Correctly handle discovery cleanup

Author: cmaglie

arduino/discovery/discovery.go

@@ -274,10 +274,7 @@ func (disc *PluggableDiscovery) killProcess() error {
 	}
 	disc.statusMutex.Lock()
 	defer disc.statusMutex.Unlock()
-	if disc.eventChan != nil {
-		close(disc.eventChan)
-		disc.eventChan = nil
-	}
+	disc.stopSync()
 	disc.state = Dead
 	logrus.Infof("killed discovery %s process", disc.id)
 	return nil
@@ -364,13 +361,18 @@ func (disc *PluggableDiscovery) Stop() error {
 	}
 	disc.statusMutex.Lock()
 	defer disc.statusMutex.Unlock()
-	disc.cachedPorts = map[string]*Port{}
+	disc.stopSync()
+	disc.state = Idling
+	return nil
+}
+
+func (disc *PluggableDiscovery) stopSync() {
 	if disc.eventChan != nil {
+		disc.eventChan <- &Event{"stop", nil, disc.GetID()}
 		close(disc.eventChan)
 		disc.eventChan = nil
+		disc.cachedPorts = map[string]*Port{}
 	}
-	disc.state = Idling
-	return nil
 }
 
 // Quit terminates the discovery. No more commands can be accepted by the discovery.
@@ -424,12 +426,8 @@ func (disc *PluggableDiscovery) StartSync(size int) (<-chan *Event, error) {
 	disc.statusMutex.Lock()
 	defer disc.statusMutex.Unlock()
 	disc.state = Syncing
-	disc.cachedPorts = map[string]*Port{}
-	if disc.eventChan != nil {
-		// In case there is already an existing event channel in use we close it
-		// before creating a new one.
-		close(disc.eventChan)
-	}
+	// In case there is already an existing event channel in use we close it before creating a new one.
+	disc.stopSync()
 	c := make(chan *Event, size)
 	disc.eventChan = c
 	return c, nil

arduino/discovery/discoverymanager/discoverymanager.go

@@ -52,12 +52,15 @@ func New() *DiscoveryManager {
 // Clear resets the DiscoveryManager to its initial state
 func (dm *DiscoveryManager) Clear() {
 	dm.discoveriesMutex.Lock()
-	for _, d := range dm.discoveries {
-		d.Quit()
-		logrus.Infof("Closed and removed discovery %s", d.GetID())
+	defer dm.discoveriesMutex.Unlock()
+
+	if dm.discoveriesRunning {
+		for _, d := range dm.discoveries {
+			d.Quit()
+			logrus.Infof("Closed and removed discovery %s", d.GetID())
+		}
 	}
 	dm.discoveries = map[string]*discovery.PluggableDiscovery{}
-	dm.discoveriesMutex.Unlock()
 }
 
 // IDs returns the list of discoveries' ids in this DiscoveryManager
@@ -211,6 +214,9 @@ func (dm *DiscoveryManager) cacheEvent(ev *discovery.Event) {
 		cache[eventID] = ev
 	case "remove":
 		delete(cache, eventID)
+	case "quit":
+		// Remove all the events for this discovery
+		delete(dm.watchersCache, ev.DiscoveryID)
 	default:
 		logrus.Errorf("Unhandled event from discovery: %s", ev.Type)
 		return