code: func (p *UserPrivileges) FindEdge(ctx sessionctx.Context, role *auth.RoleIdentity, user *auth.UserIdentity) bool {
  	mysqlPrivilege := p.Handle.Get()
  	ok := mysqlPrivilege.FindRole(user.Username, user.Hostname, role)
  	if !ok {
  		logutil.Logger(context.Background()).Error("find role failed", zap.Stringer("role", role))
  		return false
  	}
  	return true
  }
docs: // FindEdge implements privilege.Manager FindRelationship interface.