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OpenStack Study: mc.py**** CubicPower OpenStack Study ****
# Service heartbeat driver using Memcached # Copyright (c) 2013 Akira Yoshiyama # # 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.config import cfg from nova import conductor from nova import context from nova.openstack.common.gettextutils import _ from nova.openstack.common import log as logging from nova.openstack.common import memorycache from nova.openstack.common import timeutils from nova.servicegroup import api CONF = cfg.CONF CONF.import_opt('service_down_time', 'nova.service') CONF.import_opt('memcached_servers', 'nova.openstack.common.memorycache') LOG = logging.getLogger(__name__)
**** CubicPower OpenStack Study **** class MemcachedDriver(api.ServiceGroupDriver):
**** CubicPower OpenStack Study **** def __init__(self, *args, **kwargs): test = kwargs.get('test') if not CONF.memcached_servers and not test: raise RuntimeError(_('memcached_servers not defined')) self.mc = memorycache.get_client() self.db_allowed = kwargs.get('db_allowed', True) self.conductor_api = conductor.API(use_local=self.db_allowed)
**** CubicPower OpenStack Study **** def join(self, member_id, group_id, service=None): """Join the given service with its group.""" msg = _('Memcached_Driver: join new ServiceGroup member ' '%(member_id)s to the %(group_id)s group, ' 'service = %(service)s') LOG.debug(msg, {'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)
**** CubicPower OpenStack Study **** 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 return self.mc.get(str(key)) is not None
**** CubicPower OpenStack Study **** def get_all(self, group_id): """Returns ALL members of the given group """ LOG.debug(_('Memcached_Driver: get_all members of the %s group') % group_id) rs = [] ctxt = context.get_admin_context() services = self.conductor_api.service_get_all_by_topic(ctxt, group_id) for service in services: if self.is_up(service): rs.append(service['host']) return rs
**** CubicPower OpenStack Study **** def _report_state(self, service): """Update the state of this service in the datastore.""" ctxt = context.get_admin_context() 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(), time=CONF.service_down_time) # TODO(termie): make this pattern be more elegant. if getattr(service, 'model_disconnected', False): service.model_disconnected = False LOG.error(_('Recovered model server connection!')) # TODO(vish): this should probably only catch connection errors except Exception: # pylint: disable=W0702 if not getattr(service, 'model_disconnected', False): service.model_disconnected = True LOG.exception(_('model server went away'))
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