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OpenStack Study: filter_scheduler.py**** CubicPower OpenStack Study ****
# Copyright (c) 2011 Intel Corporation # Copyright (c) 2011 OpenStack Foundation # All Rights Reserved. # # 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. """ The FilterScheduler is for creating volumes. You can customize this scheduler by specifying your own volume Filters and Weighing Functions. """ from oslo.config import cfg from cinder import exception from cinder.openstack.common import log as logging from cinder.scheduler import driver from cinder.scheduler import scheduler_options CONF = cfg.CONF LOG = logging.getLogger(__name__)
**** CubicPower OpenStack Study **** class FilterScheduler(driver.Scheduler): """Scheduler that can be used for filtering and weighing."""
**** CubicPower OpenStack Study **** def __init__(self, *args, **kwargs): super(FilterScheduler, self).__init__(*args, **kwargs) self.cost_function_cache = None self.options = scheduler_options.SchedulerOptions() self.max_attempts = self._max_attempts()
**** CubicPower OpenStack Study **** def schedule(self, context, topic, method, *args, **kwargs): """The schedule() contract requires we return the one best-suited host for this request. """ self._schedule(context, topic, *args, **kwargs)
**** CubicPower OpenStack Study **** def _get_configuration_options(self): """Fetch options dictionary. Broken out for testing.""" return self.options.get_configuration()
**** CubicPower OpenStack Study **** def populate_filter_properties(self, request_spec, filter_properties): """Stuff things into filter_properties. Can be overridden in a subclass to add more data. """ vol = request_spec['volume_properties'] filter_properties['size'] = vol['size'] filter_properties['availability_zone'] = vol.get('availability_zone') filter_properties['user_id'] = vol.get('user_id') filter_properties['metadata'] = vol.get('metadata') filter_properties['qos_specs'] = vol.get('qos_specs')
**** CubicPower OpenStack Study **** def schedule_create_volume(self, context, request_spec, filter_properties): weighed_host = self._schedule(context, request_spec, filter_properties) if not weighed_host: raise exception.NoValidHost(reason="") host = weighed_host.obj.host volume_id = request_spec['volume_id'] snapshot_id = request_spec['snapshot_id'] image_id = request_spec['image_id'] updated_volume = driver.volume_update_db(context, volume_id, host) self._post_select_populate_filter_properties(filter_properties, weighed_host.obj) # context is not serializable filter_properties.pop('context', None) self.volume_rpcapi.create_volume(context, updated_volume, host, request_spec, filter_properties, allow_reschedule=True, snapshot_id=snapshot_id, image_id=image_id)
**** CubicPower OpenStack Study **** def host_passes_filters(self, context, host, request_spec, filter_properties): """Check if the specified host passes the filters.""" weighed_hosts = self._get_weighted_candidates(context, request_spec, filter_properties) for weighed_host in weighed_hosts: host_state = weighed_host.obj if host_state.host == host: return host_state msg = (_('cannot place volume %(id)s on %(host)s') % {'id': request_spec['volume_id'], 'host': host}) raise exception.NoValidHost(reason=msg)
**** CubicPower OpenStack Study **** def find_retype_host(self, context, request_spec, filter_properties={}, migration_policy='never'): """Find a host that can accept the volume with its new type.""" current_host = request_spec['volume_properties']['host'] # The volume already exists on this host, and so we shouldn't check if # it can accept the volume again in the CapacityFilter. filter_properties['vol_exists_on'] = current_host weighed_hosts = self._get_weighted_candidates(context, request_spec, filter_properties) if not weighed_hosts: msg = (_('No valid hosts for volume %(id)s with type %(type)s') % {'id': request_spec['volume_id'], 'type': request_spec['volume_type']}) raise exception.NoValidHost(reason=msg) for weighed_host in weighed_hosts: host_state = weighed_host.obj if host_state.host == current_host: return host_state if migration_policy == 'never': msg = (_('Current host not valid for volume %(id)s with type ' '%(type)s, migration not allowed') % {'id': request_spec['volume_id'], 'type': request_spec['volume_type']}) raise exception.NoValidHost(reason=msg) top_host = self._choose_top_host(weighed_hosts, request_spec) return top_host.obj
**** CubicPower OpenStack Study **** def _post_select_populate_filter_properties(self, filter_properties, host_state): """Add additional information to the filter properties after a host has been selected by the scheduling process. """ # Add a retry entry for the selected volume backend: self._add_retry_host(filter_properties, host_state.host)
**** CubicPower OpenStack Study **** def _add_retry_host(self, filter_properties, host): """Add a retry entry for the selected volume backend. In the event that the request gets re-scheduled, this entry will signal that the given backend has already been tried. """ retry = filter_properties.get('retry', None) if not retry: return hosts = retry['hosts'] hosts.append(host)
**** CubicPower OpenStack Study **** def _max_attempts(self): max_attempts = CONF.scheduler_max_attempts if max_attempts < 1: msg = _("Invalid value for 'scheduler_max_attempts', " "must be >=1") raise exception.InvalidParameterValue(err=msg) return max_attempts
**** CubicPower OpenStack Study **** def _log_volume_error(self, volume_id, retry): """If the request contained an exception from a previous volume create operation, log it to aid debugging """ exc = retry.pop('exc', None) # string-ified exception from volume if not exc: return # no exception info from a previous attempt, skip hosts = retry.get('hosts', None) if not hosts: return # no previously attempted hosts, skip last_host = hosts[-1] msg = _("Error scheduling %(volume_id)s from last vol-service: " "%(last_host)s : %(exc)s") % { 'volume_id': volume_id, 'last_host': last_host, 'exc': exc, } LOG.error(msg)
**** CubicPower OpenStack Study **** def _populate_retry(self, filter_properties, properties): """Populate filter properties with history of retries for this request. If maximum retries is exceeded, raise NoValidHost. """ max_attempts = self.max_attempts retry = filter_properties.pop('retry', {}) if max_attempts == 1: # re-scheduling is disabled. return # retry is enabled, update attempt count: if retry: retry['num_attempts'] += 1 else: retry = { 'num_attempts': 1, 'hosts': [] # list of volume service hosts tried } filter_properties['retry'] = retry volume_id = properties.get('volume_id') self._log_volume_error(volume_id, retry) if retry['num_attempts'] > max_attempts: msg = _("Exceeded max scheduling attempts %(max_attempts)d for " "volume %(volume_id)s") % { 'max_attempts': max_attempts, 'volume_id': volume_id, } raise exception.NoValidHost(reason=msg)
**** CubicPower OpenStack Study **** def _get_weighted_candidates(self, context, request_spec, filter_properties=None): """Returns a list of hosts that meet the required specs, ordered by their fitness. """ elevated = context.elevated() volume_properties = request_spec['volume_properties'] # Since Cinder is using mixed filters from Oslo and it's own, which # takes 'resource_XX' and 'volume_XX' as input respectively, copying # 'volume_XX' to 'resource_XX' will make both filters happy. resource_properties = volume_properties.copy() volume_type = request_spec.get("volume_type", None) resource_type = request_spec.get("volume_type", None) request_spec.update({'resource_properties': resource_properties}) config_options = self._get_configuration_options() if filter_properties is None: filter_properties = {} self._populate_retry(filter_properties, resource_properties) filter_properties.update({'context': context, 'request_spec': request_spec, 'config_options': config_options, 'volume_type': volume_type, 'resource_type': resource_type}) self.populate_filter_properties(request_spec, filter_properties) # Find our local list of acceptable hosts by filtering and # weighing our options. we virtually consume resources on # it so subsequent selections can adjust accordingly. # Note: remember, we are using an iterator here. So only # traverse this list once. hosts = self.host_manager.get_all_host_states(elevated) # Filter local hosts based on requirements ... hosts = self.host_manager.get_filtered_hosts(hosts, filter_properties) if not hosts: return [] LOG.debug(_("Filtered %s") % hosts) # weighted_host = WeightedHost() ... the best # host for the job. weighed_hosts = self.host_manager.get_weighed_hosts(hosts, filter_properties) return weighed_hosts
**** CubicPower OpenStack Study **** def _schedule(self, context, request_spec, filter_properties=None): weighed_hosts = self._get_weighted_candidates(context, request_spec, filter_properties) if not weighed_hosts: return None return self._choose_top_host(weighed_hosts, request_spec)
**** CubicPower OpenStack Study **** def _choose_top_host(self, weighed_hosts, request_spec): top_host = weighed_hosts[0] host_state = top_host.obj LOG.debug(_("Choosing %s") % host_state.host) volume_properties = request_spec['volume_properties'] host_state.consume_from_volume(volume_properties) return top_host
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