From 75871287a1e3f37492296efc599ad401a1a5454d Mon Sep 17 00:00:00 2001
From: Milos Gajdos <milosgajdos83@gmail.com>
Date: Wed, 21 Aug 2019 21:10:42 +0100
Subject: [PATCH] Make stop idempotent. Small refactoring. Router name is
 memory.

---
 router/default.go | 93 ++++++++++++++++++++++++-----------------------
 1 file changed, 47 insertions(+), 46 deletions(-)

diff --git a/router/default.go b/router/default.go
index a6aa4f70..bf3f0e60 100644
--- a/router/default.go
+++ b/router/default.go
@@ -181,10 +181,6 @@ func (r *router) manageRegistryRoutes(reg registry.Registry, action string) erro
 // 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 {
-	// wait in the background for the router to stop
-	// when the router stops, stop the watcher and exit
-	r.wg.Add(1)
-
 	exit := make(chan bool)
 
 	defer func() {
@@ -193,6 +189,9 @@ func (r *router) watchRegistry(w registry.Watcher) error {
 		r.wg.Done()
 	}()
 
+	// wait in the background for the router to stop
+	// when the router stops, stop the watcher and exit
+	r.wg.Add(1)
 	go func() {
 		defer w.Stop()
 
@@ -226,9 +225,6 @@ func (r *router) watchRegistry(w registry.Watcher) error {
 // 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 {
-	// wait in the background for the router to stop
-	// when the router stops, stop the watcher and exit
-	r.wg.Add(1)
 	exit := make(chan bool)
 
 	defer func() {
@@ -237,6 +233,9 @@ func (r *router) watchTable(w Watcher) error {
 		r.wg.Done()
 	}()
 
+	// wait in the background for the router to stop
+	// when the router stops, stop the watcher and exit
+	r.wg.Add(1)
 	go func() {
 		defer w.Stop()
 
@@ -471,12 +470,38 @@ func (r *router) advertiseEvents() error {
 	}
 }
 
+// close closes exit channels
+func (r *router) close() {
+	// notify all goroutines to finish
+	close(r.exit)
+
+	// drain the advertise channel only if advertising
+	if r.status.Code == Advertising {
+		// drain the event channel
+		for range r.eventChan {
+		}
+
+		// close advert subscribers
+		for id, sub := range r.subscribers {
+			// close the channel
+			close(sub)
+
+			// delete the subscriber
+			delete(r.subscribers, id)
+		}
+	}
+
+	// mark the router as Stopped and set its Error to nil
+	r.status = Status{Code: Stopped, Error: nil}
+}
+
 // watchErrors watches router errors and takes appropriate actions
 func (r *router) watchErrors() {
 	var err error
 
 	select {
 	case <-r.exit:
+		return
 	case err = <-r.errChan:
 	}
 
@@ -484,22 +509,12 @@ func (r *router) watchErrors() {
 	defer r.Unlock()
 	// if the router is not stopped, stop it
 	if r.status.Code != Stopped {
-		// notify all goroutines to finish
-		close(r.exit)
-
-		// drain the advertise channel only if the router is advertising
-		if r.status.Code == Advertising {
-			// drain the event channel
-			for range r.eventChan {
-			}
+		// close all the channels
+		r.close()
+		// set the status error
+		if err != nil {
+			r.status.Error = err
 		}
-
-		// mark the router as Stopped and set its Error to nil
-		r.status = Status{Code: Stopped, Error: nil}
-	}
-
-	if err != nil {
-		r.status = Status{Code: Error, Error: err}
 	}
 }
 
@@ -665,10 +680,12 @@ func (r *router) Process(a *Advert) error {
 	return nil
 }
 
+// Lookup routes in the routing table
 func (r *router) Lookup(q Query) ([]Route, error) {
 	return r.table.Query(q)
 }
 
+// Watch routes
 func (r *router) Watch(opts ...WatchOption) (Watcher, error) {
 	return r.table.Watch(opts...)
 }
@@ -687,31 +704,15 @@ func (r *router) Status() Status {
 // Stop stops the router
 func (r *router) Stop() error {
 	r.Lock()
-	// only close the channel if the router is running and/or advertising
-	if r.status.Code == Running || r.status.Code == Advertising {
-		// notify all goroutines to finish
-		close(r.exit)
+	defer r.Unlock()
 
-		// drain the advertise channel only if advertising
-		if r.status.Code == Advertising {
-			// drain the event channel
-			for range r.eventChan {
-			}
-		}
-
-		// close advert subscribers
-		for id, sub := range r.subscribers {
-			// close the channel
-			close(sub)
-
-			// delete the subscriber
-			delete(r.subscribers, id)
-		}
-
-		// mark the router as Stopped and set its Error to nil
-		r.status = Status{Code: Stopped, Error: nil}
+	switch r.status.Code {
+	case Stopped, Error:
+		return r.status.Error
+	case Running, Advertising:
+		// close all the channels
+		r.close()
 	}
-	r.Unlock()
 
 	// wait for all goroutines to finish
 	r.wg.Wait()
@@ -721,5 +722,5 @@ func (r *router) Stop() error {
 
 // String prints debugging information about router
 func (r *router) String() string {
-	return "mucp"
+	return "memory"
 }