Method SocketThread

mlx/distributed/ring/ring.cpp:130–134

class SocketThread {
 public:
  SocketThread(int fd) : fd_(fd), stop_(false) {
    worker_ = std::thread(&SocketThread::worker, this);
    int flags = fcntl(fd, F_GETFL, 0);
    fcntl(fd, F_SETFL, flags | O_NONBLOCK);
  }
  ~SocketThread() {
    stop_ = true;
    condition_.notify_all();