Method updateState

balancer_wrapper.go:307–339

updateState is invoked by grpc to push a subConn state update to the underlying balancer.

(s connectivity.State, err error)

// updateState is invoked by grpc to push a subConn state update to the
// underlying balancer.
func (acbw *acBalancerWrapper) updateState(s connectivity.State, err error) {
	acbw.ccb.serializer.TrySchedule(func(ctx context.Context) {
		if ctx.Err() != nil || acbw.ccb.balancer == nil {
			return
		}
		// Invalidate all producers on any state change.
		acbw.closeProducers()

		// Even though it is optional for balancers, gracefulswitch ensures
		// opts.StateListener is set, so this cannot ever be nil.
		// TODO: delete this comment when UpdateSubConnState is removed.
		scs := balancer.SubConnState{ConnectivityState: s, ConnectionError: err}
		// Invalidate the health listener by updating the healthData.
		acbw.healthMu.Lock()
		// A race may occur if a health listener is registered soon after the
		// connectivity state is set but before the stateListener is called.
		// Two cases may arise:
		// 1. The new state is not READY: RegisterHealthListener has checks to
		//    ensure no updates are sent when the connectivity state is not
		//    READY.
		// 2. The new state is READY: This means that the old state wasn't Ready.
		//    The RegisterHealthListener API mentions that a health listener
		//    must not be registered when a SubConn is not ready to avoid such
		//    races. When this happens, the LB policy would get health updates
		//    on the old listener. When the LB policy registers a new listener
		//    on receiving the connectivity update, the health updates will be
		//    sent to the new health listener.
		acbw.healthData = newHealthData(scs.ConnectivityState)
		acbw.healthMu.Unlock()

		acbw.stateListener(scs)
	})
}

func (acbw *acBalancerWrapper) String() string {
	return fmt.Sprintf("SubConn(id:%d)", acbw.ac.channelz.ID)