Minor refactoring (#106)

- `s/Server/OutputRoomEvent/` in `consumers` to accurately reflect what is being consumed.
- `s/set/userIDSet/` in `notifier.go` for clarity.
- Removed lying comments.

src/github.com/matrix-org/dendrite/cmd/dendrite-sync-api-server/main.go

@@ -81,12 +81,12 @@ func main() {
 	if err := n.Load(db); err != nil {
 		log.Panicf("startup: failed to set up notifier: %s", err)
 	}
-	server, err := consumers.NewServer(cfg, n, db)
+	consumer, err := consumers.NewOutputRoomEvent(cfg, n, db)
 	if err != nil {
-		log.Panicf("startup: failed to create sync server: %s", err)
+		log.Panicf("startup: failed to create room server consumer: %s", err)
 	}
-	if err = server.Start(); err != nil {
-		log.Panicf("startup: failed to start sync server")
+	if err = consumer.Start(); err != nil {
+		log.Panicf("startup: failed to start room server consumer")
 	}
 
 	log.Info("Starting sync server on ", *bindAddr)

src/github.com/matrix-org/dendrite/syncapi/consumers/roomserver.go

@@ -28,15 +28,15 @@ import (
 	sarama "gopkg.in/Shopify/sarama.v1"
 )
 
-// Server contains all the logic for running a sync server
-type Server struct {
+// OutputRoomEvent consumes events that originated in the room server.
+type OutputRoomEvent struct {
 	roomServerConsumer *common.ContinualConsumer
 	db                 *storage.SyncServerDatabase
 	notifier           *sync.Notifier
 }
 
-// NewServer creates a new sync server. Call Start() to begin consuming from room servers.
-func NewServer(cfg *config.Sync, n *sync.Notifier, store *storage.SyncServerDatabase) (*Server, error) {
+// NewOutputRoomEvent creates a new OutputRoomEvent consumer. Call Start() to begin consuming from room servers.
+func NewOutputRoomEvent(cfg *config.Sync, n *sync.Notifier, store *storage.SyncServerDatabase) (*OutputRoomEvent, error) {
 	kafkaConsumer, err := sarama.NewConsumer(cfg.KafkaConsumerURIs, nil)
 	if err != nil {
 		return nil, err
@@ -47,7 +47,7 @@ func NewServer(cfg *config.Sync, n *sync.Notifier, store *storage.SyncServerData
 		Consumer:       kafkaConsumer,
 		PartitionStore: store,
 	}
-	s := &Server{
+	s := &OutputRoomEvent{
 		roomServerConsumer: &consumer,
 		db:                 store,
 		notifier:           n,
@@ -58,14 +58,14 @@ func NewServer(cfg *config.Sync, n *sync.Notifier, store *storage.SyncServerData
 }
 
 // Start consuming from room servers
-func (s *Server) Start() error {
+func (s *OutputRoomEvent) Start() error {
 	return s.roomServerConsumer.Start()
 }
 
 // onMessage is called when the sync server receives a new event from the room server output log.
 // It is not safe for this function to be called from multiple goroutines, or else the
 // sync stream position may race and be incorrectly calculated.
-func (s *Server) onMessage(msg *sarama.ConsumerMessage) error {
+func (s *OutputRoomEvent) onMessage(msg *sarama.ConsumerMessage) error {
 	// Parse out the event JSON
 	var output api.OutputRoomEvent
 	if err := json.Unmarshal(msg.Value, &output); err != nil {

src/github.com/matrix-org/dendrite/syncapi/sync/notifier.go

@@ -32,11 +32,10 @@ import (
 // in missed events.
 type Notifier struct {
 	// A map of RoomID => Set<UserID> : Must only be accessed by the OnNewEvent goroutine
-	roomIDToJoinedUsers map[string]set
+	roomIDToJoinedUsers map[string]userIDSet
 	// Protects currPos and userStreams.
 	streamLock *sync.Mutex
-	// The latest sync stream position: guarded by 'currPosMutex' which is RW to allow
-	// for concurrent reads on /sync requests
+	// The latest sync stream position
 	currPos types.StreamPosition
 	// A map of user_id => UserStream which can be used to wake a given user's /sync request.
 	userStreams map[string]*UserStream
@@ -44,11 +43,11 @@ type Notifier struct {
 
 // NewNotifier creates a new notifier set to the given stream position.
 // In order for this to be of any use, the Notifier needs to be told all rooms and
-// the joined users within each of them by calling Notifier.LoadFromDatabase().
+// the joined users within each of them by calling Notifier.Load(*storage.SyncServerDatabase).
 func NewNotifier(pos types.StreamPosition) *Notifier {
 	return &Notifier{
 		currPos:             pos,
-		roomIDToJoinedUsers: make(map[string]set),
+		roomIDToJoinedUsers: make(map[string]userIDSet),
 		userStreams:         make(map[string]*UserStream),
 		streamLock:          &sync.Mutex{},
 	}
@@ -142,7 +141,7 @@ func (n *Notifier) setUsersJoinedToRooms(roomIDToUserIDs map[string][]string) {
 	// This is just the bulk form of addJoinedUser
 	for roomID, userIDs := range roomIDToUserIDs {
 		if _, ok := n.roomIDToJoinedUsers[roomID]; !ok {
-			n.roomIDToJoinedUsers[roomID] = make(set)
+			n.roomIDToJoinedUsers[roomID] = make(userIDSet)
 		}
 		for _, userID := range userIDs {
 			n.roomIDToJoinedUsers[roomID].add(userID)
@@ -174,7 +173,7 @@ func (n *Notifier) fetchUserStream(userID string, makeIfNotExists bool) *UserStr
 // Not thread-safe: must be called on the OnNewEvent goroutine only
 func (n *Notifier) addJoinedUser(roomID, userID string) {
 	if _, ok := n.roomIDToJoinedUsers[roomID]; !ok {
-		n.roomIDToJoinedUsers[roomID] = make(set)
+		n.roomIDToJoinedUsers[roomID] = make(userIDSet)
 	}
 	n.roomIDToJoinedUsers[roomID].add(userID)
 }
@@ -182,7 +181,7 @@ func (n *Notifier) addJoinedUser(roomID, userID string) {
 // Not thread-safe: must be called on the OnNewEvent goroutine only
 func (n *Notifier) removeJoinedUser(roomID, userID string) {
 	if _, ok := n.roomIDToJoinedUsers[roomID]; !ok {
-		n.roomIDToJoinedUsers[roomID] = make(set)
+		n.roomIDToJoinedUsers[roomID] = make(userIDSet)
 	}
 	n.roomIDToJoinedUsers[roomID].remove(userID)
 }
@@ -196,17 +195,17 @@ func (n *Notifier) joinedUsers(roomID string) (userIDs []string) {
 }
 
 // A string set, mainly existing for improving clarity of structs in this file.
-type set map[string]bool
+type userIDSet map[string]bool
 
-func (s set) add(str string) {
+func (s userIDSet) add(str string) {
 	s[str] = true
 }
 
-func (s set) remove(str string) {
+func (s userIDSet) remove(str string) {
 	delete(s, str)
 }
 
-func (s set) values() (vals []string) {
+func (s userIDSet) values() (vals []string) {
 	for str := range s {
 		vals = append(vals, str)
 	}