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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.
# Copyright 2011 Justin Santa Barbara
# 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 base class for all workers that run on hosts."""
import signal
import sys
import eventlet
import greenlet
from openstack.common import log as logging
from openstack.common.gettextutils import _
LOG = logging.getLogger(__name__)
class Launcher(object):
"""Launch one or more services and wait for them to complete."""
def __init__(self):
"""Initialize the service launcher.
:returns: None
"""
self._services = []
@staticmethod
def run_service(service):
"""Start and wait for a service to finish.
:param service: service to run and wait for.
:returns: None
"""
service.start()
service.wait()
def launch_service(self, service):
"""Load and start the given service.
:param service: The service you would like to start.
:returns: None
"""
gt = eventlet.spawn(self.run_service, service)
self._services.append(gt)
def stop(self):
"""Stop all services which are currently running.
:returns: None
"""
for service in self._services:
service.kill()
def wait(self):
"""Waits until all services have been stopped, and then returns.
:returns: None
"""
for service in self._services:
try:
service.wait()
except greenlet.GreenletExit:
pass
class SignalExit(SystemExit):
def __init__(self, signo, exccode=1):
super(SignalExit, self).__init__(exccode)
self.signo = signo
class ServiceLauncher(Launcher):
def _handle_signal(self, signo, frame):
# Allow the process to be killed again and die from natural causes
signal.signal(signal.SIGTERM, signal.SIG_DFL)
signal.signal(signal.SIGINT, signal.SIG_DFL)
raise SignalExit(signo)
def wait(self):
signal.signal(signal.SIGTERM, self._handle_signal)
signal.signal(signal.SIGINT, self._handle_signal)
status = None
try:
super(ServiceLauncher, self).wait()
except SignalExit as exc:
signame = {signal.SIGTERM: 'SIGTERM',
signal.SIGINT: 'SIGINT'}[exc.signo]
LOG.info(_('Caught %s, exiting'), signame)
status = exc.code
except SystemExit as exc:
status = exc.code
finally:
self.stop()
return status
class Service(object):
"""Service object for binaries running on hosts.
A service takes a manager."""
def __init__(self, host, manager, *args, **kwargs):
self.host = host
self.manager = manager
def start(self):
if self.manager:
self.manager.init_host()
def stop(self):
pass
def wait(self):
pass
def launcher(service):
l = Launcher()
l.launch_service(service)
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