text: # Copyright 2010 United States Government as represented by the
  # Administrator of the National Aeronautics and Space Administration.
  # 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.
  
  """Quotas for instances, and floating ips."""
  
  import datetime
  import six
  
  from nova import db
  from nova import exception
  from nova.i18n import _LE
  from nova import objects
  from nova.openstack.common import log as logging
  from oslo.config import cfg
  from oslo.utils import importutils
  from oslo.utils import timeutils
  
  LOG = logging.getLogger(__name__)
  
  quota_opts = [
      cfg.IntOpt('quota_instances',
                 default=0,
                 help='Number of instances allowed per project'),
      cfg.IntOpt('quota_cores',
                 default=0,
                 help='Number of instance cores allowed per project'),
      cfg.IntOpt('quota_ram',
                 default=0,
                 help='Megabytes of instance RAM allowed per project'),
      cfg.IntOpt('quota_floating_ips',
                 default=0,
                 help='Number of floating IPs allowed per project'),
      cfg.IntOpt('quota_fixed_ips',
                 default=0,
                 help=('Number of fixed IPs allowed per project (this should be '
                       'at least the number of instances allowed)')),
      cfg.IntOpt('quota_metadata_items',
                 default=0,
                 help='Number of metadata items allowed per instance'),
      cfg.IntOpt('quota_injected_files',
                 default=0,
                 help='Number of injected files allowed'),
      cfg.IntOpt('quota_injected_file_content_bytes',
                 default=0,
                 help='Number of bytes allowed per injected file'),
      cfg.IntOpt('quota_injected_file_path_length',
                 default=0,
                 help='Length of injected file path'),
      cfg.IntOpt('quota_security_groups',
                 default=0,
                 help='Number of security groups per project'),
      cfg.IntOpt('quota_security_group_rules',
                 default=0,
                 help='Number of security rules per security group'),
      cfg.IntOpt('quota_key_pairs',
                 default=0,
                 help='Number of key pairs per user'),
      cfg.IntOpt('quota_server_groups',
                 default=0,
                 help='Number of server groups per project'),
      cfg.IntOpt('quota_server_group_members',
                 default=0,
                 help='Number of servers per server group'),
      cfg.IntOpt('reservation_expire',
                 default=0,
                 help='Number of seconds until a reservation expires'),
      cfg.IntOpt('until_refresh',
                 default=0,
                 help='Count of reservations until usage is refreshed'),
      cfg.IntOpt('max_age',
                 default=0,
                 help='Number of seconds between subsequent usage refreshes'),
      cfg.StrOpt('quota_driver',
                 default='nova.quota.NestedQuotaDriver',
                 help='Driver to use for nested quota checks'),
      ]
  
  CONF = cfg.CONF
  CONF.register_opts(quota_opts)
  
  
  class DbQuotaDriver(object):
      """Driver to perform necessary checks to enforce quotas and obtain
      quota information.  The default driver utilizes the local
      database.
      """
      UNLIMITED_VALUE = -1
  
      def get_by_project_and_user(self, context, project_id, user_id, resource):
          """Get a specific quota by project and user."""
  
          return db.quota_get(context, project_id, resource, user_id=user_id)
  
      def get_by_project(self, context, project_id, resource):
          """Get a specific quota by project."""
  
          return db.quota_get(context, project_id, resource)
  
      def get_by_class(self, context, quota_class, resource):
          """Get a specific quota by quota class."""
  
          return db.quota_class_get(context, quota_class, resource)
  
      def get_defaults(self, context, resources):
          """Given a list of resources, retrieve the default quotas.
          Use the class quotas named `_DEFAULT_QUOTA_NAME` as default quotas,
          if it exists.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          """
  
          quotas = {}
          default_quotas = db.quota_class_get_default(context)
          for resource in resources.values():
              quotas[resource.name] = default_quotas.get(resource.name,
                                                         resource.default)
  
          return quotas
  
      def get_class_quotas(self, context, resources, quota_class,
                           defaults=True):
          """Given a list of resources, retrieve the quotas for the given
          quota class.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param quota_class: The name of the quota class to return
                              quotas for.
          :param defaults: If True, the default value will be reported
                           if there is no specific value for the
                           resource.
          """
  
          quotas = {}
          class_quotas = db.quota_class_get_all_by_name(context, quota_class)
          for resource in resources.values():
              if defaults or resource.name in class_quotas:
                  quotas[resource.name] = class_quotas.get(resource.name,
                                                           resource.default)
  
          return quotas
  
      def _process_quotas(self, context, resources, project_id, quotas,
                          quota_class=None, defaults=True, usages=None,
                          remains=False):
          modified_quotas = {}
          # Get the quotas for the appropriate class.  If the project ID
          # matches the one in the context, we use the quota_class from
          # the context, otherwise, we use the provided quota_class (if
          # any)
          if project_id == context.project_id:
              quota_class = context.quota_class
          if quota_class:
              class_quotas = db.quota_class_get_all_by_name(context, quota_class)
          else:
              class_quotas = {}
  
          default_quotas = self.get_defaults(context, resources)
          for resource in resources.values():
              # Omit default/quota class values
              if not defaults and resource.name not in quotas:
                  continue
  
              limit = quotas.get(resource.name, class_quotas.get(
                          resource.name, default_quotas[resource.name]))
              modified_quotas[resource.name] = dict(limit=limit)
  
              # Include usages if desired.  This is optional because one
              # internal consumer of this interface wants to access the
              # usages directly from inside a transaction.
              if usages:
                  usage = usages.get(resource.name, {})
                  modified_quotas[resource.name].update(
                      in_use=usage.get('in_use', 0),
                      reserved=usage.get('reserved', 0),
                      )
              # Initialize remains quotas.
              if remains:
                  modified_quotas[resource.name].update(remains=limit)
  
          if remains:
              all_quotas = db.quota_get_all(context, project_id)
              for quota in all_quotas:
                  if quota.resource in modified_quotas:
                      modified_quotas[quota.resource]['remains'] -= \
                              quota.hard_limit
          return modified_quotas
  
      def get_user_quotas(self, context, resources, project_id, user_id,
                          quota_class=None, defaults=True,
                          usages=True, project_quotas=None,
                          user_quotas=None):
          """Given a list of resources, retrieve the quotas for the given
          user and project.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param project_id: The ID of the project to return quotas for.
          :param user_id: The ID of the user to return quotas for.
          :param quota_class: If project_id != context.project_id, the
                              quota class cannot be determined.  This
                              parameter allows it to be specified.  It
                              will be ignored if project_id ==
                              context.project_id.
          :param defaults: If True, the quota class value (or the
                           default value, if there is no value from the
                           quota class) will be reported if there is no
                           specific value for the resource.
          :param usages: If True, the current in_use and reserved counts
                         will also be returned.
          :param project_quotas: Quotas dictionary for the specified project.
          :param user_quotas: Quotas dictionary for the specified project
                              and user.
          """
          if user_quotas:
              user_quotas = user_quotas.copy()
          else:
              user_quotas = db.quota_get_all_by_project_and_user(context,
                                                                 project_id,
                                                                 user_id)
          # Use the project quota for default user quota.
          proj_quotas = project_quotas or db.quota_get_all_by_project(
              context, project_id)
          for key, value in proj_quotas.iteritems():
              if key not in user_quotas.keys():
                  user_quotas[key] = value
          user_usages = None
          if usages:
              user_usages = db.quota_usage_get_all_by_project_and_user(context,
                                                           project_id,
                                                           user_id)
          return self._process_quotas(context, resources, project_id,
                                      user_quotas, quota_class,
                                      defaults=defaults, usages=user_usages)
  
      def get_project_quotas(self, context, resources, project_id,
                             quota_class=None, defaults=True,
                             usages=True, remains=False, project_quotas=None):
          """Given a list of resources, retrieve the quotas for the given
          project.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param project_id: The ID of the project to return quotas for.
          :param quota_class: If project_id != context.project_id, the
                              quota class cannot be determined.  This
                              parameter allows it to be specified.  It
                              will be ignored if project_id ==
                              context.project_id.
          :param defaults: If True, the quota class value (or the
                           default value, if there is no value from the
                           quota class) will be reported if there is no
                           specific value for the resource.
          :param usages: If True, the current in_use and reserved counts
                         will also be returned.
          :param remains: If True, the current remains of the project will
                          will be returned.
          :param project_quotas: Quotas dictionary for the specified project.
          """
          project_quotas = project_quotas or db.quota_get_all_by_project(
              context, project_id)
          project_usages = None
          if usages:
              project_usages = db.quota_usage_get_all_by_project(context,
                                                                 project_id)
          return self._process_quotas(context, resources, project_id,
                                      project_quotas, quota_class,
                                      defaults=defaults, usages=project_usages,
                                      remains=remains)
  
      def _is_unlimited_value(self, v):
          """A helper method to check for unlimited value.
          """
  
          return v <= self.UNLIMITED_VALUE
  
      def _sum_quota_values(self, v1, v2):
          """A helper method that handles unlimited values when performing
          sum operation.
          """
  
          if self._is_unlimited_value(v1) or self._is_unlimited_value(v2):
              return self.UNLIMITED_VALUE
          return v1 + v2
  
      def _sub_quota_values(self, v1, v2):
          """A helper method that handles unlimited values when performing
          subtraction operation.
          """
  
          if self._is_unlimited_value(v1) or self._is_unlimited_value(v2):
              return self.UNLIMITED_VALUE
          return v1 - v2
  
      def get_settable_quotas(self, context, resources, project_id,
                              parent_id=None,user_id=None):
          """Given a list of resources, retrieve the range of settable quotas for
          the given user or project.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param project_id: The ID of the project to return quotas for.
          :param user_id: The ID of the user to return quotas for.
          """
          settable_quotas = {}
          db_proj_quotas = db.quota_get_all_by_project(context, project_id)
          project_quotas = self.get_project_quotas(context, resources,
                                                   project_id, remains=True,
                                                   project_quotas=db_proj_quotas)
          if user_id:
              setted_quotas = db.quota_get_all_by_project_and_user(context,
                                                       project_id,
                                                       user_id)
              user_quotas = self.get_user_quotas(context, resources,
                                                 project_id, user_id,
                                                 project_quotas=db_proj_quotas,
                                                 user_quotas=setted_quotas)
              for key, value in user_quotas.items():
                  maximum = \
                      self._sum_quota_values(project_quotas[key]['remains'],
                                             setted_quotas.get(key, 0))
                  minimum = value['in_use'] + value['reserved']
                  settable_quotas[key] = {'minimum': minimum, 'maximum': maximum}
          else:
              for key, value in project_quotas.items():
                  minimum = \
                      max(int(self._sub_quota_values(value['limit'],
                                                     value['remains'])),
                          int(value['in_use'] + value['reserved']))
                  settable_quotas[key] = {'minimum': minimum, 'maximum': -1}
          return settable_quotas
  
      def _get_quotas(self, context, resources, keys, has_sync, project_id=None,
                      user_id=None, project_quotas=None):
          """A helper method which retrieves the quotas for the specific
          resources identified by keys, and which apply to the current
          context.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param keys: A list of the desired quotas to retrieve.
          :param has_sync: If True, indicates that the resource must
                           have a sync function; if False, indicates
                           that the resource must NOT have a sync
                           function.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          :param project_quotas: Quotas dictionary for the specified project.
          """
  
          # Filter resources
          if has_sync:
              sync_filt = lambda x: hasattr(x, 'sync')
          else:
              sync_filt = lambda x: not hasattr(x, 'sync')
          desired = set(keys)
          sub_resources = {k: v for k, v in resources.items()
                          if k in desired and sync_filt(v)}
  
          # Make sure we accounted for all of them...
          if len(keys) != len(sub_resources):
              unknown = desired - set(sub_resources.keys())
              raise exception.QuotaResourceUnknown(unknown=sorted(unknown))
  
          if user_id:
              # Grab and return the quotas (without usages)
              quotas = self.get_user_quotas(context, sub_resources,
                                            project_id, user_id,
                                            context.quota_class, usages=False,
                                            project_quotas=project_quotas)
          else:
              # Grab and return the quotas (without usages)
              quotas = self.get_project_quotas(context, sub_resources,
                                               project_id,
                                               context.quota_class,
                                               usages=False,
                                               project_quotas=project_quotas)
  
          return {k: v['limit'] for k, v in quotas.items()}
  
      def limit_check(self, context, resources, values, project_id=None,
                      user_id=None):
          """Check simple quota limits.
  
          For limits--those quotas for which there is no usage
          synchronization function--this method checks that a set of
          proposed values are permitted by the limit restriction.
  
          This method will raise a QuotaResourceUnknown exception if a
          given resource is unknown or if it is not a simple limit
          resource.
  
          If any of the proposed values is over the defined quota, an
          OverQuota exception will be raised with the sorted list of the
          resources which are too high.  Otherwise, the method returns
          nothing.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param values: A dictionary of the values to check against the
                         quota.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
          _valid_method_call_check_resources(values, 'check')
  
          # Ensure no value is less than zero
          unders = [key for key, val in values.items() if val < 0]
          if unders:
              raise exception.InvalidQuotaValue(unders=sorted(unders))
  
          # If project_id is None, then we use the project_id in context
          if project_id is None:
              project_id = context.project_id
          # If user id is None, then we use the user_id in context
          if user_id is None:
              user_id = context.user_id
  
          # Get the applicable quotas
          project_quotas = db.quota_get_all_by_project(context, project_id)
          quotas = self._get_quotas(context, resources, values.keys(),
                                    has_sync=False, project_id=project_id,
                                    project_quotas=project_quotas)
          user_quotas = self._get_quotas(context, resources, values.keys(),
                                         has_sync=False, project_id=project_id,
                                         user_id=user_id,
                                         project_quotas=project_quotas)
  
          # Check the quotas and construct a list of the resources that
          # would be put over limit by the desired values
          overs = [key for key, val in values.items()
                   if quotas[key] >= 0 and quotas[key] < val or
                   (user_quotas[key] >= 0 and user_quotas[key] < val)]
          if overs:
              headroom = {}
              for key in overs:
                  headroom[key] = min(
                      val for val in (quotas.get(key), project_quotas.get(key))
                      if val is not None
                  )
              raise exception.OverQuota(overs=sorted(overs), quotas=quotas,
                                        usages={}, headroom=headroom)
  
      def reserve(self, context, resources, deltas, expire=None,
                  project_id=None, user_id=None):
          """Check quotas and reserve resources.
  
          For counting quotas--those quotas for which there is a usage
          synchronization function--this method checks quotas against
          current usage and the desired deltas.
  
          This method will raise a QuotaResourceUnknown exception if a
          given resource is unknown or if it does not have a usage
          synchronization function.
  
          If any of the proposed values is over the defined quota, an
          OverQuota exception will be raised with the sorted list of the
          resources which are too high.  Otherwise, the method returns a
          list of reservation UUIDs which were created.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param deltas: A dictionary of the proposed delta changes.
          :param expire: An optional parameter specifying an expiration
                         time for the reservations.  If it is a simple
                         number, it is interpreted as a number of
                         seconds and added to the current time; if it is
                         a datetime.timedelta object, it will also be
                         added to the current time.  A datetime.datetime
                         object will be interpreted as the absolute
                         expiration time.  If None is specified, the
                         default expiration time set by
                         --default-reservation-expire will be used (this
                         value will be treated as a number of seconds).
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
          _valid_method_call_check_resources(deltas, 'reserve')
  
          # Set up the reservation expiration
          if expire is None:
              expire = CONF.reservation_expire
          if isinstance(expire, (int, long)):
              expire = datetime.timedelta(seconds=expire)
          if isinstance(expire, datetime.timedelta):
              expire = timeutils.utcnow() + expire
          if not isinstance(expire, datetime.datetime):
              raise exception.InvalidReservationExpiration(expire=expire)
  
          # If project_id is None, then we use the project_id in context
          if project_id is None:
              project_id = context.project_id
          # If user_id is None, then we use the project_id in context
          if user_id is None:
              user_id = context.user_id
  
          # Get the applicable quotas.
          # NOTE(Vek): We're not worried about races at this point.
          #            Yes, the admin may be in the process of reducing
          #            quotas, but that's a pretty rare thing.
          project_quotas = db.quota_get_all_by_project(context, project_id)
          quotas = self._get_quotas(context, resources, deltas.keys(),
                                    has_sync=True, project_id=project_id,
                                    project_quotas=project_quotas)
          user_quotas = self._get_quotas(context, resources, deltas.keys(),
                                         has_sync=True, project_id=project_id,
                                         user_id=user_id,
                                         project_quotas=project_quotas)
  
          # NOTE(Vek): Most of the work here has to be done in the DB
          #            API, because we have to do it in a transaction,
          #            which means access to the session.  Since the
          #            session isn't available outside the DBAPI, we
          #            have to do the work there.
          return db.quota_reserve(context, resources, quotas, user_quotas,
                                  deltas, expire,
                                  CONF.until_refresh, CONF.max_age,
                                  project_id=project_id, user_id=user_id)
  
      def commit(self, context, reservations, project_id=None, user_id=None):
          """Commit reservations.
  
          :param context: The request context, for access checks.
          :param reservations: A list of the reservation UUIDs, as
                               returned by the reserve() method.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
          # If project_id is None, then we use the project_id in context
          if project_id is None:
              project_id = context.project_id
          # If user_id is None, then we use the user_id in context
          if user_id is None:
              user_id = context.user_id
  
          db.reservation_commit(context, reservations, project_id=project_id,
                                user_id=user_id)
  
      def rollback(self, context, reservations, project_id=None, user_id=None):
          """Roll back reservations.
  
          :param context: The request context, for access checks.
          :param reservations: A list of the reservation UUIDs, as
                               returned by the reserve() method.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
          # If project_id is None, then we use the project_id in context
          if project_id is None:
              project_id = context.project_id
          # If user_id is None, then we use the user_id in context
          if user_id is None:
              user_id = context.user_id
  
          db.reservation_rollback(context, reservations, project_id=project_id,
                                  user_id=user_id)
  
      def usage_reset(self, context, resources):
          """Reset the usage records for a particular user on a list of
          resources.  This will force that user's usage records to be
          refreshed the next time a reservation is made.
  
          Note: this does not affect the currently outstanding
          reservations the user has; those reservations must be
          committed or rolled back (or expired).
  
          :param context: The request context, for access checks.
          :param resources: A list of the resource names for which the
                            usage must be reset.
          """
  
          # We need an elevated context for the calls to
          # quota_usage_update()
          elevated = context.elevated()
  
          for resource in resources:
              try:
                  # Reset the usage to -1, which will force it to be
                  # refreshed
                  db.quota_usage_update(elevated, context.project_id,
                                        context.user_id,
                                        resource, in_use=-1)
              except exception.QuotaUsageNotFound:
                  # That means it'll be refreshed anyway
                  pass
  
      def destroy_all_by_project_and_user(self, context, project_id, user_id):
          """Destroy all quotas, usages, and reservations associated with a
          project and user.
  
          :param context: The request context, for access checks.
          :param project_id: The ID of the project being deleted.
          :param user_id: The ID of the user being deleted.
          """
  
          db.quota_destroy_all_by_project_and_user(context, project_id, user_id)
  
      def destroy_all_by_project(self, context, project_id):
          """Destroy all quotas, usages, and reservations associated with a
          project.
  
          :param context: The request context, for access checks.
          :param project_id: The ID of the project being deleted.
          """
  
          db.quota_destroy_all_by_project(context, project_id)
  
      def expire(self, context):
          """Expire reservations.
  
          Explores all currently existing reservations and rolls back
          any that have expired.
  
          :param context: The request context, for access checks.
          """
  
          db.reservation_expire(context)
  
  
  class NestedQuotaDriver(object):
      """Driver to perform necessary checks to enforce nested quotas and
      obtain quota information for hierarchical project.
      The default driver utilizes the local database.
      """
      UNLIMITED_VALUE = -1
  
      def get_by_project_and_user(self, context, project_id, user_id, resource):
          """Get a specific quota by project and user."""
  
          return db.quota_get(context, project_id, resource, user_id=user_id)
  
      def get_by_project(self, context, project_id, resource):
          """Get a specific quota by project."""
  
          return db.quota_get(context, project_id, resource)
  
      def get_by_class(self, context, quota_class, resource):
          """Get a specific quota by quota class."""
  
          return db.quota_class_get(context, quota_class, resource)
  
      def get_defaults(self, context, resources):
          """Given a list of resources, retrieve the default quotas.
          Use the class quotas named `_DEFAULT_QUOTA_NAME` as default quotas,
          if it exists.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          """
  
          quotas = {}
          default_quotas = db.quota_class_get_default(context)
          for resource in resources.values():
              quotas[resource.name] = default_quotas.get(resource.name,
                                                         resource.default)
  
          return quotas
  
      def get_class_quotas(self, context, resources, quota_class,
                           defaults=True):
          """Given a list of resources, retrieve the quotas for the given
          quota class.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param quota_class: The name of the quota class to return
                              quotas for.
          :param defaults: If True, the default value will be reported
                           if there is no specific value for the
                           resource.
          """
  
          quotas = {}
          class_quotas = db.quota_class_get_all_by_name(context, quota_class)
          for resource in resources.values():
              if defaults or resource.name in class_quotas:
                  quotas[resource.name] = class_quotas.get(resource.name,
                                                           resource.default)
  
          return quotas
  
      def _process_quotas(self, context, resources, project_id, quotas,
                          quota_class=None, defaults=True,
                          usages=None, remains=False):
          modified_quotas = {}
  
          # Get the quotas for the appropriate class.  If the project ID
          # matches the one in the context, we use the quota_class from
          # the context, otherwise, we use the provided quota_class (if
          # any)
          if project_id == context.project_id:
              quota_class = context.quota_class
          if quota_class:
              class_quotas = db.quota_class_get_all_by_name(context, quota_class)
          else:
              class_quotas = {}
  
          default_quotas = self.get_defaults(context, resources)
          for resource in resources.values():
              # Omit default/quota class values
              if not defaults and resource.name not in quotas:
                  continue
  
              limit = quotas.get(resource.name, class_quotas.get(
                          resource.name, default_quotas[resource.name]))
              modified_quotas[resource.name] = dict(limit=limit)
  
              # Include usages if desired.  This is optional because one
              # internal consumer of this interface wants to access the
              # usages directly from inside a transaction.
              if usages:
                  usage = usages.get(resource.name, {})
                  modified_quotas[resource.name].update(
                      in_use=usage.get('in_use', 0),
                      reserved=usage.get('reserved', 0),
                      )
              # Initialize remains quotas.
              if remains:
                  modified_quotas[resource.name].update(remains=limit)
  
          if remains:
              all_quotas = db.quota_get_all(context, project_id)
              for quota in all_quotas:
                  if quota.resource in modified_quotas:
                      modified_quotas[quota.resource]['remains'] -= \
                              quota.hard_limit
          return modified_quotas
  
      def get_user_quotas(self, context, resources, project_id, user_id,
                          quota_class=None, defaults=True,
                          usages=True, project_quotas=None,
                          user_quotas=None):
          """Given a list of resources, retrieve the quotas for the given
          user and project.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param project_id: The ID of the project to return quotas for.
          :param user_id: The ID of the user to return quotas for.
          :param quota_class: If project_id != context.project_id, the
                              quota class cannot be determined.  This
                              parameter allows it to be specified.  It
                              will be ignored if project_id ==
                              context.project_id.
          :param defaults: If True, the quota class value (or the
                           default value, if there is no value from the
                           quota class) will be reported if there is no
                           specific value for the resource.
          :param usages: If True, the current in_use and reserved counts
                         will also be returned.
          :param project_quotas: Quotas dictionary for the specified project.
          :param user_quotas: Quotas dictionary for the specified project
                              and user.
          """
          if user_quotas:
              user_quotas = user_quotas.copy()
          else:
              user_quotas = db.quota_get_all_by_project_and_user(context,
                                                                 project_id,
                                                                 user_id)
  
          # Use the project quota for default user quota.
          proj_quotas = project_quotas or db.quota_get_all_by_project(
              context, project_id)
          for key, value in proj_quotas.iteritems():
              if key not in user_quotas.keys():
                  user_quotas[key] = 0
          user_usages = None
          if usages:
              user_usages = db.quota_usage_get_all_by_project_and_user(context,
                                                           project_id,
                                                           user_id)
          return self._process_quotas(context, resources, project_id,
                                      user_quotas, quota_class,
                                      defaults=defaults, usages=user_usages)
  
      def get_project_quotas(self, context, resources, project_id,
                             quota_class=None, defaults=True,
                             usages=True, remains=False,
                             project_quotas=None):
          """Given a list of resources, retrieve the quotas for the given
          project.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param project_id: The ID of the project to return quotas for.
          :param quota_class: If project_id != context.project_id, the
                              quota class cannot be determined.  This
                              parameter allows it to be specified.  It
                              will be ignored if project_id ==
                              context.project_id.
          :param defaults: If True, the quota class value (or the
                           default value, if there is no value from the
                           quota class) will be reported if there is no
                           specific value for the resource.
          :param usages: If True, the current in_use and reserved counts
                         will also be returned.
          :param remains: If True, the current remains of the project will
                          will be returned.
          :param project_quotas: Quotas dictionary for the specified project.
          """
          project_quotas = project_quotas or db.quota_get_all_by_project(
              context, project_id)
          project_usages = None
          if usages:
              project_usages = db.quota_usage_get_all_by_project(context,
                                                                 project_id)
          return self._process_quotas(context, resources, project_id,
                                      project_quotas, quota_class,
                                      defaults=defaults, usages=project_usages,
                                      remains=remains)
  
      def _is_unlimited_value(self, v):
          """A helper method to check for unlimited value.
          """
  
          return v <= self.UNLIMITED_VALUE
  
      def _sum_quota_values(self, v1, v2):
          """A helper method that handles unlimited values when performing
          sum operation.
          """
  
          if self._is_unlimited_value(v1) or self._is_unlimited_value(v2):
              return self.UNLIMITED_VALUE
          return v1 + v2
  
      def _sub_quota_values(self, v1, v2):
          """A helper method that handles unlimited values when performing
          subtraction operation.
          """
  
          if self._is_unlimited_value(v1) or self._is_unlimited_value(v2):
              return self.UNLIMITED_VALUE
          return v1 - v2
  
      def get_settable_quotas(self, context, resources, project_id,
                              parent_id = None, user_id=None):
          """Given a list of resources, retrieve the range of settable quotas for
          the given user or project.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param project_id: The ID of the project to return quotas for.
          :param user_id: The ID of the user to return quotas for.
          """
          settable_quotas = {}
          db_project_quotas = db.quota_get_all_by_project(context, project_id)
          project_quotas = self.get_project_quotas(context, resources,
                                                   project_id, remains=True,
                                                   project_quotas=
                                                   db_project_quotas)
          project_allocated_quotas = \
              db.quota_allocated_get_all_by_project(context, project_id)
          if user_id:
              setted_quotas = db.quota_get_all_by_project_and_user(context,
                                                       project_id,
                                                       user_id)
              user_quotas = self.get_user_quotas(context, resources,
                                                 project_id, user_id,
                                                 project_quotas=
                                                 db_project_quotas,
                                                 user_quotas=
                                                 setted_quotas)
              for key, value in user_quotas.items():
                  maximum = \
                      self._sum_quota_values(project_quotas[key]['remains'],
                                             setted_quotas.get(key, 0))
                  maximum = maximum - project_allocated_quotas.get(key, 0)
                  minimum = value['in_use'] + value['reserved']
                  settable_quotas[key] = {'minimum': minimum, 'maximum': maximum}
          else:
              if parent_id:
                  db_parent_project_quotas = \
                      db.quota_get_all_by_project(context, parent_id)
                  parent_project_allocated_quotas = \
                      db.quota_allocated_get_all_by_project(context, parent_id)
                  parent_project_quotas =\
                      self.get_project_quotas(context, resources,
                      parent_id, remains=True,
                      project_quotas=db_parent_project_quotas)
              for key, value in project_quotas.items():
                  maximum = -1
                  if(parent_id):
                      maximum = parent_project_quotas[key]['remains'] - \
                                parent_project_allocated_quotas.get(key, 0)\
                                + value['limit']
                  minimum = \
                      max(int(self._sub_quota_values(value['limit'],
                                                     value['remains'])),
                          int(value['in_use'] + value['reserved'])) + \
                                project_allocated_quotas.get(key, 0)
                  settable_quotas[key] = {'minimum': minimum, 'maximum': maximum}
          return settable_quotas
  
      def _get_quotas(self, context, resources, keys, has_sync, project_id=None,
                      user_id=None, project_quotas=None):
          """A helper method which retrieves the quotas for the specific
          resources identified by keys, and which apply to the current
          context.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param keys: A list of the desired quotas to retrieve.
          :param has_sync: If True, indicates that the resource must
                           have a sync function; if False, indicates
                           that the resource must NOT have a sync
                           function.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          :param project_quotas: Quotas dictionary for the specified project.
          """
  
          # Filter resources
          if has_sync:
              sync_filt = lambda x: hasattr(x, 'sync')
          else:
              sync_filt = lambda x: not hasattr(x, 'sync')
          desired = set(keys)
          sub_resources = {k: v for k, v in resources.items()
                          if k in desired and sync_filt(v)}
  
          # Make sure we accounted for all of them...
          if len(keys) != len(sub_resources):
              unknown = desired - set(sub_resources.keys())
              raise exception.QuotaResourceUnknown(unknown=sorted(unknown))
  
          if user_id:
              # Grab and return the quotas (without usages)
              quotas = self.get_user_quotas(context, sub_resources,
                                            project_id, user_id,
                                            context.quota_class, usages=False,
                                            project_quotas=project_quotas)
          else:
              # Grab and return the quotas (without usages)
              quotas = self.get_project_quotas(context, sub_resources,
                                               project_id,
                                               context.quota_class,
                                               usages=False,
                                               project_quotas=project_quotas)
  
          return {k: v['limit'] for k, v in quotas.items()}
  
      def limit_check(self, context, resources, values, project_id=None,
                      user_id=None):
          """Check simple quota limits.
  
          For limits--those quotas for which there is no usage
          synchronization function--this method checks that a set of
          proposed values are permitted by the limit restriction.
  
          This method will raise a QuotaResourceUnknown exception if a
          given resource is unknown or if it is not a simple limit
          resource.
  
          If any of the proposed values is over the defined quota, an
          OverQuota exception will be raised with the sorted list of the
          resources which are too high.  Otherwise, the method returns
          nothing.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param values: A dictionary of the values to check against the
                         quota.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
          _valid_method_call_check_resources(values, 'check')
  
          # Ensure no value is less than zero
          unders = [key for key, val in values.items() if val < 0]
          if unders:
              raise exception.InvalidQuotaValue(unders=sorted(unders))
  
          # If project_id is None, then we use the project_id in context
          if project_id is None:
              project_id = context.project_id
          # If user id is None, then we use the user_id in context
          if user_id is None:
              user_id = context.user_id
  
          # Get the applicable quotas
          project_quotas = db.quota_get_all_by_project(context, project_id)
          quotas = self._get_quotas(context, resources, values.keys(),
                                    has_sync=False, project_id=project_id,
                                    project_quotas=project_quotas)
          user_quotas = self._get_quotas(context, resources, values.keys(),
                                         has_sync=False, project_id=project_id,
                                         user_id=user_id,
                                         project_quotas=project_quotas)
  
          # Check the quotas and construct a list of the resources that
          # would be put over limit by the desired values
          overs = [key for key, val in values.items()
                   if quotas[key] >= 0 and quotas[key] < val or
                   (user_quotas[key] >= 0 and user_quotas[key] < val)]
          if overs:
              headroom = {}
              for key in overs:
                  headroom[key] = min(
                      val for val in (quotas.get(key), project_quotas.get(key))
                      if val is not None
                  )
              raise exception.OverQuota(overs=sorted(overs), quotas=quotas,
                                        usages={}, headroom=headroom)
  
      def reserve(self, context, resources, deltas, expire=None,
                  project_id=None, user_id=None):
          """Check quotas and reserve resources.
  
          For counting quotas--those quotas for which there is a usage
          synchronization function--this method checks quotas against
          current usage and the desired deltas.
  
          This method will raise a QuotaResourceUnknown exception if a
          given resource is unknown or if it does not have a usage
          synchronization function.
  
          If any of the proposed values is over the defined quota, an
          OverQuota exception will be raised with the sorted list of the
          resources which are too high.  Otherwise, the method returns a
          list of reservation UUIDs which were created.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param deltas: A dictionary of the proposed delta changes.
          :param expire: An optional parameter specifying an expiration
                         time for the reservations.  If it is a simple
                         number, it is interpreted as a number of
                         seconds and added to the current time; if it is
                         a datetime.timedelta object, it will also be
                         added to the current time.  A datetime.datetime
                         object will be interpreted as the absolute
                         expiration time.  If None is specified, the
                         default expiration time set by
                         --default-reservation-expire will be used (this
                         value will be treated as a number of seconds).
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
          _valid_method_call_check_resources(deltas, 'reserve')
  
          # Set up the reservation expiration
          if expire is None:
              expire = CONF.reservation_expire
          if isinstance(expire, (int, long)):
              expire = datetime.timedelta(seconds=expire)
          if isinstance(expire, datetime.timedelta):
              expire = timeutils.utcnow() + expire
          if not isinstance(expire, datetime.datetime):
              raise exception.InvalidReservationExpiration(expire=expire)
  
          # If project_id is None, then we use the project_id in context
          if project_id is None:
              project_id = context.project_id
          # If user_id is None, then we use the project_id in context
          if user_id is None:
              user_id = context.user_id
  
          # Get the applicable quotas.
          # NOTE(Vek): We're not worried about races at this point.
          #            Yes, the admin may be in the process of reducing
          #            quotas, but that's a pretty rare thing.
          project_quotas = db.quota_get_all_by_project(context, project_id)
          quotas = self._get_quotas(context, resources, deltas.keys(),
                                    has_sync=True, project_id=project_id,
                                    project_quotas=project_quotas)
          user_quotas = self._get_quotas(context, resources, deltas.keys(),
                                         has_sync=True, project_id=project_id,
                                         user_id=user_id,
                                         project_quotas=project_quotas)
  
          # NOTE(Vek): Most of the work here has to be done in the DB
          #            API, because we have to do it in a transaction,
          #            which means access to the session.  Since the
          #            session isn't available outside the DBAPI, we
          #            have to do the work there.
          return db.quota_reserve(context, resources, quotas, user_quotas,
                                  deltas, expire,
                                  CONF.until_refresh, CONF.max_age,
                                  project_id=project_id, user_id=user_id)
  
      def commit(self, context, reservations, project_id=None, user_id=None):
          """Commit reservations.
  
          :param context: The request context, for access checks.
          :param reservations: A list of the reservation UUIDs, as
                               returned by the reserve() method.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
          # If project_id is None, then we use the project_id in context
          if project_id is None:
              project_id = context.project_id
          # If user_id is None, then we use the user_id in context
          if user_id is None:
              user_id = context.user_id
  
          db.reservation_commit(context, reservations, project_id=project_id,
                                user_id=user_id)
  
      def rollback(self, context, reservations, project_id=None, user_id=None):
          """Roll back reservations.
  
          :param context: The request context, for access checks.
          :param reservations: A list of the reservation UUIDs, as
                               returned by the reserve() method.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
          # If project_id is None, then we use the project_id in context
          if project_id is None:
              project_id = context.project_id
          # If user_id is None, then we use the user_id in context
          if user_id is None:
              user_id = context.user_id
  
          db.reservation_rollback(context, reservations, project_id=project_id,
                                  user_id=user_id)
  
      def usage_reset(self, context, resources):
          """Reset the usage records for a particular user on a list of
          resources.  This will force that user's usage records to be
          refreshed the next time a reservation is made.
  
          Note: this does not affect the currently outstanding
          reservations the user has; those reservations must be
          committed or rolled back (or expired).
  
          :param context: The request context, for access checks.
          :param resources: A list of the resource names for which the
                            usage must be reset.
          """
  
          # We need an elevated context for the calls to
          # quota_usage_update()
          elevated = context.elevated()
  
          for resource in resources:
              try:
                  # Reset the usage to -1, which will force it to be
                  # refreshed
                  db.quota_usage_update(elevated, context.project_id,
                                        context.user_id,
                                        resource, in_use=-1)
              except exception.QuotaUsageNotFound:
                  # That means it'll be refreshed anyway
                  pass
  
      def destroy_all_by_project_and_user(self, context, project_id, user_id):
          """Destroy all quotas, usages, and reservations associated with a
          project and user.
  
          :param context: The request context, for access checks.
          :param project_id: The ID of the project being deleted.
          :param user_id: The ID of the user being deleted.
          """
  
          db.quota_destroy_all_by_project_and_user(context, project_id, user_id)
  
      def destroy_all_by_project(self, context, project_id):
          """Destroy all quotas, usages, and reservations associated with a
          project.
  
          :param context: The request context, for access checks.
          :param project_id: The ID of the project being deleted.
          """
  
          db.quota_destroy_all_by_project(context, project_id)
  
      def expire(self, context):
          """Expire reservations.
  
          Explores all currently existing reservations and rolls back
          any that have expired.
  
          :param context: The request context, for access checks.
          """
  
          db.reservation_expire(context)
  
  
  class NoopQuotaDriver(object):
      """Driver that turns quotas calls into no-ops and pretends that quotas
      for all resources are unlimited.  This can be used if you do not
      wish to have any quota checking.  For instance, with nova compute
      cells, the parent cell should do quota checking, but the child cell
      should not.
      """
  
      def get_by_project_and_user(self, context, project_id, user_id, resource):
          """Get a specific quota by project and user."""
          # Unlimited
          return -1
  
      def get_by_project(self, context, project_id, resource):
          """Get a specific quota by project."""
          # Unlimited
          return -1
  
      def get_by_class(self, context, quota_class, resource):
          """Get a specific quota by quota class."""
          # Unlimited
          return -1
  
      def get_defaults(self, context, resources):
          """Given a list of resources, retrieve the default quotas.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          """
          quotas = {}
          for resource in resources.values():
              quotas[resource.name] = -1
          return quotas
  
      def get_class_quotas(self, context, resources, quota_class,
                           defaults=True):
          """Given a list of resources, retrieve the quotas for the given
          quota class.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param quota_class: The name of the quota class to return
                              quotas for.
          :param defaults: If True, the default value will be reported
                           if there is no specific value for the
                           resource.
          """
          quotas = {}
          for resource in resources.values():
              quotas[resource.name] = -1
          return quotas
  
      def _get_noop_quotas(self, resources, usages=None, remains=False):
          quotas = {}
          for resource in resources.values():
              quotas[resource.name] = {}
              quotas[resource.name]['limit'] = -1
              if usages:
                  quotas[resource.name]['in_use'] = -1
                  quotas[resource.name]['reserved'] = -1
              if remains:
                  quotas[resource.name]['remains'] = -1
          return quotas
  
      def get_user_quotas(self, context, resources, project_id, user_id,
                          quota_class=None, defaults=True,
                          usages=True):
          """Given a list of resources, retrieve the quotas for the given
          user and project.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param project_id: The ID of the project to return quotas for.
          :param user_id: The ID of the user to return quotas for.
          :param quota_class: If project_id != context.project_id, the
                              quota class cannot be determined.  This
                              parameter allows it to be specified.  It
                              will be ignored if project_id ==
                              context.project_id.
          :param defaults: If True, the quota class value (or the
                           default value, if there is no value from the
                           quota class) will be reported if there is no
                           specific value for the resource.
          :param usages: If True, the current in_use and reserved counts
                         will also be returned.
          """
          return self._get_noop_quotas(resources, usages=usages)
  
      def get_project_quotas(self, context, resources, project_id,
                             quota_class=None, defaults=True,
                             usages=True, remains=False):
          """Given a list of resources, retrieve the quotas for the given
          project.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param project_id: The ID of the project to return quotas for.
          :param quota_class: If project_id != context.project_id, the
                              quota class cannot be determined.  This
                              parameter allows it to be specified.  It
                              will be ignored if project_id ==
                              context.project_id.
          :param defaults: If True, the quota class value (or the
                           default value, if there is no value from the
                           quota class) will be reported if there is no
                           specific value for the resource.
          :param usages: If True, the current in_use and reserved counts
                         will also be returned.
          :param remains: If True, the current remains of the project will
                          will be returned.
          """
          return self._get_noop_quotas(resources, usages=usages, remains=remains)
  
      def get_settable_quotas(self, context, resources, project_id,
                              user_id=None):
          """Given a list of resources, retrieve the range of settable quotas for
          the given user or project.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param project_id: The ID of the project to return quotas for.
          :param user_id: The ID of the user to return quotas for.
          """
          quotas = {}
          for resource in resources.values():
              quotas[resource.name] = {'minimum': 0, 'maximum': -1}
          return quotas
  
      def limit_check(self, context, resources, values, project_id=None,
                      user_id=None):
          """Check simple quota limits.
  
          For limits--those quotas for which there is no usage
          synchronization function--this method checks that a set of
          proposed values are permitted by the limit restriction.
  
          This method will raise a QuotaResourceUnknown exception if a
          given resource is unknown or if it is not a simple limit
          resource.
  
          If any of the proposed values is over the defined quota, an
          OverQuota exception will be raised with the sorted list of the
          resources which are too high.  Otherwise, the method returns
          nothing.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param values: A dictionary of the values to check against the
                         quota.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
          pass
  
      def reserve(self, context, resources, deltas, expire=None,
                  project_id=None, user_id=None):
          """Check quotas and reserve resources.
  
          For counting quotas--those quotas for which there is a usage
          synchronization function--this method checks quotas against
          current usage and the desired deltas.
  
          This method will raise a QuotaResourceUnknown exception if a
          given resource is unknown or if it does not have a usage
          synchronization function.
  
          If any of the proposed values is over the defined quota, an
          OverQuota exception will be raised with the sorted list of the
          resources which are too high.  Otherwise, the method returns a
          list of reservation UUIDs which were created.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param deltas: A dictionary of the proposed delta changes.
          :param expire: An optional parameter specifying an expiration
                         time for the reservations.  If it is a simple
                         number, it is interpreted as a number of
                         seconds and added to the current time; if it is
                         a datetime.timedelta object, it will also be
                         added to the current time.  A datetime.datetime
                         object will be interpreted as the absolute
                         expiration time.  If None is specified, the
                         default expiration time set by
                         --default-reservation-expire will be used (this
                         value will be treated as a number of seconds).
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
          return []
  
      def commit(self, context, reservations, project_id=None, user_id=None):
          """Commit reservations.
  
          :param context: The request context, for access checks.
          :param reservations: A list of the reservation UUIDs, as
                               returned by the reserve() method.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
          pass
  
      def rollback(self, context, reservations, project_id=None, user_id=None):
          """Roll back reservations.
  
          :param context: The request context, for access checks.
          :param reservations: A list of the reservation UUIDs, as
                               returned by the reserve() method.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
          pass
  
      def usage_reset(self, context, resources):
          """Reset the usage records for a particular user on a list of
          resources.  This will force that user's usage records to be
          refreshed the next time a reservation is made.
  
          Note: this does not affect the currently outstanding
          reservations the user has; those reservations must be
          committed or rolled back (or expired).
  
          :param context: The request context, for access checks.
          :param resources: A list of the resource names for which the
                            usage must be reset.
          """
          pass
  
      def destroy_all_by_project_and_user(self, context, project_id, user_id):
          """Destroy all quotas, usages, and reservations associated with a
          project and user.
  
          :param context: The request context, for access checks.
          :param project_id: The ID of the project being deleted.
          :param user_id: The ID of the user being deleted.
          """
          pass
  
      def destroy_all_by_project(self, context, project_id):
          """Destroy all quotas, usages, and reservations associated with a
          project.
  
          :param context: The request context, for access checks.
          :param project_id: The ID of the project being deleted.
          """
          pass
  
      def expire(self, context):
          """Expire reservations.
  
          Explores all currently existing reservations and rolls back
          any that have expired.
  
          :param context: The request context, for access checks.
          """
          pass
  
  
  class BaseResource(object):
      """Describe a single resource for quota checking."""
  
      def __init__(self, name, flag=None):
          """Initializes a Resource.
  
          :param name: The name of the resource, i.e., "instances".
          :param flag: The name of the flag or configuration option
                       which specifies the default value of the quota
                       for this resource.
          """
  
          self.name = name
          self.flag = flag
  
      def quota(self, driver, context, **kwargs):
          """Given a driver and context, obtain the quota for this
          resource.
  
          :param driver: A quota driver.
          :param context: The request context.
          :param project_id: The project to obtain the quota value for.
                             If not provided, it is taken from the
                             context.  If it is given as None, no
                             project-specific quota will be searched
                             for.
          :param quota_class: The quota class corresponding to the
                              project, or for which the quota is to be
                              looked up.  If not provided, it is taken
                              from the context.  If it is given as None,
                              no quota class-specific quota will be
                              searched for.  Note that the quota class
                              defaults to the value in the context,
                              which may not correspond to the project if
                              project_id is not the same as the one in
                              the context.
          """
  
          # Get the project ID
          project_id = kwargs.get('project_id', context.project_id)
  
          # Ditto for the quota class
          quota_class = kwargs.get('quota_class', context.quota_class)
  
          # Look up the quota for the project
          if project_id:
              try:
                  return driver.get_by_project(context, project_id, self.name)
              except exception.ProjectQuotaNotFound:
                  pass
  
          # Try for the quota class
          if quota_class:
              try:
                  return driver.get_by_class(context, quota_class, self.name)
              except exception.QuotaClassNotFound:
                  pass
  
          # OK, return the default
          return self.default
  
      @property
      def default(self):
          """Return the default value of the quota."""
  
          return CONF[self.flag] if self.flag else -1
  
  
  class ReservableResource(BaseResource):
      """Describe a reservable resource."""
      valid_method = 'reserve'
  
      def __init__(self, name, sync, flag=None):
          """Initializes a ReservableResource.
  
          Reservable resources are those resources which directly
          correspond to objects in the database, i.e., instances,
          cores, etc.
  
          Usage synchronization function must be associated with each
          object. This function will be called to determine the current
          counts of one or more resources. This association is done in
          database backend.
  
          The usage synchronization function will be passed three
          arguments: an admin context, the project ID, and an opaque
          session object, which should in turn be passed to the
          underlying database function.  Synchronization functions
          should return a dictionary mapping resource names to the
          current in_use count for those resources; more than one
          resource and resource count may be returned.  Note that
          synchronization functions may be associated with more than one
          ReservableResource.
  
          :param name: The name of the resource, i.e., "volumes".
          :param sync: A dbapi methods name which returns a dictionary
                       to resynchronize the in_use count for one or more
                       resources, as described above.
          :param flag: The name of the flag or configuration option
                       which specifies the default value of the quota
                       for this resource.
          """
          super(ReservableResource, self).__init__(name, flag=flag)
          self.sync = sync
  
  
  class AbsoluteResource(BaseResource):
      """Describe a non-reservable resource."""
      valid_method = 'check'
  
  
  class CountableResource(AbsoluteResource):
      """Describe a resource where the counts aren't based solely on the
      project ID.
      """
  
      def __init__(self, name, count, flag=None):
          """Initializes a CountableResource.
  
          Countable resources are those resources which directly
          correspond to objects in the database, i.e., instances, cores,
          etc., but for which a count by project ID is inappropriate.  A
          CountableResource must be constructed with a counting
          function, which will be called to determine the current counts
          of the resource.
  
          The counting function will be passed the context, along with
          the extra positional and keyword arguments that are passed to
          Quota.count().  It should return an integer specifying the
          count.
  
          Note that this counting is not performed in a transaction-safe
          manner.  This resource class is a temporary measure to provide
          required functionality, until a better approach to solving
          this problem can be evolved.
  
          :param name: The name of the resource, i.e., "instances".
          :param count: A callable which returns the count of the
                        resource.  The arguments passed are as described
                        above.
          :param flag: The name of the flag or configuration option
                       which specifies the default value of the quota
                       for this resource.
          """
  
          super(CountableResource, self).__init__(name, flag=flag)
          self.count = count
  
  
  class QuotaEngine(object):
      """Represent the set of recognized quotas."""
  
      def __init__(self, quota_driver_class=None):
          """Initialize a Quota object."""
          self._resources = {}
          self._driver_cls = quota_driver_class
          self.__driver = None
  
      @property
      def _driver(self):
          if self.__driver:
              return self.__driver
          if not self._driver_cls:
              self._driver_cls = CONF.quota_driver
          if isinstance(self._driver_cls, six.string_types):
              self._driver_cls = importutils.import_object(self._driver_cls)
          self.__driver = self._driver_cls
          return self.__driver
  
      def __contains__(self, resource):
          return resource in self._resources
  
      def __getitem__(self, key):
          if key in self._resources:
              return self._resources[key]
  
      def register_resource(self, resource):
          """Register a resource."""
  
          self._resources[resource.name] = resource
  
      def register_resources(self, resources):
          """Register a list of resources."""
  
          for resource in resources:
              self.register_resource(resource)
  
      def get_by_project_and_user(self, context, project_id, user_id, resource):
          """Get a specific quota by project and user."""
  
          return self._driver.get_by_project_and_user(context, project_id,
                                                      user_id, resource)
  
      def get_by_project(self, context, project_id, resource):
          """Get a specific quota by project."""
  
          return self._driver.get_by_project(context, project_id, resource)
  
      def get_by_class(self, context, quota_class, resource):
          """Get a specific quota by quota class."""
  
          return self._driver.get_by_class(context, quota_class, resource)
  
      def get_defaults(self, context):
          """Retrieve the default quotas.
  
          :param context: The request context, for access checks.
          """
  
          return self._driver.get_defaults(context, self._resources)
  
      def get_class_quotas(self, context, quota_class, defaults=True):
          """Retrieve the quotas for the given quota class.
  
          :param context: The request context, for access checks.
          :param quota_class: The name of the quota class to return
                              quotas for.
          :param defaults: If True, the default value will be reported
                           if there is no specific value for the
                           resource.
          """
  
          return self._driver.get_class_quotas(context, self._resources,
                                               quota_class, defaults=defaults)
  
      def get_user_quotas(self, context, project_id, user_id, quota_class=None,
                          defaults=True, usages=True):
          """Retrieve the quotas for the given user and project.
  
          :param context: The request context, for access checks.
          :param project_id: The ID of the project to return quotas for.
          :param user_id: The ID of the user to return quotas for.
          :param quota_class: If project_id != context.project_id, the
                              quota class cannot be determined.  This
                              parameter allows it to be specified.
          :param defaults: If True, the quota class value (or the
                           default value, if there is no value from the
                           quota class) will be reported if there is no
                           specific value for the resource.
          :param usages: If True, the current in_use and reserved counts
                         will also be returned.
          """
  
          return self._driver.get_user_quotas(context, self._resources,
                                              project_id, user_id,
                                              quota_class=quota_class,
                                              defaults=defaults,
                                              usages=usages)
  
      def get_project_quotas(self, context, project_id, quota_class=None,
                             defaults=True, usages=True, remains=False):
          """Retrieve the quotas for the given project.
  
          :param context: The request context, for access checks.
          :param project_id: The ID of the project to return quotas for.
          :param quota_class: If project_id != context.project_id, the
                              quota class cannot be determined.  This
                              parameter allows it to be specified.
          :param defaults: If True, the quota class value (or the
                           default value, if there is no value from the
                           quota class) will be reported if there is no
                           specific value for the resource.
          :param usages: If True, the current in_use and reserved counts
                         will also be returned.
          :param remains: If True, the current remains of the project will
                          will be returned.
          """
  
          return self._driver.get_project_quotas(context, self._resources,
                                                project_id,
                                                quota_class=quota_class,
                                                defaults=defaults,
                                                usages=usages,
                                                remains=remains)
  
      def get_settable_quotas(self, context, project_id, parent_id=None,
                                                          user_id=None):
          """Given a list of resources, retrieve the range of settable quotas for
          the given user or project.
  
          :param context: The request context, for access checks.
          :param resources: A dictionary of the registered resources.
          :param project_id: The ID of the project to return quotas for.
          :param user_id: The ID of the user to return quotas for.
          """
  
          return self._driver.get_settable_quotas(context, self._resources,
                                                  project_id,
                                                  parent_id=parent_id,
                                                  user_id=user_id)
  
      def count(self, context, resource, *args, **kwargs):
          """Count a resource.
  
          For countable resources, invokes the count() function and
          returns its result.  Arguments following the context and
          resource are passed directly to the count function declared by
          the resource.
  
          :param context: The request context, for access checks.
          :param resource: The name of the resource, as a string.
          """
  
          # Get the resource
          res = self._resources.get(resource)
          if not res or not hasattr(res, 'count'):
              raise exception.QuotaResourceUnknown(unknown=[resource])
  
          return res.count(context, *args, **kwargs)
  
      def limit_check(self, context, project_id=None, user_id=None, **values):
          """Check simple quota limits.
  
          For limits--those quotas for which there is no usage
          synchronization function--this method checks that a set of
          proposed values are permitted by the limit restriction.  The
          values to check are given as keyword arguments, where the key
          identifies the specific quota limit to check, and the value is
          the proposed value.
  
          This method will raise a QuotaResourceUnknown exception if a
          given resource is unknown or if it is not a simple limit
          resource.
  
          If any of the proposed values is over the defined quota, an
          OverQuota exception will be raised with the sorted list of the
          resources which are too high.  Otherwise, the method returns
          nothing.
  
          :param context: The request context, for access checks.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          :param user_id: Specify the user_id if current context
                          is admin and admin wants to impact on
                          common user.
          """
  
          return self._driver.limit_check(context, self._resources, values,
                                          project_id=project_id, user_id=user_id)
  
      def reserve(self, context, expire=None, project_id=None, user_id=None,
                  **deltas):
          """Check quotas and reserve resources.
  
          For counting quotas--those quotas for which there is a usage
          synchronization function--this method checks quotas against
          current usage and the desired deltas.  The deltas are given as
          keyword arguments, and current usage and other reservations
          are factored into the quota check.
  
          This method will raise a QuotaResourceUnknown exception if a
          given resource is unknown or if it does not have a usage
          synchronization function.
  
          If any of the proposed values is over the defined quota, an
          OverQuota exception will be raised with the sorted list of the
          resources which are too high.  Otherwise, the method returns a
          list of reservation UUIDs which were created.
  
          :param context: The request context, for access checks.
          :param expire: An optional parameter specifying an expiration
                         time for the reservations.  If it is a simple
                         number, it is interpreted as a number of
                         seconds and added to the current time; if it is
                         a datetime.timedelta object, it will also be
                         added to the current time.  A datetime.datetime
                         object will be interpreted as the absolute
                         expiration time.  If None is specified, the
                         default expiration time set by
                         --default-reservation-expire will be used (this
                         value will be treated as a number of seconds).
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          """
  
          reservations = self._driver.reserve(context, self._resources, deltas,
                                              expire=expire,
                                              project_id=project_id,
                                              user_id=user_id)
  
          LOG.debug("Created reservations %s", reservations)
  
          return reservations
  
      def commit(self, context, reservations, project_id=None, user_id=None):
          """Commit reservations.
  
          :param context: The request context, for access checks.
          :param reservations: A list of the reservation UUIDs, as
                               returned by the reserve() method.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          """
  
          try:
              self._driver.commit(context, reservations, project_id=project_id,
                                  user_id=user_id)
          except Exception:
              # NOTE(Vek): Ignoring exceptions here is safe, because the
              # usage resynchronization and the reservation expiration
              # mechanisms will resolve the issue.  The exception is
              # logged, however, because this is less than optimal.
              LOG.exception(_LE("Failed to commit reservations %s"),
                            reservations)
              return
          LOG.debug("Committed reservations %s", reservations)
  
      def rollback(self, context, reservations, project_id=None, user_id=None):
          """Roll back reservations.
  
          :param context: The request context, for access checks.
          :param reservations: A list of the reservation UUIDs, as
                               returned by the reserve() method.
          :param project_id: Specify the project_id if current context
                             is admin and admin wants to impact on
                             common user's tenant.
          """
  
          try:
              self._driver.rollback(context, reservations, project_id=project_id,
                                    user_id=user_id)
          except Exception:
              # NOTE(Vek): Ignoring exceptions here is safe, because the
              # usage resynchronization and the reservation expiration
              # mechanisms will resolve the issue.  The exception is
              # logged, however, because this is less than optimal.
              LOG.exception(_LE("Failed to roll back reservations %s"),
                            reservations)
              return
          LOG.debug("Rolled back reservations %s", reservations)
  
      def usage_reset(self, context, resources):
          """Reset the usage records for a particular user on a list of
          resources.  This will force that user's usage records to be
          refreshed the next time a reservation is made.
  
          Note: this does not affect the currently outstanding
          reservations the user has; those reservations must be
          committed or rolled back (or expired).
  
          :param context: The request context, for access checks.
          :param resources: A list of the resource names for which the
                            usage must be reset.
          """
  
          self._driver.usage_reset(context, resources)
  
      def destroy_all_by_project_and_user(self, context, project_id, user_id):
          """Destroy all quotas, usages, and reservations associated with a
          project and user.
  
          :param context: The request context, for access checks.
          :param project_id: The ID of the project being deleted.
          :param user_id: The ID of the user being deleted.
          """
  
          self._driver.destroy_all_by_project_and_user(context,
                                                       project_id, user_id)
  
      def destroy_all_by_project(self, context, project_id):
          """Destroy all quotas, usages, and reservations associated with a
          project.
  
          :param context: The request context, for access checks.
          :param project_id: The ID of the project being deleted.
          """
  
          self._driver.destroy_all_by_project(context, project_id)
  
      def expire(self, context):
          """Expire reservations.
  
          Explores all currently existing reservations and rolls back
          any that have expired.
  
          :param context: The request context, for access checks.
          """
  
          self._driver.expire(context)
  
      @property
      def resources(self):
          return sorted(self._resources.keys())
  
  
  def _keypair_get_count_by_user(*args, **kwargs):
      """Helper method to avoid referencing objects.KeyPairList on import."""
      return objects.KeyPairList.get_count_by_user(*args, **kwargs)
  
  
  def _server_group_count_members_by_user(context, group, user_id):
      """Helper method to avoid referencing objects.InstanceGroup on import."""
      return group.count_members_by_user(context, user_id)
  
  
  QUOTAS = QuotaEngine()
  
  
  resources = [
      ReservableResource('instances', '_sync_instances', 'quota_instances'),
      ReservableResource('cores', '_sync_instances', 'quota_cores'),
      ReservableResource('ram', '_sync_instances', 'quota_ram'),
      ReservableResource('security_groups', '_sync_security_groups',
                         'quota_security_groups'),
      ReservableResource('floating_ips', '_sync_floating_ips',
                         'quota_floating_ips'),
      ReservableResource('fixed_ips', '_sync_fixed_ips', 'quota_fixed_ips'),
      AbsoluteResource('metadata_items', 'quota_metadata_items'),
      AbsoluteResource('injected_files', 'quota_injected_files'),
      AbsoluteResource('injected_file_content_bytes',
                       'quota_injected_file_content_bytes'),
      AbsoluteResource('injected_file_path_bytes',
                       'quota_injected_file_path_length'),
      CountableResource('security_group_rules',
                        db.security_group_rule_count_by_group,
                        'quota_security_group_rules'),
      CountableResource('key_pairs', _keypair_get_count_by_user,
                        'quota_key_pairs'),
      ReservableResource('server_groups', '_sync_server_groups',
                        'quota_server_groups'),
      CountableResource('server_group_members',
                        _server_group_count_members_by_user,
                        'quota_server_group_members'),
      ]
  
  
  QUOTAS.register_resources(resources)
  
  
  def _valid_method_call_check_resource(name, method):
      if name not in QUOTAS:
          raise exception.InvalidQuotaMethodUsage(method=method, res=name)
      res = QUOTAS[name]
  
      if res.valid_method != method:
          raise exception.InvalidQuotaMethodUsage(method=method, res=name)
  
  
  def _valid_method_call_check_resources(resource, method):
      """A method to check whether the resource can use the quota method."""
  
      for name in resource.keys():
          _valid_method_call_check_resource(name, method)
  