Implement /_matrix/client/v1/rooms/{roomId}/threads (I am being lazy so can someone finish off this for me?)

syncapi/routing/routing.go

@@ -157,6 +157,18 @@ func Setup(
 		}, httputil.WithAllowGuests()),
 	).Methods(http.MethodGet, http.MethodOptions)
 
+	v1unstablemux.Handle("/rooms/{roomId}/threads",
+		httputil.MakeAuthAPI("threads", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
+			vars, err := httputil.URLDecodeMapValues(mux.Vars(req))
+			if err != nil {
+				return util.ErrorResponse(err)
+			}
+
+			return Threads(
+				req, device, syncDB, rsAPI, vars["roomId"],
+			)
+		})).Methods(http.MethodGet)
+
 	v3mux.Handle("/search",
 		httputil.MakeAuthAPI("search", userAPI, func(req *http.Request, device *userapi.Device) util.JSONResponse {
 			if !cfg.Fulltext.Enabled {
@@ -200,4 +212,5 @@ func Setup(
 			return GetMemberships(req, device, vars["roomID"], syncDB, rsAPI, membership, notMembership, at)
 		}, httputil.WithAllowGuests()),
 	).Methods(http.MethodGet, http.MethodOptions)
+
 }

syncapi/routing/threads.go

@@ -0,0 +1,107 @@
+package routing
+
+import (
+	rstypes "github.com/matrix-org/dendrite/roomserver/types"
+	"net/http"
+	"strconv"
+
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/dendrite/roomserver/api"
+	"github.com/matrix-org/dendrite/syncapi/storage"
+	"github.com/matrix-org/dendrite/syncapi/synctypes"
+	"github.com/matrix-org/dendrite/syncapi/types"
+	userapi "github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/gomatrixserverlib/spec"
+	"github.com/matrix-org/util"
+	"github.com/sirupsen/logrus"
+)
+
+type ThreadsResponse struct {
+	Chunk     []synctypes.ClientEvent `json:"chunk"`
+	NextBatch string                  `json:"next_batch,omitempty"`
+}
+
+func Threads(
+	req *http.Request,
+	device *userapi.Device,
+	syncDB storage.Database,
+	rsAPI api.SyncRoomserverAPI,
+	rawRoomID string) util.JSONResponse {
+	var err error
+	roomID, err := spec.NewRoomID(rawRoomID)
+	if err != nil {
+		return util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: spec.InvalidParam("invalid room ID"),
+		}
+	}
+
+	limit, err := strconv.ParseUint(req.URL.Query().Get("limit"), 10, 64)
+	if err != nil {
+		limit = 50
+	}
+	if limit > 100 {
+		limit = 100
+	}
+
+	var from types.StreamPosition
+	if f := req.URL.Query().Get("from"); f != "" {
+		if from, err = types.NewStreamPositionFromString(f); err != nil {
+			return util.ErrorResponse(err)
+		}
+	}
+
+	include := req.URL.Query().Get("include")
+
+	snapshot, err := syncDB.NewDatabaseSnapshot(req.Context())
+	if err != nil {
+		logrus.WithError(err).Error("Failed to get snapshot for relations")
+		return util.JSONResponse{
+			Code: http.StatusInternalServerError,
+			JSON: spec.InternalServerError{},
+		}
+	}
+	var succeeded bool
+	defer sqlutil.EndTransactionWithCheck(snapshot, &succeeded, &err)
+
+	res := &ThreadsResponse{
+		Chunk: []synctypes.ClientEvent{},
+	}
+
+	var userID string
+	if include == "participated" {
+		_, err := spec.NewUserID(device.UserID, true)
+		if err != nil {
+			util.GetLogger(req.Context()).WithError(err).Error("device.UserID invalid")
+			return util.JSONResponse{
+				Code: http.StatusInternalServerError,
+				JSON: spec.Unknown("internal server error"),
+			}
+		}
+		userID = device.UserID
+	} else {
+		userID = ""
+	}
+	var headeredEvents []*rstypes.HeaderedEvent
+	headeredEvents, _, res.NextBatch, err = snapshot.ThreadsFor(
+		req.Context(), roomID.String(), userID, from, limit,
+	)
+	if err != nil {
+		return util.ErrorResponse(err)
+	}
+
+	for _, event := range headeredEvents {
+		ce, err := synctypes.ToClientEvent(event, synctypes.FormatAll, func(roomID spec.RoomID, senderID spec.SenderID) (*spec.UserID, error) {
+			return rsAPI.QueryUserIDForSender(req.Context(), roomID, senderID)
+		})
+		if err != nil {
+			return util.ErrorResponse(err)
+		}
+		res.Chunk = append(res.Chunk, *ce)
+	}
+
+	return util.JSONResponse{
+		Code: http.StatusOK,
+		JSON: res,
+	}
+}

syncapi/storage/postgres/relations_table.go

@@ -63,13 +63,32 @@ const selectRelationsInRangeDescSQL = "" +
 	" AND id >= $5 AND id < $6" +
 	" ORDER BY id DESC LIMIT $7"
 
+const selectThreadsSQL = "" +
+	"SELECT syncapi_relations.id, syncapi_relations.event_id FROM syncapi_relations" +
+	" JOIN syncapi_output_room_events ON syncapi_output_room_events.event_id = syncapi_relations.event_id" +
+	" WHERE syncapi_relations.room_id = $1" +
+	" AND syncapi_relations.rel_type = 'm.thread'" +
+	" AND syncapi_relations.id >= $2" +
+	" ORDER BY syncapi_relations.id LIMIT $3"
+
+const selectThreadsWithSenderSQL = "" +
+	"SELECT syncapi_relations.id, syncapi_relations.event_id FROM syncapi_relations" +
+	" JOIN syncapi_output_room_events ON syncapi_output_room_events.event_id = syncapi_relations.event_id" +
+	" WHERE syncapi_relations.room_id = $1" +
+	" AND syncapi_output_room_events.sender = $2" +
+	" AND syncapi_relations.rel_type = 'm.thread'" +
+	" AND syncapi_relations.id >= $3" +
+	" ORDER BY syncapi_relations.id LIMIT $4"
+
 const selectMaxRelationIDSQL = "" +
 	"SELECT COALESCE(MAX(id), 0) FROM syncapi_relations"
 
 type relationsStatements struct {
 	insertRelationStmt             *sql.Stmt
 	selectRelationsInRangeAscStmt  *sql.Stmt
 	selectRelationsInRangeDescStmt *sql.Stmt
+	selectThreadsStmt              *sql.Stmt
+	selectThreadsWithSenderStmt    *sql.Stmt
 	deleteRelationStmt             *sql.Stmt
 	selectMaxRelationIDStmt        *sql.Stmt
 }
@@ -84,6 +103,8 @@ func NewPostgresRelationsTable(db *sql.DB) (tables.Relations, error) {
 		{&s.insertRelationStmt, insertRelationSQL},
 		{&s.selectRelationsInRangeAscStmt, selectRelationsInRangeAscSQL},
 		{&s.selectRelationsInRangeDescStmt, selectRelationsInRangeDescSQL},
+		{&s.selectThreadsStmt, selectThreadsSQL},
+		{&s.selectThreadsWithSenderStmt, selectThreadsWithSenderSQL},
 		{&s.deleteRelationStmt, deleteRelationSQL},
 		{&s.selectMaxRelationIDStmt, selectMaxRelationIDSQL},
 	}.Prepare(db)
@@ -149,6 +170,49 @@ func (s *relationsStatements) SelectRelationsInRange(
 	return result, lastPos, rows.Err()
 }
 
+func (s *relationsStatements) SelectThreads(
+	ctx context.Context,
+	txn *sql.Tx,
+	roomID, userID string,
+	from types.StreamPosition,
+	limit uint64,
+) ([]string, types.StreamPosition, error) {
+	var lastPos types.StreamPosition
+	var stmt *sql.Stmt
+	var rows *sql.Rows
+	var err error
+
+	if userID == "" {
+		stmt = sqlutil.TxStmt(txn, s.selectThreadsStmt)
+		rows, err = stmt.QueryContext(ctx, roomID, from, limit)
+	} else {
+		stmt = sqlutil.TxStmt(txn, s.selectThreadsWithSenderStmt)
+		rows, err = stmt.QueryContext(ctx, roomID, userID, from, limit)
+	}
+	if err != nil {
+		return nil, lastPos, err
+	}
+
+	defer internal.CloseAndLogIfError(ctx, rows, "selectThreads: rows.close() failed")
+	var result []string
+	var (
+		id      types.StreamPosition
+		eventId string
+	)
+
+	for rows.Next() {
+		if err = rows.Scan(&id, &eventId); err != nil {
+			return nil, lastPos, err
+		}
+		if id > lastPos {
+			lastPos = id
+		}
+		result = append(result, eventId)
+	}
+
+	return result, lastPos, rows.Err()
+}
+
 func (s *relationsStatements) SelectMaxRelationID(
 	ctx context.Context, txn *sql.Tx,
 ) (id int64, err error) {

syncapi/storage/shared/storage_sync.go

@@ -811,3 +811,39 @@ func (d *DatabaseTransaction) RelationsFor(ctx context.Context, roomID, eventID,
 
 	return events, prevBatch, nextBatch, nil
 }
+
+func (d *DatabaseTransaction) ThreadsFor(ctx context.Context, roomID, userID string, from types.StreamPosition, limit uint64) (
+	events []*rstypes.HeaderedEvent, prevBatch, nextBatch string, err error,
+) {
+	r := types.Range{
+		From: from,
+	}
+
+	if r.From == 0 {
+		// If we're working backwards (dir=b) and there's no ?from= specified then
+		// we will automatically want to work backwards from the current position,
+		// so find out what that is.
+		if r.From, err = d.MaxStreamPositionForRelations(ctx); err != nil {
+			return nil, "", "", fmt.Errorf("d.MaxStreamPositionForRelations: %w", err)
+		}
+		// The result normally isn't inclusive of the event *at* the ?from=
+		// position, so add 1 here so that we include the most recent relation.
+		r.From++
+	}
+
+	// First look up any threads from the database. We add one to the limit here
+	// so that we can tell if we're overflowing, as we will only set the "next_batch"
+	// in the response if we are.
+	eventIDs, pos, err := d.Relations.SelectThreads(ctx, d.txn, roomID, userID, from, limit+1)
+
+	if err != nil {
+		return nil, "", "", fmt.Errorf("d.Relations.SelectRelationsInRange: %w", err)
+	}
+
+	events, err = d.Events(ctx, eventIDs)
+	if err != nil {
+		return nil, "", "", fmt.Errorf("d.OutputEvents.SelectEvents: %w", err)
+	}
+
+	return events, prevBatch, fmt.Sprintf("%d", pos), nil
+}

syncapi/storage/sqlite3/relations_table.go

@@ -64,11 +64,30 @@ const selectRelationsInRangeDescSQL = "" +
 const selectMaxRelationIDSQL = "" +
 	"SELECT COALESCE(MAX(id), 0) FROM syncapi_relations"
 
+const selectThreadsSQL = "" +
+	"SELECT syncapi_relations.id, syncapi_relations.event_id FROM syncapi_relations" +
+	" JOIN syncapi_output_room_events ON syncapi_output_room_events.event_id = syncapi_relations.event_id" +
+	" WHERE syncapi_relations.room_id = $1" +
+	" AND syncapi_relations.rel_type = 'm.thread'" +
+	" AND syncapi_relations.id >= $2" +
+	" ORDER BY syncapi_relations.id LIMIT $3"
+
+const selectThreadsWithSenderSQL = "" +
+	"SELECT syncapi_relations.id, syncapi_relations.event_id FROM syncapi_relations" +
+	" JOIN syncapi_output_room_events ON syncapi_output_room_events.event_id = syncapi_relations.event_id" +
+	" WHERE syncapi_relations.room_id = $1" +
+	" AND syncapi_output_room_events.sender = $2" +
+	" AND syncapi_relations.rel_type = 'm.thread'" +
+	" AND syncapi_relations.id >= $3" +
+	" ORDER BY syncapi_relations.id LIMIT $4"
+
 type relationsStatements struct {
 	streamIDStatements             *StreamIDStatements
 	insertRelationStmt             *sql.Stmt
 	selectRelationsInRangeAscStmt  *sql.Stmt
 	selectRelationsInRangeDescStmt *sql.Stmt
+	selectThreadsStmt              *sql.Stmt
+	selectThreadsWithSenderStmt    *sql.Stmt
 	deleteRelationStmt             *sql.Stmt
 	selectMaxRelationIDStmt        *sql.Stmt
 }
@@ -85,6 +104,8 @@ func NewSqliteRelationsTable(db *sql.DB, streamID *StreamIDStatements) (tables.R
 		{&s.insertRelationStmt, insertRelationSQL},
 		{&s.selectRelationsInRangeAscStmt, selectRelationsInRangeAscSQL},
 		{&s.selectRelationsInRangeDescStmt, selectRelationsInRangeDescSQL},
+		{&s.selectThreadsStmt, selectThreadsSQL},
+		{&s.selectThreadsWithSenderStmt, selectThreadsWithSenderSQL},
 		{&s.deleteRelationStmt, deleteRelationSQL},
 		{&s.selectMaxRelationIDStmt, selectMaxRelationIDSQL},
 	}.Prepare(db)
@@ -154,6 +175,49 @@ func (s *relationsStatements) SelectRelationsInRange(
 	return result, lastPos, rows.Err()
 }
 
+func (s *relationsStatements) SelectThreads(
+	ctx context.Context,
+	txn *sql.Tx,
+	roomID, userID string,
+	from types.StreamPosition,
+	limit uint64,
+) ([]string, types.StreamPosition, error) {
+	var lastPos types.StreamPosition
+	var stmt *sql.Stmt
+	var rows *sql.Rows
+	var err error
+
+	if userID == "" {
+		stmt = sqlutil.TxStmt(txn, s.selectThreadsStmt)
+		rows, err = stmt.QueryContext(ctx, roomID, from, limit)
+	} else {
+		stmt = sqlutil.TxStmt(txn, s.selectThreadsWithSenderStmt)
+		rows, err = stmt.QueryContext(ctx, roomID, userID, from, limit)
+	}
+	if err != nil {
+		return nil, lastPos, err
+	}
+
+	defer internal.CloseAndLogIfError(ctx, rows, "selectThreads: rows.close() failed")
+	var result []string
+	var (
+		id      types.StreamPosition
+		eventId string
+	)
+
+	for rows.Next() {
+		if err = rows.Scan(&id, &eventId); err != nil {
+			return nil, lastPos, err
+		}
+		if id > lastPos {
+			lastPos = id
+		}
+		result = append(result, eventId)
+	}
+
+	return result, lastPos, rows.Err()
+}
+
 func (s *relationsStatements) SelectMaxRelationID(
 	ctx context.Context, txn *sql.Tx,
 ) (id int64, err error) {

syncapi/storage/tables/interface.go

@@ -223,10 +223,10 @@ type Presence interface {
 }
 
 type Relations interface {
-	// Inserts a relation which refers from the child event ID to the event ID in the given room.
+	// InsertRelation Inserts a relation which refers from the child event ID to the event ID in the given room.
 	// If the relation already exists then this function will do nothing and return no error.
 	InsertRelation(ctx context.Context, txn *sql.Tx, roomID, eventID, childEventID, childEventType, relType string) (err error)
-	// Deletes a relation which already exists as the result of an event redaction. If the relation
+	// DeleteRelation Deletes a relation which already exists as the result of an event redaction. If the relation
 	// does not exist then this function will do nothing and return no error.
 	DeleteRelation(ctx context.Context, txn *sql.Tx, roomID, childEventID string) error
 	// SelectRelationsInRange will return relations grouped by relation type within the given range.
@@ -235,6 +235,9 @@ type Relations interface {
 	// will be returned, inclusive of the "to" position but excluding the "from" position. The stream
 	// position returned is the maximum position of the returned results.
 	SelectRelationsInRange(ctx context.Context, txn *sql.Tx, roomID, eventID, relType, eventType string, r types.Range, limit int) (map[string][]types.RelationEntry, types.StreamPosition, error)
+	// SelectThreads will find threads from a room, if userID is not empty
+	// then it will only include the threads that the user has participated in.
+	SelectThreads(ctx context.Context, txn *sql.Tx, roomID, userID string, from types.StreamPosition, limit uint64) ([]string, types.StreamPosition, error)
 	// SelectMaxRelationID returns the maximum ID of all relations, used to determine what the boundaries
 	// should be if there are no boundaries supplied (i.e. we want to work backwards but don't have a
 	// "from" or want to work forwards and don't have a "to").