Method lookup

balancer/rls/control_channel.go:197–219

lookup starts a RouteLookup RPC in a separate goroutine and returns the results (and error, if any) in the provided callback. The returned boolean indicates whether the request was throttled by the client-side adaptive throttling algorithm in which case the provided callback will not be invoked.

(reqKeys map[string]string, reason rlspb.RouteLookupRequest_Reason, staleHeaders string, cb lookupCallback)

// client-side adaptive throttling algorithm in which case the provided callback
// will not be invoked.
func (cc *controlChannel) lookup(reqKeys map[string]string, reason rlspb.RouteLookupRequest_Reason, staleHeaders string, cb lookupCallback) (throttled bool) {
	if cc.throttler.ShouldThrottle() {
		cc.logger.Infof("RLS request throttled by client-side adaptive throttling")
		return true
	}
	go func() {
		req := &rlspb.RouteLookupRequest{
			TargetType:      "grpc",
			KeyMap:          reqKeys,
			Reason:          reason,
			StaleHeaderData: staleHeaders,
		}
		if cc.logger.V(2) {
			cc.logger.Infof("Sending RLS request %+v", pretty.ToJSON(req))
		}

		ctx, cancel := context.WithTimeout(context.Background(), cc.rpcTimeout)
		defer cancel()
		resp, err := cc.client.RouteLookup(ctx, req)
		cb(resp.GetTargets(), resp.GetHeaderData(), err)
	}()
	return false
}