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#!/usr/bin/env python |
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import sys |
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import os |
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import time |
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import atexit |
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from signal import SIGTERM |
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class Daemon(object): |
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""" |
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Generic daemon class. |
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Usage: subclass the Daemon class and override the run() method |
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""" |
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def __init__(self, pidfile, stdin='/dev/null', stdout='/dev/null', |
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stderr='/dev/null'): |
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self.stdin = stdin |
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self.stdout = stdout |
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self.stderr = stderr |
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self.pidfile = pidfile |
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def daemonize(self): |
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""" |
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Do the UNIX double-fork magic. |
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See Stevens' "Advanced Programming in the UNIX Environment" |
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http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC16 |
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(ISBN 0201563177) |
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""" |
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try: |
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pid = os.fork() |
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if pid > 0: |
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# exit first parent |
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sys.exit(0) |
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except OSError, e: |
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sys.stderr.write("fork #1 failed: {0:d} ({1!s})\n".format(e.errno, e.strerror)) |
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sys.exit(1) |
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# decouple from parent environment |
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os.chdir("/") |
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os.setsid() |
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os.umask(0) |
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# do second fork |
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try: |
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pid = os.fork() |
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if pid > 0: |
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# exit from second parent |
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sys.exit(0) |
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except OSError, e: |
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sys.stderr.write("fork #2 failed: {0:d} ({1!s})\n".format(e.errno, e.strerror)) |
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sys.exit(1) |
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# redirect standard file descriptors |
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sys.stdout.flush() |
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sys.stderr.flush() |
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si = file(self.stdin, 'r') |
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so = file(self.stdout, 'a+') |
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se = file(self.stderr, 'a+', 0) |
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os.dup2(si.fileno(), sys.stdin.fileno()) |
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os.dup2(so.fileno(), sys.stdout.fileno()) |
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os.dup2(se.fileno(), sys.stderr.fileno()) |
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# write pidfile |
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atexit.register(self.delpid) |
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pid = str(os.getpid()) |
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file(self.pidfile, 'w+').write("{0!s}\n".format(pid)) |
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def delpid(self): |
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os.remove(self.pidfile) |
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def start(self): |
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"""Start the daemon.""" |
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# Check for a pidfile to see if the daemon already runs |
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try: |
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pf = file(self.pidfile, 'r') |
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pid = int(pf.read().strip()) |
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pf.close() |
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except IOError: |
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pid = None |
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if pid: |
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message = "pidfile %s already exists. Daemon already running?\n" |
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sys.stderr.write(message % self.pidfile) |
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sys.exit(1) |
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# Start the daemon |
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self.daemonize() |
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self.run() |
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def stop(self): |
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"""Stop the daemon.""" |
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# Get the pid from the pidfile |
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try: |
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pf = file(self.pidfile, 'r') |
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pid = int(pf.read().strip()) |
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pf.close() |
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except IOError: |
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pid = None |
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if not pid: |
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message = "pidfile %s does not exist. Daemon not running?\n" |
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sys.stderr.write(message % self.pidfile) |
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return # not an error in a restart |
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# Try killing the daemon process |
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try: |
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while 1: |
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os.kill(pid, SIGTERM) |
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time.sleep(0.1) |
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except OSError, err: |
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err = str(err) |
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if err.find("No such process") > 0: |
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if os.path.exists(self.pidfile): |
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os.remove(self.pidfile) |
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else: |
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print str(err) |
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sys.exit(1) |
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def restart(self): |
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"""Restart the daemon.""" |
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self.stop() |
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self.start() |
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def run(self): |
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""" |
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You should override this method when you subclass Daemon. |
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It will be called after the process has been |
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daemonized by start() or restart(). |
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""" |
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Psywerx /
botko
