[Bug] RoleManager's MatchingFunc Lost After Calling (*SyncedEnforcer).LoadPolicyFast

[yougahu]

Describe the bug

(*SyncedEnforcer).LoadPolicyFast do not inherit the previous RoleManager's MatchingFunc because it rebuilds all RoleManagers.

// LoadPolicyFast is not blocked when adapter calls LoadPolicy.
func (e *SyncedEnforcer) LoadPolicyFast() error {
        ...
	if e.autoBuildRoleLinks {
		for ptype := range newModel["g"] {
			newRmMap[ptype] = defaultrolemanager.NewRoleManager(10)
		}
		err = newModel.BuildRoleLinks(newRmMap)
		if err != nil {
			return err
		}
	}
        ...
}

Compare to (*Enforcer).LoadPolicy(which maintains RoleManager's MatchingFunc):

func (e *Enforcer) LoadPolicy() error {
        ...
	if e.autoBuildRoleLinks {
		needToRebuild = true
		if err := e.rebuildRoleLinks(newModel); err != nil {
			return err
		}

		if err := e.rebuildConditionalRoleLinks(newModel); err != nil {
			return err
		}
	}
        ...
}

func (e *Enforcer) rebuildRoleLinks(newModel model.Model) error {
	if len(e.rmMap) != 0 {
		for _, rm := range e.rmMap {
			err := rm.Clear()
			if err != nil {
				return err
			}
		}

		err := newModel.BuildRoleLinks(e.rmMap)
		if err != nil {
			return err
		}
	}

	return nil
}

Expected behavior

(*SyncedEnforcer).LoadPolicyFast maintains all RoleManager's MatchingFunc.

Actual behavior

RoleManager's MatchingFunc lost after calling (*SyncedEnforcer).LoadPolicyFast, which could cause enforce fail.

[casbin-bot]

@tangyang9464 @JalinWang

[CaffreyZhang]

I'm having the same problem right now.
But I use the trick way to avoid it.

e, err := genEnforcer(db)
if err != nil {
log.WithField("err", err.Error()).Error("New casbin enforcer error.")
return
}

E.GetLock().Lock()
defer E.GetLock().Unlock()
E.Enforcer = e.Enforcer