Method registerHandle

src/windows/libwinio.cpp:397–426

NOTE: The following functions use `int_fd` instead of the native Win32 `HANDLE`, because they are the more "public" libwinio APIs that interface directly with the libprocess IO, socket and event loop code.

// `HANDLE`, because they are the more "public" libwinio APIs that interface
// directly with the libprocess IO, socket and event loop code.
Try<Nothing> EventLoop::registerHandle(const int_fd& fd)
{
  Try<HANDLE> assigned_handle = fd.assign_iocp(iocp_handle_.get(), KEY_IO);
  if (assigned_handle.isError()) {
    return Error(assigned_handle.error());
  }

  // In this case, the IOCP handle was already assigned. So, we check if the
  // right one is assigned.
  if (assigned_handle.get() != nullptr) {
    if (assigned_handle.get() != iocp_handle_.get()) {
      return Error(
          "fd is already registered to a different Windows Event Loop");
    }
    return Nothing();
  }

  // This is the first time the handle was assigned. We continue the
  // initialization. These are some optimizations that prevent IOCP
  // notifications on success and event notifications, so that we have less
  // context switches.
  BOOL success = ::SetFileCompletionNotificationModes(
      fd, FILE_SKIP_COMPLETION_PORT_ON_SUCCESS | FILE_SKIP_SET_EVENT_ON_HANDLE);

  if (!success) {
    return WindowsError();
  }

  return Nothing();
}


template <typename T, typename O>