {
    send(s, strlen(s));
  }

  void onRead(const TcpCallBack& cb) {
    assert(!readcb_);
    readcb_ = cb;
  }
};

struct TcpServer : private noncopyable {
  TcpServer(EventBase* bases);
  int bind(const std::string& host, unsigned short port, bool reusePort = false);
  static TcpServerPtr startServer(EventBases* bases, const std::string& host, unsigned short port, bool reusePort = false);
  ~TcpServer() {
    delete listen_channel_;
  }
  Ip4Addr getAddr() {
    return addr_;
  }
  EventBase* getBase() {
    return base_;
  }
  void onConnCreate(const std::function<TcpConnPtr()>& cb) {
    createcb_ = cb;
  }
  void onConnRead(const TcpCallBack& cb) {
    readcb_ = cb;
    assert(!msgcb_);
  }

private：
  EventBase* base_;
  EventBases* bases_;
  Ip4Addr addr_;
  Channel* listen_channel_;
  TcpCallBack statecb_, readcb_;
  MsgCallBack msgcb_;
  std::function<TcpConnPtr()> createcb_;
  std::unique_ptr<CodecBase> codec_;
  void handleAccept();
};

tcp类和udp类实现很相似，除了在处理连接监听方式不同外，都是用epoll_wait来等待内核通知处理指定的文件描述符的事件。