Function Stepper

coderd/database/migrations/migrate.go:240–283

Stepper returns a function that runs SQL migrations one step at a time. Stepper cannot be closed pre-emptively, it must be run to completion (or until an error is encountered).

(db *sql.DB)

// Stepper cannot be closed pre-emptively, it must be run to completion
// (or until an error is encountered).
func Stepper(db *sql.DB) (next func() (version uint, more bool, err error), err error) {
	_, m, err := setup(db, migrations)
	if err != nil {
		return nil, xerrors.Errorf("migrate setup: %w", err)
	}

	return func() (version uint, more bool, err error) {
		defer func() {
			if !more {
				srcErr, dbErr := m.Close()
				if err != nil {
					return
				}
				if dbErr != nil {
					err = dbErr
					return
				}
				err = srcErr
			}
		}()

		err = m.Steps(1)
		if err != nil {
			switch {
			case errors.Is(err, migrate.ErrNoChange):
				// It's OK if no changes happened!
				return 0, false, nil
			case errors.Is(err, fs.ErrNotExist):
				// This error is encountered at the of Steps when
				// reading from embed.FS.
				return 0, false, nil
			}

			return 0, false, xerrors.Errorf("Step: %w", err)
		}

		v, _, err := m.Version()
		if err != nil {
			return 0, false, err
		}

		return v, true, nil
	}, nil
}