Add support for logs in StreamingToken (#1229)

* Add support for logs in StreamingToken

Tokens now end up looking like `s11_22|dl-0-123|ab-0-12224`
where `dl` and `ab` are log names, `0` is the partition and
`123` and `12224` are the offsets.

* Also test reserialisation

* s/|/./g so tokens url escape nicely

12 files changed, 189 insertions, 55 deletions

diff --git a/syncapi/consumers/clientapi.go b/syncapi/consumers/clientapi.go
index ad6290e3..f7cf96d9 100644
--- a/syncapi/consumers/clientapi.go
+++ b/syncapi/consumers/clientapi.go
@@ -91,7 +91,7 @@ func (s *OutputClientDataConsumer) onMessage(msg *sarama.ConsumerMessage) error
 		}).Panicf("could not save account data")
 	}
 
-	s.notifier.OnNewEvent(nil, "", []string{string(msg.Key)}, types.NewStreamToken(pduPos, 0))
+	s.notifier.OnNewEvent(nil, "", []string{string(msg.Key)}, types.NewStreamToken(pduPos, 0, nil))
 
 	return nil
 }
diff --git a/syncapi/consumers/eduserver_sendtodevice.go b/syncapi/consumers/eduserver_sendtodevice.go
index 48701803..06a8928d 100644
--- a/syncapi/consumers/eduserver_sendtodevice.go
+++ b/syncapi/consumers/eduserver_sendtodevice.go
@@ -106,7 +106,7 @@ func (s *OutputSendToDeviceEventConsumer) onMessage(msg *sarama.ConsumerMessage)
 	s.notifier.OnNewSendToDevice(
 		output.UserID,
 		[]string{output.DeviceID},
-		types.NewStreamToken(0, streamPos),
+		types.NewStreamToken(0, streamPos, nil),
 	)
 
 	return nil
diff --git a/syncapi/consumers/eduserver_typing.go b/syncapi/consumers/eduserver_typing.go
index 12b1efbc..0a9a9c0c 100644
--- a/syncapi/consumers/eduserver_typing.go
+++ b/syncapi/consumers/eduserver_typing.go
@@ -65,7 +65,7 @@ func (s *OutputTypingEventConsumer) Start() error {
 	s.db.SetTypingTimeoutCallback(func(userID, roomID string, latestSyncPosition int64) {
 		s.notifier.OnNewEvent(
 			nil, roomID, nil,
-			types.NewStreamToken(0, types.StreamPosition(latestSyncPosition)),
+			types.NewStreamToken(0, types.StreamPosition(latestSyncPosition), nil),
 		)
 	})
 
@@ -94,6 +94,6 @@ func (s *OutputTypingEventConsumer) onMessage(msg *sarama.ConsumerMessage) error
 		typingPos = s.db.RemoveTypingUser(typingEvent.UserID, typingEvent.RoomID)
 	}
 
-	s.notifier.OnNewEvent(nil, output.Event.RoomID, nil, types.NewStreamToken(0, typingPos))
+	s.notifier.OnNewEvent(nil, output.Event.RoomID, nil, types.NewStreamToken(0, typingPos, nil))
 	return nil
 }
diff --git a/syncapi/consumers/keychange_test.go b/syncapi/consumers/keychange_test.go
index f8e96570..3ecb3f58 100644
--- a/syncapi/consumers/keychange_test.go
+++ b/syncapi/consumers/keychange_test.go
@@ -14,6 +14,7 @@ import (
 
 var (
 	syncingUser = "@alice:localhost"
+	emptyToken  = types.NewStreamToken(0, 0, nil)
 )
 
 type mockKeyAPI struct{}
@@ -167,7 +168,7 @@ func TestKeyChangeCatchupOnJoinShareNewUser(t *testing.T) {
 	syncResponse := types.NewResponse()
 	syncResponse = joinResponseWithRooms(syncResponse, syncingUser, []string{newlyJoinedRoom})
 
-	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, types.NewStreamToken(0, 0))
+	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, emptyToken)
 	if err != nil {
 		t.Fatalf("Catchup returned an error: %s", err)
 	}
@@ -190,7 +191,7 @@ func TestKeyChangeCatchupOnLeaveShareLeftUser(t *testing.T) {
 	syncResponse := types.NewResponse()
 	syncResponse = leaveResponseWithRooms(syncResponse, syncingUser, []string{newlyLeftRoom})
 
-	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, types.NewStreamToken(0, 0))
+	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, emptyToken)
 	if err != nil {
 		t.Fatalf("Catchup returned an error: %s", err)
 	}
@@ -213,7 +214,7 @@ func TestKeyChangeCatchupOnJoinShareNoNewUsers(t *testing.T) {
 	syncResponse := types.NewResponse()
 	syncResponse = joinResponseWithRooms(syncResponse, syncingUser, []string{newlyJoinedRoom})
 
-	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, types.NewStreamToken(0, 0))
+	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, emptyToken)
 	if err != nil {
 		t.Fatalf("Catchup returned an error: %s", err)
 	}
@@ -235,7 +236,7 @@ func TestKeyChangeCatchupOnLeaveShareNoUsers(t *testing.T) {
 	syncResponse := types.NewResponse()
 	syncResponse = leaveResponseWithRooms(syncResponse, syncingUser, []string{newlyLeftRoom})
 
-	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, types.NewStreamToken(0, 0))
+	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, emptyToken)
 	if err != nil {
 		t.Fatalf("Catchup returned an error: %s", err)
 	}
@@ -294,7 +295,7 @@ func TestKeyChangeCatchupNoNewJoinsButMessages(t *testing.T) {
 	jr.Timeline.Events = roomTimelineEvents
 	syncResponse.Rooms.Join[roomID] = jr
 
-	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, types.NewStreamToken(0, 0))
+	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, emptyToken)
 	if err != nil {
 		t.Fatalf("Catchup returned an error: %s", err)
 	}
@@ -322,7 +323,7 @@ func TestKeyChangeCatchupChangeAndLeft(t *testing.T) {
 	syncResponse = joinResponseWithRooms(syncResponse, syncingUser, []string{newlyJoinedRoom})
 	syncResponse = leaveResponseWithRooms(syncResponse, syncingUser, []string{newlyLeftRoom})
 
-	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, types.NewStreamToken(0, 0))
+	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, emptyToken)
 	if err != nil {
 		t.Fatalf("Catchup returned an error: %s", err)
 	}
@@ -407,7 +408,7 @@ func TestKeyChangeCatchupChangeAndLeftSameRoom(t *testing.T) {
 	lr.Timeline.Events = roomEvents
 	syncResponse.Rooms.Leave[roomID] = lr
 
-	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, types.NewStreamToken(0, 0))
+	_, hasNew, err := consumer.Catchup(context.Background(), syncingUser, syncResponse, emptyToken)
 	if err != nil {
 		t.Fatalf("Catchup returned an error: %s", err)
 	}
diff --git a/syncapi/consumers/roomserver.go b/syncapi/consumers/roomserver.go
index c6502716..da4a5366 100644
--- a/syncapi/consumers/roomserver.go
+++ b/syncapi/consumers/roomserver.go
@@ -158,7 +158,7 @@ func (s *OutputRoomEventConsumer) onNewRoomEvent(
 		}).Panicf("roomserver output log: write event failure")
 		return nil
 	}
-	s.notifier.OnNewEvent(&ev, "", nil, types.NewStreamToken(pduPos, 0))
+	s.notifier.OnNewEvent(&ev, "", nil, types.NewStreamToken(pduPos, 0, nil))
 
 	return nil
 }
@@ -176,7 +176,7 @@ func (s *OutputRoomEventConsumer) onNewInviteEvent(
 		}).Panicf("roomserver output log: write invite failure")
 		return nil
 	}
-	s.notifier.OnNewEvent(&msg.Event, "", nil, types.NewStreamToken(pduPos, 0))
+	s.notifier.OnNewEvent(&msg.Event, "", nil, types.NewStreamToken(pduPos, 0, nil))
 	return nil
 }
 
@@ -194,7 +194,7 @@ func (s *OutputRoomEventConsumer) onRetireInviteEvent(
 	}
 	// Notify any active sync requests that the invite has been retired.
 	// Invites share the same stream counter as PDUs
-	s.notifier.OnNewEvent(nil, "", []string{msg.TargetUserID}, types.NewStreamToken(sp, 0))
+	s.notifier.OnNewEvent(nil, "", []string{msg.TargetUserID}, types.NewStreamToken(sp, 0, nil))
 	return nil
 }
 
diff --git a/syncapi/storage/shared/syncserver.go b/syncapi/storage/shared/syncserver.go
index e1312671..dd5b838c 100644
--- a/syncapi/storage/shared/syncserver.go
+++ b/syncapi/storage/shared/syncserver.go
@@ -434,7 +434,7 @@ func (d *Database) syncPositionTx(
 	if maxInviteID > maxEventID {
 		maxEventID = maxInviteID
 	}
-	sp = types.NewStreamToken(types.StreamPosition(maxEventID), types.StreamPosition(d.EDUCache.GetLatestSyncPosition()))
+	sp = types.NewStreamToken(types.StreamPosition(maxEventID), types.StreamPosition(d.EDUCache.GetLatestSyncPosition()), nil)
 	return
 }
 
@@ -731,7 +731,7 @@ func (d *Database) CompleteSync(
 
 	// Use a zero value SyncPosition for fromPos so all EDU states are added.
 	err = d.addEDUDeltaToResponse(
-		types.NewStreamToken(0, 0), toPos, joinedRoomIDs, res,
+		types.NewStreamToken(0, 0, nil), toPos, joinedRoomIDs, res,
 	)
 	if err != nil {
 		return nil, err
diff --git a/syncapi/storage/storage_test.go b/syncapi/storage/storage_test.go
index 474d3222..1f679def 100644
--- a/syncapi/storage/storage_test.go
+++ b/syncapi/storage/storage_test.go
@@ -163,7 +163,7 @@ func TestSyncResponse(t *testing.T) {
 			Name: "IncrementalSync penultimate",
 			DoSync: func() (*types.Response, error) {
 				from := types.NewStreamToken( // pretend we are at the penultimate event
-					positions[len(positions)-2], types.StreamPosition(0),
+					positions[len(positions)-2], types.StreamPosition(0), nil,
 				)
 				res := types.NewResponse()
 				return db.IncrementalSync(ctx, res, testUserDeviceA, from, latest, 5, false)
@@ -176,7 +176,7 @@ func TestSyncResponse(t *testing.T) {
 			Name: "IncrementalSync limited",
 			DoSync: func() (*types.Response, error) {
 				from := types.NewStreamToken( // pretend we are 10 events behind
-					positions[len(positions)-11], types.StreamPosition(0),
+					positions[len(positions)-11], types.StreamPosition(0), nil,
 				)
 				res := types.NewResponse()
 				// limit is set to 5
@@ -219,7 +219,7 @@ func TestSyncResponse(t *testing.T) {
 			if err != nil {
 				st.Fatalf("failed to do sync: %s", err)
 			}
-			next := types.NewStreamToken(latest.PDUPosition(), latest.EDUPosition())
+			next := types.NewStreamToken(latest.PDUPosition(), latest.EDUPosition(), nil)
 			if res.NextBatch != next.String() {
 				st.Errorf("NextBatch got %s want %s", res.NextBatch, next.String())
 			}
@@ -243,7 +243,7 @@ func TestGetEventsInRangeWithPrevBatch(t *testing.T) {
 		t.Fatalf("failed to get SyncPosition: %s", err)
 	}
 	from := types.NewStreamToken(
-		positions[len(positions)-2], types.StreamPosition(0),
+		positions[len(positions)-2], types.StreamPosition(0), nil,
 	)
 
 	res := types.NewResponse()
@@ -288,7 +288,7 @@ func TestGetEventsInRangeWithStreamToken(t *testing.T) {
 		t.Fatalf("failed to get SyncPosition: %s", err)
 	}
 	// head towards the beginning of time
-	to := types.NewStreamToken(0, 0)
+	to := types.NewStreamToken(0, 0, nil)
 
 	// backpaginate 5 messages starting at the latest position.
 	paginatedEvents, err := db.GetEventsInStreamingRange(ctx, &latest, &to, testRoomID, 5, true)
@@ -531,14 +531,14 @@ func TestSendToDeviceBehaviour(t *testing.T) {
 
 	// At this point there should be no messages. We haven't sent anything
 	// yet.
-	events, updates, deletions, err := db.SendToDeviceUpdatesForSync(ctx, "alice", "one", types.NewStreamToken(0, 0))
+	events, updates, deletions, err := db.SendToDeviceUpdatesForSync(ctx, "alice", "one", types.NewStreamToken(0, 0, nil))
 	if err != nil {
 		t.Fatal(err)
 	}
 	if len(events) != 0 || len(updates) != 0 || len(deletions) != 0 {
 		t.Fatal("first call should have no updates")
 	}
-	err = db.CleanSendToDeviceUpdates(context.Background(), updates, deletions, types.NewStreamToken(0, 0))
+	err = db.CleanSendToDeviceUpdates(context.Background(), updates, deletions, types.NewStreamToken(0, 0, nil))
 	if err != nil {
 		return
 	}
@@ -556,14 +556,14 @@ func TestSendToDeviceBehaviour(t *testing.T) {
 	// At this point we should get exactly one message. We're sending the sync position
 	// that we were given from the update and the send-to-device update will be updated
 	// in the database to reflect that this was the sync position we sent the message at.
-	events, updates, deletions, err = db.SendToDeviceUpdatesForSync(ctx, "alice", "one", types.NewStreamToken(0, streamPos))
+	events, updates, deletions, err = db.SendToDeviceUpdatesForSync(ctx, "alice", "one", types.NewStreamToken(0, streamPos, nil))
 	if err != nil {
 		t.Fatal(err)
 	}
 	if len(events) != 1 || len(updates) != 1 || len(deletions) != 0 {
 		t.Fatal("second call should have one update")
 	}
-	err = db.CleanSendToDeviceUpdates(context.Background(), updates, deletions, types.NewStreamToken(0, streamPos))
+	err = db.CleanSendToDeviceUpdates(context.Background(), updates, deletions, types.NewStreamToken(0, streamPos, nil))
 	if err != nil {
 		return
 	}
@@ -571,35 +571,35 @@ func TestSendToDeviceBehaviour(t *testing.T) {
 	// At this point we should still have one message because we haven't progressed the
 	// sync position yet. This is equivalent to the client failing to /sync and retrying
 	// with the same position.
-	events, updates, deletions, err = db.SendToDeviceUpdatesForSync(ctx, "alice", "one", types.NewStreamToken(0, streamPos))
+	events, updates, deletions, err = db.SendToDeviceUpdatesForSync(ctx, "alice", "one", types.NewStreamToken(0, streamPos, nil))
 	if err != nil {
 		t.Fatal(err)
 	}
 	if len(events) != 1 || len(updates) != 0 || len(deletions) != 0 {
 		t.Fatal("third call should have one update still")
 	}
-	err = db.CleanSendToDeviceUpdates(context.Background(), updates, deletions, types.NewStreamToken(0, streamPos))
+	err = db.CleanSendToDeviceUpdates(context.Background(), updates, deletions, types.NewStreamToken(0, streamPos, nil))
 	if err != nil {
 		return
 	}
 
 	// At this point we should now have no updates, because we've progressed the sync
 	// position. Therefore the update from before will not be sent again.
-	events, updates, deletions, err = db.SendToDeviceUpdatesForSync(ctx, "alice", "one", types.NewStreamToken(0, streamPos+1))
+	events, updates, deletions, err = db.SendToDeviceUpdatesForSync(ctx, "alice", "one", types.NewStreamToken(0, streamPos+1, nil))
 	if err != nil {
 		t.Fatal(err)
 	}
 	if len(events) != 0 || len(updates) != 0 || len(deletions) != 1 {
 		t.Fatal("fourth call should have no updates")
 	}
-	err = db.CleanSendToDeviceUpdates(context.Background(), updates, deletions, types.NewStreamToken(0, streamPos+1))
+	err = db.CleanSendToDeviceUpdates(context.Background(), updates, deletions, types.NewStreamToken(0, streamPos+1, nil))
 	if err != nil {
 		return
 	}
 
 	// At this point we should still have no updates, because no new updates have been
 	// sent.
-	events, updates, deletions, err = db.SendToDeviceUpdatesForSync(ctx, "alice", "one", types.NewStreamToken(0, streamPos+2))
+	events, updates, deletions, err = db.SendToDeviceUpdatesForSync(ctx, "alice", "one", types.NewStreamToken(0, streamPos+2, nil))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -636,7 +636,7 @@ func TestInviteBehaviour(t *testing.T) {
 	}
 	// both invite events should appear in a new sync
 	beforeRetireRes := types.NewResponse()
-	beforeRetireRes, err = db.IncrementalSync(ctx, beforeRetireRes, testUserDeviceA, types.NewStreamToken(0, 0), latest, 0, false)
+	beforeRetireRes, err = db.IncrementalSync(ctx, beforeRetireRes, testUserDeviceA, types.NewStreamToken(0, 0, nil), latest, 0, false)
 	if err != nil {
 		t.Fatalf("IncrementalSync failed: %s", err)
 	}
@@ -651,7 +651,7 @@ func TestInviteBehaviour(t *testing.T) {
 		t.Fatalf("failed to get SyncPosition: %s", err)
 	}
 	res := types.NewResponse()
-	res, err = db.IncrementalSync(ctx, res, testUserDeviceA, types.NewStreamToken(0, 0), latest, 0, false)
+	res, err = db.IncrementalSync(ctx, res, testUserDeviceA, types.NewStreamToken(0, 0, nil), latest, 0, false)
 	if err != nil {
 		t.Fatalf("IncrementalSync failed: %s", err)
 	}
diff --git a/syncapi/sync/notifier_test.go b/syncapi/sync/notifier_test.go
index f2a368ec..5a4c7b31 100644
--- a/syncapi/sync/notifier_test.go
+++ b/syncapi/sync/notifier_test.go
@@ -32,11 +32,11 @@ var (
 	randomMessageEvent  gomatrixserverlib.HeaderedEvent
 	aliceInviteBobEvent gomatrixserverlib.HeaderedEvent
 	bobLeaveEvent       gomatrixserverlib.HeaderedEvent
-	syncPositionVeryOld = types.NewStreamToken(5, 0)
-	syncPositionBefore  = types.NewStreamToken(11, 0)
-	syncPositionAfter   = types.NewStreamToken(12, 0)
-	syncPositionNewEDU  = types.NewStreamToken(syncPositionAfter.PDUPosition(), 1)
-	syncPositionAfter2  = types.NewStreamToken(13, 0)
+	syncPositionVeryOld = types.NewStreamToken(5, 0, nil)
+	syncPositionBefore  = types.NewStreamToken(11, 0, nil)
+	syncPositionAfter   = types.NewStreamToken(12, 0, nil)
+	syncPositionNewEDU  = types.NewStreamToken(syncPositionAfter.PDUPosition(), 1, nil)
+	syncPositionAfter2  = types.NewStreamToken(13, 0, nil)
 )
 
 var (
diff --git a/syncapi/sync/request.go b/syncapi/sync/request.go
index 41b18aa1..0996729e 100644
--- a/syncapi/sync/request.go
+++ b/syncapi/sync/request.go
@@ -65,7 +65,7 @@ func newSyncRequest(req *http.Request, device userapi.Device, syncDB storage.Dat
 		since = &tok
 	}
 	if since == nil {
-		tok := types.NewStreamToken(0, 0)
+		tok := types.NewStreamToken(0, 0, nil)
 		since = &tok
 	}
 	timelineLimit := DefaultTimelineLimit
diff --git a/syncapi/sync/requestpool.go b/syncapi/sync/requestpool.go
index 196d446a..bf6a9e01 100644
--- a/syncapi/sync/requestpool.go
+++ b/syncapi/sync/requestpool.go
@@ -138,7 +138,7 @@ func (rp *RequestPool) OnIncomingSyncRequest(req *http.Request, device *userapi.
 func (rp *RequestPool) currentSyncForUser(req syncRequest, latestPos types.StreamingToken) (res *types.Response, err error) {
 	res = types.NewResponse()
 
-	since := types.NewStreamToken(0, 0)
+	since := types.NewStreamToken(0, 0, nil)
 	if req.since != nil {
 		since = *req.since
 	}
diff --git a/syncapi/types/types.go b/syncapi/types/types.go
index 7dc02281..7bba8e52 100644
--- a/syncapi/types/types.go
+++ b/syncapi/types/types.go
@@ -39,6 +39,23 @@ var (
 // StreamPosition represents the offset in the sync stream a client is at.
 type StreamPosition int64
 
+// LogPosition represents the offset in a Kafka log a client is at.
+type LogPosition struct {
+	Partition int32
+	Offset    int64
+}
+
+// IsAfter returns true if this position is after `lp`.
+func (p *LogPosition) IsAfter(lp *LogPosition) bool {
+	if lp == nil {
+		return false
+	}
+	if p.Partition != lp.Partition {
+		return false
+	}
+	return p.Offset > lp.Offset
+}
+
 // StreamEvent is the same as gomatrixserverlib.Event but also has the PDU stream position for this event.
 type StreamEvent struct {
 	gomatrixserverlib.HeaderedEvent
@@ -90,6 +107,15 @@ const (
 
 type StreamingToken struct {
 	syncToken
+	logs map[string]*LogPosition
+}
+
+func (t *StreamingToken) Log(name string) *LogPosition {
+	l, ok := t.logs[name]
+	if !ok {
+		return nil
+	}
+	return l
 }
 
 func (t *StreamingToken) PDUPosition() StreamPosition {
@@ -99,7 +125,15 @@ func (t *StreamingToken) EDUPosition() StreamPosition {
 	return t.Positions[1]
 }
 func (t *StreamingToken) String() string {
-	return t.syncToken.String()
+	logStrings := []string{
+		t.syncToken.String(),
+	}
+	for name, lp := range t.logs {
+		logStr := fmt.Sprintf("%s-%d-%d", name, lp.Partition, lp.Offset)
+		logStrings = append(logStrings, logStr)
+	}
+	// E.g s11_22_33.dl0-134.ab1-441
+	return strings.Join(logStrings, ".")
 }
 
 // IsAfter returns true if ANY position in this token is greater than `other`.
@@ -109,12 +143,22 @@ func (t *StreamingToken) IsAfter(other StreamingToken) bool {
 			return true
 		}
 	}
+	for name := range t.logs {
+		otherLog := other.Log(name)
+		if otherLog == nil {
+			continue
+		}
+		if t.logs[name].IsAfter(otherLog) {
+			return true
+		}
+	}
 	return false
 }
 
 // WithUpdates returns a copy of the StreamingToken with updates applied from another StreamingToken.
 // If the latter StreamingToken contains a field that is not 0, it is considered an update,
 // and its value will replace the corresponding value in the StreamingToken on which WithUpdates is called.
+// If the other token has a log, they will replace any existing log on this token.
 func (t *StreamingToken) WithUpdates(other StreamingToken) (ret StreamingToken) {
 	ret.Type = t.Type
 	ret.Positions = make([]StreamPosition, len(t.Positions))
@@ -125,6 +169,13 @@ func (t *StreamingToken) WithUpdates(other StreamingToken) (ret StreamingToken)
 		}
 		ret.Positions[i] = other.Positions[i]
 	}
+	for name := range t.logs {
+		otherLog := other.Log(name)
+		if otherLog == nil {
+			continue
+		}
+		t.logs[name] = otherLog
+	}
 	return ret
 }
 
@@ -139,7 +190,7 @@ func (t *TopologyToken) PDUPosition() StreamPosition {
 	return t.Positions[1]
 }
 func (t *TopologyToken) StreamToken() StreamingToken {
-	return NewStreamToken(t.PDUPosition(), 0)
+	return NewStreamToken(t.PDUPosition(), 0, nil)
 }
 func (t *TopologyToken) String() string {
 	return t.syncToken.String()
@@ -174,9 +225,9 @@ func (t *TopologyToken) Decrement() {
 // error if the token couldn't be parsed into an int64, or if the token type
 // isn't a known type (returns ErrInvalidSyncTokenType in the latter
 // case).
-func newSyncTokenFromString(s string) (token *syncToken, err error) {
+func newSyncTokenFromString(s string) (token *syncToken, categories []string, err error) {
 	if len(s) == 0 {
-		return nil, ErrInvalidSyncTokenLen
+		return nil, nil, ErrInvalidSyncTokenLen
 	}
 
 	token = new(syncToken)
@@ -185,16 +236,17 @@ func newSyncTokenFromString(s string) (token *syncToken, err error) {
 	switch t := SyncTokenType(s[:1]); t {
 	case SyncTokenTypeStream, SyncTokenTypeTopology:
 		token.Type = t
-		positions = strings.Split(s[1:], "_")
+		categories = strings.Split(s[1:], ".")
+		positions = strings.Split(categories[0], "_")
 	default:
-		return nil, ErrInvalidSyncTokenType
+		return nil, nil, ErrInvalidSyncTokenType
 	}
 
 	for _, pos := range positions {
 		if posInt, err := strconv.ParseInt(pos, 10, 64); err != nil {
-			return nil, err
+			return nil, nil, err
 		} else if posInt < 0 {
-			return nil, errors.New("negative position not allowed")
+			return nil, nil, errors.New("negative position not allowed")
 		} else {
 			token.Positions = append(token.Positions, StreamPosition(posInt))
 		}
@@ -215,7 +267,7 @@ func NewTopologyToken(depth, streamPos StreamPosition) TopologyToken {
 	}
 }
 func NewTopologyTokenFromString(tok string) (token TopologyToken, err error) {
-	t, err := newSyncTokenFromString(tok)
+	t, _, err := newSyncTokenFromString(tok)
 	if err != nil {
 		return
 	}
@@ -233,16 +285,20 @@ func NewTopologyTokenFromString(tok string) (token TopologyToken, err error) {
 }
 
 // NewStreamToken creates a new sync token for /sync
-func NewStreamToken(pduPos, eduPos StreamPosition) StreamingToken {
+func NewStreamToken(pduPos, eduPos StreamPosition, logs map[string]*LogPosition) StreamingToken {
+	if logs == nil {
+		logs = make(map[string]*LogPosition)
+	}
 	return StreamingToken{
 		syncToken: syncToken{
 			Type:      SyncTokenTypeStream,
 			Positions: []StreamPosition{pduPos, eduPos},
 		},
+		logs: logs,
 	}
 }
 func NewStreamTokenFromString(tok string) (token StreamingToken, err error) {
-	t, err := newSyncTokenFromString(tok)
+	t, categories, err := newSyncTokenFromString(tok)
 	if err != nil {
 		return
 	}
@@ -254,8 +310,35 @@ func NewStreamTokenFromString(tok string) (token StreamingToken, err error) {
 		err = fmt.Errorf("token %s wrong number of values, got %d want at least 2", tok, len(t.Positions))
 		return
 	}
+	logs := make(map[string]*LogPosition)
+	if len(categories) > 1 {
+		// dl-0-1234
+		// $log_name-$partition-$offset
+		for _, logStr := range categories[1:] {
+			segments := strings.Split(logStr, "-")
+			if len(segments) != 3 {
+				err = fmt.Errorf("token %s - invalid log: %s", tok, logStr)
+				return
+			}
+			var partition int64
+			partition, err = strconv.ParseInt(segments[1], 10, 32)
+			if err != nil {
+				return
+			}
+			var offset int64
+			offset, err = strconv.ParseInt(segments[2], 10, 64)
+			if err != nil {
+				return
+			}
+			logs[segments[0]] = &LogPosition{
+				Partition: int32(partition),
+				Offset:    offset,
+			}
+		}
+	}
 	return StreamingToken{
 		syncToken: *t,
+		logs:      logs,
 	}, nil
 }
 
diff --git a/syncapi/types/types_test.go b/syncapi/types/types_test.go
index 1e27a8e3..7590ea52 100644
--- a/syncapi/types/types_test.go
+++ b/syncapi/types/types_test.go
@@ -1,11 +1,61 @@
 package types
 
-import "testing"
+import (
+	"reflect"
+	"testing"
+)
+
+func TestNewSyncTokenWithLogs(t *testing.T) {
+	tests := map[string]*StreamingToken{
+		"s4_0": &StreamingToken{
+			syncToken: syncToken{Type: "s", Positions: []StreamPosition{4, 0}},
+			logs:      make(map[string]*LogPosition),
+		},
+		"s4_0.dl-0-123": &StreamingToken{
+			syncToken: syncToken{Type: "s", Positions: []StreamPosition{4, 0}},
+			logs: map[string]*LogPosition{
+				"dl": &LogPosition{
+					Partition: 0,
+					Offset:    123,
+				},
+			},
+		},
+		"s4_0.dl-0-123.ab-1-14419482332": &StreamingToken{
+			syncToken: syncToken{Type: "s", Positions: []StreamPosition{4, 0}},
+			logs: map[string]*LogPosition{
+				"ab": &LogPosition{
+					Partition: 1,
+					Offset:    14419482332,
+				},
+				"dl": &LogPosition{
+					Partition: 0,
+					Offset:    123,
+				},
+			},
+		},
+	}
+	for tok, want := range tests {
+		got, err := NewStreamTokenFromString(tok)
+		if err != nil {
+			if want == nil {
+				continue // error expected
+			}
+			t.Errorf("%s errored: %s", tok, err)
+			continue
+		}
+		if !reflect.DeepEqual(got, *want) {
+			t.Errorf("%s mismatch: got %v want %v", tok, got, want)
+		}
+		if got.String() != tok {
+			t.Errorf("%s reserialisation mismatch: got %s want %s", tok, got.String(), tok)
+		}
+	}
+}
 
 func TestNewSyncTokenFromString(t *testing.T) {
 	shouldPass := map[string]syncToken{
-		"s4_0": NewStreamToken(4, 0).syncToken,
-		"s3_1": NewStreamToken(3, 1).syncToken,
+		"s4_0": NewStreamToken(4, 0, nil).syncToken,
+		"s3_1": NewStreamToken(3, 1, nil).syncToken,
 		"t3_1": NewTopologyToken(3, 1).syncToken,
 	}
 
@@ -21,7 +71,7 @@ func TestNewSyncTokenFromString(t *testing.T) {
 	}
 
 	for test, expected := range shouldPass {
-		result, err := newSyncTokenFromString(test)
+		result, _, err := newSyncTokenFromString(test)
 		if err != nil {
 			t.Error(err)
 		}
@@ -31,7 +81,7 @@ func TestNewSyncTokenFromString(t *testing.T) {
 	}
 
 	for _, test := range shouldFail {
-		if _, err := newSyncTokenFromString(test); err == nil {
+		if _, _, err := newSyncTokenFromString(test); err == nil {
 			t.Errorf("input '%v' should have errored but didn't", test)
 		}
 	}