vmware-nsx/neutron/openstack/common/service.py
Ihar Hrachyshka 3aca3f7745 Port to oslo.messaging
Now that all preparations are done, actually port the code to use
oslo.messaging. This patch does as little as possible. Follow up patches
that refactor and cleanup the code and configuration files, will be
merged later. The reason for this is to make the patch as slim as
possible, to make review process more smooth and concentrated.

Details:
* neutron/common/rpc.py:
  - added init() and cleanup() to set global RPC layer state.
  - added utility functions: get_server(), get_client(), get_notifier()
    that wrap up oslo.messaging API a bit, enforcing eventlet executor
    and setting serializer, among other things.
  - removed PluginRpcDispatcher, instead introduced PluginRpcSerializer
    to use as a default serializer for API callbacks.

* neutron/common/rpc_compat.py:
  - emulated incubator RPC layer behaviour thru previously introduced
    stub classes (RpcCallback, RpcProxy, ...) using new oslo.messaging
    API.
  - switched to using new oslo.messaging exception types.

* neutron/service.py:
  - expect multiple RPC listeners that are of MessageHandlingServer
    type, not GreenThread.

* neutron/common/config.py:
  - initialize RPC layer in init()

* setup.cfg:
  - added entry points for old notifier drivers to retain backward
    compatibility.

* neutron/tests/...:
  - introduced fake_notifier to replace impl_fake.
  - faked out consume_in_thread() to avoid starting RPC listeners when
    running unit tests.
  - used 'fake' transport driver.
  - made sure neutron.test.* exceptions are caught.
  - initialize and clean up RPC layer for each test case.

* Ported all affected code from using neutron.openstack.common.notifier
  API to oslo.messaging.Notifier.

* rpc.set_defaults() was renamed to rpc.set_transport_defaults()

* other changes not worth mentioning here.

blueprint oslo-messaging

DocImpact

Change-Id: I5a91c34df6e300f2dc46217b1b16352fcc3039fc
2014-06-19 12:58:01 +02:00

515 lines
15 KiB
Python

# 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 errno
import logging as std_logging
import os
import random
import signal
import sys
import time
try:
# Importing just the symbol here because the io module does not
# exist in Python 2.6.
from io import UnsupportedOperation # noqa
except ImportError:
# Python 2.6
UnsupportedOperation = None
import eventlet
from eventlet import event
from oslo.config import cfg
from neutron.openstack.common import eventlet_backdoor
from neutron.openstack.common.gettextutils import _LE, _LI, _LW
from neutron.openstack.common import importutils
from neutron.openstack.common import log as logging
from neutron.openstack.common import systemd
from neutron.openstack.common import threadgroup
#rpc = importutils.try_import('neutron.openstack.common.rpc')
# TODO(ihrachys): restore once oslo-rpc code is removed from the tree
rpc = None
CONF = cfg.CONF
LOG = logging.getLogger(__name__)
def _sighup_supported():
return hasattr(signal, 'SIGHUP')
def _is_daemon():
# The process group for a foreground process will match the
# process group of the controlling terminal. If those values do
# not match, or ioctl() fails on the stdout file handle, we assume
# the process is running in the background as a daemon.
# http://www.gnu.org/software/bash/manual/bashref.html#Job-Control-Basics
try:
is_daemon = os.getpgrp() != os.tcgetpgrp(sys.stdout.fileno())
except OSError as err:
if err.errno == errno.ENOTTY:
# Assume we are a daemon because there is no terminal.
is_daemon = True
else:
raise
except UnsupportedOperation:
# Could not get the fileno for stdout, so we must be a daemon.
is_daemon = True
return is_daemon
def _is_sighup_and_daemon(signo):
if not (_sighup_supported() and signo == signal.SIGHUP):
# Avoid checking if we are a daemon, because the signal isn't
# SIGHUP.
return False
return _is_daemon()
def _signo_to_signame(signo):
signals = {signal.SIGTERM: 'SIGTERM',
signal.SIGINT: 'SIGINT'}
if _sighup_supported():
signals[signal.SIGHUP] = 'SIGHUP'
return signals[signo]
def _set_signals_handler(handler):
signal.signal(signal.SIGTERM, handler)
signal.signal(signal.SIGINT, handler)
if _sighup_supported():
signal.signal(signal.SIGHUP, handler)
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 = Services()
self.backdoor_port = eventlet_backdoor.initialize_if_enabled()
def launch_service(self, service):
"""Load and start the given service.
:param service: The service you would like to start.
:returns: None
"""
service.backdoor_port = self.backdoor_port
self.services.add(service)
def stop(self):
"""Stop all services which are currently running.
:returns: None
"""
self.services.stop()
def wait(self):
"""Waits until all services have been stopped, and then returns.
:returns: None
"""
self.services.wait()
def restart(self):
"""Reload config files and restart service.
:returns: None
"""
cfg.CONF.reload_config_files()
self.services.restart()
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
_set_signals_handler(signal.SIG_DFL)
raise SignalExit(signo)
def handle_signal(self):
_set_signals_handler(self._handle_signal)
def _wait_for_exit_or_signal(self, ready_callback=None):
status = None
signo = 0
LOG.debug('Full set of CONF:')
CONF.log_opt_values(LOG, std_logging.DEBUG)
try:
if ready_callback:
ready_callback()
super(ServiceLauncher, self).wait()
except SignalExit as exc:
signame = _signo_to_signame(exc.signo)
LOG.info(_LI('Caught %s, exiting'), signame)
status = exc.code
signo = exc.signo
except SystemExit as exc:
status = exc.code
finally:
self.stop()
if rpc:
try:
rpc.cleanup()
except Exception:
# We're shutting down, so it doesn't matter at this point.
LOG.exception(_LE('Exception during rpc cleanup.'))
return status, signo
def wait(self, ready_callback=None):
systemd.notify_once()
while True:
self.handle_signal()
status, signo = self._wait_for_exit_or_signal(ready_callback)
if not _is_sighup_and_daemon(signo):
return status
self.restart()
class ServiceWrapper(object):
def __init__(self, service, workers):
self.service = service
self.workers = workers
self.children = set()
self.forktimes = []
class ProcessLauncher(object):
def __init__(self, wait_interval=0.01):
"""Constructor.
:param wait_interval: The interval to sleep for between checks
of child process exit.
"""
self.children = {}
self.sigcaught = None
self.running = True
self.wait_interval = wait_interval
rfd, self.writepipe = os.pipe()
self.readpipe = eventlet.greenio.GreenPipe(rfd, 'r')
self.handle_signal()
def handle_signal(self):
_set_signals_handler(self._handle_signal)
def _handle_signal(self, signo, frame):
self.sigcaught = signo
self.running = False
# Allow the process to be killed again and die from natural causes
_set_signals_handler(signal.SIG_DFL)
def _pipe_watcher(self):
# This will block until the write end is closed when the parent
# dies unexpectedly
self.readpipe.read()
LOG.info(_LI('Parent process has died unexpectedly, exiting'))
sys.exit(1)
def _child_process_handle_signal(self):
# Setup child signal handlers differently
def _sigterm(*args):
signal.signal(signal.SIGTERM, signal.SIG_DFL)
raise SignalExit(signal.SIGTERM)
def _sighup(*args):
signal.signal(signal.SIGHUP, signal.SIG_DFL)
raise SignalExit(signal.SIGHUP)
signal.signal(signal.SIGTERM, _sigterm)
if _sighup_supported():
signal.signal(signal.SIGHUP, _sighup)
# Block SIGINT and let the parent send us a SIGTERM
signal.signal(signal.SIGINT, signal.SIG_IGN)
def _child_wait_for_exit_or_signal(self, launcher):
status = 0
signo = 0
# NOTE(johannes): All exceptions are caught to ensure this
# doesn't fallback into the loop spawning children. It would
# be bad for a child to spawn more children.
try:
launcher.wait()
except SignalExit as exc:
signame = _signo_to_signame(exc.signo)
LOG.info(_LI('Child caught %s, exiting'), signame)
status = exc.code
signo = exc.signo
except SystemExit as exc:
status = exc.code
except BaseException:
LOG.exception(_LE('Unhandled exception'))
status = 2
finally:
launcher.stop()
return status, signo
def _child_process(self, service):
self._child_process_handle_signal()
# Reopen the eventlet hub to make sure we don't share an epoll
# fd with parent and/or siblings, which would be bad
eventlet.hubs.use_hub()
# Close write to ensure only parent has it open
os.close(self.writepipe)
# Create greenthread to watch for parent to close pipe
eventlet.spawn_n(self._pipe_watcher)
# Reseed random number generator
random.seed()
launcher = Launcher()
launcher.launch_service(service)
return launcher
def _start_child(self, wrap):
if len(wrap.forktimes) > wrap.workers:
# Limit ourselves to one process a second (over the period of
# number of workers * 1 second). This will allow workers to
# start up quickly but ensure we don't fork off children that
# die instantly too quickly.
if time.time() - wrap.forktimes[0] < wrap.workers:
LOG.info(_LI('Forking too fast, sleeping'))
time.sleep(1)
wrap.forktimes.pop(0)
wrap.forktimes.append(time.time())
pid = os.fork()
if pid == 0:
launcher = self._child_process(wrap.service)
while True:
self._child_process_handle_signal()
status, signo = self._child_wait_for_exit_or_signal(launcher)
if not _is_sighup_and_daemon(signo):
break
launcher.restart()
os._exit(status)
LOG.info(_LI('Started child %d'), pid)
wrap.children.add(pid)
self.children[pid] = wrap
return pid
def launch_service(self, service, workers=1):
wrap = ServiceWrapper(service, workers)
LOG.info(_LI('Starting %d workers'), wrap.workers)
while self.running and len(wrap.children) < wrap.workers:
self._start_child(wrap)
def _wait_child(self):
try:
# Don't block if no child processes have exited
pid, status = os.waitpid(0, os.WNOHANG)
if not pid:
return None
except OSError as exc:
if exc.errno not in (errno.EINTR, errno.ECHILD):
raise
return None
if os.WIFSIGNALED(status):
sig = os.WTERMSIG(status)
LOG.info(_LI('Child %(pid)d killed by signal %(sig)d'),
dict(pid=pid, sig=sig))
else:
code = os.WEXITSTATUS(status)
LOG.info(_LI('Child %(pid)s exited with status %(code)d'),
dict(pid=pid, code=code))
if pid not in self.children:
LOG.warning(_LW('pid %d not in child list'), pid)
return None
wrap = self.children.pop(pid)
wrap.children.remove(pid)
return wrap
def _respawn_children(self):
while self.running:
wrap = self._wait_child()
if not wrap:
# Yield to other threads if no children have exited
# Sleep for a short time to avoid excessive CPU usage
# (see bug #1095346)
eventlet.greenthread.sleep(self.wait_interval)
continue
while self.running and len(wrap.children) < wrap.workers:
self._start_child(wrap)
def wait(self):
"""Loop waiting on children to die and respawning as necessary."""
systemd.notify_once()
LOG.debug('Full set of CONF:')
CONF.log_opt_values(LOG, std_logging.DEBUG)
try:
while True:
self.handle_signal()
self._respawn_children()
# No signal means that stop was called. Don't clean up here.
if not self.sigcaught:
return
signame = _signo_to_signame(self.sigcaught)
LOG.info(_LI('Caught %s, stopping children'), signame)
if not _is_sighup_and_daemon(self.sigcaught):
break
for pid in self.children:
os.kill(pid, signal.SIGHUP)
self.running = True
self.sigcaught = None
except eventlet.greenlet.GreenletExit:
LOG.info(_LI("Wait called after thread killed. Cleaning up."))
self.stop()
def stop(self):
"""Terminate child processes and wait on each."""
self.running = False
for pid in self.children:
try:
os.kill(pid, signal.SIGTERM)
except OSError as exc:
if exc.errno != errno.ESRCH:
raise
# Wait for children to die
if self.children:
LOG.info(_LI('Waiting on %d children to exit'), len(self.children))
while self.children:
self._wait_child()
class Service(object):
"""Service object for binaries running on hosts."""
def __init__(self, threads=1000):
self.tg = threadgroup.ThreadGroup(threads)
# signal that the service is done shutting itself down:
self._done = event.Event()
def reset(self):
# NOTE(Fengqian): docs for Event.reset() recommend against using it
self._done = event.Event()
def start(self):
pass
def stop(self):
self.tg.stop()
self.tg.wait()
# Signal that service cleanup is done:
if not self._done.ready():
self._done.send()
def wait(self):
self._done.wait()
class Services(object):
def __init__(self):
self.services = []
self.tg = threadgroup.ThreadGroup()
self.done = event.Event()
def add(self, service):
self.services.append(service)
self.tg.add_thread(self.run_service, service, self.done)
def stop(self):
# wait for graceful shutdown of services:
for service in self.services:
service.stop()
service.wait()
# Each service has performed cleanup, now signal that the run_service
# wrapper threads can now die:
if not self.done.ready():
self.done.send()
# reap threads:
self.tg.stop()
def wait(self):
self.tg.wait()
def restart(self):
self.stop()
self.done = event.Event()
for restart_service in self.services:
restart_service.reset()
self.tg.add_thread(self.run_service, restart_service, self.done)
@staticmethod
def run_service(service, done):
"""Service start wrapper.
:param service: service to run
:param done: event to wait on until a shutdown is triggered
:returns: None
"""
service.start()
done.wait()
def launch(service, workers=1):
if workers is None or workers == 1:
launcher = ServiceLauncher()
launcher.launch_service(service)
else:
launcher = ProcessLauncher()
launcher.launch_service(service, workers=workers)
return launcher