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# Service heartbeat driver using Memcached
# Copyright (c) 2013 Akira Yoshiyama <akirayoshiyama at gmail dot com>
#
# This is derived from nova/servicegroup/drivers/db.py.
# Copyright 2012 IBM Corp.
#
# 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 oslo_log import log as logging
from oslo_utils import timeutils
from nova import cache_utils
import nova.conf
from nova.i18n import _, _LI, _LW
from nova.servicegroup import api
from nova.servicegroup.drivers import base
CONF = nova.conf.CONF
LOG = logging.getLogger(__name__)
class MemcachedDriver(base.Driver):
def __init__(self, *args, **kwargs):
self.mc = cache_utils.get_memcached_client(
expiration_time=CONF.service_down_time)
def join(self, member_id, group_id, service=None):
"""Join the given service with its group."""
LOG.debug('Memcached_Driver: join new ServiceGroup member '
'%(member_id)s to the %(group_id)s group, '
'service = %(service)s',
{'member_id': member_id,
'group_id': group_id,
'service': service})
if service is None:
raise RuntimeError(_('service is a mandatory argument for '
'Memcached based ServiceGroup driver'))
report_interval = service.report_interval
if report_interval:
service.tg.add_timer(report_interval, self._report_state,
api.INITIAL_REPORTING_DELAY, service)
def is_up(self, service_ref):
"""Moved from nova.utils
Check whether a service is up based on last heartbeat.
"""
key = "%(topic)s:%(host)s" % service_ref
is_up = self.mc.get(str(key)) is not None
if not is_up:
LOG.debug('Seems service %s is down', key)
return is_up
def _report_state(self, service):
"""Update the state of this service in the datastore."""
try:
key = "%(topic)s:%(host)s" % service.service_ref
# memcached has data expiration time capability.
# set(..., time=CONF.service_down_time) uses it and
# reduces key-deleting code.
self.mc.set(str(key),
timeutils.utcnow())
# TODO(termie): make this pattern be more elegant.
if getattr(service, 'model_disconnected', False):
service.model_disconnected = False
LOG.info(
_LI('Recovered connection to memcache server '
'for reporting service status.'))
# TODO(vish): this should probably only catch connection errors
except Exception:
if not getattr(service, 'model_disconnected', False):
service.model_disconnected = True
LOG.warning(_LW('Lost connection to memcache server '
'for reporting service status.'))
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