deb-heat/heat/engine/timestamp.py
Steve Baker 90203b89d5 Do not refresh timestamp from database on read.
Doing a database refresh on timestamp read is causing errors
such as:
heat.openstack.common.rpc.amqp InvalidRequestError:
  Could not refresh instance '<Stack at 0x2c95a90>'

This has only been seen using postgres, possibly because the problem is
being masked on mysql due to the driver's lack of concurrency.

The database refresh seems to be unnecessary, as there appears to be
no logic which depends on timestamps being accurate (nor is there
any timestamp comparison logic at all)

Fixes bug: #1193132
Change-Id: I22c3c4546a0f44b76a95e473b68b6fbb2e423b90
2013-06-21 10:43:34 +12:00

49 lines
1.6 KiB
Python

# vim: tabstop=4 shiftwidth=4 softtabstop=4
#
# 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.
from heat.common import exception
class Timestamp(object):
'''
A descriptor for writing a timestamp to the database.
'''
def __init__(self, db_fetch, attribute):
'''
Initialise with a function to fetch the database representation of an
object (given a context and ID) and the name of the attribute to
retrieve.
'''
self.db_fetch = db_fetch
self.attribute = attribute
def __get__(self, obj, obj_class):
'''
Get timestamp for the given object and class.
'''
if obj is None or obj.id is None:
return None
o = self.db_fetch(obj.context, obj.id)
return getattr(o, self.attribute)
def __set__(self, obj, timestamp):
'''Update the timestamp for the given object.'''
if obj.id is None:
raise exception.ResourceNotAvailable(resource_name=obj.name)
o = self.db_fetch(obj.context, obj.id)
o.update_and_save({self.attribute: timestamp})