Add router advertisement Strategy option to router.

router/default.go

@@ -319,23 +319,13 @@ func (r *router) advertiseTable() error {
 	for {
 		select {
 		case <-ticker.C:
-			// list routing table routes to announce
-			routes, err := r.table.List()
+			// do full table flush
+			events, err := r.flushRouteEvents(Update)
 			if err != nil {
-				return fmt.Errorf("failed listing routes: %s", err)
-			}
-			// collect all the added routes before we attempt to add default gateway
-			events := make([]*Event, len(routes))
-			for i, route := range routes {
-				event := &Event{
-					Type:      Update,
-					Timestamp: time.Now(),
-					Route:     route,
-				}
-				events[i] = event
+				return fmt.Errorf("failed flushing routes: %s", err)
 			}
 
-			// advertise all routes as Update events to subscribers
+			// advertise routes to subscribers
 			if len(events) > 0 {
 				log.Debugf("Router flushing table with %d events: %s", len(events), r.options.Id)
 				r.advertWg.Add(1)
@@ -692,6 +682,9 @@ func (r *router) flushRouteEvents(evType EventType) ([]*Event, error) {
 		return nil, fmt.Errorf("failed listing routes: %s", err)
 	}
 
+	// TODO: flush the routes based on strategy here
+	// - collapse the routes per service-metric-locality (prefer your routes)
+
 	// build a list of events to advertise
 	events := make([]*Event, len(routes))
 	for i, route := range routes {

router/options.go

@@ -18,6 +18,8 @@ type Options struct {
 	Network string
 	// Registry is the local registry
 	Registry registry.Registry
+	// Advertise is the advertising strategy
+	Advertise Strategy
 	// Client for calling router
 	Client client.Client
 }
@@ -64,6 +66,13 @@ func Registry(r registry.Registry) Option {
 	}
 }
 
+// Strategy sets route advertising strategy
+func Advertise(a Strategy) Option {
+	return func(o *Options) {
+		o.Advertise = a
+	}
+}
+
 // DefaultOptions returns router default options
 func DefaultOptions() Options {
 	return Options{

router/router.go

@@ -139,6 +139,16 @@ type Advert struct {
 	Events []*Event
 }
 
+// Strategy is route advertisement strategy
+type Strategy int
+
+const (
+	// All advertises all routes to the network
+	All Strategy = iota
+	// Optimal advertises optimal routes to the network
+	Optimal
+)
+
 // NewRouter creates new Router and returns it
 func NewRouter(opts ...Option) Router {
 	return newRouter(opts...)