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# Copyright (C) 2011-2014 by the Free Software Foundation, Inc.
#
# This file is part of GNU Mailman.
#
# GNU Mailman is free software: you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option)
# any later version.
#
# GNU Mailman is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
# more details.
#
# You should have received a copy of the GNU General Public License along with
# GNU Mailman. If not, see <http://www.gnu.org/licenses/>.
"""Unique IDs."""
from __future__ import absolute_import, print_function, unicode_literals
__metaclass__ = type
__all__ = [
'UID',
]
from storm.locals import Int
from storm.properties import UUID
from mailman.database.model import Model
from mailman.database.transaction import dbconnection
class UID(Model):
"""Enforce uniqueness of uids through a database table.
This is used so that unique ids don't have to be tracked by each
individual model object that uses them. So for example, when a user is
deleted, we don't have to keep separate track of its uid to prevent it
from ever being used again. This class, hooked up to the
`UniqueIDFactory` serves that purpose.
There is no interface for this class, because it's purely an internal
implementation detail.
"""
id = Int(primary=True)
uid = UUID()
@dbconnection
def __init__(self, store, uid):
super(UID, self).__init__()
self.uid = uid
store.add(self)
def __repr__(self):
return '<UID {0} at {1}>'.format(self.uid, id(self))
@staticmethod
@dbconnection
# Note that the parameter order is deliberate reversed here. Normally,
# `store` is the first parameter after `self`, but since this is a
# staticmethod and there is no self, the decorator will see the uid in
# arg[0].
def record(uid, store):
"""Record the uid in the database.
:param uid: The unique id.
:type uid: unicode
:raises ValueError: if the id is not unique.
"""
existing = store.find(UID, uid=uid)
if existing.count() != 0:
raise ValueError(uid)
return UID(uid)
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