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undead.py
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undead.py
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#!/usr/bin/python
# -*- coding: utf-8 -*-
"""
Undead
===========
Dead Easy UNIX Daemons!
"""
class Undead(object):
""" This is the Undead module """
name = None
pid = None
log_level = "WARNING"
log_handler = None
def __call__(self, action, *args, **kwargs):
""" Alias for start """
self.start = self.start(action)
def start(self, action):
""" Does the daemon dance """
import os
import sys
import signal
import resource
import atexit
import inspect
from resource import getrlimit, RLIMIT_NOFILE
from lockfile import FileLock
from logbook import Logger, FileHandler
self.action = action
self.name = self.name or action.__name__
home = os.path.join(os.path.expanduser("~"),
".{0}".format(self.name)
)
if self.pid is None:
if not os.path.exists(home):
os.makedirs(home)
self.pid = os.path.join(home, "{0}.pid".format(self.name))
process_id = os.fork()
if process_id < 0:
sys.exit(1)
elif process_id is not 0:
sys.exit(0)
process_id = os.setsid()
if process_id is -1:
sys.exit(1)
devnull = "/dev/null"
if hasattr(os, "devnull"):
devnull = os.devnull
for fd in range(getrlimit(RLIMIT_NOFILE)[0]):
try:
os.close(fd)
except OSError:
pass
os.open(devnull, os.O_RDWR)
os.dup(0)
os.dup(0)
os.umask(0o27)
os.chdir("/")
self.lock = FileLock(self.pid)
if self.lock.is_locked():
sys.stderr.write("Error: {0} is locked.\n".format(self.pid))
sys.exit(0)
with open(self.pid, "w") as lockfile:
lockfile.write("{0}".format(os.getpid()))
self.lock.acquire()
# Initialize logging.
self.log = Logger(self.name)
if self.log_handler is None:
if not os.path.exists(home):
os.makedirs(home)
self.log_handler = FileHandler(
os.path.join(home, "{0}.log".format(self.name)),
level=self.log_level
)
with self.log_handler.applicationbound():
# Set custom action on SIGTERM.
signal.signal(signal.SIGTERM, self._sigterm)
atexit.register(self._sigterm)
self.log.warning("Starting daemon.")
args = inspect.getargspec(self.action)[0]
if 'log' not in args:
return self.action()
self.action(log=self.log)
def _sigterm(self, signum=None, frame=None):
import os
import sys
with self.log_handler.applicationbound():
if not signum:
self.log.warning("Stopping daemon.")
else:
self.log.warning("Signal: {0} -Stopping daemon.".format(signum))
try:
self.lock.release()
os.remove(self.pid)
except OSError:
pass
finally:
sys.exit(0)
undead = Undead()
import sys
sys.modules[__name__] = undead
# Removing from module ns
del sys