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"""
Serializer code for cobbler
Now adapted to support different storage backends
Copyright 2006-2008, Red Hat, Inc
Michael DeHaan <mdehaan@redhat.com>
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
"""
import errno
import os
from utils import _
import fcntl
import traceback
import sys
import signal
import time
from cexceptions import *
import api as cobbler_api
LOCK_ENABLED = True
LOCK_HANDLE = None
BLOCK_SIGNAL = True
def handler(num,frame):
print sys.stderr, "Ctrl-C not allowed during writes. Please wait."
return True
def no_ctrl_c():
signal.signal(signal.SIGINT, handler)
return True
def ctrl_c_ok():
signal.signal(signal.SIGINT, signal.default_int_handler)
return True
def __grab_lock():
"""
Dual purpose locking:
(A) flock to avoid multiple process access
(B) block signal handler to avoid ctrl+c while writing YAML
"""
try:
if LOCK_ENABLED:
if not os.path.exists("/var/lib/cobbler/lock"):
fd = open("/var/lib/cobbler/lock","w+")
fd.close()
LOCK_HANDLE = open("/var/lib/cobbler/lock","r")
fcntl.flock(LOCK_HANDLE.fileno(), fcntl.LOCK_EX)
if BLOCK_SIGNAL:
no_ctrl_c()
return True
except:
# this is pretty much FATAL, avoid corruption and quit now.
traceback.print_exc()
sys.exit(7)
def __release_lock(with_changes=False):
if with_changes:
# this file is used to know when the last config change
# was made -- allowing the API to work more smoothly without
# a lot of unneccessary reloads.
fd = open("/var/lib/cobbler/.mtime","w")
fd.write("%f" % time.time())
fd.close()
if LOCK_ENABLED:
LOCK_HANDLE = open("/var/lib/cobbler/lock","r")
fcntl.flock(LOCK_HANDLE.fileno(), fcntl.LOCK_UN)
LOCK_HANDLE.close()
if BLOCK_SIGNAL:
ctrl_c_ok()
return True
def serialize(obj):
"""
Save a collection to disk or other storage.
"""
__grab_lock()
storage_module = __get_storage_module(obj.collection_type())
storage_module.serialize(obj)
__release_lock()
return True
def serialize_item(collection, item):
"""
Save an item.
"""
__grab_lock()
storage_module = __get_storage_module(collection.collection_type())
save_fn = getattr(storage_module, "serialize_item", None)
if save_fn is None:
rc = storage_module.serialize(collection)
else:
rc = save_fn(collection,item)
__release_lock(with_changes=True)
return rc
def serialize_delete(collection, item):
"""
Delete an object from a saved state.
"""
__grab_lock()
storage_module = __get_storage_module(collection.collection_type())
delete_fn = getattr(storage_module, "serialize_delete", None)
if delete_fn is None:
rc = storage_module.serialize(collection)
else:
rc = delete_fn(collection,item)
__release_lock(with_changes=True)
return rc
def deserialize(obj,topological=True):
"""
Fill in an empty collection from disk or other storage
"""
__grab_lock()
storage_module = __get_storage_module(obj.collection_type())
rc = storage_module.deserialize(obj,topological)
__release_lock()
return rc
def deserialize_raw(collection_type):
"""
Return the datastructure corresponding to the serialized
disk state, without going through the Cobbler object system.
Much faster, when you don't need the objects.
"""
__grab_lock()
storage_module = __get_storage_module(collection_type)
rc = storage_module.deserialize_raw(collection_type)
__release_lock()
return rc
def deserialize_item(collection_type, item_name):
"""
Get a specific record.
"""
__grab_lock()
storage_module = __get_storage_module(collection_type)
rc = storage_module.deserialize_item(collection_type, item_name)
__release_lock()
return rc
def deserialize_item_raw(collection_type, item_name):
__grab_lock()
storage_module = __get_storage_module(collection_type)
rc = storage_module.deserialize_item_raw(collection_type, item_name)
__release_lock()
return rc
def __get_storage_module(collection_type):
"""
Look up serializer in /etc/cobbler/modules.conf
"""
capi = cobbler_api.BootAPI()
return capi.get_module_from_file("serializers",collection_type,"serializer_yaml")
if __name__ == "__main__":
__grab_lock()
__release_lock()
|
