Do not make snapshots for lone leave events

pubsub/v2.go

@@ -70,8 +70,9 @@ type V2AccountData struct {
 func (*V2AccountData) Type() string { return "V2AccountData" }
 
 type V2LeaveRoom struct {
-	UserID string
-	RoomID string
+	UserID     string
+	RoomID     string
+	LeaveEvent json.RawMessage
 }
 
 func (*V2LeaveRoom) Type() string { return "V2LeaveRoom" }

state/accumulator.go

@@ -293,7 +293,7 @@ func (a *Accumulator) Initialise(roomID string, state []json.RawMessage) (Initia
 //     to exist in the database, and the sync stream is already linearised for us.
 //   - Else it creates a new room state snapshot if the timeline contains state events (as this now represents the current state)
 //   - It adds entries to the membership log for membership events.
-func (a *Accumulator) Accumulate(txn *sqlx.Tx, roomID string, prevBatch string, timeline []json.RawMessage) (numNew int, timelineNIDs []int64, err error) {
+func (a *Accumulator) Accumulate(txn *sqlx.Tx, userID, roomID string, prevBatch string, timeline []json.RawMessage) (numNew int, timelineNIDs []int64, err error) {
 	// The first stage of accumulating events is mostly around validation around what the upstream HS sends us. For accumulation to work correctly
 	// we expect:
 	// - there to be no duplicate events
@@ -308,6 +308,33 @@ func (a *Accumulator) Accumulate(txn *sqlx.Tx, roomID string, prevBatch string,
 		return 0, nil, err // nothing to do
 	}
 
+	// Given a timeline of [E1, E2, S3, E4, S5, S6, E7] (E=message event, S=state event)
+	// And a prior state snapshot of SNAP0 then the BEFORE snapshot IDs are grouped as:
+	// E1,E2,S3 => SNAP0
+	// E4, S5 => (SNAP0 + S3)
+	// S6 => (SNAP0 + S3 + S5)
+	// E7 => (SNAP0 + S3 + S5 + S6)
+	// We can track this by loading the current snapshot ID (after snapshot) then rolling forward
+	// the timeline until we hit a state event, at which point we make a new snapshot but critically
+	// do NOT assign the new state event in the snapshot so as to represent the state before the event.
+	snapID, err := a.roomsTable.CurrentAfterSnapshotID(txn, roomID)
+	if err != nil {
+		return 0, nil, err
+	}
+
+	// if we have just got a leave event for the polling user, and there is no snapshot for this room already, then
+	// we do NOT want to add this event to the events table, nor do we want to make a room snapshot. This is because
+	// this leave event is an invite rejection, rather than a normal event. Invite rejections cannot be processed in
+	// a normal way because we lack room state (no create event, PLs, etc). If we were to process the invite rejection,
+	// the room state would just be a single event: this leave event, which is wrong.
+	if len(dedupedEvents) == 1 && dedupedEvents[0].Type == "m.room.member" && dedupedEvents[0].Membership == "leave" &&
+		dedupedEvents[0].StateKey == userID && snapID == 0 {
+		logger.Info().Str("event_id", dedupedEvents[0].ID).Str("room_id", roomID).Str("user_id", userID).Err(err).Msg(
+			"Accumulator: skipping processing of leave event, as no snapshot exists",
+		)
+		return 0, nil, nil
+	}
+
 	eventIDToNID, err := a.eventsTable.Insert(txn, dedupedEvents, false)
 	if err != nil {
 		return 0, nil, err
@@ -339,19 +366,6 @@ func (a *Accumulator) Accumulate(txn *sqlx.Tx, roomID string, prevBatch string,
 		}
 	}
 
-	// Given a timeline of [E1, E2, S3, E4, S5, S6, E7] (E=message event, S=state event)
-	// And a prior state snapshot of SNAP0 then the BEFORE snapshot IDs are grouped as:
-	// E1,E2,S3 => SNAP0
-	// E4, S5 => (SNAP0 + S3)
-	// S6 => (SNAP0 + S3 + S5)
-	// E7 => (SNAP0 + S3 + S5 + S6)
-	// We can track this by loading the current snapshot ID (after snapshot) then rolling forward
-	// the timeline until we hit a state event, at which point we make a new snapshot but critically
-	// do NOT assign the new state event in the snapshot so as to represent the state before the event.
-	snapID, err := a.roomsTable.CurrentAfterSnapshotID(txn, roomID)
-	if err != nil {
-		return 0, nil, err
-	}
 	for _, ev := range newEvents {
 		var replacesNID int64
 		// the snapshot ID we assign to this event is unaffected by whether /this/ event is state or not,

state/accumulator_test.go

@@ -14,6 +14,10 @@ import (
 	"github.com/tidwall/gjson"
 )
 
+var (
+	userID = "@me:localhost"
+)
+
 func TestAccumulatorInitialise(t *testing.T) {
 	roomID := "!TestAccumulatorInitialise:localhost"
 	roomEvents := []json.RawMessage{
@@ -118,7 +122,7 @@ func TestAccumulatorAccumulate(t *testing.T) {
 	var numNew int
 	var latestNIDs []int64
 	err = sqlutil.WithTransaction(accumulator.db, func(txn *sqlx.Tx) error {
-		numNew, latestNIDs, err = accumulator.Accumulate(txn, roomID, "", newEvents)
+		numNew, latestNIDs, err = accumulator.Accumulate(txn, userID, roomID, "", newEvents)
 		return err
 	})
 	if err != nil {
@@ -192,7 +196,7 @@ func TestAccumulatorAccumulate(t *testing.T) {
 
 	// subsequent calls do nothing and are not an error
 	err = sqlutil.WithTransaction(accumulator.db, func(txn *sqlx.Tx) error {
-		_, _, err = accumulator.Accumulate(txn, roomID, "", newEvents)
+		_, _, err = accumulator.Accumulate(txn, userID, roomID, "", newEvents)
 		return err
 	})
 	if err != nil {
@@ -228,7 +232,7 @@ func TestAccumulatorMembershipLogs(t *testing.T) {
 		[]byte(`{"event_id":"` + roomEventIDs[7] + `", "type":"m.room.member", "state_key":"@me:localhost","unsigned":{"prev_content":{"membership":"join", "displayname":"Me"}}, "content":{"membership":"leave"}}`),
 	}
 	err = sqlutil.WithTransaction(accumulator.db, func(txn *sqlx.Tx) error {
-		_, _, err = accumulator.Accumulate(txn, roomID, "", roomEvents)
+		_, _, err = accumulator.Accumulate(txn, userID, roomID, "", roomEvents)
 		return err
 	})
 	if err != nil {
@@ -355,7 +359,7 @@ func TestAccumulatorDupeEvents(t *testing.T) {
 	}
 
 	err = sqlutil.WithTransaction(accumulator.db, func(txn *sqlx.Tx) error {
-		_, _, err = accumulator.Accumulate(txn, roomID, "", joinRoom.Timeline.Events)
+		_, _, err = accumulator.Accumulate(txn, userID, roomID, "", joinRoom.Timeline.Events)
 		return err
 	})
 	if err != nil {
@@ -555,7 +559,7 @@ func TestAccumulatorConcurrency(t *testing.T) {
 			defer wg.Done()
 			subset := newEvents[:(i + 1)] // i=0 => [1], i=1 => [1,2], etc
 			err := sqlutil.WithTransaction(accumulator.db, func(txn *sqlx.Tx) error {
-				numNew, _, err := accumulator.Accumulate(txn, roomID, "", subset)
+				numNew, _, err := accumulator.Accumulate(txn, userID, roomID, "", subset)
 				totalNumNew += numNew
 				return err
 			})

state/storage.go

@@ -307,12 +307,12 @@ func (s *Storage) currentNotMembershipStateEventsInAllRooms(txn *sqlx.Tx, eventT
 	return result, nil
 }
 
-func (s *Storage) Accumulate(roomID, prevBatch string, timeline []json.RawMessage) (numNew int, timelineNIDs []int64, err error) {
+func (s *Storage) Accumulate(userID, roomID, prevBatch string, timeline []json.RawMessage) (numNew int, timelineNIDs []int64, err error) {
 	if len(timeline) == 0 {
 		return 0, nil, nil
 	}
 	err = sqlutil.WithTransaction(s.Accumulator.db, func(txn *sqlx.Tx) error {
-		numNew, timelineNIDs, err = s.Accumulator.Accumulate(txn, roomID, prevBatch, timeline)
+		numNew, timelineNIDs, err = s.Accumulator.Accumulate(txn, userID, roomID, prevBatch, timeline)
 		return err
 	})
 	return

state/storage_test.go

@@ -31,7 +31,7 @@ func TestStorageRoomStateBeforeAndAfterEventPosition(t *testing.T) {
 		testutils.NewStateEvent(t, "m.room.join_rules", "", alice, map[string]interface{}{"join_rule": "invite"}),
 		testutils.NewStateEvent(t, "m.room.member", bob, alice, map[string]interface{}{"membership": "invite"}),
 	}
-	_, latestNIDs, err := store.Accumulate(roomID, "", events)
+	_, latestNIDs, err := store.Accumulate(userID, roomID, "", events)
 	if err != nil {
 		t.Fatalf("Accumulate returned error: %s", err)
 	}
@@ -161,7 +161,7 @@ func TestStorageJoinedRoomsAfterPosition(t *testing.T) {
 	var latestNIDs []int64
 	var err error
 	for roomID, eventMap := range roomIDToEventMap {
-		_, latestNIDs, err = store.Accumulate(roomID, "", eventMap)
+		_, latestNIDs, err = store.Accumulate(userID, roomID, "", eventMap)
 		if err != nil {
 			t.Fatalf("Accumulate on %s failed: %s", roomID, err)
 		}
@@ -351,7 +351,7 @@ func TestVisibleEventNIDsBetween(t *testing.T) {
 		},
 	}
 	for _, tl := range timelineInjections {
-		numNew, _, err := store.Accumulate(tl.RoomID, "", tl.Events)
+		numNew, _, err := store.Accumulate(userID, tl.RoomID, "", tl.Events)
 		if err != nil {
 			t.Fatalf("Accumulate on %s failed: %s", tl.RoomID, err)
 		}
@@ -454,7 +454,7 @@ func TestVisibleEventNIDsBetween(t *testing.T) {
 		t.Fatalf("LatestEventNID: %s", err)
 	}
 	for _, tl := range timelineInjections {
-		numNew, _, err := store.Accumulate(tl.RoomID, "", tl.Events)
+		numNew, _, err := store.Accumulate(userID, tl.RoomID, "", tl.Events)
 		if err != nil {
 			t.Fatalf("Accumulate on %s failed: %s", tl.RoomID, err)
 		}
@@ -534,7 +534,7 @@ func TestStorageLatestEventsInRoomsPrevBatch(t *testing.T) {
 	}
 	eventIDs := []string{}
 	for _, timeline := range timelines {
-		_, _, err = store.Accumulate(roomID, timeline.prevBatch, timeline.timeline)
+		_, _, err = store.Accumulate(userID, roomID, timeline.prevBatch, timeline.timeline)
 		if err != nil {
 			t.Fatalf("failed to accumulate: %s", err)
 		}
@@ -776,7 +776,7 @@ func TestAllJoinedMembers(t *testing.T) {
 		}, serialise(tc.InitMemberships)...))
 		assertNoError(t, err)
 
-		_, _, err = store.Accumulate(roomID, "foo", serialise(tc.AccumulateMemberships))
+		_, _, err = store.Accumulate(userID, roomID, "foo", serialise(tc.AccumulateMemberships))
 		assertNoError(t, err)
 		testCases[i].RoomID = roomID // remember this for later
 	}

sync2/handler2/handler.go

@@ -259,7 +259,7 @@ func (h *Handler) Accumulate(ctx context.Context, userID, deviceID, roomID, prev
 	}
 
 	// Insert new events
-	numNew, latestNIDs, err := h.Store.Accumulate(roomID, prevBatch, timeline)
+	numNew, latestNIDs, err := h.Store.Accumulate(userID, roomID, prevBatch, timeline)
 	if err != nil {
 		logger.Err(err).Int("timeline", len(timeline)).Str("room", roomID).Msg("V2: failed to accumulate room")
 		internal.GetSentryHubFromContextOrDefault(ctx).CaptureException(err)
@@ -448,16 +448,18 @@ func (h *Handler) OnInvite(ctx context.Context, userID, roomID string, inviteSta
 	})
 }
 
-func (h *Handler) OnLeftRoom(ctx context.Context, userID, roomID string) {
+func (h *Handler) OnLeftRoom(ctx context.Context, userID, roomID string, leaveEv json.RawMessage) {
 	// remove any invites for this user if they are rejecting an invite
 	err := h.Store.InvitesTable.RemoveInvite(userID, roomID)
 	if err != nil {
 		logger.Err(err).Str("user", userID).Str("room", roomID).Msg("failed to retire invite")
 		internal.GetSentryHubFromContextOrDefault(ctx).CaptureException(err)
 	}
+
 	h.v2Pub.Notify(pubsub.ChanV2, &pubsub.V2LeaveRoom{
-		UserID: userID,
-		RoomID: roomID,
+		UserID:     userID,
+		RoomID:     roomID,
+		LeaveEvent: leaveEv,
 	})
 }
 

sync2/poller.go

@@ -51,7 +51,7 @@ type V2DataReceiver interface {
 	// Sent when there is a room in the `invite` section of the v2 response.
 	OnInvite(ctx context.Context, userID, roomID string, inviteState []json.RawMessage) // invitestate in db
 	// Sent when there is a room in the `leave` section of the v2 response.
-	OnLeftRoom(ctx context.Context, userID, roomID string)
+	OnLeftRoom(ctx context.Context, userID, roomID string, leaveEvent json.RawMessage)
 	// Sent when there is a _change_ in E2EE data, not all the time
 	OnE2EEData(ctx context.Context, userID, deviceID string, otkCounts map[string]int, fallbackKeyTypes []string, deviceListChanges map[string]int)
 	// Sent when the poll loop terminates
@@ -301,11 +301,11 @@ func (h *PollerMap) OnInvite(ctx context.Context, userID, roomID string, inviteS
 	wg.Wait()
 }
 
-func (h *PollerMap) OnLeftRoom(ctx context.Context, userID, roomID string) {
+func (h *PollerMap) OnLeftRoom(ctx context.Context, userID, roomID string, leaveEvent json.RawMessage) {
 	var wg sync.WaitGroup
 	wg.Add(1)
 	h.executor <- func() {
-		h.callbacks.OnLeftRoom(ctx, userID, roomID)
+		h.callbacks.OnLeftRoom(ctx, userID, roomID, leaveEvent)
 		wg.Done()
 	}
 	wg.Wait()
@@ -716,12 +716,23 @@ func (p *poller) parseRoomsResponse(ctx context.Context, res *SyncResponse) {
 		}
 	}
 	for roomID, roomData := range res.Rooms.Leave {
-		// TODO: do we care about state?
 		if len(roomData.Timeline.Events) > 0 {
 			p.trackTimelineSize(len(roomData.Timeline.Events), roomData.Timeline.Limited)
 			p.receiver.Accumulate(ctx, p.userID, p.deviceID, roomID, roomData.Timeline.PrevBatch, roomData.Timeline.Events)
 		}
-		p.receiver.OnLeftRoom(ctx, p.userID, roomID)
+		// Pass the leave event directly to OnLeftRoom. We need to do this _in addition_ to calling Accumulate to handle
+		// the case where a user rejects an invite (there will be no room state, but the user still expects to see the leave event).
+		var leaveEvent json.RawMessage
+		for _, ev := range roomData.Timeline.Events {
+			leaveEv := gjson.ParseBytes(ev)
+			if leaveEv.Get("content.membership").Str == "leave" && leaveEv.Get("state_key").Str == p.userID {
+				leaveEvent = ev
+				break
+			}
+		}
+		if leaveEvent != nil {
+			p.receiver.OnLeftRoom(ctx, p.userID, roomID, leaveEvent)
+		}
 	}
 	for roomID, roomData := range res.Rooms.Invite {
 		p.receiver.OnInvite(ctx, p.userID, roomID, roomData.InviteState.Events)

sync2/poller_test.go

@@ -617,7 +617,8 @@ func (s *mockDataReceiver) OnReceipt(ctx context.Context, userID, roomID, ephEve
 }
 func (s *mockDataReceiver) OnInvite(ctx context.Context, userID, roomID string, inviteState []json.RawMessage) {
 }
-func (s *mockDataReceiver) OnLeftRoom(ctx context.Context, userID, roomID string) {}
+func (s *mockDataReceiver) OnLeftRoom(ctx context.Context, userID, roomID string, leaveEvent json.RawMessage) {
+}
 func (s *mockDataReceiver) OnE2EEData(ctx context.Context, userID, deviceID string, otkCounts map[string]int, fallbackKeyTypes []string, deviceListChanges map[string]int) {
 }
 func (s *mockDataReceiver) OnTerminated(ctx context.Context, userID, deviceID string) {}

sync3/caches/global_test.go

@@ -38,12 +38,12 @@ func TestGlobalCacheLoadState(t *testing.T) {
 		testutils.NewStateEvent(t, "m.room.name", "", alice, map[string]interface{}{"name": "The Room Name"}),
 		testutils.NewStateEvent(t, "m.room.name", "", alice, map[string]interface{}{"name": "The Updated Room Name"}),
 	}
-	_, _, err := store.Accumulate(roomID2, "", eventsRoom2)
+	_, _, err := store.Accumulate(alice, roomID2, "", eventsRoom2)
 	if err != nil {
 		t.Fatalf("Accumulate: %s", err)
 	}
 
-	_, latestNIDs, err := store.Accumulate(roomID, "", events)
+	_, latestNIDs, err := store.Accumulate(alice, roomID, "", events)
 	if err != nil {
 		t.Fatalf("Accumulate: %s", err)
 	}

sync3/caches/update.go

@@ -38,15 +38,6 @@ func (u *InviteUpdate) Type() string {
 	return fmt.Sprintf("InviteUpdate[%s]", u.RoomID())
 }
 
-// LeftRoomUpdate corresponds to a key-value pair from a v2 sync's `leave` section.
-type LeftRoomUpdate struct {
-	RoomUpdate
-}
-
-func (u *LeftRoomUpdate) Type() string {
-	return fmt.Sprintf("LeftRoomUpdate[%s]", u.RoomID())
-}
-
 // TypingEdu corresponds to a typing EDU in the `ephemeral` section of a joined room's v2 sync resposne.
 type TypingUpdate struct {
 	RoomUpdate

sync3/caches/user.go

@@ -606,7 +606,7 @@ func (c *UserCache) OnInvite(ctx context.Context, roomID string, inviteStateEven
 	c.emitOnRoomUpdate(ctx, up)
 }
 
-func (c *UserCache) OnLeftRoom(ctx context.Context, roomID string) {
+func (c *UserCache) OnLeftRoom(ctx context.Context, roomID string, leaveEvent json.RawMessage) {
 	urd := c.LoadRoomData(roomID)
 	urd.IsInvite = false
 	urd.HasLeft = true
@@ -616,14 +616,29 @@ func (c *UserCache) OnLeftRoom(ctx context.Context, roomID string) {
 	c.roomToData[roomID] = urd
 	c.roomToDataMu.Unlock()
 
-	up := &LeftRoomUpdate{
+	ev := gjson.ParseBytes(leaveEvent)
+	stateKey := ev.Get("state_key").Str
+
+	up := &RoomEventUpdate{
 		RoomUpdate: &roomUpdateCache{
 			roomID: roomID,
 			// do NOT pull from the global cache as it is a snapshot of the room at the point of
 			// the invite: don't leak additional data!!!
 			globalRoomData: internal.NewRoomMetadata(roomID),
 			userRoomData:   &urd,
 		},
+		EventData: &EventData{
+			Event:     leaveEvent,
+			RoomID:    roomID,
+			EventType: ev.Get("type").Str,
+			StateKey:  &stateKey,
+			Content:   ev.Get("content"),
+			Timestamp: ev.Get("origin_server_ts").Uint(),
+			Sender:    ev.Get("sender").Str,
+			// if this is an invite rejection we need to make sure we tell the client, and not
+			// skip it because of the lack of a NID (this event may not be in the events table)
+			AlwaysProcess: true,
+		},
 	}
 	c.emitOnRoomUpdate(ctx, up)
 }

sync3/handler/connstate_live.go

@@ -181,11 +181,13 @@ func (s *connStateLive) processLiveUpdate(ctx context.Context, up caches.Update,
 		if roomEventUpdate != nil && roomEventUpdate.EventData.Event != nil {
 			r.NumLive++
 			advancedPastEvent := false
-			if roomEventUpdate.EventData.NID <= s.loadPositions[roomEventUpdate.RoomID()] {
-				// this update has been accounted for by the initial:true room snapshot
-				advancedPastEvent = true
+			if !roomEventUpdate.EventData.AlwaysProcess {
+				if roomEventUpdate.EventData.NID <= s.loadPositions[roomEventUpdate.RoomID()] {
+					// this update has been accounted for by the initial:true room snapshot
+					advancedPastEvent = true
+				}
+				s.loadPositions[roomEventUpdate.RoomID()] = roomEventUpdate.EventData.NID
 			}
-			s.loadPositions[roomEventUpdate.RoomID()] = roomEventUpdate.EventData.NID
 			// we only append to the timeline if we haven't already got this event. This can happen when:
 			// - 2 live events for a room mid-connection
 			// - next request bumps a room from outside to inside the window

sync3/handler/handler.go

@@ -317,7 +317,6 @@ func (h *SyncLiveHandler) serve(w http.ResponseWriter, req *http.Request) error
 // setupConnection associates this request with an existing connection or makes a new connection.
 // It also sets a v2 sync poll loop going if one didn't exist already for this user.
 // When this function returns, the connection is alive and active.
-
 func (h *SyncLiveHandler) setupConnection(req *http.Request, syncReq *sync3.Request, containsPos bool) (*sync3.Conn, *internal.HandlerError) {
 	taskCtx, task := internal.StartTask(req.Context(), "setupConnection")
 	defer task.End()
@@ -697,7 +696,7 @@ func (h *SyncLiveHandler) OnLeftRoom(p *pubsub.V2LeaveRoom) {
 	if !ok {
 		return
 	}
-	userCache.(*caches.UserCache).OnLeftRoom(ctx, p.RoomID)
+	userCache.(*caches.UserCache).OnLeftRoom(ctx, p.RoomID, p.LeaveEvent)
 }
 
 func (h *SyncLiveHandler) OnReceipt(p *pubsub.V2Receipt) {