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Daemonized

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commit 48fc4ace79d6e6c4421ddd4570eb8f08bd479cdc 1 parent 52cafc1
@DFectuoso authored
Showing with 159 additions and 6 deletions.
  1. +130 −0 daemon.py
  2. +29 −6 task.py
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130 daemon.py
@@ -0,0 +1,130 @@
+#!/usr/bin/env python
+
+import sys, os, time, atexit
+from signal import SIGTERM
+
+class Daemon:
+ """
+ A generic daemon class.
+
+ Usage: subclass the Daemon class and override the run() method
+ """
+ def __init__(self, pidfile, stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):
+ self.stdin = stdin
+ self.stdout = stdout
+ self.stderr = stderr
+ self.pidfile = pidfile
+
+ def daemonize(self):
+ """
+ do the UNIX double-fork magic, see Stevens' "Advanced
+ Programming in the UNIX Environment" for details (ISBN 0201563177)
+ http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC16
+ """
+ try:
+ pid = os.fork()
+ if pid > 0:
+ # exit first parent
+ sys.exit(0)
+ except OSError, e:
+ sys.stderr.write("fork #1 failed: %d (%s)\n" % (e.errno, e.strerror))
+ sys.exit(1)
+
+ # decouple from parent environment
+ 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, e:
+ sys.stderr.write("fork #2 failed: %d (%s)\n" % (e.errno, e.strerror))
+ sys.exit(1)
+
+ # redirect standard file descriptors
+ sys.stdout.flush()
+ sys.stderr.flush()
+ si = file(self.stdin, 'r')
+ so = file(self.stdout, 'a+')
+ se = file(self.stderr, 'a+', 0)
+ os.dup2(si.fileno(), sys.stdin.fileno())
+ os.dup2(so.fileno(), sys.stdout.fileno())
+ os.dup2(se.fileno(), sys.stderr.fileno())
+
+ # write pidfile
+ atexit.register(self.delpid)
+ pid = str(os.getpid())
+ file(self.pidfile,'w+').write("%s\n" % pid)
+
+ def delpid(self):
+ os.remove(self.pidfile)
+
+ def start(self):
+ """
+ Start the daemon
+ """
+ # Check for a pidfile to see if the daemon already runs
+ try:
+ pf = file(self.pidfile,'r')
+ pid = int(pf.read().strip())
+ pf.close()
+ except IOError:
+ pid = None
+
+ if pid:
+ message = "pidfile %s already exist. Daemon already running?\n"
+ sys.stderr.write(message % self.pidfile)
+ sys.exit(1)
+
+ # Start the daemon
+ self.daemonize()
+ self.run()
+
+ def stop(self):
+ """
+ Stop the daemon
+ """
+ # Get the pid from the pidfile
+ try:
+ pf = file(self.pidfile,'r')
+ pid = int(pf.read().strip())
+ pf.close()
+ except IOError:
+ pid = None
+
+ if not pid:
+ message = "pidfile %s does not exist. Daemon not running?\n"
+ sys.stderr.write(message % self.pidfile)
+ return # not an error in a restart
+
+ # Try killing the daemon process
+ try:
+ while 1:
+ os.kill(pid, SIGTERM)
+ time.sleep(0.1)
+ except OSError, err:
+ err = str(err)
+ if err.find("No such process") > 0:
+ if os.path.exists(self.pidfile):
+ os.remove(self.pidfile)
+ else:
+ print str(err)
+ sys.exit(1)
+
+ def restart(self):
+ """
+ Restart the daemon
+ """
+ self.stop()
+ self.start()
+
+ def run(self):
+ """
+ You should override this method when you subclass Daemon. It will be called after the process has been
+ daemonized by start() or restart().
+ """
+
View
35 task.py
@@ -1,13 +1,36 @@
+#!/usr/bin/env python
-import time
+import sys, time
+from daemon import Daemon
import random
import urllib2
random.seed()
-while True:
- time.sleep(1)
- req = urllib2.Request('http://dfectuoso.com/')
- response = urllib2.urlopen(req)
- the_page = response.read()
+
+class MyDaemon(Daemon):
+ def run(self):
+ while True:
+ time.sleep(1)
+ req = urllib2.Request('http://dfectuoso.com/')
+ response = urllib2.urlopen(req)
+ the_page = response.read()
+
+
+if __name__ == "__main__":
+ daemon = MyDaemon('/tmp/daemon-example.pid')
+ if len(sys.argv) == 2:
+ if 'start' == sys.argv[1]:
+ daemon.start()
+ elif 'stop' == sys.argv[1]:
+ daemon.stop()
+ elif 'restart' == sys.argv[1]:
+ daemon.restart()
+ else:
+ print "Unknown command"
+ sys.exit(2)
+ sys.exit(0)
+ else:
+ print "usage: %s start|stop|restart" % sys.argv[0]
+ sys.exit(2)

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