OpenStack Study: retry_filter.py

**** CubicPower OpenStack Study ****

# Copyright (c) 2012 OpenStack Foundation

# All Rights Reserved.

#

# Licensed under the Apache License, Version 2.0 (the "License"); you may

# not use this file except in compliance with the License. You may obtain

# a copy of the License at

#

# http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT

# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the

# License for the specific language governing permissions and limitations

# under the License.

from nova.openstack.common.gettextutils import _

from nova.openstack.common import log as logging

from nova.scheduler import filters

LOG = logging.getLogger(__name__)

**** CubicPower OpenStack Study ****

class RetryFilter(filters.BaseHostFilter):

"""Filter out nodes that have already been attempted for scheduling

purposes

"""

**** CubicPower OpenStack Study ****

    def host_passes(self, host_state, filter_properties):

        """Skip nodes that have already been attempted."""

        retry = filter_properties.get('retry', None)

        if not retry:

            # Re-scheduling is disabled

            LOG.debug("Re-scheduling is disabled")

            return True

        hosts = retry.get('hosts', [])

        host = [host_state.host, host_state.nodename]

        passes = host not in hosts

        pass_msg = "passes" if passes else "fails"

        LOG.debug(_("Host %(host)s %(pass_msg)s.  Previously tried hosts: "

                    "%(hosts)s") % {'host': host,

                                    'pass_msg': pass_msg,

                                    'hosts': hosts})

        # Host passes if it's not in the list of previously attempted hosts:

        return passes