Use TransactionWriter in other component SQLite (#1209)

* Use TransactionWriter on other component SQLites

* Fix sync API tests

* Fix panic in media API

* Fix a couple of transactions

* Fix wrong query, add some logging output

* Add debug logging into StoreEvent

* Adjust InsertRoomNID

* Update logging

appservice/storage/sqlite3/appservice_events_table.go

@@ -21,6 +21,7 @@ import (
 	"encoding/json"
 	"time"
 
+	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/gomatrixserverlib"
 	log "github.com/sirupsen/logrus"
 )
@@ -65,6 +66,8 @@ const (
 )
 
 type eventsStatements struct {
+	db                                     *sql.DB
+	writer                                 *sqlutil.TransactionWriter
 	selectEventsByApplicationServiceIDStmt *sql.Stmt
 	countEventsByApplicationServiceIDStmt  *sql.Stmt
 	insertEventStmt                        *sql.Stmt
@@ -73,6 +76,8 @@ type eventsStatements struct {
 }
 
 func (s *eventsStatements) prepare(db *sql.DB) (err error) {
+	s.db = db
+	s.writer = sqlutil.NewTransactionWriter()
 	_, err = db.Exec(appserviceEventsSchema)
 	if err != nil {
 		return
@@ -217,13 +222,15 @@ func (s *eventsStatements) insertEvent(
 		return err
 	}
 
-	_, err = s.insertEventStmt.ExecContext(
+	return s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
+		_, err := s.insertEventStmt.ExecContext(
 			ctx,
 			appServiceID,
 			eventJSON,
 			-1, // No transaction ID yet
 		)
-	return
+		return err
+	})
 }
 
 // updateTxnIDForEvents sets the transactionID for a collection of events. Done
@@ -234,8 +241,10 @@ func (s *eventsStatements) updateTxnIDForEvents(
 	appserviceID string,
 	maxID, txnID int,
 ) (err error) {
-	_, err = s.updateTxnIDForEventsStmt.ExecContext(ctx, txnID, appserviceID, maxID)
-	return
+	return s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
+		_, err := s.updateTxnIDForEventsStmt.ExecContext(ctx, txnID, appserviceID, maxID)
+		return err
+	})
 }
 
 // deleteEventsBeforeAndIncludingID removes events matching given IDs from the database.
@@ -244,6 +253,8 @@ func (s *eventsStatements) deleteEventsBeforeAndIncludingID(
 	appserviceID string,
 	eventTableID int,
 ) (err error) {
-	_, err = s.deleteEventsBeforeAndIncludingIDStmt.ExecContext(ctx, appserviceID, eventTableID)
-	return
+	return s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
+		_, err := s.deleteEventsBeforeAndIncludingIDStmt.ExecContext(ctx, appserviceID, eventTableID)
+		return err
+	})
 }

appservice/storage/sqlite3/txn_id_counter_table.go

@@ -18,6 +18,8 @@ package sqlite3
 import (
 	"context"
 	"database/sql"
+
+	"github.com/matrix-org/dendrite/internal/sqlutil"
 )
 
 const txnIDSchema = `
@@ -35,10 +37,14 @@ const selectTxnIDSQL = `
 `
 
 type txnStatements struct {
+	db              *sql.DB
+	writer          *sqlutil.TransactionWriter
 	selectTxnIDStmt *sql.Stmt
 }
 
 func (s *txnStatements) prepare(db *sql.DB) (err error) {
+	s.db = db
+	s.writer = sqlutil.NewTransactionWriter()
 	_, err = db.Exec(txnIDSchema)
 	if err != nil {
 		return
@@ -55,6 +61,9 @@ func (s *txnStatements) prepare(db *sql.DB) (err error) {
 func (s *txnStatements) selectTxnID(
 	ctx context.Context,
 ) (txnID int, err error) {
-	err = s.selectTxnIDStmt.QueryRowContext(ctx).Scan(&txnID)
+	err = s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
+		err := s.selectTxnIDStmt.QueryRowContext(ctx).Scan(&txnID)
+		return err
+	})
 	return
 }

currentstateserver/storage/sqlite3/current_room_state_table.go

@@ -68,6 +68,7 @@ const selectBulkStateContentWildSQL = "" +
 
 type currentRoomStateStatements struct {
 	db                              *sql.DB
+	writer                          *sqlutil.TransactionWriter
 	upsertRoomStateStmt             *sql.Stmt
 	deleteRoomStateByEventIDStmt    *sql.Stmt
 	selectRoomIDsWithMembershipStmt *sql.Stmt
@@ -77,6 +78,7 @@ type currentRoomStateStatements struct {
 func NewSqliteCurrentRoomStateTable(db *sql.DB) (tables.CurrentRoomState, error) {
 	s := &currentRoomStateStatements{
 		db:     db,
+		writer: sqlutil.NewTransactionWriter(),
 	}
 	_, err := db.Exec(currentRoomStateSchema)
 	if err != nil {
@@ -125,9 +127,11 @@ func (s *currentRoomStateStatements) SelectRoomIDsWithMembership(
 func (s *currentRoomStateStatements) DeleteRoomStateByEventID(
 	ctx context.Context, txn *sql.Tx, eventID string,
 ) error {
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		stmt := sqlutil.TxStmt(txn, s.deleteRoomStateByEventIDStmt)
 		_, err := stmt.ExecContext(ctx, eventID)
 		return err
+	})
 }
 
 func (s *currentRoomStateStatements) UpsertRoomState(
@@ -140,6 +144,7 @@ func (s *currentRoomStateStatements) UpsertRoomState(
 	}
 
 	// upsert state event
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		stmt := sqlutil.TxStmt(txn, s.upsertRoomStateStmt)
 		_, err = stmt.ExecContext(
 			ctx,
@@ -152,6 +157,7 @@ func (s *currentRoomStateStatements) UpsertRoomState(
 			contentVal,
 		)
 		return err
+	})
 }
 
 func (s *currentRoomStateStatements) SelectEventsWithEventIDs(

mediaapi/storage/sqlite3/media_repository_table.go

@@ -20,6 +20,7 @@ import (
 	"database/sql"
 	"time"
 
+	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/mediaapi/types"
 	"github.com/matrix-org/gomatrixserverlib"
 )
@@ -60,11 +61,16 @@ SELECT content_type, file_size_bytes, creation_ts, upload_name, base64hash, user
 `
 
 type mediaStatements struct {
+	db              *sql.DB
+	writer          *sqlutil.TransactionWriter
 	insertMediaStmt *sql.Stmt
 	selectMediaStmt *sql.Stmt
 }
 
 func (s *mediaStatements) prepare(db *sql.DB) (err error) {
+	s.db = db
+	s.writer = sqlutil.NewTransactionWriter()
+
 	_, err = db.Exec(mediaSchema)
 	if err != nil {
 		return
@@ -80,7 +86,9 @@ func (s *mediaStatements) insertMedia(
 	ctx context.Context, mediaMetadata *types.MediaMetadata,
 ) error {
 	mediaMetadata.CreationTimestamp = types.UnixMs(time.Now().UnixNano() / 1000000)
-	_, err := s.insertMediaStmt.ExecContext(
+	return s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
+		stmt := sqlutil.TxStmt(txn, s.insertMediaStmt)
+		_, err := stmt.ExecContext(
 			ctx,
 			mediaMetadata.MediaID,
 			mediaMetadata.Origin,
@@ -92,6 +100,7 @@ func (s *mediaStatements) insertMedia(
 			mediaMetadata.UserID,
 		)
 		return err
+	})
 }
 
 func (s *mediaStatements) selectMedia(

roomserver/internal/input_events.go

@@ -18,6 +18,7 @@ package internal
 
 import (
 	"context"
+	"fmt"
 
 	"github.com/matrix-org/dendrite/internal/eventutil"
 	"github.com/matrix-org/dendrite/roomserver/api"
@@ -65,13 +66,13 @@ func (r *RoomserverInternalAPI) processRoomEvent(
 	// Store the event.
 	roomNID, stateAtEvent, redactionEvent, redactedEventID, err := r.DB.StoreEvent(ctx, event, input.TransactionID, authEventNIDs)
 	if err != nil {
-		return
+		return "", fmt.Errorf("r.DB.StoreEvent: %w", err)
 	}
 	// if storing this event results in it being redacted then do so.
 	if redactedEventID == event.EventID() {
 		r, rerr := eventutil.RedactEvent(redactionEvent, &event)
 		if rerr != nil {
-			return "", rerr
+			return "", fmt.Errorf("eventutil.RedactEvent: %w", rerr)
 		}
 		event = *r
 	}
@@ -93,7 +94,7 @@ func (r *RoomserverInternalAPI) processRoomEvent(
 		// Lets calculate one.
 		err = r.calculateAndSetState(ctx, input, roomNID, &stateAtEvent, event)
 		if err != nil {
-			return
+			return "", fmt.Errorf("r.calculateAndSetState: %w", err)
 		}
 	}
 
@@ -105,7 +106,7 @@ func (r *RoomserverInternalAPI) processRoomEvent(
 		input.SendAsServer,  // send as server
 		input.TransactionID, // transaction ID
 	); err != nil {
-		return
+		return "", fmt.Errorf("r.updateLatestEvents: %w", err)
 	}
 
 	// processing this event resulted in an event (which may not be the one we're processing)
@@ -123,7 +124,7 @@ func (r *RoomserverInternalAPI) processRoomEvent(
 			},
 		})
 		if err != nil {
-			return
+			return "", fmt.Errorf("r.WriteOutputEvents: %w", err)
 		}
 	}
 

roomserver/storage/shared/storage.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"encoding/json"
+	"fmt"
 
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/roomserver/api"
@@ -362,7 +363,7 @@ func (d *Database) StoreEvent(
 				ctx, txn, txnAndSessionID.TransactionID,
 				txnAndSessionID.SessionID, event.Sender(), event.EventID(),
 			); err != nil {
-				return err
+				return fmt.Errorf("d.TransactionsTable.InsertTransaction: %w", err)
 			}
 		}
 
@@ -377,15 +378,15 @@ func (d *Database) StoreEvent(
 		// room.
 		var roomVersion gomatrixserverlib.RoomVersion
 		if roomVersion, err = extractRoomVersionFromCreateEvent(event); err != nil {
-			return err
+			return fmt.Errorf("extractRoomVersionFromCreateEvent: %w", err)
 		}
 
 		if roomNID, err = d.assignRoomNID(ctx, txn, event.RoomID(), roomVersion); err != nil {
-			return err
+			return fmt.Errorf("d.assignRoomNID: %w", err)
 		}
 
 		if eventTypeNID, err = d.assignEventTypeNID(ctx, txn, event.Type()); err != nil {
-			return err
+			return fmt.Errorf("d.assignEventTypeNID: %w", err)
 		}
 
 		eventStateKey := event.StateKey()
@@ -393,7 +394,7 @@ func (d *Database) StoreEvent(
 		// Otherwise set the numeric ID for the state_key to 0.
 		if eventStateKey != nil {
 			if eventStateKeyNID, err = d.assignStateKeyNID(ctx, txn, *eventStateKey); err != nil {
-				return err
+				return fmt.Errorf("d.assignStateKeyNID: %w", err)
 			}
 		}
 
@@ -411,17 +412,20 @@ func (d *Database) StoreEvent(
 			if err == sql.ErrNoRows {
 				// We've already inserted the event so select the numeric event ID
 				eventNID, stateNID, err = d.EventsTable.SelectEvent(ctx, txn, event.EventID())
+				if err != nil {
+					return fmt.Errorf("d.EventsTable.SelectEvent: %w", err)
+				}
 			}
 			if err != nil {
-				return err
+				return fmt.Errorf("d.EventsTable.InsertEvent: %w", err)
 			}
 		}
 
 		if err = d.EventJSONTable.InsertEventJSON(ctx, txn, eventNID, event.JSON()); err != nil {
-			return err
+			return fmt.Errorf("d.EventJSONTable.InsertEventJSON: %w", err)
 		}
 		redactionEvent, redactedEventID, err = d.handleRedactions(ctx, txn, eventNID, event)
-		return err
+		return nil
 	})
 	if err != nil {
 		return 0, types.StateAtEvent{}, nil, "", err

roomserver/storage/sqlite3/events_table.go

@@ -287,7 +287,8 @@ func (s *eventStatements) UpdateEventState(
 	ctx context.Context, eventNID types.EventNID, stateNID types.StateSnapshotNID,
 ) error {
 	return s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
-		_, err := s.updateEventStateStmt.ExecContext(ctx, int64(stateNID), int64(eventNID))
+		stmt := sqlutil.TxStmt(txn, s.updateEventStateStmt)
+		_, err := stmt.ExecContext(ctx, int64(stateNID), int64(eventNID))
 		return err
 	})
 }

roomserver/storage/sqlite3/published_table.go

@@ -71,7 +71,8 @@ func (s *publishedStatements) UpsertRoomPublished(
 	ctx context.Context, roomID string, published bool,
 ) (err error) {
 	return s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
-		_, err := s.upsertPublishedStmt.ExecContext(ctx, roomID, published)
+		stmt := sqlutil.TxStmt(txn, s.upsertPublishedStmt)
+		_, err := stmt.ExecContext(ctx, roomID, published)
 		return err
 	})
 }

roomserver/storage/sqlite3/room_aliases_table.go

@@ -87,7 +87,8 @@ func (s *roomAliasesStatements) InsertRoomAlias(
 	ctx context.Context, alias string, roomID string, creatorUserID string,
 ) (err error) {
 	return s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
-		_, err := s.insertRoomAliasStmt.ExecContext(ctx, alias, roomID, creatorUserID)
+		stmt := sqlutil.TxStmt(txn, s.insertRoomAliasStmt)
+		_, err := stmt.ExecContext(ctx, alias, roomID, creatorUserID)
 		return err
 	})
 }
@@ -139,7 +140,8 @@ func (s *roomAliasesStatements) DeleteRoomAlias(
 	ctx context.Context, alias string,
 ) (err error) {
 	return s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
-		_, err := s.deleteRoomAliasStmt.ExecContext(ctx, alias)
+		stmt := sqlutil.TxStmt(txn, s.deleteRoomAliasStmt)
+		_, err := stmt.ExecContext(ctx, alias)
 		return err
 	})
 }

roomserver/storage/sqlite3/rooms_table.go

@@ -20,6 +20,7 @@ import (
 	"database/sql"
 	"encoding/json"
 	"errors"
+	"fmt"
 
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/roomserver/storage/shared"
@@ -98,17 +99,23 @@ func NewSqliteRoomsTable(db *sql.DB) (tables.Rooms, error) {
 func (s *roomStatements) InsertRoomNID(
 	ctx context.Context, txn *sql.Tx,
 	roomID string, roomVersion gomatrixserverlib.RoomVersion,
-) (types.RoomNID, error) {
-	err := s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
+) (roomNID types.RoomNID, err error) {
+	err = s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		insertStmt := sqlutil.TxStmt(txn, s.insertRoomNIDStmt)
-		_, err := insertStmt.ExecContext(ctx, roomID, roomVersion)
-		return err
+		_, err = insertStmt.ExecContext(ctx, roomID, roomVersion)
+		if err != nil {
+			return fmt.Errorf("insertStmt.ExecContext: %w", err)
+		}
+		roomNID, err = s.SelectRoomNID(ctx, txn, roomID)
+		if err != nil {
+			return fmt.Errorf("s.SelectRoomNID: %w", err)
+		}
+		return nil
 	})
-	if err == nil {
-		return s.SelectRoomNID(ctx, txn, roomID)
-	} else {
+	if err != nil {
 		return types.RoomNID(0), err
 	}
+	return
 }
 
 func (s *roomStatements) SelectRoomNID(

serverkeyapi/storage/sqlite3/server_key_table.go

@@ -63,12 +63,14 @@ const upsertServerKeysSQL = "" +
 
 type serverKeyStatements struct {
 	db                       *sql.DB
+	writer                   *sqlutil.TransactionWriter
 	bulkSelectServerKeysStmt *sql.Stmt
 	upsertServerKeysStmt     *sql.Stmt
 }
 
 func (s *serverKeyStatements) prepare(db *sql.DB) (err error) {
 	s.db = db
+	s.writer = sqlutil.NewTransactionWriter()
 	_, err = db.Exec(serverKeysSchema)
 	if err != nil {
 		return
@@ -136,7 +138,9 @@ func (s *serverKeyStatements) upsertServerKeys(
 	request gomatrixserverlib.PublicKeyLookupRequest,
 	key gomatrixserverlib.PublicKeyLookupResult,
 ) error {
-	_, err := s.upsertServerKeysStmt.ExecContext(
+	return s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
+		stmt := sqlutil.TxStmt(txn, s.upsertServerKeysStmt)
+		_, err := stmt.ExecContext(
 			ctx,
 			string(request.ServerName),
 			string(request.KeyID),
@@ -146,6 +150,7 @@ func (s *serverKeyStatements) upsertServerKeys(
 			key.Key.Encode(),
 		)
 		return err
+	})
 }
 
 func nameAndKeyID(request gomatrixserverlib.PublicKeyLookupRequest) string {

syncapi/storage/shared/syncserver.go

@@ -281,16 +281,16 @@ func (d *Database) WriteEvent(
 			ctx, txn, ev, addStateEventIDs, removeStateEventIDs, transactionID, excludeFromSync,
 		)
 		if err != nil {
-			return err
+			return fmt.Errorf("d.OutputEvents.InsertEvent: %w", err)
 		}
 		pduPosition = pos
 
 		if err = d.Topology.InsertEventInTopology(ctx, txn, ev, pos); err != nil {
-			return err
+			return fmt.Errorf("d.Topology.InsertEventInTopology: %w", err)
 		}
 
 		if err = d.handleBackwardExtremities(ctx, txn, ev); err != nil {
-			return err
+			return fmt.Errorf("d.handleBackwardExtremities: %w", err)
 		}
 
 		if len(addStateEvents) == 0 && len(removeStateEventIDs) == 0 {
@@ -313,7 +313,7 @@ func (d *Database) updateRoomState(
 	// remove first, then add, as we do not ever delete state, but do replace state which is a remove followed by an add.
 	for _, eventID := range removedEventIDs {
 		if err := d.CurrentRoomState.DeleteRoomStateByEventID(ctx, txn, eventID); err != nil {
-			return err
+			return fmt.Errorf("d.CurrentRoomState.DeleteRoomStateByEventID: %w", err)
 		}
 	}
 
@@ -326,13 +326,13 @@ func (d *Database) updateRoomState(
 		if event.Type() == "m.room.member" {
 			value, err := event.Membership()
 			if err != nil {
-				return err
+				return fmt.Errorf("event.Membership: %w", err)
 			}
 			membership = &value
 		}
 
 		if err := d.CurrentRoomState.UpsertRoomState(ctx, txn, event, membership, pduPosition); err != nil {
-			return err
+			return fmt.Errorf("d.CurrentRoomState.UpsertRoomState: %w", err)
 		}
 	}
 

syncapi/storage/sqlite3/account_data_table.go

@@ -20,6 +20,7 @@ import (
 	"database/sql"
 
 	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/syncapi/storage/tables"
 	"github.com/matrix-org/dendrite/syncapi/types"
 	"github.com/matrix-org/gomatrixserverlib"
@@ -49,6 +50,8 @@ const selectMaxAccountDataIDSQL = "" +
 	"SELECT MAX(id) FROM syncapi_account_data_type"
 
 type accountDataStatements struct {
+	db                           *sql.DB
+	writer                       *sqlutil.TransactionWriter
 	streamIDStatements           *streamIDStatements
 	insertAccountDataStmt        *sql.Stmt
 	selectMaxAccountDataIDStmt   *sql.Stmt
@@ -57,6 +60,8 @@ type accountDataStatements struct {
 
 func NewSqliteAccountDataTable(db *sql.DB, streamID *streamIDStatements) (tables.AccountData, error) {
 	s := &accountDataStatements{
+		db:                 db,
+		writer:             sqlutil.NewTransactionWriter(),
 		streamIDStatements: streamID,
 	}
 	_, err := db.Exec(accountDataSchema)
@@ -79,12 +84,15 @@ func (s *accountDataStatements) InsertAccountData(
 	ctx context.Context, txn *sql.Tx,
 	userID, roomID, dataType string,
 ) (pos types.StreamPosition, err error) {
+	return pos, s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
+		var err error
 		pos, err = s.streamIDStatements.nextStreamID(ctx, txn)
 		if err != nil {
-		return
+			return err
 		}
 		_, err = txn.Stmt(s.insertAccountDataStmt).ExecContext(ctx, pos, userID, roomID, dataType)
-	return
+		return err
+	})
 }
 
 func (s *accountDataStatements) SelectAccountDataInRange(

syncapi/storage/sqlite3/backwards_extremities_table.go

@@ -19,6 +19,7 @@ import (
 	"database/sql"
 
 	"github.com/matrix-org/dendrite/internal"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/syncapi/storage/tables"
 )
 
@@ -47,13 +48,18 @@ const deleteBackwardExtremitySQL = "" +
 	"DELETE FROM syncapi_backward_extremities WHERE room_id = $1 AND prev_event_id = $2"
 
 type backwardExtremitiesStatements struct {
+	db                                   *sql.DB
+	writer                               *sqlutil.TransactionWriter
 	insertBackwardExtremityStmt          *sql.Stmt
 	selectBackwardExtremitiesForRoomStmt *sql.Stmt
 	deleteBackwardExtremityStmt          *sql.Stmt
 }
 
 func NewSqliteBackwardsExtremitiesTable(db *sql.DB) (tables.BackwardsExtremities, error) {
-	s := &backwardExtremitiesStatements{}
+	s := &backwardExtremitiesStatements{
+		db:     db,
+		writer: sqlutil.NewTransactionWriter(),
+	}
 	_, err := db.Exec(backwardExtremitiesSchema)
 	if err != nil {
 		return nil, err
@@ -73,8 +79,10 @@ func NewSqliteBackwardsExtremitiesTable(db *sql.DB) (tables.BackwardsExtremities
 func (s *backwardExtremitiesStatements) InsertsBackwardExtremity(
 	ctx context.Context, txn *sql.Tx, roomID, eventID string, prevEventID string,
 ) (err error) {
-	_, err = txn.Stmt(s.insertBackwardExtremityStmt).ExecContext(ctx, roomID, eventID, prevEventID)
-	return
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
+		_, err := txn.Stmt(s.insertBackwardExtremityStmt).ExecContext(ctx, roomID, eventID, prevEventID)
+		return err
+	})
 }
 
 func (s *backwardExtremitiesStatements) SelectBackwardExtremitiesForRoom(
@@ -102,6 +110,8 @@ func (s *backwardExtremitiesStatements) SelectBackwardExtremitiesForRoom(
 func (s *backwardExtremitiesStatements) DeleteBackwardExtremity(
 	ctx context.Context, txn *sql.Tx, roomID, knownEventID string,
 ) (err error) {
-	_, err = txn.Stmt(s.deleteBackwardExtremityStmt).ExecContext(ctx, roomID, knownEventID)
-	return
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
+		_, err := txn.Stmt(s.deleteBackwardExtremityStmt).ExecContext(ctx, roomID, knownEventID)
+		return err
+	})
 }

syncapi/storage/sqlite3/current_room_state_table.go

@@ -84,6 +84,8 @@ const selectEventsWithEventIDsSQL = "" +
 	" FROM syncapi_current_room_state WHERE event_id IN ($1)"
 
 type currentRoomStateStatements struct {
+	db                              *sql.DB
+	writer                          *sqlutil.TransactionWriter
 	streamIDStatements              *streamIDStatements
 	upsertRoomStateStmt             *sql.Stmt
 	deleteRoomStateByEventIDStmt    *sql.Stmt
@@ -95,6 +97,8 @@ type currentRoomStateStatements struct {
 
 func NewSqliteCurrentRoomStateTable(db *sql.DB, streamID *streamIDStatements) (tables.CurrentRoomState, error) {
 	s := &currentRoomStateStatements{
+		db:                 db,
+		writer:             sqlutil.NewTransactionWriter(),
 		streamIDStatements: streamID,
 	}
 	_, err := db.Exec(currentRoomStateSchema)
@@ -196,9 +200,11 @@ func (s *currentRoomStateStatements) SelectCurrentState(
 func (s *currentRoomStateStatements) DeleteRoomStateByEventID(
 	ctx context.Context, txn *sql.Tx, eventID string,
 ) error {
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		stmt := sqlutil.TxStmt(txn, s.deleteRoomStateByEventIDStmt)
 		_, err := stmt.ExecContext(ctx, eventID)
 		return err
+	})
 }
 
 func (s *currentRoomStateStatements) UpsertRoomState(
@@ -219,8 +225,9 @@ func (s *currentRoomStateStatements) UpsertRoomState(
 	}
 
 	// upsert state event
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		stmt := sqlutil.TxStmt(txn, s.upsertRoomStateStmt)
-	_, err = stmt.ExecContext(
+		_, err := stmt.ExecContext(
 			ctx,
 			event.RoomID(),
 			event.EventID(),
@@ -233,6 +240,7 @@ func (s *currentRoomStateStatements) UpsertRoomState(
 			addedAt,
 		)
 		return err
+	})
 }
 
 func (s *currentRoomStateStatements) SelectEventsWithEventIDs(

syncapi/storage/sqlite3/filter_table.go

@@ -20,6 +20,7 @@ import (
 	"encoding/json"
 	"fmt"
 
+	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/syncapi/storage/tables"
 	"github.com/matrix-org/gomatrixserverlib"
 )
@@ -50,6 +51,8 @@ const insertFilterSQL = "" +
 	"INSERT INTO syncapi_filter (filter, localpart) VALUES ($1, $2)"
 
 type filterStatements struct {
+	db                          *sql.DB
+	writer                      *sqlutil.TransactionWriter
 	selectFilterStmt            *sql.Stmt
 	selectFilterIDByContentStmt *sql.Stmt
 	insertFilterStmt            *sql.Stmt
@@ -60,7 +63,10 @@ func NewSqliteFilterTable(db *sql.DB) (tables.Filter, error) {
 	if err != nil {
 		return nil, err
 	}
-	s := &filterStatements{}
+	s := &filterStatements{
+		db:     db,
+		writer: sqlutil.NewTransactionWriter(),
+	}
 	if s.selectFilterStmt, err = db.Prepare(selectFilterSQL); err != nil {
 		return nil, err
 	}
@@ -108,6 +114,7 @@ func (s *filterStatements) InsertFilter(
 		return "", err
 	}
 
+	err = s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
 		// Check if filter already exists in the database using its localpart and content
 		//
 		// This can result in a race condition when two clients try to insert the
@@ -116,22 +123,24 @@ func (s *filterStatements) InsertFilter(
 		err = s.selectFilterIDByContentStmt.QueryRowContext(ctx,
 			localpart, filterJSON).Scan(&existingFilterID)
 		if err != nil && err != sql.ErrNoRows {
-		return "", err
+			return err
 		}
 		// If it does, return the existing ID
 		if existingFilterID != "" {
-		return existingFilterID, err
+			return nil
 		}
 
 		// Otherwise insert the filter and return the new ID
 		res, err := s.insertFilterStmt.ExecContext(ctx, filterJSON, localpart)
 		if err != nil {
-		return "", err
+			return err
 		}
 		rowid, err := res.LastInsertId()
 		if err != nil {
-		return "", err
+			return err
 		}
 		filterID = fmt.Sprintf("%d", rowid)
+		return nil
+	})
 	return
 }

syncapi/storage/sqlite3/invites_table.go

@@ -58,6 +58,8 @@ const selectMaxInviteIDSQL = "" +
 	"SELECT MAX(id) FROM syncapi_invite_events"
 
 type inviteEventsStatements struct {
+	db                            *sql.DB
+	writer                        *sqlutil.TransactionWriter
 	streamIDStatements            *streamIDStatements
 	insertInviteEventStmt         *sql.Stmt
 	selectInviteEventsInRangeStmt *sql.Stmt
@@ -67,6 +69,8 @@ type inviteEventsStatements struct {
 
 func NewSqliteInvitesTable(db *sql.DB, streamID *streamIDStatements) (tables.Invites, error) {
 	s := &inviteEventsStatements{
+		db:                 db,
+		writer:             sqlutil.NewTransactionWriter(),
 		streamIDStatements: streamID,
 	}
 	_, err := db.Exec(inviteEventsSchema)
@@ -91,15 +95,17 @@ func NewSqliteInvitesTable(db *sql.DB, streamID *streamIDStatements) (tables.Inv
 func (s *inviteEventsStatements) InsertInviteEvent(
 	ctx context.Context, txn *sql.Tx, inviteEvent gomatrixserverlib.HeaderedEvent,
 ) (streamPos types.StreamPosition, err error) {
+	err = s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
+		var err error
 		streamPos, err = s.streamIDStatements.nextStreamID(ctx, txn)
 		if err != nil {
-		return
+			return err
 		}
 
 		var headeredJSON []byte
 		headeredJSON, err = json.Marshal(inviteEvent)
 		if err != nil {
-		return
+			return err
 		}
 
 		_, err = txn.Stmt(s.insertInviteEventStmt).ExecContext(
@@ -110,17 +116,24 @@ func (s *inviteEventsStatements) InsertInviteEvent(
 			*inviteEvent.StateKey(),
 			headeredJSON,
 		)
+		return err
+	})
 	return
 }
 
 func (s *inviteEventsStatements) DeleteInviteEvent(
 	ctx context.Context, inviteEventID string,
 ) (types.StreamPosition, error) {
-	streamPos, err := s.streamIDStatements.nextStreamID(ctx, nil)
+	var streamPos types.StreamPosition
+	err := s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
+		var err error
+		streamPos, err = s.streamIDStatements.nextStreamID(ctx, nil)
 		if err != nil {
-		return streamPos, err
+			return err
 		}
 		_, err = s.deleteInviteEventStmt.ExecContext(ctx, streamPos, inviteEventID)
+		return err
+	})
 	return streamPos, err
 }
 

syncapi/storage/sqlite3/output_room_events_table.go

@@ -104,6 +104,8 @@ const selectStateInRangeSQL = "" +
 	" LIMIT $8" // limit
 
 type outputRoomEventsStatements struct {
+	db                            *sql.DB
+	writer                        *sqlutil.TransactionWriter
 	streamIDStatements            *streamIDStatements
 	insertEventStmt               *sql.Stmt
 	selectEventsStmt              *sql.Stmt
@@ -117,6 +119,8 @@ type outputRoomEventsStatements struct {
 
 func NewSqliteEventsTable(db *sql.DB, streamID *streamIDStatements) (tables.Events, error) {
 	s := &outputRoomEventsStatements{
+		db:                 db,
+		writer:             sqlutil.NewTransactionWriter(),
 		streamIDStatements: streamID,
 	}
 	_, err := db.Exec(outputRoomEventsSchema)
@@ -155,8 +159,10 @@ func (s *outputRoomEventsStatements) UpdateEventJSON(ctx context.Context, event
 	if err != nil {
 		return err
 	}
+	return s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
 		_, err = s.updateEventJSONStmt.ExecContext(ctx, headeredJSON, event.EventID())
 		return err
+	})
 }
 
 // selectStateInRange returns the state events between the two given PDU stream positions, exclusive of oldPos, inclusive of newPos.
@@ -267,7 +273,7 @@ func (s *outputRoomEventsStatements) InsertEvent(
 	ctx context.Context, txn *sql.Tx,
 	event *gomatrixserverlib.HeaderedEvent, addState, removeState []string,
 	transactionID *api.TransactionID, excludeFromSync bool,
-) (streamPos types.StreamPosition, err error) {
+) (types.StreamPosition, error) {
 	var txnID *string
 	var sessionID *int64
 	if transactionID != nil {
@@ -284,27 +290,29 @@ func (s *outputRoomEventsStatements) InsertEvent(
 	}
 
 	var headeredJSON []byte
-	headeredJSON, err = json.Marshal(event)
+	headeredJSON, err := json.Marshal(event)
 	if err != nil {
-		return
-	}
-
-	streamPos, err = s.streamIDStatements.nextStreamID(ctx, txn)
-	if err != nil {
-		return
+		return 0, err
 	}
 
 	addStateJSON, err := json.Marshal(addState)
 	if err != nil {
-		return
+		return 0, err
 	}
 	removeStateJSON, err := json.Marshal(removeState)
 	if err != nil {
-		return
+		return 0, err
+	}
+
+	var streamPos types.StreamPosition
+	err = s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
+		streamPos, err = s.streamIDStatements.nextStreamID(ctx, txn)
+		if err != nil {
+			return err
 		}
 
 		insertStmt := sqlutil.TxStmt(txn, s.insertEventStmt)
-	_, err = insertStmt.ExecContext(
+		_, ierr := insertStmt.ExecContext(
 			ctx,
 			streamPos,
 			event.RoomID(),
@@ -320,7 +328,9 @@ func (s *outputRoomEventsStatements) InsertEvent(
 			excludeFromSync,
 			excludeFromSync,
 		)
-	return
+		return ierr
+	})
+	return streamPos, err
 }
 
 func (s *outputRoomEventsStatements) SelectRecentEvents(

syncapi/storage/sqlite3/output_room_events_topology_table.go

@@ -66,6 +66,8 @@ const selectMaxPositionInTopologySQL = "" +
 	" WHERE room_id = $1 ORDER BY stream_position DESC"
 
 type outputRoomEventsTopologyStatements struct {
+	db                              *sql.DB
+	writer                          *sqlutil.TransactionWriter
 	insertEventInTopologyStmt       *sql.Stmt
 	selectEventIDsInRangeASCStmt    *sql.Stmt
 	selectEventIDsInRangeDESCStmt   *sql.Stmt
@@ -74,7 +76,10 @@ type outputRoomEventsTopologyStatements struct {
 }
 
 func NewSqliteTopologyTable(db *sql.DB) (tables.Topology, error) {
-	s := &outputRoomEventsTopologyStatements{}
+	s := &outputRoomEventsTopologyStatements{
+		db:     db,
+		writer: sqlutil.NewTransactionWriter(),
+	}
 	_, err := db.Exec(outputRoomEventsTopologySchema)
 	if err != nil {
 		return nil, err
@@ -102,11 +107,13 @@ func NewSqliteTopologyTable(db *sql.DB) (tables.Topology, error) {
 func (s *outputRoomEventsTopologyStatements) InsertEventInTopology(
 	ctx context.Context, txn *sql.Tx, event *gomatrixserverlib.HeaderedEvent, pos types.StreamPosition,
 ) (err error) {
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		stmt := sqlutil.TxStmt(txn, s.insertEventInTopologyStmt)
-	_, err = stmt.ExecContext(
+		_, err := stmt.ExecContext(
 			ctx, event.EventID(), event.Depth(), event.RoomID(), pos,
 		)
-	return
+		return err
+	})
 }
 
 func (s *outputRoomEventsTopologyStatements) SelectEventIDsInRange(

syncapi/storage/sqlite3/send_to_device_table.go

@@ -72,13 +72,18 @@ const deleteSendToDeviceMessagesSQL = `
 `
 
 type sendToDeviceStatements struct {
+	db                             *sql.DB
+	writer                         *sqlutil.TransactionWriter
 	insertSendToDeviceMessageStmt  *sql.Stmt
 	selectSendToDeviceMessagesStmt *sql.Stmt
 	countSendToDeviceMessagesStmt  *sql.Stmt
 }
 
 func NewSqliteSendToDeviceTable(db *sql.DB) (tables.SendToDevice, error) {
-	s := &sendToDeviceStatements{}
+	s := &sendToDeviceStatements{
+		db:     db,
+		writer: sqlutil.NewTransactionWriter(),
+	}
 	_, err := db.Exec(sendToDeviceSchema)
 	if err != nil {
 		return nil, err
@@ -98,8 +103,10 @@ func NewSqliteSendToDeviceTable(db *sql.DB) (tables.SendToDevice, error) {
 func (s *sendToDeviceStatements) InsertSendToDeviceMessage(
 	ctx context.Context, txn *sql.Tx, userID, deviceID, content string,
 ) (err error) {
-	_, err = sqlutil.TxStmt(txn, s.insertSendToDeviceMessageStmt).ExecContext(ctx, userID, deviceID, content)
-	return
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
+		_, err := sqlutil.TxStmt(txn, s.insertSendToDeviceMessageStmt).ExecContext(ctx, userID, deviceID, content)
+		return err
+	})
 }
 
 func (s *sendToDeviceStatements) CountSendToDeviceMessages(
@@ -156,8 +163,10 @@ func (s *sendToDeviceStatements) UpdateSentSendToDeviceMessages(
 	for k, v := range nids {
 		params[k+1] = v
 	}
-	_, err = txn.ExecContext(ctx, query, params...)
-	return
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
+		_, err := txn.ExecContext(ctx, query, params...)
+		return err
+	})
 }
 
 func (s *sendToDeviceStatements) DeleteSendToDeviceMessages(
@@ -168,6 +177,8 @@ func (s *sendToDeviceStatements) DeleteSendToDeviceMessages(
 	for k, v := range nids {
 		params[k] = v
 	}
-	_, err = txn.ExecContext(ctx, query, params...)
-	return
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
+		_, err := txn.ExecContext(ctx, query, params...)
+		return err
+	})
 }

syncapi/storage/sqlite3/stream_id_table.go

@@ -27,11 +27,15 @@ const selectStreamIDStmt = "" +
 	"SELECT stream_id FROM syncapi_stream_id WHERE stream_name = $1"
 
 type streamIDStatements struct {
+	db                   *sql.DB
+	writer               *sqlutil.TransactionWriter
 	increaseStreamIDStmt *sql.Stmt
 	selectStreamIDStmt   *sql.Stmt
 }
 
 func (s *streamIDStatements) prepare(db *sql.DB) (err error) {
+	s.db = db
+	s.writer = sqlutil.NewTransactionWriter()
 	_, err = db.Exec(streamIDTableSchema)
 	if err != nil {
 		return
@@ -48,11 +52,14 @@ func (s *streamIDStatements) prepare(db *sql.DB) (err error) {
 func (s *streamIDStatements) nextStreamID(ctx context.Context, txn *sql.Tx) (pos types.StreamPosition, err error) {
 	increaseStmt := sqlutil.TxStmt(txn, s.increaseStreamIDStmt)
 	selectStmt := sqlutil.TxStmt(txn, s.selectStreamIDStmt)
-	if _, err = increaseStmt.ExecContext(ctx, "global"); err != nil {
-		return
-	}
-	if err = selectStmt.QueryRowContext(ctx, "global").Scan(&pos); err != nil {
-		return
-	}
+	err = s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
+		if _, ierr := increaseStmt.ExecContext(ctx, "global"); err != nil {
+			return ierr
+		}
+		if serr := selectStmt.QueryRowContext(ctx, "global").Scan(&pos); err != nil {
+			return serr
+		}
+		return nil
+	})
 	return
 }

syncapi/storage/storage_test.go

@@ -5,6 +5,7 @@ import (
 	"crypto/ed25519"
 	"encoding/json"
 	"fmt"
+	"os"
 	"testing"
 	"time"
 
@@ -52,7 +53,13 @@ func MustCreateEvent(t *testing.T, roomID string, prevs []gomatrixserverlib.Head
 }
 
 func MustCreateDatabase(t *testing.T) storage.Database {
-	db, err := sqlite3.NewDatabase("file::memory:")
+	dbname := fmt.Sprintf("test_%s.db", t.Name())
+	if _, err := os.Stat(dbname); err == nil {
+		if err = os.Remove(dbname); err != nil {
+			t.Fatalf("tried to delete stale test database but failed: %s", err)
+		}
+	}
+	db, err := sqlite3.NewDatabase(fmt.Sprintf("file:%s", dbname))
 	if err != nil {
 		t.Fatalf("NewSyncServerDatasource returned %s", err)
 	}

userapi/storage/accounts/sqlite3/account_data_table.go

@@ -18,6 +18,8 @@ import (
 	"context"
 	"database/sql"
 	"encoding/json"
+
+	"github.com/matrix-org/dendrite/internal/sqlutil"
 )
 
 const accountDataSchema = `
@@ -48,12 +50,16 @@ const selectAccountDataByTypeSQL = "" +
 	"SELECT content FROM account_data WHERE localpart = $1 AND room_id = $2 AND type = $3"
 
 type accountDataStatements struct {
+	db                          *sql.DB
+	writer                      *sqlutil.TransactionWriter
 	insertAccountDataStmt       *sql.Stmt
 	selectAccountDataStmt       *sql.Stmt
 	selectAccountDataByTypeStmt *sql.Stmt
 }
 
 func (s *accountDataStatements) prepare(db *sql.DB) (err error) {
+	s.db = db
+	s.writer = sqlutil.NewTransactionWriter()
 	_, err = db.Exec(accountDataSchema)
 	if err != nil {
 		return
@@ -73,8 +79,10 @@ func (s *accountDataStatements) prepare(db *sql.DB) (err error) {
 func (s *accountDataStatements) insertAccountData(
 	ctx context.Context, txn *sql.Tx, localpart, roomID, dataType string, content json.RawMessage,
 ) (err error) {
-	_, err = txn.Stmt(s.insertAccountDataStmt).ExecContext(ctx, localpart, roomID, dataType, content)
-	return
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
+		_, err := txn.Stmt(s.insertAccountDataStmt).ExecContext(ctx, localpart, roomID, dataType, content)
+		return err
+	})
 }
 
 func (s *accountDataStatements) selectAccountData(

userapi/storage/accounts/sqlite3/accounts_table.go

@@ -20,6 +20,7 @@ import (
 	"time"
 
 	"github.com/matrix-org/dendrite/clientapi/userutil"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/userapi/api"
 	"github.com/matrix-org/gomatrixserverlib"
 
@@ -57,6 +58,8 @@ const selectNewNumericLocalpartSQL = "" +
 // TODO: Update password
 
 type accountsStatements struct {
+	db                            *sql.DB
+	writer                        *sqlutil.TransactionWriter
 	insertAccountStmt             *sql.Stmt
 	selectAccountByLocalpartStmt  *sql.Stmt
 	selectPasswordHashStmt        *sql.Stmt
@@ -65,6 +68,8 @@ type accountsStatements struct {
 }
 
 func (s *accountsStatements) prepare(db *sql.DB, server gomatrixserverlib.ServerName) (err error) {
+	s.db = db
+	s.writer = sqlutil.NewTransactionWriter()
 	_, err = db.Exec(accountsSchema)
 	if err != nil {
 		return
@@ -94,12 +99,15 @@ func (s *accountsStatements) insertAccount(
 	createdTimeMS := time.Now().UnixNano() / 1000000
 	stmt := s.insertAccountStmt
 
+	err := s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		var err error
 		if appserviceID == "" {
 			_, err = txn.Stmt(stmt).ExecContext(ctx, localpart, createdTimeMS, hash, nil)
 		} else {
 			_, err = txn.Stmt(stmt).ExecContext(ctx, localpart, createdTimeMS, hash, appserviceID)
 		}
+		return err
+	})
 	if err != nil {
 		return nil, err
 	}

userapi/storage/accounts/sqlite3/profile_table.go

@@ -19,6 +19,7 @@ import (
 	"database/sql"
 
 	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
+	"github.com/matrix-org/dendrite/internal/sqlutil"
 )
 
 const profilesSchema = `
@@ -46,6 +47,8 @@ const setDisplayNameSQL = "" +
 	"UPDATE account_profiles SET display_name = $1 WHERE localpart = $2"
 
 type profilesStatements struct {
+	db                           *sql.DB
+	writer                       *sqlutil.TransactionWriter
 	insertProfileStmt            *sql.Stmt
 	selectProfileByLocalpartStmt *sql.Stmt
 	setAvatarURLStmt             *sql.Stmt
@@ -53,6 +56,8 @@ type profilesStatements struct {
 }
 
 func (s *profilesStatements) prepare(db *sql.DB) (err error) {
+	s.db = db
+	s.writer = sqlutil.NewTransactionWriter()
 	_, err = db.Exec(profilesSchema)
 	if err != nil {
 		return
@@ -75,8 +80,10 @@ func (s *profilesStatements) prepare(db *sql.DB) (err error) {
 func (s *profilesStatements) insertProfile(
 	ctx context.Context, txn *sql.Tx, localpart string,
 ) (err error) {
-	_, err = txn.Stmt(s.insertProfileStmt).ExecContext(ctx, localpart, "", "")
-	return
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
+		_, err := txn.Stmt(s.insertProfileStmt).ExecContext(ctx, localpart, "", "")
+		return err
+	})
 }
 
 func (s *profilesStatements) selectProfileByLocalpart(

userapi/storage/accounts/sqlite3/threepid_table.go

@@ -53,6 +53,8 @@ const deleteThreePIDSQL = "" +
 	"DELETE FROM account_threepid WHERE threepid = $1 AND medium = $2"
 
 type threepidStatements struct {
+	db                              *sql.DB
+	writer                          *sqlutil.TransactionWriter
 	selectLocalpartForThreePIDStmt  *sql.Stmt
 	selectThreePIDsForLocalpartStmt *sql.Stmt
 	insertThreePIDStmt              *sql.Stmt
@@ -60,6 +62,8 @@ type threepidStatements struct {
 }
 
 func (s *threepidStatements) prepare(db *sql.DB) (err error) {
+	s.db = db
+	s.writer = sqlutil.NewTransactionWriter()
 	_, err = db.Exec(threepidSchema)
 	if err != nil {
 		return
@@ -118,13 +122,18 @@ func (s *threepidStatements) selectThreePIDsForLocalpart(
 func (s *threepidStatements) insertThreePID(
 	ctx context.Context, txn *sql.Tx, threepid, medium, localpart string,
 ) (err error) {
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		stmt := sqlutil.TxStmt(txn, s.insertThreePIDStmt)
-	_, err = stmt.ExecContext(ctx, threepid, medium, localpart)
-	return
+		_, err := stmt.ExecContext(ctx, threepid, medium, localpart)
+		return err
+	})
 }
 
 func (s *threepidStatements) deleteThreePID(
 	ctx context.Context, threepid string, medium string) (err error) {
-	_, err = s.deleteThreePIDStmt.ExecContext(ctx, threepid, medium)
-	return
+	return s.writer.Do(s.db, nil, func(txn *sql.Tx) error {
+		stmt := sqlutil.TxStmt(txn, s.deleteThreePIDStmt)
+		_, err := stmt.ExecContext(ctx, threepid, medium)
+		return err
+	})
 }

userapi/storage/devices/sqlite3/devices_table.go

@@ -74,6 +74,7 @@ const deleteDevicesSQL = "" +
 
 type devicesStatements struct {
 	db                           *sql.DB
+	writer                       *sqlutil.TransactionWriter
 	insertDeviceStmt             *sql.Stmt
 	selectDevicesCountStmt       *sql.Stmt
 	selectDeviceByTokenStmt      *sql.Stmt
@@ -87,6 +88,7 @@ type devicesStatements struct {
 
 func (s *devicesStatements) prepare(db *sql.DB, server gomatrixserverlib.ServerName) (err error) {
 	s.db = db
+	s.writer = sqlutil.NewTransactionWriter()
 	_, err = db.Exec(devicesSchema)
 	if err != nil {
 		return
@@ -128,13 +130,19 @@ func (s *devicesStatements) insertDevice(
 ) (*api.Device, error) {
 	createdTimeMS := time.Now().UnixNano() / 1000000
 	var sessionID int64
+	err := s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		countStmt := sqlutil.TxStmt(txn, s.selectDevicesCountStmt)
 		insertStmt := sqlutil.TxStmt(txn, s.insertDeviceStmt)
 		if err := countStmt.QueryRowContext(ctx).Scan(&sessionID); err != nil {
-		return nil, err
+			return err
 		}
 		sessionID++
 		if _, err := insertStmt.ExecContext(ctx, id, localpart, accessToken, createdTimeMS, displayName, sessionID); err != nil {
+			return err
+		}
+		return nil
+	})
+	if err != nil {
 		return nil, err
 	}
 	return &api.Device{
@@ -148,9 +156,11 @@ func (s *devicesStatements) insertDevice(
 func (s *devicesStatements) deleteDevice(
 	ctx context.Context, txn *sql.Tx, id, localpart string,
 ) error {
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		stmt := sqlutil.TxStmt(txn, s.deleteDeviceStmt)
 		_, err := stmt.ExecContext(ctx, id, localpart)
 		return err
+	})
 }
 
 func (s *devicesStatements) deleteDevices(
@@ -161,6 +171,7 @@ func (s *devicesStatements) deleteDevices(
 	if err != nil {
 		return err
 	}
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		stmt := sqlutil.TxStmt(txn, prep)
 		params := make([]interface{}, len(devices)+1)
 		params[0] = localpart
@@ -170,22 +181,27 @@ func (s *devicesStatements) deleteDevices(
 		params = append(params, params...)
 		_, err = stmt.ExecContext(ctx, params...)
 		return err
+	})
 }
 
 func (s *devicesStatements) deleteDevicesByLocalpart(
 	ctx context.Context, txn *sql.Tx, localpart string,
 ) error {
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		stmt := sqlutil.TxStmt(txn, s.deleteDevicesByLocalpartStmt)
 		_, err := stmt.ExecContext(ctx, localpart)
 		return err
+	})
 }
 
 func (s *devicesStatements) updateDeviceName(
 	ctx context.Context, txn *sql.Tx, localpart, deviceID string, displayName *string,
 ) error {
+	return s.writer.Do(s.db, txn, func(txn *sql.Tx) error {
 		stmt := sqlutil.TxStmt(txn, s.updateDeviceNameStmt)
 		_, err := stmt.ExecContext(ctx, displayName, localpart, deviceID)
 		return err
+	})
 }
 
 func (s *devicesStatements) selectDeviceByToken(