or users group name

        :param perm: Instance of Permission, or permission_name

        """

        repo = self._get_repo(repo)

        group_name = self.__get_users_group(group_name)

        permission = self._get_perm(perm)

        # check if we have that permission already

        obj = self.sa.query(UsersGroupRepoToPerm)\

            .filter(UsersGroupRepoToPerm.users_group == group_name)\

            .filter(UsersGroupRepoToPerm.repository == repo)\

            .scalar()

        if obj is None:

            # create new

            obj = UsersGroupRepoToPerm()

        obj.repository = repo

        obj.users_group = group_name

        obj.permission = permission

        self.sa.add(obj)

        log.debug('Granted perm %s to %s on %s' % (perm, group_name, repo))

    def revoke_users_group_permission(self, repo, group_name):

        """

        Revoke permission for users group on given repository

        :param repo: Instance of Repository, repository_id, or repository name

        :param group_name: Instance of UserGroup, users_group_id,

            or users group name

        """

        repo = self._get_repo(repo)

        group_name = self.__get_users_group(group_name)

        obj = self.sa.query(UsersGroupRepoToPerm)\

            .filter(UsersGroupRepoToPerm.repository == repo)\

            .filter(UsersGroupRepoToPerm.users_group == group_name)\

            .scalar()

        if obj:

            self.sa.delete(obj)

            log.debug('Revoked perm to %s on %s' % (repo, group_name))

    def delete_stats(self, repo_name):

        """

        removes stats for given repo

        :param repo_name:

        """

        try:

            obj = self.sa.query(Statistics)\

            self.sa.delete(obj)

        except:

            log.error(traceback.format_exc())

            raise

    def __create_repo(self, repo_name, alias, parent, clone_uri=False):

        """

        makes repository on filesystem. It's group aware means it'll create

        a repository within a group, and alter the paths accordingly of

        group location

        :param repo_name:

        :param alias:

        :param parent_id:

        :param clone_uri:

        """

        from rhodecode.lib.utils import is_valid_repo, is_valid_repos_group

        from rhodecode.model.scm import ScmModel

        if parent:

            new_parent_path = os.sep.join(parent.full_path_splitted)

        else:

            new_parent_path = ''

        # we need to make it str for mercurial

        repo_path = os.path.join(*map(lambda x: safe_str(x),

                                [self.repos_path, new_parent_path, repo_name]))

        # check if this path is not a repository

        if is_valid_repo(repo_path, self.repos_path):

            raise Exception('This path %s is a valid repository' % repo_path)

        # check if this path is a group

        if is_valid_repos_group(repo_path, self.repos_path):

            raise Exception('This path %s is a valid group' % repo_path)

        log.info('creating repo %s in %s @ %s' % (

                     repo_name, safe_unicode(repo_path), clone_uri

                )

        )

        backend = get_backend(alias)

        if alias == 'hg':

            backend(repo_path, create=True, src_url=clone_uri)

        elif alias == 'git':

            r = backend(repo_path, create=True, src_url=clone_uri, bare=True)

            # add rhodecode hook into this repo

            ScmModel().install_git_hook(repo=r)

        else: