Method updateClientConnState

balancer_wrapper.go:111–139

updateClientConnState is invoked by grpc to push a ClientConnState update to the underlying balancer. This is always executed from the serializer, so it is safe to call into the balancer here.

(ccs *balancer.ClientConnState)

// the underlying balancer.  This is always executed from the serializer, so
// it is safe to call into the balancer here.
func (ccb *ccBalancerWrapper) updateClientConnState(ccs *balancer.ClientConnState) error {
	errCh := make(chan error)
	uccs := func(ctx context.Context) {
		defer close(errCh)
		if ctx.Err() != nil || ccb.balancer == nil {
			return
		}
		name := gracefulswitch.ChildName(ccs.BalancerConfig)
		if ccb.curBalancerName != name {
			ccb.curBalancerName = name
			channelz.Infof(logger, ccb.cc.channelz, "Channel switches to new LB policy %q", name)
		}
		err := ccb.balancer.UpdateClientConnState(*ccs)
		if logger.V(2) && err != nil {
			logger.Infof("error from balancer.UpdateClientConnState: %v", err)
		}
		errCh <- err
	}
	onFailure := func() { close(errCh) }

	// UpdateClientConnState can race with Close, and when the latter wins, the
	// serializer is closed, and the attempt to schedule the callback will fail.
	// It is acceptable to ignore this failure. But since we want to handle the
	// state update in a blocking fashion (when we successfully schedule the
	// callback), we have to use the ScheduleOr method and not the MaybeSchedule
	// method on the serializer.
	ccb.serializer.ScheduleOr(uccs, onFailure)
	return <-errCh
}

// resolverError is invoked by grpc to push a resolver error to the underlying
// balancer.  The call to the balancer is executed from the serializer.