[win32] fix deadlock occuring on the sequence tables with SQLServer
actually, this deadlock would occur with any db backend other that PostgreSQL
as the previous code was heavily relying on PG's SEQUENCE facility, not available
elsewhere.
Deadlock description:
Thread1 starts creating entities (and therefore calls create_eid):
-> this creates a DB-level lock on the entities_id_seq table, which
will last until end of transaction
Thread2 calls create_eid, which acquires the Python lock object, but
updating the entities_id_seq is held by the DB lock
Thread1 wants to create a new entity, calls create_eid, and is stuck by
the Python lock object held by Thread2.
Solution:
use a separate connection to read and write the entities_id_seq table.
# 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/>.
"""Fake objects to ease testing of cubicweb without a fully working environment
"""
__docformat__ = "restructuredtext en"
from logilab.database import get_db_helper
from cubicweb.req import RequestSessionBase
from cubicweb.cwvreg import CubicWebVRegistry
from cubicweb.web.request import CubicWebRequestBase
from cubicweb.devtools import BASE_URL, BaseApptestConfiguration
class FakeConfig(dict, BaseApptestConfiguration):
translations = {}
apphome = None
def __init__(self, appid='data', apphome=None, cubes=()):
self.appid = appid
self.apphome = apphome
self._cubes = cubes
self['auth-mode'] = 'cookie'
self['uid'] = None
self['base-url'] = BASE_URL
self['rql-cache-size'] = 100
def cubes(self, expand=False):
return self._cubes
def sources(self):
return {}
class FakeRequest(CubicWebRequestBase):
"""test implementation of an cubicweb request object"""
def __init__(self, *args, **kwargs):
if not (args or 'vreg' in kwargs):
kwargs['vreg'] = CubicWebVRegistry(FakeConfig(), initlog=False)
kwargs['https'] = False
self._url = kwargs.pop('url', 'view?rql=Blop&vid=blop')
super(FakeRequest, self).__init__(*args, **kwargs)
self._session_data = {}
self._headers = {}
def header_accept_language(self):
"""returns an ordered list of preferred languages"""
return ('en',)
def header_if_modified_since(self):
return None
def base_url(self):
"""return the root url of the instance"""
return BASE_URL
def relative_path(self, includeparams=True):
"""return the normalized path of the request (ie at least relative
to the instance's root, but some other normalization may be needed
so that the returned path may be used to compare to generated urls
"""
if self._url.startswith(BASE_URL):
url = self._url[len(BASE_URL):]
else:
url = self._url
if includeparams:
return url
return url.split('?', 1)[0]
def set_content_type(self, content_type, filename=None, encoding=None):
"""set output content type for this request. An optional filename
may be given
"""
pass
def set_header(self, header, value, raw=True):
"""set an output HTTP header"""
self._headers[header] = value
def add_header(self, header, value):
"""set an output HTTP header"""
self._headers[header] = value # XXX
def remove_header(self, header):
"""remove an output HTTP header"""
self._headers.pop(header, None)
def get_header(self, header, default=None):
"""return the value associated with the given input header,
raise KeyError if the header is not set
"""
return self._headers.get(header, default)
def set_cookie(self, cookie, key, maxage=300, expires=None):
"""set / update a cookie key
by default, cookie will be available for the next 5 minutes
"""
morsel = cookie[key]
if maxage is not None:
morsel['Max-Age'] = maxage
if expires:
morsel['expires'] = expires.strftime('%a, %d %b %Y %H:%M:%S %z')
# make sure cookie is set on the correct path
morsel['path'] = self.base_url_path()
self.add_header('Set-Cookie', morsel.OutputString())
self.add_header('Cookie', morsel.OutputString())
def remove_cookie(self, cookie, key):
self.remove_header('Set-Cookie')
self.remove_header('Cookie')
def validate_cache(self):
pass
class FakeUser(object):
login = 'toto'
eid = 0
def in_groups(self, groups):
return True
class FakeSession(RequestSessionBase):
read_security = write_security = True
set_read_security = set_write_security = lambda *args, **kwargs: None
def __init__(self, repo=None, user=None):
self.repo = repo
self.vreg = getattr(self.repo, 'vreg', CubicWebVRegistry(FakeConfig(), initlog=False))
self.pool = FakePool()
self.user = user or FakeUser()
self.is_internal_session = False
self.transaction_data = {}
def execute(self, *args, **kwargs):
pass
def commit(self, *args):
self.transaction_data.clear()
def close(self, *args):
pass
def system_sql(self, sql, args=None):
pass
def set_entity_cache(self, entity):
pass
class FakeRepo(object):
querier = None
def __init__(self, schema, vreg=None, config=None):
self.extids = {}
self.eids = {}
self._count = 0
self.schema = schema
self.config = config or FakeConfig()
self.vreg = vreg or CubicWebVRegistry(self.config, initlog=False)
self.vreg.schema = schema
def internal_session(self):
return FakeSession(self)
def extid2eid(self, source, extid, etype, session, insert=True,
recreate=False):
try:
return self.extids[extid]
except KeyError:
if not insert:
return None
self._count += 1
eid = self._count
entity = source.before_entity_insertion(session, extid, etype, eid)
self.extids[extid] = eid
self.eids[eid] = extid
source.after_entity_insertion(session, extid, entity)
return eid
def eid2extid(self, source, eid, session=None):
return self.eids[eid]
class FakeSource(object):
dbhelper = get_db_helper('sqlite')
def __init__(self, uri):
self.uri = uri
class FakePool(object):
def source(self, uri):
return FakeSource(uri)