Method StreamMembership

dgraph/cmd/zero/zero.go:834–864

StreamMembership periodically streams the membership state to the given stream.

(_ *api.Payload, stream pb.Zero_StreamMembershipServer)

// StreamMembership periodically streams the membership state to the given stream.
func (s *Server) StreamMembership(_ *api.Payload, stream pb.Zero_StreamMembershipServer) error {
	// Send MembershipState right away. So, the connection is correctly established.
	ctx := stream.Context()
	ms, err := s.latestMembershipState(ctx)
	if err != nil {
		return err
	}
	if err := stream.Send(ms); err != nil {
		return err
	}

	ticker := time.Tick(time.Second)

	for {
		select {
		case <-ticker:
			// Send an update every second.
			ms, err := s.latestMembershipState(ctx)
			if err != nil {
				return err
			}
			if err := stream.Send(ms); err != nil {
				return err
			}
		case <-ctx.Done():
			return ctx.Err()
		case <-s.closer.HasBeenClosed():
			return errServerShutDown
		}
	}
}

func (s *Server) latestMembershipState(ctx context.Context) (*pb.MembershipState, error) {
	if err := s.Node.WaitLinearizableRead(ctx); err != nil {