[session] use a dedicated class to track cnxset
We introduce a new CnxSetTracker to track `cnxset` used by Transaction and
allows to wait for them. This new class does not use Thread ID not thread
joining to work. This allows to use multiple transaction per thread and a
transaction in multiple thread.
The class itself is totally threadsafe by the Transaction is still not
thread safe.
The old _threads_in_transaction attribute is dropped in favor of a new logic
based on this object. The registration of cnxset used is not done by the
Transaction itself. tx.cnset is a property handling the Consistency of its value
with the CnxSetTracker instance.
Note: The CnxSetTracker instance only track transaction id, not transaction
itself, So not reference cycle are created.
# pylint: disable=W0614,W0401
# copyright 2003-2010 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of CubicWeb.
#
# CubicWeb is free software: you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option)
# any later version.
#
# CubicWeb 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 Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with CubicWeb. If not, see <http://www.gnu.org/licenses/>.
from warnings import warn
warn('moved to cubicweb.dataimport', DeprecationWarning, stacklevel=2)
from cubicweb.dataimport import *