91 lines
2.6 KiB
Python
91 lines
2.6 KiB
Python
# Copyright 2011 VMware, Inc.
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# 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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import contextlib
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import six
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from oslo_config import cfg
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from oslo_db import api as oslo_db_api
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from oslo_db import exception as os_db_exception
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from oslo_db.sqlalchemy import session
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from sqlalchemy import exc
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from sqlalchemy import orm
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_FACADE = None
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MAX_RETRIES = 10
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retry_db_errors = oslo_db_api.wrap_db_retry(max_retries=MAX_RETRIES,
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retry_on_deadlock=True)
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def _create_facade_lazily():
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global _FACADE
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if _FACADE is None:
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_FACADE = session.EngineFacade.from_config(cfg.CONF, sqlite_fk=True)
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return _FACADE
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def get_engine():
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"""Helper method to grab engine."""
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facade = _create_facade_lazily()
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return facade.get_engine()
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def dispose():
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# Don't need to do anything if an enginefacade hasn't been created
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if _FACADE is not None:
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get_engine().pool.dispose()
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def get_session(autocommit=True, expire_on_commit=False, use_slave=False):
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"""Helper method to grab session."""
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facade = _create_facade_lazily()
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return facade.get_session(autocommit=autocommit,
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expire_on_commit=expire_on_commit,
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use_slave=use_slave)
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@contextlib.contextmanager
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def autonested_transaction(sess):
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"""This is a convenience method to not bother with 'nested' parameter."""
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try:
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session_context = sess.begin_nested()
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except exc.InvalidRequestError:
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session_context = sess.begin(subtransactions=True)
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finally:
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with session_context as tx:
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yield tx
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class convert_db_exception_to_retry(object):
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"""Converts other types of DB exceptions into RetryRequests."""
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def __init__(self, stale_data=False):
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self.to_catch = ()
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if stale_data:
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self.to_catch += (orm.exc.StaleDataError, )
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def __call__(self, f):
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@six.wraps(f)
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def wrapper(*args, **kwargs):
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try:
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return f(*args, **kwargs)
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except self.to_catch as e:
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raise os_db_exception.RetryRequest(e)
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return wrapper
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