key = (repo_name + '_' + kind) if kind else repo_name

        cache_key = cls._get_cache_key(key)

        if valid_cache_keys and cache_key in valid_cache_keys:

            return True

        inv_obj = cls.query().filter(cls.cache_key == cache_key).scalar()

        if inv_obj is None:

            inv_obj = cls(cache_key, repo_name)

        elif inv_obj.cache_active:

            return True

        inv_obj.cache_active = True

        Session().add(inv_obj)

        try:

            Session().commit()

        except sqlalchemy.exc.IntegrityError:

            log.error('commit of CacheInvalidation failed - retrying')

            Session().rollback()

            inv_obj = cls.query().filter(cls.cache_key == cache_key).scalar()

            if inv_obj is None:

                log.error('failed to create CacheInvalidation entry')

                # TODO: fail badly?

            # else: TOCTOU - another thread added the key at the same time; no further action required

        return False

    @classmethod

    def get_valid_cache_keys(cls):

        """

        Return opaque object with information of which caches still are valid

        and can be used without checking for invalidation.

        """

        return set(inv_obj.cache_key for inv_obj in cls.query().filter(cls.cache_active).all())

class ChangesetComment(Base, BaseModel):

    __tablename__ = 'changeset_comments'

    __table_args__ = (

        Index('cc_revision_idx', 'revision'),

        Index('cc_pull_request_id_idx', 'pull_request_id'),

        _table_args_default_dict,

    )

    comment_id = Column(Integer(), unique=True, primary_key=True)

    repo_id = Column(Integer(), ForeignKey('repositories.repo_id'), nullable=False)

    revision = Column(String(40), nullable=True)

    pull_request_id = Column(Integer(), ForeignKey('pull_requests.pull_request_id'), nullable=True)

    line_no = Column(Unicode(10), nullable=True)

    f_path = Column(Unicode(1000), nullable=True)

    user_id = Column(Integer(), ForeignKey('users.user_id'), nullable=False)

    text = Column(UnicodeText(25000), nullable=False)

    created_on = Column(DateTime(timezone=False), nullable=False, default=datetime.datetime.now)

    modified_at = Column(DateTime(timezone=False), nullable=False, default=datetime.datetime.now)

    author = relationship('User')

    repo = relationship('Repository')

    # status_change is frequently used directly in templates - make it a lazy

    # join to avoid fetching each related ChangesetStatus on demand.

    # There will only be one ChangesetStatus referencing each comment so the join will not explode.

    status_change = relationship('ChangesetStatus',

                                 cascade="all, delete-orphan", lazy='joined')

    pull_request = relationship('PullRequest')

    @classmethod

    def get_users(cls, revision=None, pull_request_id=None):

        """

        Returns user associated with this ChangesetComment. ie those

        who actually commented

        :param cls:

        :param revision:

        """

        q = Session().query(User) \

                .join(ChangesetComment.author)

        if revision is not None:

            q = q.filter(cls.revision == revision)

        elif pull_request_id is not None:

            q = q.filter(cls.pull_request_id == pull_request_id)

        return q.all()

    def url(self):

        anchor = "comment-%s" % self.comment_id

        import kallithea.lib.helpers as h

        if self.revision:

            return h.url('changeset_home', repo_name=self.repo.repo_name, revision=self.revision, anchor=anchor)

        elif self.pull_request_id is not None:

            return self.pull_request.url(anchor=anchor)

    def deletable(self):

        return self.created_on > datetime.datetime.now() - datetime.timedelta(minutes=5)

class ChangesetStatus(Base, BaseModel):

    __tablename__ = 'changeset_statuses'

    __table_args__ = (

        Index('cs_revision_idx', 'revision'),

        Index('cs_version_idx', 'version'),

        Index('cs_pull_request_id_idx', 'pull_request_id'),

        Index('cs_changeset_comment_id_idx', 'changeset_comment_id'),

        Index('cs_pull_request_id_user_id_version_idx', 'pull_request_id', 'user_id', 'version'),

        UniqueConstraint('repo_id', 'revision', 'version'),

        _table_args_default_dict,

    )

    STATUS_NOT_REVIEWED = DEFAULT = 'not_reviewed'

    STATUS_APPROVED = 'approved'

    STATUS_REJECTED = 'rejected'

    STATUS_UNDER_REVIEW = 'under_review'

    STATUSES = [

        (STATUS_NOT_REVIEWED, _("Not reviewed")),  # (no icon) and default

        (STATUS_APPROVED, _("Approved")),

        (STATUS_REJECTED, _("Rejected")),

        (STATUS_UNDER_REVIEW, _("Under review")),

    ]

    changeset_status_id = Column(Integer(), unique=True, primary_key=True)

    repo_id = Column(Integer(), ForeignKey('repositories.repo_id'), nullable=False)

    user_id = Column(Integer(), ForeignKey('users.user_id'), nullable=False)

    revision = Column(String(40), nullable=True)

    status = Column(String(128), nullable=False, default=DEFAULT)

    changeset_comment_id = Column(Integer(), ForeignKey('changeset_comments.comment_id'), nullable=False)

    modified_at = Column(DateTime(), nullable=False, default=datetime.datetime.now)

    version = Column(Integer(), nullable=False, default=0)

    pull_request_id = Column(Integer(), ForeignKey('pull_requests.pull_request_id'), nullable=True)

    author = relationship('User')

    repo = relationship('Repository')

    comment = relationship('ChangesetComment')

    pull_request = relationship('PullRequest')

    def __unicode__(self):

        return u"<%s('%s:%s')>" % (

            self.__class__.__name__,

            self.status, self.author

        )

    @classmethod

    def get_status_lbl(cls, value):

        return dict(cls.STATUSES).get(value)

    @property

    def status_lbl(self):

        return ChangesetStatus.get_status_lbl(self.status)

class PullRequest(Base, BaseModel):

    __tablename__ = 'pull_requests'

    __table_args__ = (

        Index('pr_org_repo_id_idx', 'org_repo_id'),

        Index('pr_other_repo_id_idx', 'other_repo_id'),

        _table_args_default_dict,

    )

    # values for .status

    STATUS_NEW = u'new'

    STATUS_CLOSED = u'closed'

    pull_request_id = Column(Integer(), unique=True, primary_key=True)

    title = Column(Unicode(255), nullable=False)

    description = Column(UnicodeText(10240), nullable=False)

    status = Column(Unicode(255), nullable=False, default=STATUS_NEW) # only for closedness, not approve/reject/etc

    created_on = Column(DateTime(timezone=False), nullable=False, default=datetime.datetime.now)

    updated_on = Column(DateTime(timezone=False), nullable=False, default=datetime.datetime.now)

    user_id = Column(Integer(), ForeignKey('users.user_id'), nullable=False)

    _revisions = Column('revisions', UnicodeText(20500), nullable=False)  # 500 revisions max

    org_repo_id = Column(Integer(), ForeignKey('repositories.repo_id'), nullable=False)

    org_ref = Column(Unicode(255), nullable=False)

    other_repo_id = Column(Integer(), ForeignKey('repositories.repo_id'), nullable=False)

    other_ref = Column(Unicode(255), nullable=False)

    @hybrid_property

    def revisions(self):

        return self._revisions.split(':')

    @revisions.setter

    def revisions(self, val):

        self._revisions = safe_unicode(':'.join(val))

    @property

    def org_ref_parts(self):

        return self.org_ref.split(':')

    @property

    def other_ref_parts(self):

        return self.other_ref.split(':')

    owner = relationship('User')

    reviewers = relationship('PullRequestReviewers',

                             cascade="all, delete-orphan")

    org_repo = relationship('Repository', primaryjoin='PullRequest.org_repo_id==Repository.repo_id')

    other_repo = relationship('Repository', primaryjoin='PullRequest.other_repo_id==Repository.repo_id')

                             cascade="all, delete-orphan")

    def is_closed(self):

        return self.status == self.STATUS_CLOSED

    def user_review_status(self, user_id):

        """Return the user's latest status votes on PR"""

        # note: no filtering on repo - that would be redundant

        status = ChangesetStatus.query() \

            .filter(ChangesetStatus.pull_request == self) \

            .filter(ChangesetStatus.user_id == user_id) \

            .order_by(ChangesetStatus.version) \

            .first()

        return str(status.status) if status else ''

    @classmethod

    def make_nice_id(cls, pull_request_id):

        '''Return pull request id nicely formatted for displaying'''

        return '#%s' % pull_request_id

    def nice_id(self):

        '''Return the id of this pull request, nicely formatted for displaying'''

        return self.make_nice_id(self.pull_request_id)

    def __json__(self):

        return dict(

            revisions=self.revisions

        )

    def url(self, **kwargs):

        canonical = kwargs.pop('canonical', None)

        import kallithea.lib.helpers as h

        b = self.org_ref_parts[1]

        if b != self.other_ref_parts[1]:

            s = '/_/' + b

        else:

            s = '/_/' + self.title

        kwargs['extra'] = urlreadable(s)

        if canonical:

            return h.canonical_url('pullrequest_show', repo_name=self.other_repo.repo_name,

                                   pull_request_id=self.pull_request_id, **kwargs)

        return h.url('pullrequest_show', repo_name=self.other_repo.repo_name,

                     pull_request_id=self.pull_request_id, **kwargs)

class PullRequestReviewers(Base, BaseModel):

    __tablename__ = 'pull_request_reviewers'

    __table_args__ = (

        Index('pull_request_reviewers_user_id_idx', 'user_id'),

        _table_args_default_dict,

    )

    def __init__(self, user=None, pull_request=None):

        self.user = user

        self.pull_request = pull_request

    pull_requests_reviewers_id = Column(Integer(), unique=True, primary_key=True)

    pull_request_id = Column(Integer(), ForeignKey('pull_requests.pull_request_id'), nullable=False)

    user_id = Column(Integer(), ForeignKey('users.user_id'), nullable=False)

    user = relationship('User')

    pull_request = relationship('PullRequest')

class Notification(Base, BaseModel):

    __tablename__ = 'notifications'

    __table_args__ = (

        Index('notification_type_idx', 'type'),

        _table_args_default_dict,

    )

    TYPE_CHANGESET_COMMENT = u'cs_comment'

    TYPE_MESSAGE = u'message'

    TYPE_MENTION = u'mention'

    TYPE_REGISTRATION = u'registration'

    TYPE_PULL_REQUEST = u'pull_request'

    TYPE_PULL_REQUEST_COMMENT = u'pull_request_comment'

    notification_id = Column(Integer(), unique=True, primary_key=True)

    subject = Column(Unicode(512), nullable=False)

    body = Column(UnicodeText(50000), nullable=False)

    created_by = Column(Integer(), ForeignKey('users.user_id'), nullable=False)

    created_on = Column(DateTime(timezone=False), nullable=False, default=datetime.datetime.now)

    type_ = Column('type', Unicode(255), nullable=False)

    created_by_user = relationship('User')

    notifications_to_users = relationship('UserNotification', cascade="all, delete-orphan")

    @property

    def recipients(self):

        return [x.user for x in UserNotification.query()

                .filter(UserNotification.notification == self)

                .order_by(UserNotification.user_id.asc()).all()]

    @classmethod

    def create(cls, created_by, subject, body, recipients, type_=None):

        if type_ is None:

            type_ = Notification.TYPE_MESSAGE

        notification = cls()

        notification.created_by_user = created_by

        notification.subject = subject

        notification.body = body

        notification.type_ = type_

        notification.created_on = datetime.datetime.now()

        for recipient in recipients:

            un = UserNotification()

            un.notification = notification

            un.user_id = recipient.user_id

            # Mark notifications to self "pre-read" - should perhaps just be skipped

            if recipient == created_by:

                un.read = True

            Session().add(un)

        Session().add(notification)

        Session().flush() # assign notificaiton.notification_id

        return notification

    @property

    def description(self):

        from kallithea.model.notification import NotificationModel

        return NotificationModel().make_description(self)

class UserNotification(Base, BaseModel):

    __tablename__ = 'user_to_notification'

    __table_args__ = (

        UniqueConstraint('user_id', 'notification_id'),

        _table_args_default_dict,

    )

    user_id = Column(Integer(), ForeignKey('users.user_id'), primary_key=True)

    notification_id = Column(Integer(), ForeignKey('notifications.notification_id'), primary_key=True)

    read = Column(Boolean, nullable=False, default=False)

    sent_on = Column(DateTime(timezone=False), nullable=True) # FIXME: not nullable?

    user = relationship('User')

    notification = relationship('Notification')

    def mark_as_read(self):

        self.read = True

        Session().add(self)

class Gist(Base, BaseModel):

    __tablename__ = 'gists'

    __table_args__ = (

        Index('g_gist_access_id_idx', 'gist_access_id'),

        Index('g_created_on_idx', 'created_on'),

        _table_args_default_dict,

    )

    GIST_PUBLIC = u'public'

    GIST_PRIVATE = u'private'

    DEFAULT_FILENAME = u'gistfile1.txt'

    gist_id = Column(Integer(), unique=True, primary_key=True)

    gist_access_id = Column(Unicode(250), nullable=False)

    gist_description = Column(UnicodeText(1024), nullable=False)

    gist_owner = Column('user_id', Integer(), ForeignKey('users.user_id'), nullable=False)

    gist_expires = Column(Float(53), nullable=False)

    gist_type = Column(Unicode(128), nullable=False)

    created_on = Column(DateTime(timezone=False), nullable=False, default=datetime.datetime.now)

    modified_at = Column(DateTime(timezone=False), nullable=False, default=datetime.datetime.now)

    owner = relationship('User')

    def __repr__(self):

        return '<Gist:[%s]%s>' % (self.gist_type, self.gist_access_id)

    @classmethod

    def get_or_404(cls, id_):

        res = cls.query().filter(cls.gist_access_id == id_).scalar()

        if res is None:

            raise HTTPNotFound

        return res

    @classmethod

    def get_by_access_id(cls, gist_access_id):

        return cls.query().filter(cls.gist_access_id == gist_access_id).scalar()

    def gist_url(self):

        import kallithea

        alias_url = kallithea.CONFIG.get('gist_alias_url')

        if alias_url:

            return alias_url.replace('{gistid}', self.gist_access_id)

        import kallithea.lib.helpers as h

        return h.canonical_url('gist', gist_id=self.gist_access_id)

    @classmethod

    def base_path(cls):