package router import ( "errors" "fmt" "sort" "strings" "sync" "time" "github.com/google/uuid" "github.com/micro/go-micro/v2/logger" "github.com/micro/go-micro/v2/registry" ) var ( // AdvertiseEventsTick is time interval in which the router advertises route updates AdvertiseEventsTick = 10 * time.Second // DefaultAdvertTTL is default advertisement TTL DefaultAdvertTTL = 2 * time.Minute ) // router implements default router type router struct { sync.RWMutex running bool table *table options Options exit chan bool eventChan chan *Event // advert subscribers sub sync.RWMutex subscribers map[string]chan *Advert } // newRouter creates new router and returns it func newRouter(opts ...Option) Router { // get default options options := DefaultOptions() // apply requested options for _, o := range opts { o(&options) } // construct the router r := &router{ options: options, subscribers: make(map[string]chan *Advert), } // create the new table, passing the fetchRoute method in as a fallback if // the table doesn't contain the result for a query. r.table = newTable(r.fetchRoutes) // start the router and return r.start() return r } // Init initializes router with given options func (r *router) Init(opts ...Option) error { // stop the router before we initialize if err := r.Close(); err != nil { return err } r.Lock() defer r.Unlock() for _, o := range opts { o(&r.options) } // restart the router if err := r.start(); err != nil { return err } return nil } // Options returns router options func (r *router) Options() Options { r.RLock() defer r.RUnlock() options := r.options return options } // Table returns routing table func (r *router) Table() Table { return r.table } // manageRoute applies action on a given route func (r *router) manageRoute(route Route, action string) error { switch action { case "create": if err := r.table.Create(route); err != nil && err != ErrDuplicateRoute { return fmt.Errorf("failed adding route for service %s: %s", route.Service, err) } case "delete": if err := r.table.Delete(route); err != nil && err != ErrRouteNotFound { return fmt.Errorf("failed deleting route for service %s: %s", route.Service, err) } case "update": if err := r.table.Update(route); err != nil { return fmt.Errorf("failed updating route for service %s: %s", route.Service, err) } default: return fmt.Errorf("failed to manage route for service %s: unknown action %s", route.Service, action) } return nil } // manageServiceRoutes applies action to all routes of the service. // It returns error of the action fails with error. func (r *router) manageRoutes(service *registry.Service, action, network string) error { // action is the routing table action action = strings.ToLower(action) // take route action on each service node for _, node := range service.Nodes { route := Route{ Service: service.Name, Address: node.Address, Gateway: "", Network: network, Router: r.options.Id, Link: DefaultLink, Metric: DefaultLocalMetric, Metadata: service.Metadata, } if err := r.manageRoute(route, action); err != nil { return err } } return nil } // manageRegistryRoutes applies action to all routes of each service found in the registry. // It returns error if either the services failed to be listed or the routing table action fails. func (r *router) manageRegistryRoutes(reg registry.Registry, action string) error { services, err := reg.ListServices(registry.ListDomain(registry.WildcardDomain)) if err != nil { return fmt.Errorf("failed listing services: %v", err) } // add each service node as a separate route for _, service := range services { // get the services domain from metadata. Fallback to wildcard. var domain string if service.Metadata != nil && len(service.Metadata["domain"]) > 0 { domain = service.Metadata["domain"] } else { domain = registry.WildcardDomain } // get the service to retrieve all its info srvs, err := reg.GetService(service.Name, registry.GetDomain(domain)) if err != nil { continue } // manage the routes for all returned services for _, srv := range srvs { if err := r.manageRoutes(srv, action, domain); err != nil { return err } } } return nil } // fetchRoutes retrieves all the routes for a given service and creates them in the routing table func (r *router) fetchRoutes(service string) error { services, err := r.options.Registry.GetService(service, registry.GetDomain(registry.WildcardDomain)) if err != nil { return fmt.Errorf("failed getting services: %v", err) } for _, srv := range services { var domain string if srv.Metadata != nil && len(srv.Metadata["domain"]) > 0 { domain = srv.Metadata["domain"] } else { domain = registry.WildcardDomain } if err := r.manageRoutes(srv, "create", domain); err != nil { return err } } return nil } // watchRegistry watches registry and updates routing table based on the received events. // It returns error if either the registry watcher fails with error or if the routing table update fails. func (r *router) watchRegistry(w registry.Watcher) error { exit := make(chan bool) defer func() { close(exit) }() go func() { defer w.Stop() select { case <-exit: return case <-r.exit: return } }() for { res, err := w.Next() if err != nil { if err != registry.ErrWatcherStopped { return err } break } if res.Service == nil { continue } // get the services domain from metadata. Fallback to wildcard. var domain string if res.Service.Metadata != nil && len(res.Service.Metadata["domain"]) > 0 { domain = res.Service.Metadata["domain"] } else { domain = registry.WildcardDomain } if err := r.manageRoutes(res.Service, res.Action, domain); err != nil { return err } } return nil } // 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 { exit := make(chan bool) defer func() { close(exit) }() // wait in the background for the router to stop // when the router stops, stop the watcher and exit go func() { defer w.Stop() select { case <-r.exit: return case <-exit: return } }() for { event, err := w.Next() if err != nil { if err != ErrWatcherStopped { return err } break } select { case <-r.exit: return nil case r.eventChan <- event: // process event } } return nil } // publishAdvert publishes router advert to advert channel func (r *router) publishAdvert(advType AdvertType, events []*Event) { a := &Advert{ Id: r.options.Id, Type: advType, TTL: DefaultAdvertTTL, Timestamp: time.Now(), Events: events, } r.sub.RLock() for _, sub := range r.subscribers { // now send the message select { case sub <- a: case <-r.exit: r.sub.RUnlock() return } } r.sub.RUnlock() } // adverts maintains a map of router adverts type adverts map[uint64]*Event // advertiseEvents advertises routing table events // It suppresses unhealthy flapping events and advertises healthy events upstream. func (r *router) advertiseEvents() error { // ticker to periodically scan event for advertising ticker := time.NewTicker(AdvertiseEventsTick) defer ticker.Stop() // adverts is a map of advert events adverts := make(adverts) // routing table watcher w, err := r.Watch() if err != nil { return err } defer w.Stop() go func() { var err error for { select { case <-r.exit: return default: if w == nil { // routing table watcher w, err = r.Watch() if err != nil { if logger.V(logger.ErrorLevel, logger.DefaultLogger) { logger.Errorf("Error creating watcher: %v", err) } time.Sleep(time.Second) continue } } if err := r.watchTable(w); err != nil { if logger.V(logger.ErrorLevel, logger.DefaultLogger) { logger.Errorf("Error watching table: %v", err) } time.Sleep(time.Second) } if w != nil { // reset w.Stop() w = nil } } } }() for { select { case <-ticker.C: // If we're not advertising any events then sip processing them entirely if r.options.Advertise == AdvertiseNone { continue } var events []*Event // collect all events which are not flapping for key, event := range adverts { // if we only advertise local routes skip processing anything not link local if r.options.Advertise == AdvertiseLocal && event.Route.Link != "local" { continue } // copy the event and append e := new(Event) // this is ok, because router.Event only contains builtin types // and no references so this creates a deep copy of struct Event *e = *event events = append(events, e) // delete the advert from adverts delete(adverts, key) } // advertise events to subscribers if len(events) > 0 { if logger.V(logger.DebugLevel, logger.DefaultLogger) { logger.Debugf("Router publishing %d events", len(events)) } go r.publishAdvert(RouteUpdate, events) } case e := <-r.eventChan: // if event is nil, continue if e == nil { continue } // If we're not advertising any events then skip processing them entirely if r.options.Advertise == AdvertiseNone { continue } // if we only advertise local routes skip processing anything not link local if r.options.Advertise == AdvertiseLocal && e.Route.Link != "local" { continue } if logger.V(logger.DebugLevel, logger.DefaultLogger) { logger.Debugf("Router processing table event %s for service %s %s", e.Type, e.Route.Service, e.Route.Address) } // check if we have already registered the route hash := e.Route.Hash() ev, ok := adverts[hash] if !ok { ev = e adverts[hash] = e continue } // override the route event only if the previous event was different if ev.Type != e.Type { ev = e } case <-r.exit: if w != nil { w.Stop() } return nil } } } // drain all the events, only called on Stop func (r *router) drain() { for { select { case <-r.eventChan: default: return } } } // start the router. Should be called under lock. func (r *router) start() error { if r.running { return nil } if r.options.Prewarm { // add all local service routes into the routing table if err := r.manageRegistryRoutes(r.options.Registry, "create"); err != nil { return fmt.Errorf("failed adding registry routes: %s", err) } } // add default gateway into routing table if r.options.Gateway != "" { // note, the only non-default value is the gateway route := Route{ Service: "*", Address: "*", Gateway: r.options.Gateway, Network: "*", Router: r.options.Id, Link: DefaultLink, Metric: DefaultLocalMetric, } if err := r.table.Create(route); err != nil { return fmt.Errorf("failed adding default gateway route: %s", err) } } // create error and exit channels r.exit = make(chan bool) // registry watcher w, err := r.options.Registry.Watch(registry.WatchDomain(registry.WildcardDomain)) if err != nil { return fmt.Errorf("failed creating registry watcher: %v", err) } go func() { var err error for { select { case <-r.exit: if w != nil { w.Stop() } return default: if w == nil { w, err = r.options.Registry.Watch() if err != nil { if logger.V(logger.ErrorLevel, logger.DefaultLogger) { logger.Errorf("failed creating registry watcher: %v", err) } time.Sleep(time.Second) continue } } if err := r.watchRegistry(w); err != nil { if logger.V(logger.ErrorLevel, logger.DefaultLogger) { logger.Errorf("Error watching the registry: %v", err) } time.Sleep(time.Second) } if w != nil { w.Stop() w = nil } } } }() r.running = true return nil } // Advertise stars advertising the routes to the network and returns the advertisements channel to consume from. // If the router is already advertising it returns the channel to consume from. // It returns error if either the router is not running or if the routing table fails to list the routes to advertise. func (r *router) Advertise() (<-chan *Advert, error) { r.Lock() defer r.Unlock() if !r.running { return nil, errors.New("not running") } // we're mutating the subscribers so they need to be locked also r.sub.Lock() defer r.sub.Unlock() // already advertising if r.eventChan != nil { advertChan := make(chan *Advert, 128) r.subscribers[uuid.New().String()] = advertChan return advertChan, nil } // list all the routes and pack them into even slice to advertise events, err := r.flushRouteEvents(Create) if err != nil { return nil, fmt.Errorf("failed to flush routes: %s", err) } // create event channels r.eventChan = make(chan *Event) // create advert channel advertChan := make(chan *Advert, 128) r.subscribers[uuid.New().String()] = advertChan // advertise your presence go r.publishAdvert(Announce, events) go func() { select { case <-r.exit: return default: if err := r.advertiseEvents(); err != nil { if logger.V(logger.ErrorLevel, logger.DefaultLogger) { logger.Errorf("Error adveritising events: %v", err) } } } }() return advertChan, nil } // Process updates the routing table using the advertised values func (r *router) Process(a *Advert) error { // NOTE: event sorting might not be necessary // copy update events intp new slices events := make([]*Event, len(a.Events)) copy(events, a.Events) // sort events by timestamp sort.Slice(events, func(i, j int) bool { return events[i].Timestamp.Before(events[j].Timestamp) }) if logger.V(logger.TraceLevel, logger.DefaultLogger) { logger.Tracef("Router %s processing advert from: %s", r.options.Id, a.Id) } for _, event := range events { // skip if the router is the origin of this route if event.Route.Router == r.options.Id { if logger.V(logger.TraceLevel, logger.DefaultLogger) { logger.Tracef("Router skipping processing its own route: %s", r.options.Id) } continue } // create a copy of the route route := event.Route action := event.Type if logger.V(logger.TraceLevel, logger.DefaultLogger) { logger.Tracef("Router %s applying %s from router %s for service %s %s", r.options.Id, action, route.Router, route.Service, route.Address) } if err := r.manageRoute(route, action.String()); err != nil { return fmt.Errorf("failed applying action %s to routing table: %s", action, err) } } return nil } // flushRouteEvents returns a slice of events, one per each route in the routing table func (r *router) flushRouteEvents(evType EventType) ([]*Event, error) { // get a list of routes for each service in our routing table // for the configured advertising strategy q := []QueryOption{ QueryStrategy(r.options.Advertise), } routes, err := r.Table().Query(q...) if err != nil && err != ErrRouteNotFound { return nil, err } if logger.V(logger.DebugLevel, logger.DefaultLogger) { logger.Debugf("Router advertising %d routes with strategy %s", len(routes), r.options.Advertise) } // build a list of events to advertise events := make([]*Event, len(routes)) var i int for _, route := range routes { event := &Event{ Type: evType, Timestamp: time.Now(), Route: route, } events[i] = event i++ } return events, nil } // Lookup routes in the routing table func (r *router) Lookup(q ...QueryOption) ([]Route, error) { return r.table.Query(q...) } // Watch routes func (r *router) Watch(opts ...WatchOption) (Watcher, error) { return r.table.Watch(opts...) } // Close the router func (r *router) Close() error { r.Lock() defer r.Unlock() select { case <-r.exit: return nil default: close(r.exit) // extract the events r.drain() r.sub.Lock() // close advert subscribers for id, sub := range r.subscribers { // close the channel close(sub) // delete the subscriber delete(r.subscribers, id) } r.sub.Unlock() } // close and remove event chan if r.eventChan != nil { close(r.eventChan) r.eventChan = nil } r.running = false return nil } // String prints debugging information about router func (r *router) String() string { return "registry" }