old_contents: #
  #
  
  # Copyright (C) 2014 Google Inc.
  #
  # This program is free software; you can redistribute it and/or modify
  # it under the terms of the GNU General Public License as published by
  # the Free Software Foundation; either version 2 of the License, or
  # (at your option) any later version.
  #
  # This program is distributed in the hope that it will be useful, but
  # WITHOUT ANY WARRANTY; without even the implied warranty of
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  # General Public License for more details.
  #
  # You should have received a copy of the GNU General Public License
  # along with this program; if not, write to the Free Software
  # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  # 02110-1301, USA.
  
  """Lockfiles to prove liveliness
  
  When requesting resources, like locks, from wconfd, requesters have
  to provide the name of a file they own an exclusive lock on, to prove
  that they are still alive. Provide methods to obtain such a file.
  """
  
  import fcntl
  import os
  import struct
  import time
  
  from ganeti.utils.algo import NiceSort
  from ganeti import pathutils
  
  
  class LiveLock(object):
    """Utility for a lockfile needed to request resources from WconfD.
  
    """
    def __init__(self, name=None):
      if name is None:
        name = "pid%d_" % os.getpid()
      # to avoid reusing existing lock files, extend name
      # by the current time
      name = "%s_%d" % (name, int(time.time()))
      fname = os.path.join(pathutils.LIVELOCK_DIR, name)
      self.lockfile = open(fname, 'w')
      fcntl.fcntl(self.lockfile, fcntl.F_SETLKW,
                  struct.pack('hhllhh', fcntl.F_WRLCK, 0, 0, 0, 0, 0))
  
    def GetPath(self):
      return self.lockfile.name
  
    def close(self):
      """Close the lockfile and clean it up.
  
      """
      self.lockfile.close()
      os.remove(self.lockfile.name)
  
  
  def GuessLockfileFor(name):
    """For a given name, take the latest file matching.
  
    @return: the file with the latest name matching the given
        prefix in LIVELOCK_DIR, or the plain name, if none
        exists.
    """
    lockfiles = filter(lambda n: n.startswith(name),
                       os.listdir(pathutils.LIVELOCK_DIR))
    if len(lockfiles) > 0:
      lockfile = NiceSort(lockfiles)[-1]
    else:
      lockfile = name
  
    return os.path.join(pathutils.LIVELOCK_DIR, lockfile)
  
new_contents: #
  #
  
  # Copyright (C) 2014 Google Inc.
  #
  # This program is free software; you can redistribute it and/or modify
  # it under the terms of the GNU General Public License as published by
  # the Free Software Foundation; either version 2 of the License, or
  # (at your option) any later version.
  #
  # This program is distributed in the hope that it will be useful, but
  # WITHOUT ANY WARRANTY; without even the implied warranty of
  # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  # General Public License for more details.
  #
  # You should have received a copy of the GNU General Public License
  # along with this program; if not, write to the Free Software
  # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  # 02110-1301, USA.
  
  """Lockfiles to prove liveliness
  
  When requesting resources, like locks, from wconfd, requesters have
  to provide the name of a file they own an exclusive lock on, to prove
  that they are still alive. Provide methods to obtain such a file.
  """
  
  import fcntl
  import os
  import struct
  import time
  
  from ganeti.utils.algo import NiceSort
  from ganeti import pathutils
  
  
  class LiveLockName(object):
    def __init__(self, name):
      self._name = name
  
    def GetPath(self):
      return self._name
  
    def close(self):
      """Clean up the lockfile.
  
      """
      os.remove(self._name)
  
  
  class LiveLock(object):
    """Utility for a lockfile needed to request resources from WconfD.
  
    """
    def __init__(self, name=None):
      if name is None:
        name = "pid%d_" % os.getpid()
      # to avoid reusing existing lock files, extend name
      # by the current time
      name = "%s_%d" % (name, int(time.time()))
      fname = os.path.join(pathutils.LIVELOCK_DIR, name)
      self.lockfile = open(fname, 'w')
      fcntl.fcntl(self.lockfile, fcntl.F_SETLKW,
                  struct.pack('hhllhh', fcntl.F_WRLCK, 0, 0, 0, 0, 0))
  
    def GetPath(self):
      return self.lockfile.name
  
    def close(self):
      """Close the lockfile and clean it up.
  
      """
      self.lockfile.close()
      os.remove(self.lockfile.name)
  
  
  def GuessLockfileFor(name):
    """For a given name, take the latest file matching.
  
    @return: the file with the latest name matching the given
        prefix in LIVELOCK_DIR, or the plain name, if none
        exists.
    """
    lockfiles = filter(lambda n: n.startswith(name),
                       os.listdir(pathutils.LIVELOCK_DIR))
    if len(lockfiles) > 0:
      lockfile = NiceSort(lockfiles)[-1]
    else:
      lockfile = name
  
    return os.path.join(pathutils.LIVELOCK_DIR, lockfile)
  
subject: Add a passive class for representing inherited live-locks