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Deamon.py 6.2 KB
f795df3ae   Thanasis Naskos   initial commit
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  '''
  Created on Sep 30, 2010
  
  @author: ikons
  '''
  #!/usr/bin/env python
  
  import sys, os, time, atexit, logging.handlers
  from signal import SIGTERM
  #import shutil, fileinput
  import Utils
  
  class Daemon:
          """
          A generic daemon class.
          Usage: subclass the Daemon class and override the run() method
          """
  
          def __init__(self, pidfile, properties_file, stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):
                  self.stdin = stdin
                  self.stdout = stdout
                  self.stderr = stderr
                  self.pidfile = pidfile
                  self.properties_file = properties_file
                  ## Read properties from file
                  self.utils = Utils.Utils(properties_file)
                  ## Make log directory
                  self.utils.mkdir_p(self.utils.install_dir+'/'+self.utils.logs_folder_name)
  
                  ## Install stdout
                  self.stdout = self.utils.install_dir+"/"+self.utils.logs_folder_name+"/Coordinator.out"
                  
                  ## Install stderr
                  self.stderr = self.utils.install_dir+"/"+self.utils.logs_folder_name+"/Coordinator.err"
                  
                  
                  ## Install logger
                  LOG_FILENAME = self.utils.install_dir+'/'+self.utils.logs_folder_name+'/Coordinator.log'
                  self.my_logger = logging.getLogger('Deamon')
                  self.my_logger.setLevel(self.utils.logging_level)
                  
                  handler = logging.handlers.RotatingFileHandler(
                                LOG_FILENAME, maxBytes=2*1024*1024, backupCount=5)
                  formatter = logging.Formatter("%(asctime)s - %(levelname)s - %(name)s - %(message)s")
                  handler.setFormatter(formatter)
                  self.my_logger.addHandler(handler)
          
          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)
  " % (e.errno, e.strerror))
                          sys.exit(1)
         
                  # decouple from parent environment
  #                os.chdir("/")
                  os.chdir(self.utils.install_dir)
                  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)
  " % (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)
                  # uncomment the above line to redirect stderr
                  
                  os.dup2(si.fileno(), sys.stdin.fileno())
                  os.dup2(so.fileno(), sys.stdout.fileno())
                  os.dup2(se.fileno(), sys.stderr.fileno())
                  # uncomment the above line to redirect stderr
         
                  # write pidfile
                  atexit.register(self.delpid)
                  pid = str(os.getpid())
                  file(self.pidfile,'w+').write("%s
  " % 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?
  "
                          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?
  "
                          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().
                  """