/usr/lib/python2.7/dist-packages/cotyledon/__init__.py is in python-cotyledon 1.2.6-3.
This file is owned by root:root, with mode 0o644.
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# 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.
import atexit
import collections
import contextlib
import errno
import logging
import os
import random
import signal
import socket
import sys
import threading
import time
import setproctitle
LOG = logging.getLogger(__name__)
SIGNAL_TO_NAME = dict((getattr(signal, name), name) for name in dir(signal)
if name.startswith("SIG") and name not in ('SIG_DFL',
'SIG_IGN'))
class _ServiceConfig(object):
def __init__(self, service, workers, args, kwargs):
self.service = service
self.workers = workers
self.args = args
self.kwargs = kwargs
def _spawn(target):
t = threading.Thread(target=target)
t.daemon = True
t.start()
return t
def _logged_sys_exit(code):
# NOTE(sileht): Ensure we send atexit exception to logs
try:
atexit._run_exitfuncs()
except Exception:
LOG.exception("unexpected atexit exception")
os._exit(code)
@contextlib.contextmanager
def _exit_on_exception():
try:
yield
except SystemExit as exc:
_logged_sys_exit(exc.code)
except BaseException:
LOG.exception('Unhandled exception')
_logged_sys_exit(2)
class Service(object):
"""Base class for a service
This class will be executed in a new child process of a
:py:class:`ServiceRunner`. It registers signals to manager the reloading
and the ending of the process.
Methods :py:meth:`run`, :py:meth:`terminate` and :py:meth:`reload` are
optional.
"""
name = None
"""Service name used in the process title and the log messages in additionnal
of the worker_id."""
def __init__(self, worker_id):
"""Create a new Service
:param worker_id: the identifier of this service instance
:type worker_id: int
"""
super(Service, self).__init__()
if self.name is None:
self.name = self.__class__.__name__
self.worker_id = worker_id
self.pid = os.getpid()
pname = os.path.basename(sys.argv[0])
self._title = "%(name)s(%(worker_id)d) [%(pid)d]" % dict(
name=self.name, worker_id=self.worker_id, pid=self.pid)
# Set process title
setproctitle.setproctitle(
"%(pname)s - %(name)s(%(worker_id)d)" % dict(
pname=pname, name=self.name,
worker_id=self.worker_id))
def terminate(self):
"""Gracefully shutdown the service
This method will be executed when the Service has to shutdown cleanly.
If not implemented the process will just end with status 0.
To customize the exit code, the :py:class:`SystemExit` exception can be
used.
"""
def reload(self):
"""Reloading of the service
This method will be executed when the Service receives a SIGHUP.
If not implemented the process will just end with status 0 and
:py:class:`ServiceRunner` will start a new fresh process for this
service with the same worker_id.
"""
self._clean_exit()
def run(self):
"""Method representing the service activity
If not implemented the process will just wait to receive an ending
signal.
"""
def _run(self):
LOG.debug("Run service %s" % self._title)
with _exit_on_exception():
self.run()
def _reload(self, sig, frame):
with _exit_on_exception():
self.reload()
def _clean_exit(self, *args, **kwargs):
signal.signal(signal.SIGTERM, signal.SIG_IGN)
LOG.info('Caught SIGTERM signal, '
'graceful exiting of service %s' % self._title)
with _exit_on_exception():
self.terminate()
sys.exit(0)
class ServiceManager(object):
"""Manage lifetimes of services
:py:class:`ServiceManager` acts as a master process that controls the
lifetime of children processes and restart them if they die unexpectedly.
It also propagate some signals (SIGTERM, SIGALRM, SIGINT and SIGHUP) to
them.
Each child process runs an instance of a :py:class:`Service`.
An application must create only one :py:class:`ServiceManager` class and
use :py:meth:`ServiceManager.run()` as main loop of the application.
Usage::
class MyService(Service):
def __init__(self, worker_id, myconf):
super(MyService, self).__init__(worker_id)
preparing_my_job(myconf)
self.running = True
def run(self):
while self.running:
do_my_job()
def terminate(self):
self.running = False
gracefully_stop_my_jobs()
def reload(self):
restart_my_job()
conf = {'foobar': 2}
sr = ServiceManager()
sr.add(MyService, 5, conf)
sr.run()
This will create 5 children processes running the service MyService.
"""
_marker = object()
_process_runner_already_created = False
def __init__(self, wait_interval=0.01):
"""Creates the ServiceManager object
:param wait_interval: time between each new process spawn
:type wait_interval: float
"""
if self._process_runner_already_created:
raise RuntimeError("Only one instance of ProcessRunner per "
"application is allowed")
ServiceManager._process_runner_already_created = True
self._wait_interval = wait_interval
self._shutdown = threading.Event()
self._running_services = collections.defaultdict(dict)
self._services = []
self._forktimes = []
self._current_process = None
# Try to create a session id if possible
try:
os.setsid()
except OSError:
pass
self.readpipe, self.writepipe = os.pipe()
signal.signal(signal.SIGTERM, self._clean_exit)
signal.signal(signal.SIGINT, self._fast_exit)
signal.signal(signal.SIGALRM, self._alarm_exit)
signal.signal(signal.SIGHUP, self._reload_services)
def add(self, service, workers=1, args=None, kwargs=None):
"""Add a new service to the ServiceManager
:param service: callable that return an instance of :py:class:`Service`
:type service: callable
:param workers: number of processes/workers for this service
:type workers: int
:param args: additional positional arguments for this service
:type args: tuple
:param kwargs: additional keywoard arguments for this service
:type kwargs: dict
"""
self._services.append(_ServiceConfig(service, workers, args, kwargs))
def run(self):
"""Start and supervise services
This method will start and supervise all children processes
until the master process asked to shutdown by a SIGTERM.
All spawned processes are part of the same unix process group.
"""
self._systemd_notify_once()
while not self._shutdown.is_set():
info = self._wait_service()
if info is not None:
# Restart this particular service
conf, worker_id = info
else:
for conf in self._services:
if len(self._running_services[conf]) < conf.workers:
worker_id = len(self._running_services[conf])
break
else:
time.sleep(self._wait_interval)
continue
pid = self._start_service(conf, worker_id)
self._running_services[conf][pid] = worker_id
LOG.debug("Killing services with signal SIGTERM")
os.killpg(0, signal.SIGTERM)
LOG.debug("Waiting services to terminate")
while True:
try:
os.waitpid(0, 0)
except OSError as e:
if e.errno == errno.ECHILD:
break
else:
raise
LOG.debug("Shutdown finish")
_logged_sys_exit(0)
def _wait_service(self):
"""Return the last died service or None"""
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 = SIGNAL_TO_NAME.get(os.WTERMSIG(status))
LOG.info('Child %(pid)d killed by signal %(sig)s',
dict(pid=pid, sig=sig))
else:
code = os.WEXITSTATUS(status)
LOG.info('Child %(pid)d exited with status %(code)d',
dict(pid=pid, code=code))
for conf in self._running_services:
if pid in self._running_services[conf]:
return conf, self._running_services[conf].pop(pid)
LOG.error('pid %d not in service list', pid)
def _reload_services(self, *args, **kwargs):
if self._shutdown.is_set():
# NOTE(sileht): We are in shutdown process no need
# to reload anything
return
# Reset forktimes to respawn services quickly
self._forktimes = []
signal.signal(signal.SIGHUP, signal.SIG_IGN)
os.killpg(0, signal.SIGHUP)
signal.signal(signal.SIGHUP, self._reload_services)
def _clean_exit(self, *args, **kwargs):
# Don't need to be called more.
signal.signal(signal.SIGTERM, signal.SIG_IGN)
LOG.info('Caught SIGTERM signal, graceful exiting of master process')
self._shutdown.set()
def _fast_exit(self, signo, frame,
reason='Caught SIGINT signal, instantaneous exiting'):
signal.signal(signal.SIGINT, signal.SIG_IGN)
signal.signal(signal.SIGALRM, signal.SIG_IGN)
LOG.info(reason)
os.killpg(0, signal.SIGINT)
os._exit(1)
def _alarm_exit(self, signo, frame):
self._fast_exit(signo, frame,
reason='Graceful shutdown timeout exceeded, '
'instantaneous exiting of master process')
def _slowdown_respawn_if_needed(self):
# 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.
expected_children = sum(s.workers for s in self._services)
if len(self._forktimes) > expected_children:
if time.time() - self._forktimes[0] < expected_children:
LOG.info('Forking too fast, sleeping')
time.sleep(1)
self._forktimes.pop(0)
self._forktimes.append(time.time())
def _start_service(self, config, worker_id):
self._slowdown_respawn_if_needed()
pid = os.fork()
if pid != 0:
return pid
# reset parent signals
signal.signal(signal.SIGINT, signal.SIG_DFL)
signal.signal(signal.SIGALRM, signal.SIG_DFL)
signal.signal(signal.SIGTERM, signal.SIG_DFL)
signal.signal(signal.SIGHUP, signal.SIG_DFL)
# Close write to ensure only parent has it open
os.close(self.writepipe)
_spawn(self._watch_parent_process)
# Reseed random number generator
random.seed()
# Create and run a new service
with _exit_on_exception():
catched_signals = {
signal.SIGHUP: None,
signal.SIGTERM: None,
}
def signal_delayer(sig, frame):
signal.signal(signal.SIGTERM, signal.SIG_IGN)
LOG.info('Caught signal (%s) during service initialisation, '
'delaying it' % sig)
catched_signals[sig] = frame
# Setup temporary signals
signal.signal(signal.SIGHUP, signal_delayer)
signal.signal(signal.SIGTERM, signal_delayer)
# Initialize the service process
args = tuple() if config.args is None else config.args
kwargs = dict() if config.kwargs is None else config.kwargs
self._current_process = config.service(worker_id, *args, **kwargs)
# Setup final signals
if catched_signals[signal.SIGTERM] is not None:
self._current_process._clean_exit(
signal.SIGTERM, catched_signals[signal.SIGTERM])
signal.signal(signal.SIGTERM, self._current_process._clean_exit)
if catched_signals[signal.SIGHUP] is not None:
self._current_process._reload(
signal.SIGHUP, catched_signals[signal.SIGHUP])
signal.signal(signal.SIGHUP, self._current_process._reload)
# Start the main thread
_spawn(self._current_process._run)
# Wait forever
# NOTE(sileht): we cannot use threading.Event().wait() or
# threading.Thread().join() because of
# https://bugs.python.org/issue5315
while True:
time.sleep(1000000000)
def _watch_parent_process(self):
# This will block until the write end is closed when the parent
# dies unexpectedly
try:
os.read(self.readpipe, 1)
except EnvironmentError:
pass
if self._current_process is not None:
LOG.info('Parent process has died unexpectedly, %s exiting'
% self._current_process._title)
with _exit_on_exception():
self._current_process.terminate()
sys.exit(0)
else:
_logged_sys_exit(0)
@staticmethod
def _systemd_notify_once():
"""Send notification once to Systemd that service is ready.
Systemd sets NOTIFY_SOCKET environment variable with the name of the
socket listening for notifications from services.
This method removes the NOTIFY_SOCKET environment variable to ensure
notification is sent only once.
"""
notify_socket = os.getenv('NOTIFY_SOCKET')
if notify_socket:
if notify_socket.startswith('@'):
# abstract namespace socket
notify_socket = '\0%s' % notify_socket[1:]
sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
with contextlib.closing(sock):
try:
sock.connect(notify_socket)
sock.sendall(b'READY=1')
del os.environ['NOTIFY_SOCKET']
except EnvironmentError:
LOG.debug("Systemd notification failed", exc_info=True)
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