Implement more CSS storage functions in roomserver (#1388)

6 files changed, 303 insertions, 20 deletions

diff --git a/roomserver/storage/postgres/membership_table.go b/roomserver/storage/postgres/membership_table.go
index 0799647e..5164f654 100644
--- a/roomserver/storage/postgres/membership_table.go
+++ b/roomserver/storage/postgres/membership_table.go
@@ -18,7 +18,9 @@ package postgres
 import (
 	"context"
 	"database/sql"
+	"fmt"
 
+	"github.com/lib/pq"
 	"github.com/matrix-org/dendrite/internal"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/roomserver/storage/shared"
@@ -62,6 +64,10 @@ CREATE TABLE IF NOT EXISTS roomserver_membership (
 );
 `
 
+var selectJoinedUsersSetForRoomsSQL = "" +
+	"SELECT target_nid, COUNT(room_nid) FROM roomserver_membership WHERE room_nid = ANY($1) AND" +
+	" membership_nid = " + fmt.Sprintf("%d", tables.MembershipStateJoin) + " GROUP BY target_nid"
+
 // Insert a row in to membership table so that it can be locked by the
 // SELECT FOR UPDATE
 const insertMembershipSQL = "" +
@@ -102,6 +108,16 @@ const updateMembershipSQL = "" +
 const selectRoomsWithMembershipSQL = "" +
 	"SELECT room_nid FROM roomserver_membership WHERE membership_nid = $1 AND target_nid = $2"
 
+// selectKnownUsersSQL uses a sub-select statement here to find rooms that the user is
+// joined to. Since this information is used to populate the user directory, we will
+// only return users that the user would ordinarily be able to see anyway.
+var selectKnownUsersSQL = "" +
+	"SELECT DISTINCT event_state_key FROM roomserver_membership INNER JOIN roomserver_event_state_keys ON " +
+	"roomserver_membership.target_nid = roomserver_event_state_keys.event_state_key_nid" +
+	" WHERE room_nid = ANY(" +
+	"  SELECT DISTINCT room_nid FROM roomserver_membership WHERE target_nid=$1 AND membership_nid = " + fmt.Sprintf("%d", tables.MembershipStateJoin) +
+	") AND membership_nid = " + fmt.Sprintf("%d", tables.MembershipStateJoin) + " AND event_state_key LIKE $2 LIMIT $3"
+
 type membershipStatements struct {
 	insertMembershipStmt                            *sql.Stmt
 	selectMembershipForUpdateStmt                   *sql.Stmt
@@ -112,6 +128,8 @@ type membershipStatements struct {
 	selectLocalMembershipsFromRoomStmt              *sql.Stmt
 	updateMembershipStmt                            *sql.Stmt
 	selectRoomsWithMembershipStmt                   *sql.Stmt
+	selectJoinedUsersSetForRoomsStmt                *sql.Stmt
+	selectKnownUsersStmt                            *sql.Stmt
 }
 
 func NewPostgresMembershipTable(db *sql.DB) (tables.Membership, error) {
@@ -131,6 +149,8 @@ func NewPostgresMembershipTable(db *sql.DB) (tables.Membership, error) {
 		{&s.selectLocalMembershipsFromRoomStmt, selectLocalMembershipsFromRoomSQL},
 		{&s.updateMembershipStmt, updateMembershipSQL},
 		{&s.selectRoomsWithMembershipStmt, selectRoomsWithMembershipSQL},
+		{&s.selectJoinedUsersSetForRoomsStmt, selectJoinedUsersSetForRoomsSQL},
+		{&s.selectKnownUsersStmt, selectKnownUsersSQL},
 	}.Prepare(db)
 }
 
@@ -246,3 +266,42 @@ func (s *membershipStatements) SelectRoomsWithMembership(
 	}
 	return roomNIDs, nil
 }
+
+func (s *membershipStatements) SelectJoinedUsersSetForRooms(ctx context.Context, roomNIDs []types.RoomNID) (map[types.EventStateKeyNID]int, error) {
+	roomIDarray := make([]int64, len(roomNIDs))
+	for i := range roomNIDs {
+		roomIDarray[i] = int64(roomNIDs[i])
+	}
+	rows, err := s.selectJoinedUsersSetForRoomsStmt.QueryContext(ctx, pq.Int64Array(roomIDarray))
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "selectJoinedUsersSetForRooms: rows.close() failed")
+	result := make(map[types.EventStateKeyNID]int)
+	for rows.Next() {
+		var userID types.EventStateKeyNID
+		var count int
+		if err := rows.Scan(&userID, &count); err != nil {
+			return nil, err
+		}
+		result[userID] = count
+	}
+	return result, rows.Err()
+}
+
+func (s *membershipStatements) SelectKnownUsers(ctx context.Context, userID types.EventStateKeyNID, searchString string, limit int) ([]string, error) {
+	rows, err := s.selectKnownUsersStmt.QueryContext(ctx, userID, fmt.Sprintf("%%%s%%", searchString), limit)
+	if err != nil {
+		return nil, err
+	}
+	result := []string{}
+	defer internal.CloseAndLogIfError(ctx, rows, "SelectKnownUsers: rows.close() failed")
+	for rows.Next() {
+		var userID string
+		if err := rows.Scan(&userID); err != nil {
+			return nil, err
+		}
+		result = append(result, userID)
+	}
+	return result, rows.Err()
+}
diff --git a/roomserver/storage/postgres/rooms_table.go b/roomserver/storage/postgres/rooms_table.go
index 9d359146..ef1b7891 100644
--- a/roomserver/storage/postgres/rooms_table.go
+++ b/roomserver/storage/postgres/rooms_table.go
@@ -81,6 +81,9 @@ const selectRoomIDsSQL = "" +
 const bulkSelectRoomIDsSQL = "" +
 	"SELECT room_id FROM roomserver_rooms WHERE room_nid IN ($1)"
 
+const bulkSelectRoomNIDsSQL = "" +
+	"SELECT room_nid FROM roomserver_rooms WHERE room_id IN ($1)"
+
 type roomStatements struct {
 	insertRoomNIDStmt                  *sql.Stmt
 	selectRoomNIDStmt                  *sql.Stmt
@@ -91,6 +94,7 @@ type roomStatements struct {
 	selectRoomInfoStmt                 *sql.Stmt
 	selectRoomIDsStmt                  *sql.Stmt
 	bulkSelectRoomIDsStmt              *sql.Stmt
+	bulkSelectRoomNIDsStmt             *sql.Stmt
 }
 
 func NewPostgresRoomsTable(db *sql.DB) (tables.Rooms, error) {
@@ -109,6 +113,7 @@ func NewPostgresRoomsTable(db *sql.DB) (tables.Rooms, error) {
 		{&s.selectRoomInfoStmt, selectRoomInfoSQL},
 		{&s.selectRoomIDsStmt, selectRoomIDsSQL},
 		{&s.bulkSelectRoomIDsStmt, bulkSelectRoomIDsSQL},
+		{&s.bulkSelectRoomNIDsStmt, bulkSelectRoomNIDsSQL},
 	}.Prepare(db)
 }
 
@@ -245,3 +250,24 @@ func (s *roomStatements) BulkSelectRoomIDs(ctx context.Context, roomNIDs []types
 	}
 	return roomIDs, nil
 }
+
+func (s *roomStatements) BulkSelectRoomNIDs(ctx context.Context, roomIDs []string) ([]types.RoomNID, error) {
+	var array pq.StringArray
+	for _, roomID := range roomIDs {
+		array = append(array, roomID)
+	}
+	rows, err := s.bulkSelectRoomNIDsStmt.QueryContext(ctx, array)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "bulkSelectRoomNIDsStmt: rows.close() failed")
+	var roomNIDs []types.RoomNID
+	for rows.Next() {
+		var roomNID types.RoomNID
+		if err = rows.Scan(&roomNID); err != nil {
+			return nil, err
+		}
+		roomNIDs = append(roomNIDs, roomNID)
+	}
+	return roomNIDs, nil
+}
diff --git a/roomserver/storage/shared/storage.go b/roomserver/storage/shared/storage.go
index 5c447d66..a3b33a4f 100644
--- a/roomserver/storage/shared/storage.go
+++ b/roomserver/storage/shared/storage.go
@@ -5,6 +5,7 @@ import (
 	"database/sql"
 	"encoding/json"
 	"fmt"
+	"sort"
 
 	csstables "github.com/matrix-org/dendrite/currentstateserver/storage/tables"
 	"github.com/matrix-org/dendrite/internal/caching"
@@ -13,6 +14,7 @@ import (
 	"github.com/matrix-org/dendrite/roomserver/storage/tables"
 	"github.com/matrix-org/dendrite/roomserver/types"
 	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
 	"github.com/tidwall/gjson"
 )
 
@@ -717,25 +719,42 @@ func (d *Database) loadEvent(ctx context.Context, eventID string) *types.Event {
 // If no event could be found, returns nil
 // If there was an issue during the retrieval, returns an error
 func (d *Database) GetStateEvent(ctx context.Context, roomID, evType, stateKey string) (*gomatrixserverlib.HeaderedEvent, error) {
-	/*
-		roomInfo, err := d.RoomInfo(ctx, roomID)
-		if err != nil {
-			return nil, err
-		}
-		eventTypeNID, err := d.EventTypesTable.SelectEventTypeNID(ctx, nil, evType)
-		if err != nil {
-			return nil, err
-		}
-		stateKeyNID, err := d.EventStateKeysTable.SelectEventStateKeyNID(ctx, nil, stateKey)
-		if err != nil {
-			return nil, err
-		}
-		blockNIDs, err := d.StateSnapshotTable.BulkSelectStateBlockNIDs(ctx, []types.StateSnapshotNID{roomInfo.StateSnapshotNID})
-		if err != nil {
-			return nil, err
+	roomInfo, err := d.RoomInfo(ctx, roomID)
+	if err != nil {
+		return nil, err
+	}
+	eventTypeNID, err := d.EventTypesTable.SelectEventTypeNID(ctx, nil, evType)
+	if err != nil {
+		return nil, err
+	}
+	stateKeyNID, err := d.EventStateKeysTable.SelectEventStateKeyNID(ctx, nil, stateKey)
+	if err != nil {
+		return nil, err
+	}
+	entries, err := d.loadStateAtSnapshot(ctx, roomInfo.StateSnapshotNID)
+	if err != nil {
+		return nil, err
+	}
+	// return the event requested
+	for _, e := range entries {
+		if e.EventTypeNID == eventTypeNID && e.EventStateKeyNID == stateKeyNID {
+			data, err := d.EventJSONTable.BulkSelectEventJSON(ctx, []types.EventNID{e.EventNID})
+			if err != nil {
+				return nil, err
+			}
+			if len(data) == 0 {
+				return nil, fmt.Errorf("GetStateEvent: no json for event nid %d", e.EventNID)
+			}
+			ev, err := gomatrixserverlib.NewEventFromTrustedJSON(data[0].EventJSON, false, roomInfo.RoomVersion)
+			if err != nil {
+				return nil, err
+			}
+			h := ev.Headered(roomInfo.RoomVersion)
+			return &h, nil
 		}
-	*/
-	return nil, nil
+	}
+
+	return nil, fmt.Errorf("GetStateEvent: no event type '%s' with key '%s' exists in room %s", evType, stateKey, roomID)
 }
 
 // GetRoomsByMembership returns a list of room IDs matching the provided membership and user ID (as state_key).
@@ -779,15 +798,106 @@ func (d *Database) GetBulkStateContent(ctx context.Context, roomIDs []string, tu
 
 // JoinedUsersSetInRooms returns all joined users in the rooms given, along with the count of how many times they appear.
 func (d *Database) JoinedUsersSetInRooms(ctx context.Context, roomIDs []string) (map[string]int, error) {
-	return nil, fmt.Errorf("not implemented yet")
+	roomNIDs, err := d.RoomsTable.BulkSelectRoomNIDs(ctx, roomIDs)
+	if err != nil {
+		return nil, err
+	}
+	userNIDToCount, err := d.MembershipTable.SelectJoinedUsersSetForRooms(ctx, roomNIDs)
+	if err != nil {
+		return nil, err
+	}
+	stateKeyNIDs := make([]types.EventStateKeyNID, len(userNIDToCount))
+	i := 0
+	for nid := range userNIDToCount {
+		stateKeyNIDs[i] = nid
+		i++
+	}
+	nidToUserID, err := d.EventStateKeysTable.BulkSelectEventStateKey(ctx, stateKeyNIDs)
+	if err != nil {
+		return nil, err
+	}
+	if len(nidToUserID) != len(userNIDToCount) {
+		return nil, fmt.Errorf("found %d users but only have state key nids for %d of them", len(userNIDToCount), len(nidToUserID))
+	}
+	result := make(map[string]int, len(userNIDToCount))
+	for nid, count := range userNIDToCount {
+		result[nidToUserID[nid]] = count
+	}
+	return result, nil
 }
 
 // GetKnownUsers searches all users that userID knows about.
 func (d *Database) GetKnownUsers(ctx context.Context, userID, searchString string, limit int) ([]string, error) {
-	return nil, fmt.Errorf("not implemented yet")
+	stateKeyNID, err := d.EventStateKeysTable.SelectEventStateKeyNID(ctx, nil, userID)
+	if err != nil {
+		return nil, err
+	}
+	return d.MembershipTable.SelectKnownUsers(ctx, stateKeyNID, searchString, limit)
 }
 
 // GetKnownRooms returns a list of all rooms we know about.
 func (d *Database) GetKnownRooms(ctx context.Context) ([]string, error) {
 	return d.RoomsTable.SelectRoomIDs(ctx)
 }
+
+// FIXME TODO: Remove all this - horrible dupe with roomserver/state. Can't use the original impl because of circular loops
+// it should live in this package!
+
+func (d *Database) loadStateAtSnapshot(
+	ctx context.Context, stateNID types.StateSnapshotNID,
+) ([]types.StateEntry, error) {
+	stateBlockNIDLists, err := d.StateBlockNIDs(ctx, []types.StateSnapshotNID{stateNID})
+	if err != nil {
+		return nil, err
+	}
+	// We've asked for exactly one snapshot from the db so we should have exactly one entry in the result.
+	stateBlockNIDList := stateBlockNIDLists[0]
+
+	stateEntryLists, err := d.StateEntries(ctx, stateBlockNIDList.StateBlockNIDs)
+	if err != nil {
+		return nil, err
+	}
+	stateEntriesMap := stateEntryListMap(stateEntryLists)
+
+	// Combine all the state entries for this snapshot.
+	// The order of state block NIDs in the list tells us the order to combine them in.
+	var fullState []types.StateEntry
+	for _, stateBlockNID := range stateBlockNIDList.StateBlockNIDs {
+		entries, ok := stateEntriesMap.lookup(stateBlockNID)
+		if !ok {
+			// This should only get hit if the database is corrupt.
+			// It should be impossible for an event to reference a NID that doesn't exist
+			panic(fmt.Errorf("Corrupt DB: Missing state block numeric ID %d", stateBlockNID))
+		}
+		fullState = append(fullState, entries...)
+	}
+
+	// Stable sort so that the most recent entry for each state key stays
+	// remains later in the list than the older entries for the same state key.
+	sort.Stable(stateEntryByStateKeySorter(fullState))
+	// Unique returns the last entry and hence the most recent entry for each state key.
+	fullState = fullState[:util.Unique(stateEntryByStateKeySorter(fullState))]
+	return fullState, nil
+}
+
+type stateEntryListMap []types.StateEntryList
+
+func (m stateEntryListMap) lookup(stateBlockNID types.StateBlockNID) (stateEntries []types.StateEntry, ok bool) {
+	list := []types.StateEntryList(m)
+	i := sort.Search(len(list), func(i int) bool {
+		return list[i].StateBlockNID >= stateBlockNID
+	})
+	if i < len(list) && list[i].StateBlockNID == stateBlockNID {
+		ok = true
+		stateEntries = list[i].StateEntries
+	}
+	return
+}
+
+type stateEntryByStateKeySorter []types.StateEntry
+
+func (s stateEntryByStateKeySorter) Len() int { return len(s) }
+func (s stateEntryByStateKeySorter) Less(i, j int) bool {
+	return s[i].StateKeyTuple.LessThan(s[j].StateKeyTuple)
+}
+func (s stateEntryByStateKeySorter) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
diff --git a/roomserver/storage/sqlite3/membership_table.go b/roomserver/storage/sqlite3/membership_table.go
index e850c80b..0d5ce516 100644
--- a/roomserver/storage/sqlite3/membership_table.go
+++ b/roomserver/storage/sqlite3/membership_table.go
@@ -18,6 +18,8 @@ package sqlite3
 import (
 	"context"
 	"database/sql"
+	"fmt"
+	"strings"
 
 	"github.com/matrix-org/dendrite/internal"
 	"github.com/matrix-org/dendrite/internal/sqlutil"
@@ -38,6 +40,10 @@ const membershipSchema = `
 	);
 `
 
+var selectJoinedUsersSetForRoomsSQL = "" +
+	"SELECT target_nid, COUNT(room_nid) FROM roomserver_membership WHERE room_nid = ANY($1) AND" +
+	" membership_nid = " + fmt.Sprintf("%d", tables.MembershipStateJoin) + " GROUP BY target_nid"
+
 // Insert a row in to membership table so that it can be locked by the
 // SELECT FOR UPDATE
 const insertMembershipSQL = "" +
@@ -78,6 +84,16 @@ const updateMembershipSQL = "" +
 const selectRoomsWithMembershipSQL = "" +
 	"SELECT room_nid FROM roomserver_membership WHERE membership_nid = $1 AND target_nid = $2"
 
+// selectKnownUsersSQL uses a sub-select statement here to find rooms that the user is
+// joined to. Since this information is used to populate the user directory, we will
+// only return users that the user would ordinarily be able to see anyway.
+var selectKnownUsersSQL = "" +
+	"SELECT DISTINCT event_state_key FROM roomserver_membership INNER JOIN roomserver_event_state_keys ON " +
+	"roomserver_membership.target_nid = roomserver_event_state_keys.event_state_key_nid" +
+	" WHERE room_nid IN (" +
+	"  SELECT DISTINCT room_nid FROM roomserver_membership WHERE target_nid=$1 AND membership_nid = " + fmt.Sprintf("%d", tables.MembershipStateJoin) +
+	") AND membership_nid = " + fmt.Sprintf("%d", tables.MembershipStateJoin) + " AND event_state_key LIKE $2 LIMIT $3"
+
 type membershipStatements struct {
 	db                                              *sql.DB
 	insertMembershipStmt                            *sql.Stmt
@@ -89,6 +105,7 @@ type membershipStatements struct {
 	selectLocalMembershipsFromRoomStmt              *sql.Stmt
 	selectRoomsWithMembershipStmt                   *sql.Stmt
 	updateMembershipStmt                            *sql.Stmt
+	selectKnownUsersStmt                            *sql.Stmt
 }
 
 func NewSqliteMembershipTable(db *sql.DB) (tables.Membership, error) {
@@ -110,6 +127,7 @@ func NewSqliteMembershipTable(db *sql.DB) (tables.Membership, error) {
 		{&s.selectLocalMembershipsFromRoomStmt, selectLocalMembershipsFromRoomSQL},
 		{&s.updateMembershipStmt, updateMembershipSQL},
 		{&s.selectRoomsWithMembershipStmt, selectRoomsWithMembershipSQL},
+		{&s.selectKnownUsersStmt, selectKnownUsersSQL},
 	}.Prepare(db)
 }
 
@@ -227,3 +245,43 @@ func (s *membershipStatements) SelectRoomsWithMembership(
 	}
 	return roomNIDs, nil
 }
+
+func (s *membershipStatements) SelectJoinedUsersSetForRooms(ctx context.Context, roomNIDs []types.RoomNID) (map[types.EventStateKeyNID]int, error) {
+	iRoomNIDs := make([]interface{}, len(roomNIDs))
+	for i, v := range roomNIDs {
+		iRoomNIDs[i] = v
+	}
+	query := strings.Replace(selectJoinedUsersSetForRoomsSQL, "($1)", sqlutil.QueryVariadic(len(iRoomNIDs)), 1)
+	rows, err := s.db.QueryContext(ctx, query, iRoomNIDs...)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "selectJoinedUsersSetForRooms: rows.close() failed")
+	result := make(map[types.EventStateKeyNID]int)
+	for rows.Next() {
+		var userID types.EventStateKeyNID
+		var count int
+		if err := rows.Scan(&userID, &count); err != nil {
+			return nil, err
+		}
+		result[userID] = count
+	}
+	return result, rows.Err()
+}
+
+func (s *membershipStatements) SelectKnownUsers(ctx context.Context, userID types.EventStateKeyNID, searchString string, limit int) ([]string, error) {
+	rows, err := s.selectKnownUsersStmt.QueryContext(ctx, userID, fmt.Sprintf("%%%s%%", searchString), limit)
+	if err != nil {
+		return nil, err
+	}
+	result := []string{}
+	defer internal.CloseAndLogIfError(ctx, rows, "SelectKnownUsers: rows.close() failed")
+	for rows.Next() {
+		var userID string
+		if err := rows.Scan(&userID); err != nil {
+			return nil, err
+		}
+		result = append(result, userID)
+	}
+	return result, rows.Err()
+}
diff --git a/roomserver/storage/sqlite3/rooms_table.go b/roomserver/storage/sqlite3/rooms_table.go
index daacf86f..b4564aff 100644
--- a/roomserver/storage/sqlite3/rooms_table.go
+++ b/roomserver/storage/sqlite3/rooms_table.go
@@ -72,6 +72,9 @@ const selectRoomIDsSQL = "" +
 const bulkSelectRoomIDsSQL = "" +
 	"SELECT room_id FROM roomserver_rooms WHERE room_nid IN ($1)"
 
+const bulkSelectRoomNIDsSQL = "" +
+	"SELECT room_nid FROM roomserver_rooms WHERE room_id IN ($1)"
+
 type roomStatements struct {
 	db                                 *sql.DB
 	insertRoomNIDStmt                  *sql.Stmt
@@ -252,3 +255,25 @@ func (s *roomStatements) BulkSelectRoomIDs(ctx context.Context, roomNIDs []types
 	}
 	return roomIDs, nil
 }
+
+func (s *roomStatements) BulkSelectRoomNIDs(ctx context.Context, roomIDs []string) ([]types.RoomNID, error) {
+	iRoomIDs := make([]interface{}, len(roomIDs))
+	for i, v := range roomIDs {
+		iRoomIDs[i] = v
+	}
+	sqlQuery := strings.Replace(bulkSelectRoomNIDsSQL, "($1)", sqlutil.QueryVariadic(len(roomIDs)), 1)
+	rows, err := s.db.QueryContext(ctx, sqlQuery, iRoomIDs...)
+	if err != nil {
+		return nil, err
+	}
+	defer internal.CloseAndLogIfError(ctx, rows, "bulkSelectRoomNIDsStmt: rows.close() failed")
+	var roomNIDs []types.RoomNID
+	for rows.Next() {
+		var roomNID types.RoomNID
+		if err = rows.Scan(&roomNID); err != nil {
+			return nil, err
+		}
+		roomNIDs = append(roomNIDs, roomNID)
+	}
+	return roomNIDs, nil
+}
diff --git a/roomserver/storage/tables/interface.go b/roomserver/storage/tables/interface.go
index 126c27b5..a142f2b1 100644
--- a/roomserver/storage/tables/interface.go
+++ b/roomserver/storage/tables/interface.go
@@ -67,6 +67,7 @@ type Rooms interface {
 	SelectRoomInfo(ctx context.Context, roomID string) (*types.RoomInfo, error)
 	SelectRoomIDs(ctx context.Context) ([]string, error)
 	BulkSelectRoomIDs(ctx context.Context, roomNIDs []types.RoomNID) ([]string, error)
+	BulkSelectRoomNIDs(ctx context.Context, roomIDs []string) ([]types.RoomNID, error)
 }
 
 type Transactions interface {
@@ -123,6 +124,10 @@ type Membership interface {
 	SelectMembershipsFromRoomAndMembership(ctx context.Context, roomNID types.RoomNID, membership MembershipState, localOnly bool) (eventNIDs []types.EventNID, err error)
 	UpdateMembership(ctx context.Context, txn *sql.Tx, roomNID types.RoomNID, targetUserNID types.EventStateKeyNID, senderUserNID types.EventStateKeyNID, membership MembershipState, eventNID types.EventNID) error
 	SelectRoomsWithMembership(ctx context.Context, userID types.EventStateKeyNID, membershipState MembershipState) ([]types.RoomNID, error)
+	// SelectJoinedUsersSetForRooms returns the set of all users in the rooms who are joined to any of these rooms, along with the
+	// counts of how many rooms they are joined.
+	SelectJoinedUsersSetForRooms(ctx context.Context, roomNIDs []types.RoomNID) (map[types.EventStateKeyNID]int, error)
+	SelectKnownUsers(ctx context.Context, userID types.EventStateKeyNID, searchString string, limit int) ([]string, error)
 }
 
 type Published interface {