Add a separate payload for redacting state

So that we don't end up nuking conns unnecessarily.

pubsub/v2.go

@@ -25,6 +25,7 @@ type V2Listener interface {
 	OnDeviceMessages(p *V2DeviceMessages)
 	OnExpiredToken(p *V2ExpiredToken)
 	OnInvalidateRoom(p *V2InvalidateRoom)
+	OnStateRedaction(p *V2StateRedaction)
 }
 
 type V2Initialise struct {
@@ -130,7 +131,17 @@ type V2ExpiredToken struct {
 
 func (*V2ExpiredToken) Type() string { return "V2ExpiredToken" }
 
-// V2InvalidateRoom is emitted after a non-incremental state change to a room.
+// V2StateRedaction is emitted when a timeline is seen that contains one or more
+// redaction events targeting a piece of room state. The redaction will be emitted
+// before its corresponding V2Accumulate payload is emitted.
+type V2StateRedaction struct {
+	RoomID string
+}
+
+func (*V2StateRedaction) Type() string { return "V2StateRedaction" }
+
+// V2InvalidateRoom is emitted after a non-incremental state change to a room, in place
+// of a V2Initialise payload.
 type V2InvalidateRoom struct {
 	RoomID string
 }
@@ -183,6 +194,8 @@ func (v *V2Sub) onMessage(p Payload) {
 		v.receiver.OnExpiredToken(pl)
 	case *V2InvalidateRoom:
 		v.receiver.OnInvalidateRoom(pl)
+	case *V2StateRedaction:
+		v.receiver.OnStateRedaction(pl)
 	default:
 		logger.Warn().Str("type", p.Type()).Msg("V2Sub: unhandled payload type")
 	}

state/accumulator.go

@@ -326,10 +326,9 @@ type AccumulateResult struct {
 	// TimelineNIDs is the list of event nids seen in a sync v2 timeline. Some of these
 	// may already be known to the proxy.
 	TimelineNIDs []int64
-	// RequiresReload is set to true when we have accumulated a non-incremental state
-	// change (typically a redaction) that requires consumers to reload the room state
-	// from the latest snapshot.
-	RequiresReload bool
+	// IncludesStateRedaction is set to true when we have accumulated a redaction to a
+	// piece of room state.
+	IncludesStateRedaction bool
 }
 
 // Accumulate internal state from a user's sync response. The timeline order MUST be in the order
@@ -546,7 +545,7 @@ func (a *Accumulator) Accumulate(txn *sqlx.Tx, userID, roomID string, timeline s
 		if err != nil {
 			return AccumulateResult{}, err
 		}
-		result.RequiresReload = currentStateRedactions > 0
+		result.IncludesStateRedaction = currentStateRedactions > 0
 	}
 
 	if err = a.invitesTable.RemoveSupersededInvites(txn, roomID, postInsertEvents); err != nil {

state/accumulator_test.go

@@ -256,7 +256,7 @@ func TestAccumulatorPromptsCacheInvalidation(t *testing.T) {
 	t.Log("We expect 3 new events and no reload required.")
 	assertValue(t, "accResult.NumNew", accResult.NumNew, 3)
 	assertValue(t, "len(accResult.TimelineNIDs)", len(accResult.TimelineNIDs), 3)
-	assertValue(t, "accResult.RequiresReload", accResult.RequiresReload, false)
+	assertValue(t, "accResult.IncludesStateRedaction", accResult.IncludesStateRedaction, false)
 
 	t.Log("Redact the old state event and the message.")
 	timeline = []json.RawMessage{
@@ -274,7 +274,7 @@ func TestAccumulatorPromptsCacheInvalidation(t *testing.T) {
 	t.Log("We expect 2 new events and no reload required.")
 	assertValue(t, "accResult.NumNew", accResult.NumNew, 2)
 	assertValue(t, "len(accResult.TimelineNIDs)", len(accResult.TimelineNIDs), 2)
-	assertValue(t, "accResult.RequiresReload", accResult.RequiresReload, false)
+	assertValue(t, "accResult.IncludesStateRedaction", accResult.IncludesStateRedaction, false)
 
 	t.Log("Redact the latest state event.")
 	timeline = []json.RawMessage{
@@ -291,7 +291,7 @@ func TestAccumulatorPromptsCacheInvalidation(t *testing.T) {
 	t.Log("We expect 1 new event and a reload required.")
 	assertValue(t, "accResult.NumNew", accResult.NumNew, 1)
 	assertValue(t, "len(accResult.TimelineNIDs)", len(accResult.TimelineNIDs), 1)
-	assertValue(t, "accResult.RequiresReload", accResult.RequiresReload, true)
+	assertValue(t, "accResult.IncludesStateRedaction", accResult.IncludesStateRedaction, true)
 }
 
 func TestAccumulatorMembershipLogs(t *testing.T) {

sync2/handler2/handler.go

@@ -302,9 +302,9 @@ func (h *Handler) Accumulate(ctx context.Context, userID, deviceID, roomID strin
 		return err
 	}
 
-	// Consumers should reload state before processing new timeline events.
-	if accResult.RequiresReload {
-		h.v2Pub.Notify(pubsub.ChanV2, &pubsub.V2InvalidateRoom{
+	// Consumers should reload state content before processing new timeline events.
+	if accResult.IncludesStateRedaction {
+		h.v2Pub.Notify(pubsub.ChanV2, &pubsub.V2StateRedaction{
 			RoomID: roomID,
 		})
 	}

sync3/handler/handler.go

@@ -803,6 +803,14 @@ func (h *SyncLiveHandler) OnExpiredToken(p *pubsub.V2ExpiredToken) {
 	h.ConnMap.CloseConnsForDevice(p.UserID, p.DeviceID)
 }
 
+func (h *SyncLiveHandler) OnStateRedaction(p *pubsub.V2StateRedaction) {
+	// We only need to reload the global metadata here: mercifully, there isn't anything
+	// in the user cache that needs to be reloaded after state gets redacted.
+	ctx, task := internal.StartTask(context.Background(), "OnStateRedaction")
+	defer task.End()
+	h.GlobalCache.OnInvalidateRoom(ctx, p.RoomID)
+}
+
 func (h *SyncLiveHandler) OnInvalidateRoom(p *pubsub.V2InvalidateRoom) {
 	ctx, task := internal.StartTask(context.Background(), "OnInvalidateRoom")
 	defer task.End()