/usr/share/pyshared/melange/db/sqlalchemy/session.py is in python-melange 1:2012.1-3.
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# Copyright 2011 OpenStack LLC.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import contextlib
import logging
import sqlalchemy as sql
from sqlalchemy import create_engine
from sqlalchemy import MetaData
from sqlalchemy.exc import DisconnectionError
from sqlalchemy.orm import sessionmaker
from melange import ipam
from melange.common import config
from melange.db.sqlalchemy import mappers
_ENGINE = None
_MAKER = None
LOG = logging.getLogger('melange.db.sqlalchemy.session')
def configure_db(options, models_mapper=None):
configure_sqlalchemy_log(options)
global _ENGINE
if not _ENGINE:
_ENGINE = _create_engine(options)
if models_mapper:
models_mapper.map(_ENGINE)
else:
mappers.map(_ENGINE, ipam.models.persisted_models())
def configure_sqlalchemy_log(options):
debug = config.get_option(options, 'debug', type='bool', default=False)
verbose = config.get_option(options, 'verbose', type='bool', default=False)
logger = logging.getLogger('sqlalchemy.engine')
if debug:
logger.setLevel(logging.DEBUG)
elif verbose:
logger.setLevel(logging.INFO)
class MySQLPingListener(object):
"""
Ensures that MySQL connections checked out of the
pool are alive.
Borrowed from:
http://groups.google.com/group/sqlalchemy/msg/a4ce563d802c929f
"""
def checkout(self, dbapi_con, con_record, con_proxy):
try:
dbapi_con.cursor().execute('select 1')
except dbapi_con.OperationalError, ex:
if ex.args[0] in (2006, 2013, 2014, 2045, 2055):
LOG.warn('Got mysql server has gone away: %s', ex)
raise DisconnectionError("Database server went away")
else:
raise
def _create_engine(options):
connection_dict = sql.engine.url.make_url(options['sql_connection'])
engine_args = {
'pool_recycle': config.get_option(options,
'sql_idle_timeout',
type='int',
default=3600),
'echo': config.get_option(options,
'sql_query_log',
type='bool',
default=False),
'convert_unicode': True,
}
if 'mysql' in connection_dict.drivername:
engine_args['listeners'] = [MySQLPingListener()]
LOG.info("Creating SQLAlchemy engine with args: %s" % engine_args)
return create_engine(options['sql_connection'], **engine_args)
def get_session(autocommit=True, expire_on_commit=False):
"""Helper method to grab session."""
global _MAKER, _ENGINE
if not _MAKER:
assert _ENGINE
_MAKER = sessionmaker(bind=_ENGINE,
autocommit=autocommit,
expire_on_commit=expire_on_commit)
return _MAKER()
def raw_query(model, autocommit=True, expire_on_commit=False):
return get_session(autocommit, expire_on_commit).query(model)
def clean_db():
global _ENGINE
meta = MetaData()
meta.reflect(bind=_ENGINE)
with contextlib.closing(_ENGINE.connect()) as con:
trans = con.begin()
for table in reversed(meta.sorted_tables):
if table.name != "migrate_version":
con.execute(table.delete())
trans.commit()
def drop_db(options):
meta = MetaData()
engine = _create_engine(options)
meta.bind = engine
meta.reflect()
meta.drop_all()
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