From 1bca0c39c6db43d85b6598b8eca197625df26a4e Mon Sep 17 00:00:00 2001
From: Antoine Catton <acatton@tiolive.com>
Date: Fri, 21 Oct 2011 18:27:07 +0200
Subject: [PATCH] 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.
---
setup.py | 2 +
slapos/recipe/lockfile.py | 90 +++++++++++++++++++++++++++++++++++++++
2 files changed, 92 insertions(+)
create mode 100644 slapos/recipe/lockfile.py
diff --git a/setup.py b/setup.py
index 07a23abf9..258ad5316 100644
--- a/setup.py
+++ b/setup.py
@@ -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',
diff --git a/slapos/recipe/lockfile.py b/slapos/recipe/lockfile.py
new file mode 100644
index 000000000..60f139dc7
--- /dev/null
+++ b/slapos/recipe/lockfile.py
@@ -0,0 +1,90 @@
+##############################################################################
+#
+# 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]
--
2.30.9