Add QueryEx, QueryRowEx, ExecEx, and RollbackEx to Tx

fixes #303

tx.go

@@ -144,11 +144,16 @@ func (tx *Tx) CommitEx(ctx context.Context) error {
 // defer tx.Rollback() is safe even if tx.Commit() will be called first in a
 // non-error condition.
 func (tx *Tx) Rollback() error {
+	ctx, _ := context.WithTimeout(context.Background(), 15*time.Second)
+	return tx.RollbackEx(ctx)
+}
+
+// RollbackEx is the context version of Rollback
+func (tx *Tx) RollbackEx(ctx context.Context) error {
 	if tx.status != TxStatusInProgress {
 		return ErrTxClosed
 	}
 
-	ctx, _ := context.WithTimeout(context.Background(), 15*time.Second)
 	_, tx.err = tx.conn.ExecEx(ctx, "rollback", nil)
 	if tx.err == nil {
 		tx.status = TxStatusRollbackSuccess
@@ -167,11 +172,16 @@ func (tx *Tx) Rollback() error {
 
 // Exec delegates to the underlying *Conn
 func (tx *Tx) Exec(sql string, arguments ...interface{}) (commandTag CommandTag, err error) {
+	return tx.ExecEx(context.Background(), sql, nil, arguments...)
+}
+
+// ExecEx delegates to the underlying *Conn
+func (tx *Tx) ExecEx(ctx context.Context, sql string, options *QueryExOptions, arguments ...interface{}) (commandTag CommandTag, err error) {
 	if tx.status != TxStatusInProgress {
 		return CommandTag(""), ErrTxClosed
 	}
 
-	return tx.conn.Exec(sql, arguments...)
+	return tx.conn.ExecEx(ctx, sql, options, arguments...)
 }
 
 // Prepare delegates to the underlying *Conn
@@ -190,13 +200,18 @@ func (tx *Tx) PrepareEx(ctx context.Context, name, sql string, opts *PrepareExOp
 
 // Query delegates to the underlying *Conn
 func (tx *Tx) Query(sql string, args ...interface{}) (*Rows, error) {
+	return tx.QueryEx(context.Background(), sql, nil, args...)
+}
+
+// QueryEx delegates to the underlying *Conn
+func (tx *Tx) QueryEx(ctx context.Context, sql string, options *QueryExOptions, args ...interface{}) (*Rows, error) {
 	if tx.status != TxStatusInProgress {
 		// Because checking for errors can be deferred to the *Rows, build one with the error
 		err := ErrTxClosed
 		return &Rows{closed: true, err: err}, err
 	}
 
-	return tx.conn.Query(sql, args...)
+	return tx.conn.QueryEx(ctx, sql, options, args...)
 }
 
 // QueryRow delegates to the underlying *Conn
@@ -205,6 +220,12 @@ func (tx *Tx) QueryRow(sql string, args ...interface{}) *Row {
 	return (*Row)(rows)
 }
 
+// QueryRowEx delegates to the underlying *Conn
+func (tx *Tx) QueryRowEx(ctx context.Context, sql string, options *QueryExOptions, args ...interface{}) *Row {
+	rows, _ := tx.QueryEx(ctx, sql, options, args...)
+	return (*Row)(rows)
+}
+
 // CopyFrom delegates to the underlying *Conn
 func (tx *Tx) CopyFrom(tableName Identifier, columnNames []string, rowSrc CopyFromSource) (int, error) {
 	if tx.status != TxStatusInProgress {