# vim: tabstop=4 shiftwidth=4 softtabstop=4 # Copyright 2011 Nicira Networks, Inc. # 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. # @author: Somik Behera, Nicira Networks, Inc. # @author: Brad Hall, Nicira Networks, Inc. # @author: Dan Wendlandt, Nicira Networks, Inc. import time from eventlet import db_pool from eventlet import greenthread try: import MySQLdb except ImportError: MySQLdb = None import sqlalchemy as sql from sqlalchemy import create_engine from sqlalchemy.exc import DisconnectionError from sqlalchemy.interfaces import PoolListener from sqlalchemy.orm import sessionmaker from quantum.db import model_base from quantum.openstack.common import cfg from quantum.openstack.common import log as logging LOG = logging.getLogger(__name__) database_opts = [ cfg.StrOpt('sql_connection', default='sqlite://', help=_('The SQLAlchemy connection string used to connect to ' 'the database')), cfg.IntOpt('sql_max_retries', default=-1, help=_('Database reconnection retry times')), cfg.IntOpt('reconnect_interval', default=2, help=_('Database reconnection interval in seconds')), cfg.IntOpt('sql_min_pool_size', default=1, help=_("Minimum number of SQL connections to keep open in a " "pool")), cfg.IntOpt('sql_max_pool_size', default=5, help=_("Maximum number of SQL connections to keep open in a " "pool")), cfg.IntOpt('sql_idle_timeout', default=3600, help=_("Timeout in seconds before idle sql connections are " "reaped")), cfg.BoolOpt('sql_dbpool_enable', default=False, help=_("Enable the use of eventlet's db_pool for MySQL")), ] cfg.CONF.register_opts(database_opts, "DATABASE") _ENGINE = None _MAKER = None BASE = model_base.BASEV2 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 class SqliteForeignKeysListener(PoolListener): """ Ensures that the foreign key constraints are enforced in SQLite. The foreign key constraints are disabled by default in SQLite, so the foreign key constraints will be enabled here for every database connection """ def connect(self, dbapi_con, con_record): dbapi_con.execute('pragma foreign_keys=ON') def configure_db(): """ Establish the database, create an engine if needed, and register the models. """ global _ENGINE if not _ENGINE: sql_connection = cfg.CONF.DATABASE.sql_connection connection_dict = sql.engine.url.make_url(sql_connection) engine_args = { 'pool_recycle': 3600, 'echo': False, 'convert_unicode': True, } if 'mysql' in connection_dict.drivername: engine_args['listeners'] = [MySQLPingListener()] if (MySQLdb is not None and cfg.CONF.DATABASE.sql_dbpool_enable): pool_args = { 'db': connection_dict.database, 'passwd': connection_dict.password or '', 'host': connection_dict.host, 'user': connection_dict.username, 'min_size': cfg.CONF.DATABASE.sql_min_pool_size, 'max_size': cfg.CONF.DATABASE.sql_max_pool_size, 'max_idle': cfg.CONF.DATABASE.sql_idle_timeout } creator = db_pool.ConnectionPool(MySQLdb, **pool_args) engine_args['creator'] = creator.create if (MySQLdb is None and cfg.CONF.DATABASE.sql_dbpool_enable): LOG.warn(_("Eventlet connection pooling will not work without " "python-mysqldb!")) if 'sqlite' in connection_dict.drivername: engine_args['listeners'] = [SqliteForeignKeysListener()] if sql_connection == "sqlite://": engine_args["connect_args"] = {'check_same_thread': False} _ENGINE = create_engine(sql_connection, **engine_args) sql.event.listen(_ENGINE, 'checkin', greenthread_yield) if not register_models(): if cfg.CONF.DATABASE.reconnect_interval: remaining = cfg.CONF.DATABASE.sql_max_retries reconnect_interval = cfg.CONF.DATABASE.reconnect_interval retry_registration(remaining, reconnect_interval) def clear_db(base=BASE): global _ENGINE, _MAKER assert _ENGINE unregister_models(base) if _MAKER: _MAKER.close_all() _MAKER = None _ENGINE.dispose() _ENGINE = None 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 retry_registration(remaining, reconnect_interval, base=BASE): if remaining == -1: remaining = 'infinite' while True: if remaining != 'infinite': if remaining == 0: LOG.error(_("Database connection lost, exit...")) break remaining -= 1 LOG.info(_("Unable to connect to database, %(remaining)s attempts " "left. Retrying in %(reconnect_interval)s seconds"), locals()) time.sleep(reconnect_interval) if register_models(base): break def register_models(base=BASE): """Register Models and create properties""" global _ENGINE assert _ENGINE try: base.metadata.create_all(_ENGINE) except sql.exc.OperationalError as e: LOG.info(_("Database registration exception: %s"), e) return False return True def unregister_models(base=BASE): """Unregister Models, useful clearing out data before testing""" global _ENGINE assert _ENGINE base.metadata.drop_all(_ENGINE) def greenthread_yield(dbapi_con, con_record): """ Ensure other greenthreads get a chance to execute by forcing a context switch. With common database backends (eg MySQLdb and sqlite), there is no implicit yield caused by network I/O since they are implemented by C libraries that eventlet cannot monkey patch. """ greenthread.sleep(0)