echel0n
11 years ago
6 changed files with 358 additions and 164 deletions
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''' |
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*** |
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Modified generic daemon class |
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*** |
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Author: http://www.jejik.com/articles/2007/02/ |
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a_simple_unix_linux_daemon_in_python/www.boxedice.com |
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License: http://creativecommons.org/licenses/by-sa/3.0/ |
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Changes: 23rd Jan 2009 (David Mytton <david@boxedice.com>) |
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- Replaced hard coded '/dev/null in __init__ with os.devnull |
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- Added OS check to conditionally remove code that doesn't |
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work on OS X |
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- Added output to console on completion |
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- Tidied up formatting |
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11th Mar 2009 (David Mytton <david@boxedice.com>) |
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- Fixed problem with daemon exiting on Python 2.4 |
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(before SystemExit was part of the Exception base) |
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13th Aug 2010 (David Mytton <david@boxedice.com> |
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- Fixed unhandled exception if PID file is empty |
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''' |
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# Core modules |
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import atexit |
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import os |
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import sys |
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import time |
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import signal |
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class Daemon(object): |
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""" |
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A 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=os.devnull, |
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stdout=os.devnull, stderr=os.devnull, |
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home_dir='.', umask=022, verbose=1): |
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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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self.home_dir = home_dir |
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self.verbose = verbose |
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self.umask = umask |
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self.daemon_alive = True |
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def daemonize(self): |
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""" |
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Do the UNIX double-fork magic, see Stevens' "Advanced |
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Programming in the UNIX Environment" for details (ISBN 0201563177) |
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http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC16 |
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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( |
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"fork #1 failed: %d (%s)\n" % (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(self.home_dir) |
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os.setsid() |
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os.umask(self.umask) |
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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( |
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"fork #2 failed: %d (%s)\n" % (e.errno, e.strerror)) |
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sys.exit(1) |
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if sys.platform != 'darwin': # This block breaks on OS X |
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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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if self.stderr: |
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se = file(self.stderr, 'a+', 0) |
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else: |
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se = so |
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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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def sigtermhandler(signum, frame): |
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self.daemon_alive = False |
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signal.signal(signal.SIGTERM, sigtermhandler) |
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signal.signal(signal.SIGINT, sigtermhandler) |
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if self.verbose >= 1: |
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print "Started" |
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# Write pidfile |
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atexit.register( |
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self.delpid) # Make sure pid file is removed if we quit |
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pid = str(os.getpid()) |
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file(self.pidfile, 'w+').write("%s\n" % pid) |
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def delpid(self): |
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os.remove(self.pidfile) |
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def start(self, daemonize=True, *args, **kwargs): |
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""" |
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Start the daemon |
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""" |
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if daemonize: |
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if self.verbose >= 1: |
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print "Starting..." |
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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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except SystemExit: |
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pid = None |
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if pid: |
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message = "pidfile %s already exists. Is it 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(*args, **kwargs) |
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def stop(self, daemonize=True): |
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""" |
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Stop the daemon |
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""" |
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if not daemonize: |
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return |
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if self.verbose >= 1: |
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print "Stopping..." |
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# Get the pid from the pidfile |
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pid = self.get_pid() |
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if not pid: |
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message = "pidfile %s does not exist. Not running?\n" |
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sys.stderr.write(message % self.pidfile) |
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# Just to be sure. A ValueError might occur if the PID file is |
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# empty but does actually exist |
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if os.path.exists(self.pidfile): |
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os.remove(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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i = 0 |
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while 1: |
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os.kill(pid, signal.SIGTERM) |
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time.sleep(0.1) |
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i = i + 1 |
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if i % 10 == 0: |
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os.kill(pid, signal.SIGHUP) |
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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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if self.verbose >= 1: |
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print "Stopped" |
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def restart(self, daemonize=True): |
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""" |
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Restart the daemon |
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""" |
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self.stop(daemonize=daemonize) |
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self.start(daemonize=daemonize) |
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def get_pid(self): |
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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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except SystemExit: |
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pid = None |
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return pid |
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def is_running(self): |
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pid = self.get_pid() |
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print(pid) |
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return pid and os.path.exists('/proc/%d' % pid) |
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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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