Rip out d.latestPos from Dispatcher; it wasn't used

sync3/caches/global.go

@@ -75,7 +75,7 @@ func NewGlobalCache(store *state.Storage) *GlobalCache {
 	}
 }
 
-func (c *GlobalCache) OnRegistered(_ context.Context, _ int64) error {
+func (c *GlobalCache) OnRegistered(_ context.Context) error {
 	return nil
 }
 

sync3/caches/user.go

@@ -219,7 +219,7 @@ func (c *UserCache) Unsubscribe(id int) {
 // externally by sync3.SyncLiveHandler.userCache. It's importatn that we don't spend too
 // long inside this function, because it is called within a global lock on the
 // sync3.Dispatcher (see sync3.Dispatcher.Register).
-func (c *UserCache) OnRegistered(ctx context.Context, _ int64) error {
+func (c *UserCache) OnRegistered(ctx context.Context) error {
 	// select all spaces the user is a part of to seed the cache correctly. This has to be done in
 	// the OnRegistered callback which has locking guarantees. This is why...
 	latestPos, joinedRooms, joinTimings, err := c.globalCache.LoadJoinedRooms(ctx, c.UserID)

sync3/dispatcher.go

@@ -24,27 +24,22 @@ type Receiver interface {
 	OnNewEvent(ctx context.Context, event *caches.EventData)
 	OnReceipt(ctx context.Context, receipt internal.Receipt)
 	OnEphemeralEvent(ctx context.Context, roomID string, ephEvent json.RawMessage)
-	// OnRegistered is called after a successful call to Dispatcher.Register. After
-	// this call, the receiver will be told about events whose NID is greater than
-	// latestPos.
-	OnRegistered(ctx context.Context, latestPos int64) error
+	// OnRegistered is called after a successful call to Dispatcher.Register
+	OnRegistered(ctx context.Context) error
 }
 
 // Dispatches live events to caches
 type Dispatcher struct {
 	jrt              *JoinedRoomsTracker
 	userToReceiver   map[string]Receiver
 	userToReceiverMu *sync.RWMutex
-	// latestPos is an eventNID, the largest that this dispatcher has seen.
-	latestPos int64
 }
 
 func NewDispatcher() *Dispatcher {
 	return &Dispatcher{
 		jrt:              NewJoinedRoomsTracker(),
 		userToReceiver:   make(map[string]Receiver),
 		userToReceiverMu: &sync.RWMutex{},
-		latestPos:        0,
 	}
 }
 
@@ -73,7 +68,7 @@ func (d *Dispatcher) Register(ctx context.Context, userID string, r Receiver) er
 		logger.Warn().Str("user", userID).Msg("Dispatcher.Register: receiver already registered")
 	}
 	d.userToReceiver[userID] = r
-	return r.OnRegistered(ctx, d.latestPos)
+	return r.OnRegistered(ctx)
 }
 
 func (d *Dispatcher) ReceiverForUser(userID string) Receiver {
@@ -154,14 +149,9 @@ func (d *Dispatcher) OnNewInitialRoomState(ctx context.Context, roomID string, s
 }
 
 func (d *Dispatcher) OnNewEvent(
-	ctx context.Context, roomID string, event json.RawMessage, pos int64,
+	ctx context.Context, roomID string, event json.RawMessage, nid int64,
 ) {
-	// keep track of the latest position. We don't care about it, but Receivers do if they want
-	// to atomically load from the global cache and receive updates.
-	if pos > d.latestPos {
-		d.latestPos = pos
-	}
-	ed := d.newEventData(event, roomID, pos)
+	ed := d.newEventData(event, roomID, nid)
 
 	// update the tracker
 	targetUser := ""