Function startUnit

cgroup2/manager.go:1080–1126

(conn *systemdDbus.Conn, group string, properties []systemdDbus.Property, ignoreExists bool)

}

func startUnit(conn *systemdDbus.Conn, group string, properties []systemdDbus.Property, ignoreExists bool) error {
	ctx := context.TODO()

	statusChan := make(chan string, 1)
	defer close(statusChan)

	retry := true
	started := false

	for !started {
		if _, err := conn.StartTransientUnitContext(ctx, group, "replace", properties, statusChan); err != nil {
			if !isUnitExists(err) {
				return err
			}

			if ignoreExists {
				return nil
			}

			if retry {
				retry = false
				// When a unit of the same name already exists, it may be a leftover failed unit.
				// If we reset it once, systemd can try to remove it.
				attemptFailedUnitReset(conn, group)
				continue
			}

			return err
		} else {
			started = true
		}
	}

	systemdStartUnitTimeout := 30 * time.Second
	select {
	case s := <-statusChan:
		if s != "done" {
			attemptFailedUnitReset(conn, group)
			return fmt.Errorf("error creating systemd unit `%s`: got `%s`", group, s)
		}
	case <-time.After(systemdStartUnitTimeout):
		attemptFailedUnitReset(conn, group)
		return fmt.Errorf("timed out while waiting for StartTransientUnit(%s) completion signal from dbus after %v", group, systemdStartUnitTimeout)
	}

	return nil
}

func attemptFailedUnitReset(conn *systemdDbus.Conn, group string) {
	ctx := context.TODO()