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# vim: tabstop=4 shiftwidth=4 softtabstop=4
# 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.
"""
Generic Node baseclass for all workers that run on hosts
"""
import inspect
import logging
import os
from twisted.internet import defer
from twisted.internet import task
from twisted.application import service
from nova import db
from nova import exception
from nova import flags
from nova import rpc
from nova import utils
FLAGS = flags.FLAGS
flags.DEFINE_integer('report_interval', 10,
'seconds between nodes reporting state to cloud',
lower_bound=1)
class Service(object, service.Service):
"""Base class for workers that run on hosts."""
def __init__(self, host, binary, topic, manager, *args, **kwargs):
self.host = host
self.binary = binary
self.topic = topic
manager_class = utils.import_class(manager)
self.manager = manager_class(host=host, *args, **kwargs)
self.manager.init_host()
self.model_disconnected = False
super(Service, self).__init__(*args, **kwargs)
try:
service_ref = db.service_get_by_args(None,
self.host,
self.binary)
self.service_id = service_ref['id']
except exception.NotFound:
self._create_service_ref()
def _create_service_ref(self):
service_ref = db.service_create(None, {'host': self.host,
'binary': self.binary,
'topic': self.topic,
'report_count': 0})
self.service_id = service_ref['id']
def __getattr__(self, key):
try:
return super(Service, self).__getattr__(key)
except AttributeError:
return getattr(self.manager, key)
@classmethod
def create(cls,
host=None,
binary=None,
topic=None,
manager=None,
report_interval=None):
"""Instantiates class and passes back application object.
Args:
host, defaults to FLAGS.host
binary, defaults to basename of executable
topic, defaults to bin_name - "nova-" part
manager, defaults to FLAGS.<topic>_manager
report_interval, defaults to FLAGS.report_interval
"""
if not host:
host = FLAGS.host
if not binary:
binary = os.path.basename(inspect.stack()[-1][1])
if not topic:
topic = binary.rpartition("nova-")[2]
if not manager:
manager = FLAGS.get('%s_manager' % topic, None)
if not report_interval:
report_interval = FLAGS.report_interval
logging.warn("Starting %s node", topic)
service_obj = cls(host, binary, topic, manager)
conn = rpc.Connection.instance()
consumer_all = rpc.AdapterConsumer(
connection=conn,
topic=topic,
proxy=service_obj)
consumer_node = rpc.AdapterConsumer(
connection=conn,
topic='%s.%s' % (topic, host),
proxy=service_obj)
pulse = task.LoopingCall(service_obj.report_state)
pulse.start(interval=report_interval, now=False)
consumer_all.attach_to_twisted()
consumer_node.attach_to_twisted()
# This is the parent service that twistd will be looking for when it
# parses this file, return it so that we can get it into globals.
application = service.Application(binary)
service_obj.setServiceParent(application)
return application
def kill(self, context=None):
"""Destroy the service object in the datastore"""
try:
db.service_destroy(context, self.service_id)
except exception.NotFound:
logging.warn("Service killed that has no database entry")
@defer.inlineCallbacks
def report_state(self, context=None):
"""Update the state of this service in the datastore."""
try:
try:
service_ref = db.service_get(context, self.service_id)
except exception.NotFound:
logging.debug("The service database object disappeared, "
"Recreating it.")
self._create_service_ref()
service_ref = db.service_get(context, self.service_id)
db.service_update(context,
self.service_id,
{'report_count': service_ref['report_count'] + 1})
# TODO(termie): make this pattern be more elegant.
if getattr(self, "model_disconnected", False):
self.model_disconnected = False
logging.error("Recovered model server connection!")
# TODO(vish): this should probably only catch connection errors
except Exception: # pylint: disable-msg=W0702
if not getattr(self, "model_disconnected", False):
self.model_disconnected = True
logging.exception("model server went away")
yield
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