218 lines
7.4 KiB
Python
218 lines
7.4 KiB
Python
# Copyright (c) 2015 OpenStack Foundation
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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 eventlet
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eventlet.monkey_patch()
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import inspect
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import random
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import time
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from sqlalchemy import func
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from sqlalchemy.orm import exc as orm_exc
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from dragonflow._i18n import _LI, _LE
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from dragonflow.common import exceptions as df_exceptions
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from dragonflow.db.neutron import models
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from neutron.db import api as db_api
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from oslo_db import api as oslo_db_api
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from oslo_db import exception as db_exc
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from oslo_log import log
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from oslo_utils import excutils
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import six
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# Used to identify each API session
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LOCK_SEED = 9876543210
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# Used to wait and retry for Galera
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DB_INIT_RETRY_INTERVAL = 1
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DB_MAX_RETRY_INTERVAL = 10
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# Used to wait and retry for distributed lock
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LOCK_MAX_RETRIES = 100
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LOCK_INIT_RETRY_INTERVAL = 2
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LOCK_MAX_RETRY_INTERVAL = 10
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LOCK_INC_RETRY_INTERVAL = 1
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# global lock id
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GLOBAL_LOCK_ID = "ffffffffffffffffffffffffffffffff"
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LOG = log.getLogger(__name__)
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class wrap_db_lock(object):
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def __init__(self):
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super(wrap_db_lock, self).__init__()
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def __call__(self, f):
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@six.wraps(f)
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def wrap_db_lock(*args, **kwargs):
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context = args[1] # the neutron context object
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session_id = 0
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result = None
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# NOTE(nick-ma-z): In some admin operations in Neutron,
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# the project_id is set to None, so we set it to a global
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# lock id.
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lock_id = context.project_id
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if not lock_id:
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lock_id = GLOBAL_LOCK_ID
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# magic to prevent from nested lock
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within_wrapper = False
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for frame in inspect.stack()[1:]:
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if frame[3] == 'wrap_db_lock':
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within_wrapper = True
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break
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if not within_wrapper:
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# test and create the lock if necessary
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_test_and_create_object(lock_id)
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session_id = _acquire_lock(lock_id)
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try:
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result = f(*args, **kwargs)
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except Exception as e:
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with excutils.save_and_reraise_exception() as ctxt:
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ctxt.reraise = True
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finally:
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if not within_wrapper:
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try:
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_release_lock(lock_id, session_id)
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except Exception as e:
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LOG.exception(e)
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return result
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return wrap_db_lock
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@oslo_db_api.wrap_db_retry(max_retries=db_api.MAX_RETRIES,
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retry_interval=DB_INIT_RETRY_INTERVAL,
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inc_retry_interval=True,
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max_retry_interval=DB_MAX_RETRY_INTERVAL,
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retry_on_deadlock=True,
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retry_on_request=True)
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def _acquire_lock(oid):
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# generate temporary session id for this API context
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sid = _generate_session_id()
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# NOTE(nick-ma-z): we disallow subtransactions because the
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# retry logic will bust any parent transactions
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wait_lock_retries = LOCK_MAX_RETRIES
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retry_interval = LOCK_INIT_RETRY_INTERVAL
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while(wait_lock_retries > 0):
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try:
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session = db_api.get_session()
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with session.begin():
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LOG.info(_LI("Try to get lock for object %(oid)s in "
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"session %(sid)s."), {'oid': oid, 'sid': sid})
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row = _get_object_with_lock(session, oid, False)
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_update_lock(session, row, True, session_id=sid)
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LOG.info(_LI("Lock is acquired for object %(oid)s in "
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"session %(sid)s."), {'oid': oid, 'sid': sid})
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return sid
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except orm_exc.NoResultFound:
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LOG.info(_LI("Lock has been obtained by other sessions. "
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"Wait here and retry."))
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time.sleep(retry_interval)
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wait_lock_retries = wait_lock_retries - 1
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# dynamically increase the retry_interval until it reaches
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# the maximum of interval and then return to the initial value.
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if retry_interval >= LOCK_MAX_RETRY_INTERVAL:
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retry_interval = LOCK_INIT_RETRY_INTERVAL
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else:
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retry_interval = retry_interval + LOCK_INC_RETRY_INTERVAL
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# NOTE(nick-ma-z): The lock cannot be acquired.
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raise df_exceptions.DBLockFailed(oid=oid, sid=sid)
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@oslo_db_api.wrap_db_retry(max_retries=db_api.MAX_RETRIES,
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retry_interval=DB_INIT_RETRY_INTERVAL,
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inc_retry_interval=True,
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max_retry_interval=DB_MAX_RETRY_INTERVAL,
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retry_on_deadlock=True,
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retry_on_request=True)
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def _release_lock(oid, sid):
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# NOTE(nick-ma-z): we disallow subtransactions because the
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# retry logic will bust any parent transactions
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try:
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session = db_api.get_session()
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with session.begin():
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LOG.info(_LI("Try to get lock for object %(oid)s in "
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"session %(sid)s."), {'oid': oid, 'sid': sid})
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row = _get_object_with_lock(session, oid, True,
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session_id=sid)
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_update_lock(session, row, False, session_id=0)
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LOG.info(_LI("Lock is released for object %(oid)s in "
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"session %(sid)s."), {'oid': oid, 'sid': sid})
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except orm_exc.NoResultFound:
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LOG.exception(_LE("The lock for object %(oid)s is lost in the "
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"session %(sid)s and obtained by other "
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"sessions."), {'oid': oid, 'sid': sid})
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def _generate_session_id():
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return random.randint(0, LOCK_SEED)
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def _test_and_create_object(id):
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try:
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session = db_api.get_session()
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with session.begin():
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session.query(models.DFLockedObjects).filter_by(
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object_uuid=id).one()
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except orm_exc.NoResultFound:
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try:
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session = db_api.get_session()
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with session.begin():
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_create_db_row(session, oid=id)
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except db_exc.DBDuplicateEntry:
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# the lock is concurrently created.
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pass
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def _get_object_with_lock(session, id, state, session_id=None):
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row = None
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if session_id:
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row = session.query(models.DFLockedObjects).filter_by(
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object_uuid=id, lock=state,
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session_id=session_id).with_for_update().one()
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else:
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row = session.query(models.DFLockedObjects).filter_by(
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object_uuid=id, lock=state).with_for_update().one()
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return row
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def _update_lock(session, row, lock, session_id):
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row.lock = lock
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row.session_id = session_id
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session.merge(row)
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session.flush()
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def _create_db_row(session, oid):
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row = models.DFLockedObjects(object_uuid=oid,
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lock=False, session_id=0,
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created_at=func.now())
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session.add(row)
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session.flush()
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