99 lines
3.0 KiB
Python
99 lines
3.0 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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"""Session Handling for SQLAlchemy backend."""
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import sqlalchemy.interfaces
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import sqlalchemy.orm
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from sqlalchemy.exc import DisconnectionError
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from heat.openstack.common import log as logging
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from heat.db import api as db_api
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from heat.openstack.common import cfg
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logger = logging.getLogger('heat.db.sqlalchemy.session')
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_ENGINE = None
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_MAKER = None
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def get_session(autocommit=True, expire_on_commit=False):
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"""Return a SQLAlchemy session."""
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global _ENGINE, _MAKER
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if _MAKER is None or _ENGINE is None:
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_ENGINE = get_engine()
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_MAKER = get_maker(_ENGINE, autocommit, expire_on_commit)
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return _MAKER()
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class SynchronousSwitchListener(sqlalchemy.interfaces.PoolListener):
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"""Switch sqlite connections to non-synchronous mode"""
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def connect(self, dbapi_con, con_record):
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dbapi_con.execute("PRAGMA synchronous = OFF")
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class MySQLPingListener(object):
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"""
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Ensures that MySQL connections checked out of the
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pool are alive.
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Borrowed from:
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http://groups.google.com/group/sqlalchemy/msg/a4ce563d802c929f
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"""
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def checkout(self, dbapi_con, con_record, con_proxy):
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try:
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dbapi_con.cursor().execute('select 1')
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except dbapi_con.OperationalError, ex:
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if ex.args[0] in (2006, 2013, 2014, 2045, 2055):
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logger.warn('Got mysql server has gone away: %s', ex)
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raise DisconnectionError("Database server went away")
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else:
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raise
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def get_engine():
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"""Return a SQLAlchemy engine."""
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connection_dict = sqlalchemy.engine.url.make_url(_get_sql_connection())
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engine_args = {
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"pool_recycle": _get_sql_idle_timeout(),
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"echo": False,
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'convert_unicode': True,
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}
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if 'mysql' in connection_dict.drivername:
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engine_args['listeners'] = [MySQLPingListener()]
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return sqlalchemy.create_engine(_get_sql_connection(), **engine_args)
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def get_maker(engine, autocommit=True, expire_on_commit=False):
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"""Return a SQLAlchemy sessionmaker using the given engine."""
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ses = sqlalchemy.orm.sessionmaker(bind=engine,
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autocommit=autocommit,
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expire_on_commit=expire_on_commit)
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return sqlalchemy.orm.scoped_session(ses)
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def _get_sql_connection():
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return db_api.SQL_CONNECTION
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def _get_sql_idle_timeout():
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return db_api.SQL_IDLE_TIMEOUT
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