Set depth of events and whether they need to be federated.

Set the depth of each new event to one greater than the maximum depth
of it's direct ancestors.

Add a flag to each event passing through the roomserver that tells us
whether the event needs to be sent over federation.

We do this by passing the name of the server to send the event as.
We will need this capability if we want to support vhosting as it is
not possible to tell from the event alone which server to send it as.

(The reason for this is that sometimes a event needs to be sent on
behalf of a different remote matrix server)

src/github.com/matrix-org/dendrite/clientapi/producers/roomserver.go

@@ -42,7 +42,7 @@ func NewRoomserverProducer(kafkaURIs []string, topic string) (*RoomserverProduce
 }
 
 // SendEvents writes the given events to the roomserver input log. The events are written with KindNew.
-func (c *RoomserverProducer) SendEvents(events []gomatrixserverlib.Event) error {
+func (c *RoomserverProducer) SendEvents(events []gomatrixserverlib.Event, sendAsServer gomatrixserverlib.ServerName) error {
 	eventIDs := make([]string, len(events))
 	ires := make([]api.InputRoomEvent, len(events))
 	for i, event := range events {
@@ -50,6 +50,7 @@ func (c *RoomserverProducer) SendEvents(events []gomatrixserverlib.Event) error
 			Kind:         api.KindNew,
 			Event:        event.JSON(),
 			AuthEventIDs: authEventIDs(event),
+			SendAsServer: string(sendAsServer),
 		}
 		eventIDs[i] = event.EventID()
 	}

src/github.com/matrix-org/dendrite/clientapi/writers/createroom.go

@@ -188,7 +188,7 @@ func createRoom(req *http.Request, device *authtypes.Device, cfg config.Dendrite
 	}
 
 	// send events to the room server
-	if err := producer.SendEvents(builtEvents); err != nil {
+	if err := producer.SendEvents(builtEvents, cfg.Matrix.ServerName); err != nil {
 		return httputil.LogThenError(req, err)
 	}
 

src/github.com/matrix-org/dendrite/clientapi/writers/sendevent.go

@@ -93,6 +93,7 @@ func SendEvent(
 		refs = append(refs, e.EventReference())
 	}
 	builder.AuthEvents = refs
+	builder.Depth = queryRes.Depth
 	eventID := fmt.Sprintf("$%s:%s", util.RandomString(16), cfg.Matrix.ServerName)
 	e, err := builder.Build(
 		eventID, time.Now(), cfg.Matrix.ServerName, cfg.Matrix.KeyID, cfg.Matrix.PrivateKey,
@@ -115,7 +116,7 @@ func SendEvent(
 	}
 
 	// pass the new event to the roomserver
-	if err := producer.SendEvents([]gomatrixserverlib.Event{e}); err != nil {
+	if err := producer.SendEvents([]gomatrixserverlib.Event{e}, cfg.Matrix.ServerName); err != nil {
 		return httputil.LogThenError(req, err)
 	}
 

src/github.com/matrix-org/dendrite/cmd/roomserver-integration-tests/main.go

@@ -340,7 +340,8 @@ func main() {
 				"state_key":"@richvdh:matrix.org",
 				"type":"m.room.member"
 			},
-			"VisibilityEventIDs":null,
+			"StateBeforeRemovesEventIDs":["$1463671339126270PnVwC:matrix.org"],
+			"StateBeforeAddsEventIDs":null,
 			"LatestEventIDs":["$1463671339126270PnVwC:matrix.org"],
 			"AddsStateEventIDs":["$1463671337126266wrSBX:matrix.org", "$1463671339126270PnVwC:matrix.org"],
 			"RemovesStateEventIDs":null,

src/github.com/matrix-org/dendrite/federationapi/writers/send.go

@@ -159,7 +159,7 @@ func (t *txnReq) processEvent(e gomatrixserverlib.Event) error {
 	// TODO: Check that the event is allowed by its auth_events.
 
 	// pass the event to the roomserver
-	if err := t.producer.SendEvents([]gomatrixserverlib.Event{e}); err != nil {
+	if err := t.producer.SendEvents([]gomatrixserverlib.Event{e}, ""); err != nil {
 		return err
 	}
 

src/github.com/matrix-org/dendrite/roomserver/api/input.go

@@ -62,6 +62,9 @@ type InputRoomEvent struct {
 	// These are only used if HasState is true.
 	// The list can be empty, for example when storing the first event in a room.
 	StateEventIDs []string
+	// The server name to use to push this event to other servers.
+	// Or empty if this event shouldn't be pushed to other servers.
+	SendAsServer string
 }
 
 // UnmarshalJSON implements json.Unmarshaller
@@ -76,6 +79,7 @@ func (ire *InputRoomEvent) UnmarshalJSON(data []byte) error {
 		AuthEventIDs  []string
 		StateEventIDs []string
 		HasState      bool
+		SendAsServer  string
 	}
 	if err := json.Unmarshal(data, &content); err != nil {
 		return err
@@ -84,6 +88,7 @@ func (ire *InputRoomEvent) UnmarshalJSON(data []byte) error {
 	ire.AuthEventIDs = content.AuthEventIDs
 	ire.StateEventIDs = content.StateEventIDs
 	ire.HasState = content.HasState
+	ire.SendAsServer = content.SendAsServer
 	if content.Event != nil {
 		ire.Event = []byte(*content.Event)
 	}
@@ -103,12 +108,14 @@ func (ire InputRoomEvent) MarshalJSON() ([]byte, error) {
 		AuthEventIDs  []string
 		StateEventIDs []string
 		HasState      bool
+		SendAsServer  string
 	}{
 		Kind:          ire.Kind,
 		AuthEventIDs:  ire.AuthEventIDs,
 		StateEventIDs: ire.StateEventIDs,
 		Event:         &event,
 		HasState:      ire.HasState,
+		SendAsServer:  ire.SendAsServer,
 	}
 	return json.Marshal(&content)
 }

src/github.com/matrix-org/dendrite/roomserver/api/output.go

@@ -22,9 +22,6 @@ import (
 type OutputRoomEvent struct {
 	// The JSON bytes of the event.
 	Event []byte
-	// The state event IDs needed to determine who can see this event.
-	// This can be used to tell which users to send the event to.
-	VisibilityEventIDs []string
 	// The latest events in the room after this event.
 	// This can be used to set the prev events for new events in the room.
 	// This also can be used to get the full current state after this event.
@@ -43,6 +40,17 @@ type OutputRoomEvent struct {
 	// If the LastSentEventID doesn't match what they were expecting it to be
 	// they can use the LatestEventIDs to request the full current state.
 	LastSentEventID string
+	// The state event IDs that are part of the state at the event, but not
+	// part of the current state. Together with the StateBeforeRemovesEventIDs
+	// this can be used to construct the state before the event from the
+	// current state.
+	StateBeforeAddsEventIDs []string
+	// The state event IDs that are part of the current state, but not part
+	// of the state at the event.
+	StateBeforeRemovesEventIDs []string
+	// The server name to use to push this event to other servers.
+	// Or empty if this event shouldn't be pushed to other servers.
+	SendAsServer string
 }
 
 // UnmarshalJSON implements json.Unmarshaller
@@ -52,12 +60,14 @@ func (ore *OutputRoomEvent) UnmarshalJSON(data []byte) error {
 	// We use json.RawMessage so that the event JSON is sent as JSON rather than
 	// being base64 encoded which is the default for []byte.
 	var content struct {
-		Event                *json.RawMessage
-		VisibilityEventIDs   []string
-		LatestEventIDs       []string
-		AddsStateEventIDs    []string
-		RemovesStateEventIDs []string
-		LastSentEventID      string
+		Event                      *json.RawMessage
+		LatestEventIDs             []string
+		AddsStateEventIDs          []string
+		RemovesStateEventIDs       []string
+		LastSentEventID            string
+		StateBeforeAddsEventIDs    []string
+		StateBeforeRemovesEventIDs []string
+		SendAsServer               string
 	}
 	if err := json.Unmarshal(data, &content); err != nil {
 		return err
@@ -65,11 +75,13 @@ func (ore *OutputRoomEvent) UnmarshalJSON(data []byte) error {
 	if content.Event != nil {
 		ore.Event = []byte(*content.Event)
 	}
-	ore.VisibilityEventIDs = content.VisibilityEventIDs
 	ore.LatestEventIDs = content.LatestEventIDs
 	ore.AddsStateEventIDs = content.AddsStateEventIDs
 	ore.RemovesStateEventIDs = content.RemovesStateEventIDs
 	ore.LastSentEventID = content.LastSentEventID
+	ore.StateBeforeAddsEventIDs = content.StateBeforeAddsEventIDs
+	ore.StateBeforeRemovesEventIDs = content.StateBeforeRemovesEventIDs
+	ore.SendAsServer = content.SendAsServer
 	return nil
 }
 
@@ -81,19 +93,23 @@ func (ore OutputRoomEvent) MarshalJSON() ([]byte, error) {
 	// being base64 encoded which is the default for []byte.
 	event := json.RawMessage(ore.Event)
 	content := struct {
-		Event                *json.RawMessage
-		VisibilityEventIDs   []string
-		LatestEventIDs       []string
-		AddsStateEventIDs    []string
-		RemovesStateEventIDs []string
-		LastSentEventID      string
+		Event                      *json.RawMessage
+		LatestEventIDs             []string
+		AddsStateEventIDs          []string
+		RemovesStateEventIDs       []string
+		LastSentEventID            string
+		StateBeforeAddsEventIDs    []string
+		StateBeforeRemovesEventIDs []string
+		SendAsServer               string
 	}{
-		Event:                &event,
-		VisibilityEventIDs:   ore.VisibilityEventIDs,
-		LatestEventIDs:       ore.LatestEventIDs,
-		AddsStateEventIDs:    ore.AddsStateEventIDs,
-		RemovesStateEventIDs: ore.RemovesStateEventIDs,
-		LastSentEventID:      ore.LastSentEventID,
+		Event:                      &event,
+		LatestEventIDs:             ore.LatestEventIDs,
+		AddsStateEventIDs:          ore.AddsStateEventIDs,
+		RemovesStateEventIDs:       ore.RemovesStateEventIDs,
+		LastSentEventID:            ore.LastSentEventID,
+		StateBeforeAddsEventIDs:    ore.StateBeforeAddsEventIDs,
+		StateBeforeRemovesEventIDs: ore.StateBeforeRemovesEventIDs,
+		SendAsServer:               ore.SendAsServer,
 	}
 	return json.Marshal(&content)
 }

src/github.com/matrix-org/dendrite/roomserver/api/query.go

@@ -43,6 +43,9 @@ type QueryLatestEventsAndStateResponse struct {
 	// The state events requested.
 	// This list will be in an arbitrary order.
 	StateEvents []gomatrixserverlib.Event
+	// The depth of the latest events.
+	// This is one greater than the depths of the latest events.
+	Depth int64
 }
 
 // QueryStateAfterEventsRequest is a request to QueryStateAfterEvents

src/github.com/matrix-org/dendrite/roomserver/input/events.go

@@ -102,7 +102,7 @@ func processRoomEvent(db RoomEventDatabase, ow OutputRoomEventWriter, input api.
 	}
 
 	// Update the extremities of the event graph for the room
-	if err := updateLatestEvents(db, ow, roomNID, stateAtEvent, event); err != nil {
+	if err := updateLatestEvents(db, ow, roomNID, stateAtEvent, event, input.SendAsServer); err != nil {
 		return err
 	}
 

src/github.com/matrix-org/dendrite/roomserver/input/latest_events.go

@@ -20,6 +20,7 @@ import (
 	"github.com/matrix-org/dendrite/roomserver/state"
 	"github.com/matrix-org/dendrite/roomserver/types"
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
 )
 
 // updateLatestEvents updates the list of latest events for this room in the database and writes the
@@ -39,7 +40,12 @@ import (
 //      7 <----- latest
 //
 func updateLatestEvents(
-	db RoomEventDatabase, ow OutputRoomEventWriter, roomNID types.RoomNID, stateAtEvent types.StateAtEvent, event gomatrixserverlib.Event,
+	db RoomEventDatabase,
+	ow OutputRoomEventWriter,
+	roomNID types.RoomNID,
+	stateAtEvent types.StateAtEvent,
+	event gomatrixserverlib.Event,
+	sendAsServer string,
 ) (err error) {
 	updater, err := db.GetLatestEventsForUpdate(roomNID)
 	if err != nil {
@@ -59,12 +65,18 @@ func updateLatestEvents(
 		}
 	}()
 
-	err = doUpdateLatestEvents(db, updater, ow, roomNID, stateAtEvent, event)
+	err = doUpdateLatestEvents(db, updater, ow, roomNID, stateAtEvent, event, sendAsServer)
 	return
 }
 
 func doUpdateLatestEvents(
-	db RoomEventDatabase, updater types.RoomRecentEventsUpdater, ow OutputRoomEventWriter, roomNID types.RoomNID, stateAtEvent types.StateAtEvent, event gomatrixserverlib.Event,
+	db RoomEventDatabase,
+	updater types.RoomRecentEventsUpdater,
+	ow OutputRoomEventWriter,
+	roomNID types.RoomNID,
+	stateAtEvent types.StateAtEvent,
+	event gomatrixserverlib.Event,
+	sendAsServer string,
 ) error {
 	var err error
 	var prevEvents []gomatrixserverlib.EventReference
@@ -110,6 +122,13 @@ func doUpdateLatestEvents(
 		return err
 	}
 
+	stateBeforeEventRemoves, stateBeforeEventAdds, err := state.DifferenceBetweeenStateSnapshots(
+		db, newStateNID, stateAtEvent.BeforeStateSnapshotNID,
+	)
+	if err != nil {
+		return err
+	}
+
 	// Send the event to the output logs.
 	// We do this inside the database transaction to ensure that we only mark an event as sent if we sent it.
 	// (n.b. this means that it's possible that the same event will be sent twice if the transaction fails but
@@ -118,7 +137,10 @@ func doUpdateLatestEvents(
 	// send the event asynchronously but we would need to ensure that 1) the events are written to the log in
 	// the correct order, 2) that pending writes are resent across restarts. In order to avoid writing all the
 	// necessary bookkeeping we'll keep the event sending synchronous for now.
-	if err = writeEvent(db, ow, lastEventIDSent, event, newLatest, removed, added); err != nil {
+	if err = writeEvent(
+		db, ow, lastEventIDSent, event, newLatest, removed, added,
+		stateBeforeEventRemoves, stateBeforeEventAdds, sendAsServer,
+	); err != nil {
 		return err
 	}
 
@@ -170,6 +192,8 @@ func writeEvent(
 	db RoomEventDatabase, ow OutputRoomEventWriter, lastEventIDSent string,
 	event gomatrixserverlib.Event, latest []types.StateAtEventAndReference,
 	removed, added []types.StateEntry,
+	stateBeforeEventRemoves, stateBeforeEventAdds []types.StateEntry,
+	sendAsServer string,
 ) error {
 
 	latestEventIDs := make([]string, len(latest))
@@ -190,6 +214,13 @@ func writeEvent(
 	for _, entry := range removed {
 		stateEventNIDs = append(stateEventNIDs, entry.EventNID)
 	}
+	for _, entry := range stateBeforeEventRemoves {
+		stateEventNIDs = append(stateEventNIDs, entry.EventNID)
+	}
+	for _, entry := range stateBeforeEventAdds {
+		stateEventNIDs = append(stateEventNIDs, entry.EventNID)
+	}
+	stateEventNIDs = stateEventNIDs[:util.SortAndUnique(eventNIDSorter(stateEventNIDs))]
 	eventIDMap, err := db.EventIDs(stateEventNIDs)
 	if err != nil {
 		return err
@@ -200,7 +231,19 @@ func writeEvent(
 	for _, entry := range removed {
 		ore.RemovesStateEventIDs = append(ore.RemovesStateEventIDs, eventIDMap[entry.EventNID])
 	}
-
+	for _, entry := range stateBeforeEventRemoves {
+		ore.StateBeforeRemovesEventIDs = append(ore.StateBeforeRemovesEventIDs, eventIDMap[entry.EventNID])
+	}
+	for _, entry := range stateBeforeEventAdds {
+		ore.StateBeforeAddsEventIDs = append(ore.StateBeforeAddsEventIDs, eventIDMap[entry.EventNID])
+	}
+	ore.SendAsServer = sendAsServer
 	// TODO: Fill out VisibilityStateIDs
 	return ow.WriteOutputRoomEvent(ore)
 }
+
+type eventNIDSorter []types.EventNID
+
+func (s eventNIDSorter) Len() int           { return len(s) }
+func (s eventNIDSorter) Less(i, j int) bool { return s[i] < s[j] }
+func (s eventNIDSorter) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }

src/github.com/matrix-org/dendrite/roomserver/query/query.go

@@ -34,7 +34,7 @@ type RoomserverQueryAPIDatabase interface {
 	RoomNID(roomID string) (types.RoomNID, error)
 	// Lookup event references for the latest events in the room and the current state snapshot.
 	// Returns an error if there was a problem talking to the database.
-	LatestEventIDs(roomNID types.RoomNID) ([]gomatrixserverlib.EventReference, types.StateSnapshotNID, error)
+	LatestEventIDs(roomNID types.RoomNID) ([]gomatrixserverlib.EventReference, types.StateSnapshotNID, int64, error)
 	// Lookup the numeric IDs for a list of events.
 	// Returns an error if there was a problem talking to the database.
 	EventNIDs(eventIDs []string) (map[string]types.EventNID, error)
@@ -60,7 +60,7 @@ func (r *RoomserverQueryAPI) QueryLatestEventsAndState(
 	}
 	response.RoomExists = true
 	var currentStateSnapshotNID types.StateSnapshotNID
-	response.LatestEvents, currentStateSnapshotNID, err = r.DB.LatestEventIDs(roomNID)
+	response.LatestEvents, currentStateSnapshotNID, response.Depth, err = r.DB.LatestEventIDs(roomNID)
 	if err != nil {
 		return err
 	}

src/github.com/matrix-org/dendrite/roomserver/storage/events_table.go

@@ -46,7 +46,9 @@ CREATE TABLE IF NOT EXISTS events (
     -- part of the event graph
     -- Since many different events can have the same state we store the
     -- state into a separate state table and refer to it by numeric ID.
-    state_snapshot_nid bigint NOT NULL DEFAULT 0,
+    state_snapshot_nid BIGINT NOT NULL DEFAULT 0,
+    -- Depth of the event in the event graph.
+    depth BIGINT NOT NULL,
     -- The textual event id.
     -- Used to lookup the numeric ID when processing requests.
     -- Needed for state resolution.
@@ -61,8 +63,8 @@ CREATE TABLE IF NOT EXISTS events (
 `
 
 const insertEventSQL = "" +
-	"INSERT INTO events (room_nid, event_type_nid, event_state_key_nid, event_id, reference_sha256, auth_event_nids)" +
-	" VALUES ($1, $2, $3, $4, $5, $6)" +
+	"INSERT INTO events (room_nid, event_type_nid, event_state_key_nid, event_id, reference_sha256, auth_event_nids, depth)" +
+	" VALUES ($1, $2, $3, $4, $5, $6, $7)" +
 	" ON CONFLICT ON CONSTRAINT event_id_unique" +
 	" DO NOTHING" +
 	" RETURNING event_nid, state_snapshot_nid"
@@ -107,6 +109,9 @@ const bulkSelectEventIDSQL = "" +
 const bulkSelectEventNIDSQL = "" +
 	"SELECT event_id, event_nid FROM events WHERE event_id = ANY($1)"
 
+const selectMaxEventDepthSQL = "" +
+	"SELECT COALESCE(MAX(depth) + 1, 0) FROM events WHERE event_nid = ANY($1)"
+
 type eventStatements struct {
 	insertEventStmt                        *sql.Stmt
 	selectEventStmt                        *sql.Stmt
@@ -120,6 +125,7 @@ type eventStatements struct {
 	bulkSelectEventReferenceStmt           *sql.Stmt
 	bulkSelectEventIDStmt                  *sql.Stmt
 	bulkSelectEventNIDStmt                 *sql.Stmt
+	selectMaxEventDepthStmt                *sql.Stmt
 }
 
 func (s *eventStatements) prepare(db *sql.DB) (err error) {
@@ -141,6 +147,7 @@ func (s *eventStatements) prepare(db *sql.DB) (err error) {
 		{&s.bulkSelectEventReferenceStmt, bulkSelectEventReferenceSQL},
 		{&s.bulkSelectEventIDStmt, bulkSelectEventIDSQL},
 		{&s.bulkSelectEventNIDStmt, bulkSelectEventNIDSQL},
+		{&s.selectMaxEventDepthStmt, selectMaxEventDepthSQL},
 	}.prepare(db)
 }
 
@@ -149,12 +156,13 @@ func (s *eventStatements) insertEvent(
 	eventID string,
 	referenceSHA256 []byte,
 	authEventNIDs []types.EventNID,
+	depth int64,
 ) (types.EventNID, types.StateSnapshotNID, error) {
 	var eventNID int64
 	var stateNID int64
 	err := s.insertEventStmt.QueryRow(
 		int64(roomNID), int64(eventTypeNID), int64(eventStateKeyNID), eventID, referenceSHA256,
-		eventNIDsAsArray(authEventNIDs),
+		eventNIDsAsArray(authEventNIDs), depth,
 	).Scan(&eventNID, &stateNID)
 	return types.EventNID(eventNID), types.StateSnapshotNID(stateNID), err
 }
@@ -357,6 +365,15 @@ func (s *eventStatements) bulkSelectEventNID(eventIDs []string) (map[string]type
 	return results, nil
 }
 
+func (s *eventStatements) selectMaxEventDepth(eventNIDs []types.EventNID) (int64, error) {
+	var result int64
+	err := s.selectMaxEventDepthStmt.QueryRow(eventNIDsAsArray(eventNIDs)).Scan(&result)
+	if err != nil {
+		return 0, err
+	}
+	return result, nil
+}
+
 func eventNIDsAsArray(eventNIDs []types.EventNID) pq.Int64Array {
 	nids := make([]int64, len(eventNIDs))
 	for i := range eventNIDs {

src/github.com/matrix-org/dendrite/roomserver/storage/storage.go

@@ -87,6 +87,7 @@ func (d *Database) StoreEvent(event gomatrixserverlib.Event, authEventNIDs []typ
 		event.EventID(),
 		event.EventReference().EventSHA256,
 		authEventNIDs,
+		event.Depth(),
 	); err != nil {
 		if err == sql.ErrNoRows {
 			// We've already inserted the event so select the numeric event ID
@@ -349,16 +350,20 @@ func (d *Database) RoomNID(roomID string) (types.RoomNID, error) {
 }
 
 // LatestEventIDs implements query.RoomserverQueryAPIDB
-func (d *Database) LatestEventIDs(roomNID types.RoomNID) ([]gomatrixserverlib.EventReference, types.StateSnapshotNID, error) {
+func (d *Database) LatestEventIDs(roomNID types.RoomNID) ([]gomatrixserverlib.EventReference, types.StateSnapshotNID, int64, error) {
 	eventNIDs, currentStateSnapshotNID, err := d.statements.selectLatestEventNIDs(roomNID)
 	if err != nil {
-		return nil, 0, err
+		return nil, 0, 0, err
 	}
 	references, err := d.statements.bulkSelectEventReference(eventNIDs)
 	if err != nil {
-		return nil, 0, err
+		return nil, 0, 0, err
 	}
-	return references, currentStateSnapshotNID, nil
+	depth, err := d.statements.selectMaxEventDepth(eventNIDs)
+	if err != nil {
+		return nil, 0, 0, err
+	}
+	return references, currentStateSnapshotNID, depth, nil
 }
 
 // StateEntriesForTuples implements state.RoomStateDatabase