Commit 1bca0c39 authored by Antoine Catton's avatar Antoine Catton

Add lockfile recipe

This add also dependency to inotifyx in order to have a better
mechanism for file system watching.

I choose inotifyx because the api is much more simpler.
parent 203134cd
......@@ -30,6 +30,7 @@ setup(name=name,
'lxml', # for full blown python interpreter
'netaddr', # to manipulate on IP addresses
'setuptools', # namespaces
'inotifyx', # to watch filesystem changes (used in pidwrapper)
'slapos.core', # uses internally
# 'slapos.toolbox', # needed for libcloud, cloudmgr, disabled for now
'xml_marshaller', # need to communication with slapgrid
......@@ -54,6 +55,7 @@ setup(name=name,
'kvm = slapos.recipe.kvm:Recipe',
'libcloud = slapos.recipe.libcloud:Recipe',
'libcloudrequest = slapos.recipe.libcloudrequest:Recipe',
'lockfile = slapos.recipe.lockfile:Recipe',
'memcached = slapos.recipe.memcached:Recipe',
'mysql = slapos.recipe.mysql:Recipe',
'mkdirectory = slapos.recipe.mkdirectory:Recipe',
......
##############################################################################
#
# Copyright (c) 2010 Vifib SARL and Contributors. All Rights Reserved.
#
# WARNING: This program as such is intended to be used by professional
# programmers who take the whole responsibility of assessing all potential
# consequences resulting from its eventual inadequacies and bugs
# End users who are looking for a ready-to-use solution with commercial
# guarantees and support are strongly adviced to contract a Free Software
# Service Company
#
# 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 3
# 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#
##############################################################################
import os
import sys
import subprocess
import inotifyx
from slapos.recipe.librecipe import GenericBaseRecipe
class LockFile(object):
class LockException(Exception):
pass
def __init__(self, filename, wait=True, exit=False):
self.filename = filename
if wait:
self.callback = lambda: self.waitDeletion()
elif not exit:
self.callback = lambda: self.raiseException()
else:
self.callback = lambda: sys.exit(1)
def raiseException(self):
raise LockFile.LockException("Not able to lock the file")
def waitDeletion(self):
inotify_fd = inotifyx.init()
try:
inotifyx.add_watch(inotify_fd, self.filename, inotifyx.IN_DELETE)
inotifyx.get_events()
except IOError: # add_watch failed
pass
finally:
os.close(inotify_fd)
self.__enter__()
def __enter__(self):
try:
# Atomic file acquisition
self._fd = os.open(self.filename, os.O_CREAT | os.O_EXCL)
except OSError:
self.callback()
def __exit__(self, exc_type, exc_value, traceback):
os.close(self._fd)
os.unlink(self.filename)
def locked_run(args):
with LockFile(args['filename'], wait=args['wait'], exit=True):
subprocess.check_call([args['binary']])
class Recipe(GenericBaseRecipe):
def install(self):
wrapper = self.createPythonScript(self.options['wrapper'],
__name__ + '.locked_run',
dict(
filename=self.options['lock-file'],
wait=self.optionIsTrue('wait', False),
binary=self.options['binary'],
)
)
return [wrapper]
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