:param cs_cache:

        """

        from kallithea.lib.vcs.backends.base import BaseChangeset

        if cs_cache is None:

            cs_cache = EmptyChangeset()

            # use no-cache version here

            scm_repo = self.scm_instance_no_cache()

            if scm_repo:

                cs_cache = scm_repo.get_changeset()

        if isinstance(cs_cache, BaseChangeset):

            cs_cache = cs_cache.__json__()

        if (not self.changeset_cache or cs_cache['raw_id'] != self.changeset_cache['raw_id']):

            _default = datetime.datetime.fromtimestamp(0)

            last_change = cs_cache.get('date') or _default

            log.debug('updated repo %s with new cs cache %s'

                      % (self.repo_name, cs_cache))

            self.updated_on = last_change

            self.changeset_cache = cs_cache

            Session().add(self)

            Session().commit()

        else:

            log.debug('changeset_cache for %s already up to date with %s'

                      % (self.repo_name, cs_cache['raw_id']))

    @property

    def tip(self):

        return self.get_changeset('tip')

    @property

    def author(self):

        return self.tip.author

    @property

    def last_change(self):

        return self.scm_instance.last_change

    def get_comments(self, revisions=None):

        """

        Returns comments for this repository grouped by revisions

        :param revisions: filter query by revisions only

        """

        cmts = ChangesetComment.query()\

            .filter(ChangesetComment.repo == self)

        if revisions is not None:

            cmts = cmts.filter(ChangesetComment.revision.in_(revisions))

        grouped = collections.defaultdict(list)

        for cmt in cmts.all():

            grouped[cmt.revision].append(cmt)

        return grouped

    def statuses(self, revisions):

        """

        Returns statuses for this repository.

        PRs without any votes do _not_ show up as unreviewed.

        :param revisions: list of revisions to get statuses for

        """

        if not revisions:

            return {}

        statuses = ChangesetStatus.query()\

            .filter(ChangesetStatus.repo == self)\

            .filter(ChangesetStatus.version == 0)\

            .filter(ChangesetStatus.revision.in_(revisions))

        grouped = {}

        for stat in statuses.all():

            pr_id = pr_repo = None

            if stat.pull_request:

                pr_id = stat.pull_request.pull_request_id

                pr_repo = stat.pull_request.other_repo.repo_name

            grouped[stat.revision] = [str(stat.status), stat.status_lbl,

                                      pr_id, pr_repo]

        return grouped

    def _repo_size(self):

        from kallithea.lib import helpers as h

        log.debug('calculating repository size...')

        return h.format_byte_size(self.scm_instance.size)

    #==========================================================================

    # SCM CACHE INSTANCE

    #==========================================================================

    def set_invalidate(self):

        """

        Mark caches of this repo as invalid.

        """

        CacheInvalidation.set_invalidate(self.repo_name)

    def scm_instance_no_cache(self):

        return self.__get_instance()