Increased Network registry TTL. Routing Table remove is now delete.

Remove has been renamed to Delete to be more in line with the framework.

A bunch of comments have been added/updated for the future generations

We have increased the Network Registry TTL to 2 minutes.

router/default_router.go

@@ -103,7 +103,7 @@ func (r *router) Start() error {
 			Name:  route.Options().DestAddr,
 			Nodes: []*registry.Node{node},
 		}
-		if err := r.opts.NetworkRegistry.Register(service, registry.RegisterTTL(10*time.Second)); err != nil {
+		if err := r.opts.NetworkRegistry.Register(service, registry.RegisterTTL(120*time.Second)); err != nil {
 			return fmt.Errorf("failed to register service %s in network registry: %v", service.Name, err)
 		}
 	}
@@ -137,8 +137,8 @@ func (r *router) Start() error {
 }
 
 // addServiceRouteslists all available services in given registry and adds them to the routing table.
-// NOTE: this is a one-off operation done to bootstrap the rouing table of the new router when it starts.
-// It returns error if any of the routes could not be added to the routing table.
+// NOTE: this is a one-off operation done when bootstrapping the routing table of the new router.
+// It returns error if either the services could not be listed or if the routes could not be added to the routing table.
 func (r *router) addServiceRoutes(reg registry.Registry, network string, metric int) error {
 	services, err := reg.ListServices()
 	if err != nil {
@@ -160,11 +160,11 @@ func (r *router) addServiceRoutes(reg registry.Registry, network string, metric
 	return nil
 }
 
-// parseToNode parses router address into registryNode.
-// It retuns error if the router network address could not be parsed into service host and port.
-// NOTE: We use ":" as a default delimiter we split the network address on and then attempt to parse port into int.
+// parseToNode parses router into registry.Node and returns the result.
+// It returns error if the router network address could not be parsed into service host and port.
+// NOTE: We use ":" as the default delimiter when we split the network address.
 func (r *router) parseToNode() (*registry.Node, error) {
-	// split on ":" as a standard host:port delimiter
+	// split on ":" as a standard host/port delimiter
 	addr := strings.Split(r.opts.NetworkAddress, ":")
 	// try to parse network port into integer
 	port, err := strconv.Atoi(addr[1])
@@ -219,13 +219,17 @@ func (r *router) manageServiceRoutes(w registry.Watcher, network string, metric
 		switch res.Action {
 		case "create":
 			if len(res.Service.Nodes) > 0 {
+				/// only return error if the route is not duplicate, but something else has failed
 				if err := r.opts.Table.Add(route); err != nil && err != ErrDuplicateRoute {
 					return fmt.Errorf("failed to add route for service: %v", res.Service.Name)
 				}
 			}
 		case "delete":
-			if err := r.opts.Table.Remove(route); err != nil && err != ErrRouteNotFound {
-				return fmt.Errorf("failed to remove route for service: %v", res.Service.Name)
+			if len(res.Service.Nodes) <= 1 {
+				// only return error if the route is present in the table, but something else has failed
+				if err := r.opts.Table.Delete(route); err != nil && err != ErrRouteNotFound {
+					return fmt.Errorf("failed to delete route for service: %v", res.Service.Name)
+				}
 			}
 		}
 	}
@@ -233,7 +237,8 @@ func (r *router) manageServiceRoutes(w registry.Watcher, network string, metric
 	return watchErr
 }
 
-// watch routing table changes
+// watchTable watches routing table entries and either adds or deletes locally registered service to/from network registry
+// It returns error if the locally registered services either fails to be added/deleted to/from network registry.
 func (r *router) watchTable(w Watcher) error {
 	defer r.wg.Done()
 
@@ -270,22 +275,29 @@ func (r *router) watchTable(w Watcher) error {
 
 		switch res.Action {
 		case "add":
-			if err := r.opts.NetworkRegistry.Register(service, registry.RegisterTTL(10*time.Second)); err != nil {
+			// only register remotely if the service is "local"
+			if res.Route.Options().Network == "local" {
+				if err := r.opts.NetworkRegistry.Register(service, registry.RegisterTTL(120*time.Second)); err != nil {
 					return fmt.Errorf("failed to register service %s in network registry: %v", service.Name, err)
 				}
-		case "remove":
-			if err := r.opts.NetworkRegistry.Register(service); err != nil {
+			}
+		case "delete":
+			// only deregister remotely if the service is "local"
+			if res.Route.Options().Network == "local" {
+				if err := r.opts.NetworkRegistry.Deregister(service); err != nil {
 					return fmt.Errorf("failed to deregister service %s from network registry: %v", service.Name, err)
 				}
 			}
 		}
+	}
 
 	return watchErr
 }
 
 // Stop stops the router
 func (r *router) Stop() error {
-	// NOTE: we need a more efficient way of doing this e.g. network routes should be autoremoved when router stops gossiping
+	// NOTE: we need a more efficient way of doing this e.g. network routes
+	// should ideally be autodeleted when the router stops gossiping
 	// deregister all services advertised by this router from remote registry
 	query := NewQuery(QueryGateway(r), QueryNetwork(r.opts.NetworkAddress))
 	routes, err := r.opts.Table.Lookup(query)

router/default_table.go

@@ -70,6 +70,7 @@ func (t *table) Add(r Route) error {
 	t.Lock()
 	defer t.Unlock()
 
+	// check if the destination has any routes in the table
 	if _, ok := t.m[destAddr]; !ok {
 		t.m[destAddr] = make(map[uint64]Route)
 		t.m[destAddr][sum] = r
@@ -77,12 +78,15 @@ func (t *table) Add(r Route) error {
 		return nil
 	}
 
+	// only add the route if it exists and if override is requested
 	if _, ok := t.m[destAddr][sum]; ok && r.Options().Policy == OverrideIfExists {
 		t.m[destAddr][sum] = r
 		go t.sendResult(&Result{Action: "update", Route: r})
 		return nil
 	}
 
+	// if we reached this point without already returning the route already exists
+	// we return nil only if explicitly requested by the client
 	if r.Options().Policy == IgnoreIfExists {
 		return nil
 	}
@@ -90,8 +94,8 @@ func (t *table) Add(r Route) error {
 	return ErrDuplicateRoute
 }
 
-// Remove removes the route from the routing table
-func (t *table) Remove(r Route) error {
+// Delete deletes the route from the routing table
+func (t *table) Delete(r Route) error {
 	t.Lock()
 	defer t.Unlock()
 
@@ -103,7 +107,7 @@ func (t *table) Remove(r Route) error {
 	}
 
 	delete(t.m[destAddr], sum)
-	go t.sendResult(&Result{Action: "remove", Route: r})
+	go t.sendResult(&Result{Action: "delete", Route: r})
 
 	return nil
 }
@@ -116,10 +120,12 @@ func (t *table) Update(r Route) error {
 	t.Lock()
 	defer t.Unlock()
 
+	// check if the destAddr has ANY routes in the table
 	if _, ok := t.m[destAddr]; !ok {
 		return ErrRouteNotFound
 	}
 
+	// if the route has been found update it
 	if _, ok := t.m[destAddr][sum]; ok {
 		t.m[destAddr][sum] = r
 		go t.sendResult(&Result{Action: "update", Route: r})

router/table.go

@@ -19,8 +19,8 @@ type Table interface {
 	Options() TableOptions
 	// Add adds new route to the routing table
 	Add(Route) error
-	// Remove removes existing route from the routing table
-	Remove(Route) error
+	// Delete deletes existing route from the routing table
+	Delete(Route) error
 	// Update updates route in the routing table
 	Update(Route) error
 	// Lookup looks up routes in the routing table and returns them

router/table_watcher.go

@@ -23,7 +23,7 @@ type Watcher interface {
 
 // Result is returned by a call to Next on the watcher.
 type Result struct {
-	// Action is routing table action which is either of add, remove or update
+	// Action is routing table action which is either of add, delete or update
 	Action string
 	// Route is table rout
 	Route Route
@@ -58,8 +58,9 @@ type tableWatcher struct {
 	done    chan struct{}
 }
 
-// TODO: this needs to be thought through properly
 // Next returns the next noticed action taken on table
+// TODO: this needs to be thought through properly
+// we are aiming to provide the same watch options Query() provides
 func (w *tableWatcher) Next() (*Result, error) {
 	for {
 		select {
@@ -74,8 +75,6 @@ func (w *tableWatcher) Next() (*Result, error) {
 					return res, nil
 				}
 			}
-			// ignore if no match is found
-			continue
 		case <-w.done:
 			return nil, ErrWatcherStopped
 		}