old_contents: # Copyright (c) 2011 Openstack, LLC.
  # All Rights Reserved.
  #
  #    Licensed under the Apache License, Version 2.0 (the "License"); you may
  #    not use this file except in compliance with the License. You may obtain
  #    a copy of the License at
  #
  #         http://www.apache.org/licenses/LICENSE-2.0
  #
  #    Unless required by applicable law or agreed to in writing, software
  #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  #    License for the specific language governing permissions and limitations
  #    under the License.
  
  """
  The Host Filter classes are a way to ensure that only hosts that are
  appropriate are considered when creating a new instance. Hosts that are
  either incompatible or insufficient to accept a newly-requested instance
  are removed by Host Filter classes from consideration. Those that pass
  the filter are then passed on for weighting or other process for ordering.
  
  Filters are in the 'filters' directory that is off the 'scheduler'
  directory of nova. Additional filters can be created and added to that
  directory; be sure to add them to the filters/__init__.py file so that
  they are part of the nova.schedulers.filters namespace.
  """
  
  import types
  
  from nova import exception
  from nova import flags
  import nova.scheduler
  from nova.scheduler import filters
  
  
  FLAGS = flags.FLAGS
  
  
  def _get_filters():
      # Imported here to avoid circular imports
      from nova.scheduler import filters
  
      def get_itm(nm):
          return getattr(filters, nm)
  
      return [get_itm(itm) for itm in dir(filters)
              if (type(get_itm(itm)) is types.TypeType)
              and issubclass(get_itm(itm), filters.AbstractHostFilter)
              and get_itm(itm) is not filters.AbstractHostFilter]
  
  
  def choose_host_filter(filter_name=None):
      """Since the caller may specify which filter to use we need
      to have an authoritative list of what is permissible. This
      function checks the filter name against a predefined set
      of acceptable filters.
      """
      if not filter_name:
          filter_name = FLAGS.default_host_filter
      for filter_class in _get_filters():
          if filter_class.__name__ == filter_name:
              return filter_class()
      raise exception.SchedulerHostFilterNotFound(filter_name=filter_name)
  
new_contents: # Copyright (c) 2011 Openstack, LLC.
  # All Rights Reserved.
  #
  #    Licensed under the Apache License, Version 2.0 (the "License"); you may
  #    not use this file except in compliance with the License. You may obtain
  #    a copy of the License at
  #
  #         http://www.apache.org/licenses/LICENSE-2.0
  #
  #    Unless required by applicable law or agreed to in writing, software
  #    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  #    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  #    License for the specific language governing permissions and limitations
  #    under the License.
  
  """
  The Host Filter classes are a way to ensure that only hosts that are
  appropriate are considered when creating a new instance. Hosts that are
  either incompatible or insufficient to accept a newly-requested instance
  are removed by Host Filter classes from consideration. Those that pass
  the filter are then passed on for weighting or other process for ordering.
  
  Filters are in the 'filters' directory that is off the 'scheduler'
  directory of nova. Additional filters can be created and added to that
  directory; be sure to add them to the filters/__init__.py file so that
  they are part of the nova.schedulers.filters namespace.
  """
  
  import types
  
  from nova import exception
  from nova import flags
  import nova.scheduler
  
  # NOTE(Vek): Even though we don't use filters in here anywhere, we
  #            depend on default_host_filter being available in FLAGS,
  #            and that happens only when filters/abstract_filter.py is
  #            imported.
  from nova.scheduler import filters
  
  
  FLAGS = flags.FLAGS
  
  
  def _get_filters():
      # Imported here to avoid circular imports
      from nova.scheduler import filters
  
      def get_itm(nm):
          return getattr(filters, nm)
  
      return [get_itm(itm) for itm in dir(filters)
              if (type(get_itm(itm)) is types.TypeType)
              and issubclass(get_itm(itm), filters.AbstractHostFilter)
              and get_itm(itm) is not filters.AbstractHostFilter]
  
  
  def choose_host_filter(filter_name=None):
      """Since the caller may specify which filter to use we need
      to have an authoritative list of what is permissible. This
      function checks the filter name against a predefined set
      of acceptable filters.
      """
      if not filter_name:
          filter_name = FLAGS.default_host_filter
      for filter_class in _get_filters():
          if filter_class.__name__ == filter_name:
              return filter_class()
      raise exception.SchedulerHostFilterNotFound(filter_name=filter_name)
  
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