sqlite: Fix UNIQUE violations and close more cursors

- Add missing `defer rows.Close()`
- Do not have the state block NID as a PRIMARY KEY else it breaks for blocks
  with >1 state event in them. Instead, rejig the queries so we can still
  have monotonically increasing integers without using AUTOINCREMENT (which
  mandates PRIMARY KEY).

roomserver/storage/sqlite3/room_aliases_table.go

@@ -103,6 +103,8 @@ func (s *roomAliasesStatements) selectAliasesFromRoomID(
 		return
 	}
 
+	defer rows.Close() // nolint: errcheck
+
 	for rows.Next() {
 		var alias string
 		if err = rows.Scan(&alias); err != nil {

roomserver/storage/sqlite3/state_block_table.go

@@ -30,7 +30,7 @@ import (
 
 const stateDataSchema = `
   CREATE TABLE IF NOT EXISTS roomserver_state_block (
-    state_block_nid INTEGER PRIMARY KEY AUTOINCREMENT,
+    state_block_nid INTEGER NOT NULL,
     event_type_nid INTEGER NOT NULL,
     event_state_key_nid INTEGER NOT NULL,
     event_nid INTEGER NOT NULL,
@@ -43,10 +43,7 @@ const insertStateDataSQL = "" +
 	" VALUES ($1, $2, $3, $4)"
 
 const selectNextStateBlockNIDSQL = `
-	SELECT COALESCE((
+SELECT IFNULL(MAX(state_block_nid), 0) + 1 FROM roomserver_state_block
-		SELECT seq+1 AS state_block_nid FROM sqlite_sequence
-		WHERE name = 'roomserver_state_block'), 1
-	) AS state_block_nid
 `
 
 // Bulk state lookup by numeric state block ID.
@@ -98,11 +95,19 @@ func (s *stateBlockStatements) prepare(db *sql.DB) (err error) {
 
 func (s *stateBlockStatements) bulkInsertStateData(
 	ctx context.Context, txn *sql.Tx,
-	stateBlockNID types.StateBlockNID,
 	entries []types.StateEntry,
-) error {
+) (types.StateBlockNID, error) {
+	if len(entries) == 0 {
+		return 0, nil
+	}
+	var stateBlockNID types.StateBlockNID
+	err := txn.Stmt(s.selectNextStateBlockNIDStmt).QueryRowContext(ctx).Scan(&stateBlockNID)
+	if err != nil {
+		return 0, err
+	}
+
 	for _, entry := range entries {
-		_, err := common.TxStmt(txn, s.insertStateDataStmt).ExecContext(
+		_, err := txn.Stmt(s.insertStateDataStmt).ExecContext(
 			ctx,
 			int64(stateBlockNID),
 			int64(entry.EventTypeNID),
@@ -110,20 +115,10 @@ func (s *stateBlockStatements) bulkInsertStateData(
 			int64(entry.EventNID),
 		)
 		if err != nil {
-			return err
+			return 0, err
 		}
 	}
-	return nil
+	return stateBlockNID, nil
-}
-
-func (s *stateBlockStatements) selectNextStateBlockNID(
-	ctx context.Context,
-	txn *sql.Tx,
-) (types.StateBlockNID, error) {
-	var stateBlockNID int64
-	selectStmt := common.TxStmt(txn, s.selectNextStateBlockNIDStmt)
-	err := selectStmt.QueryRowContext(ctx).Scan(&stateBlockNID)
-	return types.StateBlockNID(stateBlockNID), err
 }
 
 func (s *stateBlockStatements) bulkSelectStateBlockEntries(

roomserver/storage/sqlite3/storage.go

@@ -285,14 +285,10 @@ func (d *Database) AddState(
 ) (stateNID types.StateSnapshotNID, err error) {
 	err = common.WithTransaction(d.db, func(txn *sql.Tx) error {
 		if len(state) > 0 {
-			var stateBlockNID types.StateBlockNID
+			stateBlockNID, err := d.statements.bulkInsertStateData(ctx, txn, state)
-			stateBlockNID, err = d.statements.selectNextStateBlockNID(ctx, txn)
 			if err != nil {
 				return err
 			}
-			if err = d.statements.bulkInsertStateData(ctx, txn, stateBlockNID, state); err != nil {
-				return err
-			}
 			stateBlockNIDs = append(stateBlockNIDs[:len(stateBlockNIDs):len(stateBlockNIDs)], stateBlockNID)
 		}
 		stateNID, err = d.statements.insertState(ctx, txn, roomNID, stateBlockNIDs)