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# copyright 2003-2010 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of logilab-common.
#
# logilab-common is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the Free
# Software Foundation, either version 2.1 of the License, or (at your option) any
# later version.
#
# logilab-common is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with logilab-common. If not, see <http://www.gnu.org/licenses/>.
"""A daemonize function (for Unices) and daemon mix-in class"""
__docformat__ = "restructuredtext en"
import os
import errno
import signal
import sys
import time
import warnings
def daemonize(pidfile=None, uid=None, umask=077):
"""daemonize a Unix process. Set paranoid umask by default.
Return 1 in the original process, 2 in the first fork, and None for the
second fork (eg daemon process).
"""
# See http://www.erlenstar.demon.co.uk/unix/faq_toc.html#TOC16
# XXX unix specific
#
# fork so the parent can exit
if os.fork(): # launch child and...
return 1
# deconnect from tty and create a new session
os.setsid()
# fork again so the parent, (the session group leader), can exit.
# as a non-session group leader, we can never regain a controlling
# terminal.
if os.fork(): # launch child again.
return 2
# move to the root to avoit mount pb
os.chdir('/')
# set umask if specified
if umask is not None:
os.umask(umask)
# redirect standard descriptors
null = os.open('/dev/null', os.O_RDWR)
for i in range(3):
try:
os.dup2(null, i)
except OSError, e:
if e.errno != errno.EBADF:
raise
os.close(null)
# filter warnings
warnings.filterwarnings('ignore')
# write pid in a file
if pidfile:
# ensure the directory where the pid-file should be set exists (for
# instance /var/run/cubicweb may be deleted on computer restart)
piddir = os.path.dirname(pidfile)
if not os.path.exists(piddir):
os.makedirs(piddir)
f = file(pidfile, 'w')
f.write(str(os.getpid()))
f.close()
# change process uid
if uid:
try:
uid = int(uid)
except ValueError:
from pwd import getpwnam
uid = getpwnam(uid).pw_uid
os.setuid(uid)
return None
class DaemonMixIn:
"""Mixin to make a daemon from watchers/queriers.
"""
def __init__(self, configmod) :
self.delay = configmod.DELAY
self.name = str(self.__class__).split('.')[-1]
self._pid_file = os.path.join('/tmp', '%s.pid'%self.name)
if os.path.exists(self._pid_file):
raise Exception('''Another instance of %s must be running.
If it i not the case, remove the file %s''' % (self.name, self._pid_file))
self._alive = 1
self._sleeping = 0
self.config = configmod
def _daemonize(self):
if not self.config.NODETACH:
if daemonize(self._pid_file) is None:
# put signal handler
signal.signal(signal.SIGTERM, self.signal_handler)
signal.signal(signal.SIGHUP, self.signal_handler)
else:
return -1
def run(self):
""" optionally go in daemon mode and
do what concrete class has to do and pauses for delay between runs
If self.delay is negative, do a pause before starting
"""
if self._daemonize() == -1:
return
if self.delay < 0:
self.delay = -self.delay
time.sleep(self.delay)
while True:
try:
self._run()
except Exception, ex:
# display for info, sleep, and hope the problem will be solved
# later.
self.config.exception('Internal error: %s', ex)
if not self._alive:
break
try:
self._sleeping = 1
time.sleep(self.delay)
self._sleeping = 0
except SystemExit:
break
self.config.info('%s instance exited', self.name)
# remove pid file
os.remove(self._pid_file)
def signal_handler(self, sig_num, stack_frame):
if sig_num == signal.SIGTERM:
if self._sleeping:
# we are sleeping so we can exit without fear
self.config.debug('exit on SIGTERM')
sys.exit(0)
else:
self.config.debug('exit on SIGTERM (on next turn)')
self._alive = 0
elif sig_num == signal.SIGHUP:
self.config.info('reloading configuration on SIGHUP')
reload(self.config)
def _run(self):
"""should be overridden in the mixed class"""
raise NotImplementedError()
import logging
from logilab.common.logging_ext import set_log_methods
set_log_methods(DaemonMixIn, logging.getLogger('lgc.daemon'))
## command line utilities ######################################################
L_OPTIONS = ["help", "log=", "delay=", 'no-detach']
S_OPTIONS = 'hl:d:n'
def print_help(modconfig):
print """ --help or -h
displays this message
--log <log_level>
log treshold (7 record everything, 0 record only emergency.)
Defaults to %s
--delay <delay>
the number of seconds between two runs.
Defaults to %s""" % (modconfig.LOG_TRESHOLD, modconfig.DELAY)
def handle_option(modconfig, opt_name, opt_value, help_meth):
if opt_name in ('-h', '--help'):
help_meth()
sys.exit(0)
elif opt_name in ('-l', '--log'):
modconfig.LOG_TRESHOLD = int(opt_value)
elif opt_name in ('-d', '--delay'):
modconfig.DELAY = int(opt_value)
elif opt_name in ('-n', '--no-detach'):
modconfig.NODETACH = 1
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