Function dbTransaction

pkg/blobinfocache/sqlite/sqlite.go:185–213

dbTransaction calls fn within a read-write transaction in db.

(db *sql.DB, fn func(tx *sql.Tx) (T, error))

// dbTransaction calls fn within a read-write transaction in db.
func dbTransaction[T any](db *sql.DB, fn func(tx *sql.Tx) (T, error)) (T, error) {
	// Ideally we should be able to distinguish between read-only and read-write transactions, see the _txlock=exclusive discussion.

	var zeroRes T // A zero value of T

	tx, err := db.Begin()
	if err != nil {
		return zeroRes, fmt.Errorf("beginning transaction: %w", err)
	}
	succeeded := false
	defer func() {
		if !succeeded {
			if err := tx.Rollback(); err != nil {
				logrus.Errorf("Rolling back transaction: %v", err)
			}
		}
	}()

	res, err := fn(tx)
	if err != nil {
		return zeroRes, err
	}
	if err := tx.Commit(); err != nil {
		return zeroRes, fmt.Errorf("committing transaction: %w", err)
	}

	succeeded = true
	return res, nil
}

// querySingleValue executes a SELECT which is expected to return at most one row with a single column.
// It returns (value, true, nil) on success, or (value, false, nil) if no row was returned.