# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright (c) 2010 Openstack, LLC.
# 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.

"""
Scheduler base class that all Schedulers should inherit from
"""

import datetime

from nova import db
from nova import exception
from nova import flags

FLAGS = flags.FLAGS
flags.DEFINE_integer('service_down_time', 60,
                     'maximum time since last checkin for up service')


class NoValidHost(exception.Error):
    """There is no valid host for the command."""
    pass


class WillNotSchedule(exception.Error):
    """The specified host is not up or doesn't exist."""
    pass


class Scheduler(object):
    """The base class that all Scheduler clases should inherit from."""

    @staticmethod
    def service_is_up(service):
        """Check whether a service is up based on last heartbeat."""
        last_heartbeat = service['updated_at'] or service['created_at']
        # Timestamps in DB are UTC.
        elapsed = datetime.datetime.utcnow() - last_heartbeat
        return elapsed < datetime.timedelta(seconds=FLAGS.service_down_time)

    def hosts_up(self, context, topic):
        """Return the list of hosts that have a running service for topic."""

        services = db.service_get_all_by_topic(context, topic)
        return [service.host
                for service in services
                if self.service_is_up(service)]

    def schedule(self, context, topic, *_args, **_kwargs):
        """Must override at least this method for scheduler to work."""
        raise NotImplementedError(_("Must implement a fallback schedule"))

# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright (c) 2010 Openstack, LLC.
# 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.

"""
Scheduler base class that all Schedulers should inherit from
"""

import datetime

from nova import db
from nova import exception
from nova import flags

FLAGS = flags.FLAGS
flags.DEFINE_integer('service_down_time', 60,
                     'maximum time since last checkin for up service')


class NoValidHost(exception.Error):
    """There is no valid host for the command."""
    pass


class WillNotSchedule(exception.Error):
    """The specified host is not up or doesn't exist."""
    pass


class Scheduler(object):
    """The base class that all Scheduler clases should inherit from."""

    @staticmethod
    def service_is_up(service):
        """Check whether a service is up based on last heartbeat."""
        last_heartbeat = service['updated_at'] or service['created_at']
        # Timestamps in DB are UTC.
        elapsed = datetime.datetime.utcnow() - last_heartbeat
        return elapsed < datetime.timedelta(seconds=FLAGS.service_down_time)

    def hosts_up(self, context, topic):
        """Return the list of hosts that have a running service for topic."""

        services = db.service_get_all_by_topic(context, topic)
        return [service.host
                for service in services
                if self.service_is_up(service)]

    def schedule(self, context, topic, *_args, **_kwargs):
        """Must override at least this method for scheduler to work."""
        raise NotImplementedError(_("Must implement a fallback schedule"))

# vim: tabstop=4 shiftwidth=4 softtabstop=4 # Copyright (c) 2010 Openstack, LLC. # 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. Scheduler base class that all Schedulers should inherit from There is no valid host for the command. The specified host is not up or doesn't exist. The base class that all Scheduler clases should inherit from. Check whether a service is up based on last heartbeat. # Timestamps in DB are UTC. Return the list of hosts that have a running service for topic. Must override at least this method for scheduler to work.