acd545f9c2
In order to rework some of the persistence layer I would like to move around some of the files first, keeping job specifics in a jobs folder. Having some of the items which are root level taskflow items (flow, task) be at the root of the hiearchy. Also for now until the celery work is commited move that, since it doesn't make sense in backends anyway. Change-Id: If6c149710b40f70d4ec69ee8e523defe8f5e766d
112 lines
3.4 KiB
Python
112 lines
3.4 KiB
Python
# -*- coding: utf-8 -*-
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# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright (C) 2012 Yahoo! Inc. All Rights Reserved.
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# Copyright (C) 2013 Rackspace Hosting All Rights Reserved.
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#
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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 logging
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import sqlalchemy
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import sqlalchemy.engine
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import sqlalchemy.interfaces
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import sqlalchemy.orm
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from sqlalchemy.pool import NullPool
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from sqlalchemy import exc
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from taskflow.persistence.backends import api as b_api
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LOG = logging.getLogger(__name__)
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_ENGINE = None
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_MAKER = None
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def get_session(autocommit=True, expire_on_commit=True):
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"""Return a SQLAlchemy session."""
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global _MAKER
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if _MAKER is None:
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_MAKER = get_maker(get_engine(), autocommit, expire_on_commit)
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return _MAKER()
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def synchronous_switch_listener(dbapi_conn, connection_rec):
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"""Switch sqlite connections to non-synchronous mode"""
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dbapi_conn.execute("PRAGMA synchronous = OFF")
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def ping_listener(dbapi_conn, connection_rec, connection_proxy):
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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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try:
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dbapi_conn.cursor().execute('select 1')
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except dbapi_conn.OperationalError, ex:
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if ex.args[0] in (2006, 2013, 2014, 2045, 2055):
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LOG.warn(_('Got mysql server has gone away: %s'), ex)
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raise exc.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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global _ENGINE
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if _ENGINE is None:
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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 "sqlite" in connection_dict.drivername:
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engine_args['poolclass'] = NullPool
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_ENGINE = sqlalchemy.create_engine(_get_sql_connection(),
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**engine_args)
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if 'mysql' in connection_dict.drivername:
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sqlalchemy.event.listen(_ENGINE, 'checkout', ping_listener)
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if 'sqlite' in connection_dict.drivername:
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sqlalchemy.event.listen(_ENGINE, 'connect',
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synchronous_switch_listener)
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# TODO(jharlow): Check to make sure engine connected
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return _ENGINE
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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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return 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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def _get_sql_connection():
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return b_api.SQL_CONNECTION
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def _get_sql_idle_timeout():
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return b_api.SQL_IDLE_TIMEOUT
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