C++ HTTP服务器返大图片给浏览器后出现撕裂和显示不完整

int TcpConnection::write(int *err) {

  size_t len = sender_.readable(); // 可发送数据大小

  int r_len = len;

  int n = -1;

  while (true) {

    n = ::write(connfd_, sender_.peek() + len - r_len, r_len); 



    if (n < 0) {

      *err = errno;

      return n;

    }

    sender_.retired(n);

    r_len -= n;

    if (r_len <= 0) {

      n = 0;

      sender_.retired_all(); // 重置读写指针

      break;

    }

  }

  return n;

}





void TcpServer::on_write(TcpConnectionPtr conn) {

  int err;

  int n = conn->write(&err);

  if (n == 0) {

    if (conn->keep_alive()) {

      if (conn->sender()->readable() == 0) {

        mod_fd(conn->fd(), EPOLLIN | kConnEvent);

      } else {

        mod_fd(conn->fd(), EPOLLOUT | kConnEvent);

      }

      return;

    }

  } else if (n < 0) {

    if (err == EAGAIN) {

      // Continue sending messages

      mod_fd(conn->fd(), EPOLLOUT | kConnEvent);

      return;

    }

  }

  handle_conn_close(conn);

}