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Refactoring, Cleanups and prepared a new directory structure

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Johannes Findeisen 2021-12-27 21:04:49 +01:00
commit 3966cd0e0f
12 changed files with 54 additions and 19 deletions
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52
uplink/daemon.py
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@ -1,4 +1,6 @@
"""
Generic linux daemon base class for python 3.x.
Original Source:
https://web.archive.org/web/20131017130434/http://www.jejik.com/articles/2007/02/a_simple_unix_linux_daemon_in_python/
https://web.archive.org/web/20131017130434/http://www.jejik.com/files/examples/daemon3x.py
@ -9,40 +11,57 @@ https://franklingu.github.io/programming/2016/03/01/creating-daemon-process-pyth
https://dpbl.wordpress.com/2017/02/12/a-tutorial-on-python-daemon/
"""
from logging import getLogger
import sys
import os
import time
import atexit
import signal
logger = getLogger(__name__)
# TODO: Check why pid files are not being deleted when sending the TERM signal
class Daemon:
"""
A generic daemon class.
Usage: subclass the daemon class and override the run() method.
"""
def __init__(self, pid_file):
self.pid_file = pid_file
def daemonize(self):
"""
Deamonize class. UNIX double fork mechanism.
"""
try:
pid = os.fork()
if pid > 0:
# exit first parent
sys.exit(0)
except OSError as err:
sys.stderr.write('fork #1 failed: {0}\n'.format(err))
logger.error('fork #1 failed: {0}\n'.format(err))
sys.exit(1)
# decouple from parent environme
os.chdir('/')
os.setsid()
os.umask(0)
# do second fork
try:
pid = os.fork()
if pid > 0:
# exit from second parent
sys.exit(0)
except OSError as err:
sys.stderr.write('fork #2 failed: {0}\n'.format(err))
logger.error('fork #2 failed: {0}\n'.format(err))
sys.exit(1)
# redirect standard file descriptors
sys.stdout.flush()
sys.stderr.flush()
si = open(os.devnull, 'r')
@ -53,6 +72,7 @@ class Daemon:
os.dup2(so.fileno(), sys.stdout.fileno())
os.dup2(se.fileno(), sys.stderr.fileno())
# write pidfile
atexit.register(self.del_pid)
pid = str(os.getpid())
@ -63,6 +83,11 @@ class Daemon:
os.remove(self.pid_file)
def start(self):
"""
Start the daemon.
"""
# Check for a pidfile to see if the daemon already runs
try:
with open(self.pid_file, 'r') as pf:
pid = int(pf.read().strip())
@ -71,13 +96,19 @@ class Daemon:
if pid:
message = "pid_file {0} already exist. Daemon already running?\n"
sys.stderr.write(message.format(self.pid_file))
logger.error(message.format(self.pid_file))
sys.exit(1)
# Start the daemon
self.daemonize()
self.run()
def stop(self):
"""
Stop the daemon.
"""
# Get the pid from the pidfile
try:
with open(self.pid_file, 'r') as pf:
pid = int(pf.read().strip())
@ -86,9 +117,11 @@ class Daemon:
if not pid:
message = "pid_file {0} does not exist. Daemon not running?\n"
sys.stderr.write(message.format(self.pid_file))
logger.error(message.format(self.pid_file))
# not an error in a restart
return
# Try killing the daemon process
try:
while 1:
os.kill(pid, signal.SIGTERM)
@ -99,14 +132,19 @@ class Daemon:
if os.path.exists(self.pid_file):
os.remove(self.pid_file)
else:
print(str(err.args))
logger.error(str(err.args))
sys.exit(1)
def restart(self):
"""
Restart the daemon.
"""
self.stop()
self.start()
def run(self):
"""Override this method when you subclass Daemon.
"""
Override this method when you subclass Daemon.
It will be called after the process has been daemonized by
start() or restart()."""
start() or restart().
"""