Page MenuHomePhabricator
Files F7312475

__init__.py
No OneTemporary
Actions

__init__.py
View Options

# Copyright (C) 2008-2011 AG Projects. See LICENSE for details.
#
"""Generic configuration management"""
from __future__ import with_statement
__all__ = ['ConfigurationManager', 'ConfigurationError', 'ObjectNotFoundError', 'DuplicateIDError', 'DefaultValue',
'Setting', 'CorrelatedSetting', 'SettingsGroup', 'SettingsObjectID', 'SettingsObject', 'SettingsObjectExtension']
from itertools import chain
from threading import Lock
from weakref import WeakKeyDictionary
from application import log
from application.notification import NotificationCenter
from application.python.util import Singleton
from sipsimple.threading import run_in_thread
from sipsimple.util import TimestampedNotificationData
## Exceptions
class ConfigurationError(Exception): pass
class ObjectNotFoundError(ConfigurationError): pass
class DuplicateIDError(ValueError): pass
class PersistentKey(unicode):
persistent = True
def __repr__(self):
return "%s(%s)" % (self.__class__.__name__, unicode.__repr__(self))
## ConfigurationManager
class ConfigurationManager(object):
"""
Singleton class used for storing and retrieving options, organized in
sections. A section contains a list of objects, each with an assigned name
which allows access to the object.
"""
__metaclass__ = Singleton
def __init__(self):
self.backend = None
self.data = None
def start(self):
"""
Initialize the ConfigurationManager to use the specified backend. This
method can only be called once, with an object which provides IBackend.
The other methods of the object cannot be used unless this method was
called.
"""
from sipsimple.application import SIPApplication
from sipsimple.configuration.backend import IConfigurationBackend
if self.backend is not None:
raise RuntimeError("ConfigurationManager already started")
if SIPApplication.storage is None:
raise RuntimeError("SIPApplication.storage must be defined before starting the ConfigurationManager")
backend = SIPApplication.storage.configuration_backend
if not IConfigurationBackend.providedBy(backend):
raise TypeError("SIPApplication.storage.configuration_backend must implement the IConfigurationBackend interface")
self.data = backend.load()
self.backend = backend
def update(self, key, data):
"""
Save the object's data under the tree path specified by key (a list
of strings). Cannot be called before start().
"""
if self.backend is None:
raise RuntimeError("ConfigurationManager cannot be used unless started")
if not key:
raise KeyError("key cannot be empty")
self._update(self.data, list(key), data)
def rename(self, old_key, new_key):
"""
Rename the object identified by old_key to new_key (list of strings).
Cannot be called before start().
"""
if self.backend is None:
raise RuntimeError("ConfigurationManager cannot be used unless started")
if not old_key or not new_key:
raise KeyError("old_key and/or new_key cannot be empty")
try:
data = self._pop(self.data, list(old_key))
except KeyError:
raise ObjectNotFoundError("object %s does not exist" % '/'.join(old_key))
self._insert(self.data, list(new_key), data)
def delete(self, key):
"""
Delete the object in the tree path specified by key (list of strings).
Cannot be called before start().
"""
if self.backend is None:
raise RuntimeError("ConfigurationManager cannot be used unless started")
if not key:
raise KeyError("key cannot be empty")
try:
self._pop(self.data, list(key))
except KeyError:
pass
def get(self, key):
"""
Get the object in the tree path specified by key (list of strings).
Raises ObjectNotFoundError if the object does not exist. Cannot be
called before start().
"""
if self.backend is None:
raise RuntimeError("ConfigurationManager cannot be used unless started")
if not key:
raise KeyError("key cannot be empty")
try:
return self._get(self.data, list(key))
except KeyError:
raise ObjectNotFoundError("object %s does not exist" % '/'.join(key))
def get_names(self, key):
"""
Get all the names under the specified key (a list of strings).
Returns a list containing the names. Cannot be called before start().
"""
if self.backend is None:
raise RuntimeError("ConfigurationManager cannot be used unless started")
if not key:
raise KeyError("key cannot be empty")
try:
data = self._get(self.data, list(key))
return data.keys()
except:
return []
def save(self):
"""
Flush the modified objects. Cannot be called before start().
"""
if self.backend is None:
raise RuntimeError("ConfigurationManager cannot be used unless started")
self.backend.save(self.data)
def _get(self, data_tree, key):
subtree_key = key.pop(0)
data_subtree = data_tree[subtree_key]
if key:
return self._get(data_subtree, key)
else:
return data_subtree
def _insert(self, data_tree, key, data):
subtree_key = key.pop(0)
data_subtree = data_tree.setdefault(subtree_key, {})
if key:
self._insert(data_subtree, key, data)
else:
data_subtree.update(data)
def _pop(self, data_tree, key):
subtree_key = key.pop(0)
data_subtree = data_tree[subtree_key]
if key:
data = self._pop(data_subtree, key)
persistent_key = getattr(subtree_key, 'persistent', False)
if not persistent_key and not data_subtree:
del data_tree[subtree_key]
return data
else:
return data_tree.pop(subtree_key)
def _update(self, data_tree, key, data):
subtree_key = key.pop(0)
data_subtree = data_tree.setdefault(subtree_key, {})
if key:
self._update(data_subtree, key, data)
else:
self._update_dict(data_subtree, data)
persistent_key = getattr(subtree_key, 'persistent', False)
if not persistent_key and not data_subtree:
del data_tree[subtree_key]
def _update_dict(self, old_data, new_data):
for key, value in new_data.iteritems():
if value is DefaultValue:
old_data.pop(key, None)
elif type(value) is dict:
if key in old_data and type(old_data[key]) is not dict:
del old_data[key]
self._update_dict(old_data.setdefault(key, {}), value)
if not old_data[key]:
del old_data[key]
else:
old_data[key] = value
## Descriptors and base classes used for represeting configuration settings
class DefaultValue(object):
"""
This object can be set as the value for a setting and it will reset the
setting to the default value.
"""
class ModifiedValue(object):
"""
Instances of this class represent the state (the old and new values) of
settings.
"""
__slots__ = ('old', 'new')
def __init__(self, old, new):
self.old = old
self.new = new
def __repr__(self):
return '%s(old=%r, new=%r)' % (self.__class__.__name__, self.old, self.new)
class SettingsObjectID(object):
"""
Simple descriptor used for SettingsObject subclasses which have dynamic ids.
"""
lock = Lock() # need a class lock because SettingsObject IDs are correlated
def __init__(self, type):
self.type = type
self.values = WeakKeyDictionary()
self.oldvalues = WeakKeyDictionary()
self.dirty = WeakKeyDictionary()
def __get__(self, obj, objtype):
return self if obj is None else self.values[obj]
def __set__(self, obj, value):
with self.lock:
if not isinstance(value, self.type):
value = self.type(value)
if obj in self.values and self.values[obj] == value:
return
if obj in self.oldvalues and self.oldvalues[obj] == value:
self.values[obj] = self.oldvalues[obj]
self.dirty[obj] = False
return
try:
other_obj = (key for key, val in chain(self.values.iteritems(), self.oldvalues.iteritems()) if val==value).next()
except StopIteration:
pass
else:
raise DuplicateIDError('SettingsObject ID already used by another %s' % other_obj.__class__.__name__)
if obj in self.values:
self.values[obj] = value
self.dirty[obj] = True
else:
self.values[obj] = self.oldvalues[obj] = value
self.dirty[obj] = False
def get_modified(self, obj):
"""
Returns a ModifiedValue instance with references to the old and new
values or None if not modified.
"""
with self.lock:
try:
if self.dirty.get(obj, False):
return ModifiedValue(old=self.oldvalues[obj], new=self.values[obj])
else:
return None
finally:
self.oldvalues[obj] = self.values[obj]
self.dirty[obj] = False
def get_old(self, obj):
return self.oldvalues[obj]
def undo(self, obj):
with self.lock:
self.values[obj] = self.oldvalues[obj]
self.dirty[obj] = False
class Setting(object):
"""
Descriptor represeting a setting in a configuration object.
If a setting is set to the object DefaultValue, it will be reset to the
default. Also, only Setting attributes with nillable=True can be assigned
the value None. All other values are passed to the type specified.
"""
def __init__(self, type, default=None, nillable=False):
if default is None and not nillable:
raise TypeError("default must be specified if object is not nillable")
self.type = type
self.default = default
self.nillable = nillable
self.values = WeakKeyDictionary()
self.oldvalues = WeakKeyDictionary()
self.dirty = WeakKeyDictionary()
self.lock = Lock()
def __get__(self, obj, objtype):
if obj is None:
return self
return self.values.get(obj, self.default)
def __set__(self, obj, value):
with self.lock:
if value is None and not self.nillable:
raise ValueError("setting attribute is not nillable")
if value is DefaultValue:
if obj in self.values:
self.values.pop(obj)
self.dirty[obj] = obj in self.oldvalues
return
if value is not None and not isinstance(value, self.type):
value = self.type(value)
if obj in self.values and self.values[obj] == value:
return
self.values[obj] = value
self.dirty[obj] = value != self.oldvalues.get(obj, DefaultValue)
def __getstate__(self, obj):
value = self.values.get(obj, DefaultValue)
if value in (None, DefaultValue):
pass
elif issubclass(self.type, bool):
value = u'true' if value else u'false'
elif issubclass(self.type, (int, long, basestring)):
value = unicode(value)
else:
try:
value = value.__getstate__()
except AttributeError:
raise TypeError("Setting type %s does not provide __getstate__" % value.__class__.__name__)
return value
def __setstate__(self, obj, value):
with self.lock:
if value is None and not self.nillable:
raise ValueError("setting attribute is not nillable")
if value is None:
pass
elif issubclass(self.type, bool):
if value.lower() in ('true', 'yes', 'on', '1'):
value = True
elif value.lower() in ('false', 'no', 'off', '0'):
value = False
else:
raise ValueError("invalid boolean value: %s" % (value,))
elif issubclass(self.type, (int, long, basestring)):
value = self.type(value)
else:
object = self.type.__new__(self.type)
object.__setstate__(value)
value = object
self.oldvalues[obj] = self.values[obj] = value
self.dirty[obj] = False
def get_modified(self, obj):
"""
Returns a ModifiedValue instance with references to the old and new
values or None if not modified.
"""
with self.lock:
try:
if self.dirty.get(obj, False):
return ModifiedValue(old=self.oldvalues.get(obj, self.default), new=self.values.get(obj, self.default))
else:
return None
finally:
try:
self.oldvalues[obj] = self.values[obj]
except KeyError:
self.oldvalues.pop(obj, None)
self.dirty[obj] = False
def undo(self, obj):
with self.lock:
if obj in self.oldvalues:
self.values[obj] = self.oldvalues[obj]
else:
self.values.pop(obj, None)
self.dirty[obj] = False
class CorrelatedSetting(Setting):
"""
Descriptor represeting a setting in a configuration object that is
correlated with another setting on the same configuration object.
Sibling is the name of the sibling setting and validator is a callable
that will receive the setting value and the sibling setting value and
should raise an exception if the setting value is not acceptable relative
to the sibling setting value.
If a setting is set to the object DefaultValue, it will be reset to the
default. Also, only Setting attributes with nillable=True can be assigned
the value None. All other values are passed to the type specified.
"""
correlation_lock = Lock()
def __init__(self, type, sibling, validator, default=None, nillable=False):
Setting.__init__(self, type, default, nillable)
self.sibling = sibling
self.validator = validator
def __set__(self, obj, value):
with self.correlation_lock:
sibling_value = getattr(obj, self.sibling)
self.validator(value, sibling_value)
Setting.__set__(self, obj, value)
class SettingsState(object):
"""
This class represents configuration objects which can be saved and restored.
"""
def get_modified(self):
"""
Returns a dictionary containing the settings which have been changed.
The keys are the full paths to the attributes (from this object), which
are mapped to a ModifiedValue instance with references to the old and
new values.
"""
modified = {}
for name in dir(self.__class__):
attribute = getattr(self.__class__, name, None)
if isinstance(attribute, SettingsGroupMeta):
modified_settings = getattr(self, name).get_modified()
modified.update(dict((name+'.'+k if k else name, v) for k,v in modified_settings.iteritems()))
elif isinstance(attribute, Setting):
modified_value = attribute.get_modified(self)
if modified_value is not None:
modified[name] = modified_value
return modified
def clone(self):
"""
Create a copy of this object and all its sub settings.
"""
raise NotImplementedError
def update(self, object):
"""
Update the settings and subsettings of this settings object using the
ones in the specified object.
"""
raise NotImplementedError
def __getstate__(self):
state = {}
for name in dir(self.__class__):
attribute = getattr(self.__class__, name, None)
if isinstance(attribute, SettingsGroupMeta):
state[name] = getattr(self, name).__getstate__()
elif isinstance(attribute, Setting):
state[name] = attribute.__getstate__(self)
return state
def __setstate__(self, state):
configuration_manager = ConfigurationManager()
notification_center = NotificationCenter()
for name, value in state.iteritems():
attribute = getattr(self.__class__, name, None)
if isinstance(attribute, SettingsGroupMeta):
group = getattr(self, name)
try:
group.__setstate__(value)
except ValueError, e:
notification_center.post_notification('CFGManagerLoadFailed', sender=configuration_manager, data=TimestampedNotificationData(attribute=name, container=self, error=e))
elif isinstance(attribute, Setting):
try:
attribute.__setstate__(self, value)
except ValueError, e:
notification_center.post_notification('CFGManagerLoadFailed', sender=configuration_manager, data=TimestampedNotificationData(attribute=name, container=self, error=e))
class SettingsGroupMeta(type):
"""
Metaclass for SettingsGroup and its subclasses which allows them to be used
as descriptor instances.
"""
def __init__(cls, name, bases, dct):
cls.values = WeakKeyDictionary()
def __get__(cls, obj, objtype):
if obj is None:
return cls
try:
return cls.values[obj]
except KeyError:
return cls.values.setdefault(obj, cls())
def __set__(cls, obj, value):
raise AttributeError("cannot overwrite group of settings")
class SettingsGroup(SettingsState):
"""
Base class for settings groups, i.e. non-leaf and non-root nodes in the
configuration tree. All SettingsGroup subclasses are descriptor instances
which return an instance of the subclass type when accessed. All
SettingsGroup intances are created without passing any arguments to the
constructor.
class ContainedGroup(SettingsGroup):
pass
class ContainingGroup(SettingsGroup):
subgroup = ContainedGroup
"""
__metaclass__ = SettingsGroupMeta
class SettingsObject(SettingsState):
"""
Subclass for top-level configuration objects. These objects are identifiable
by either a global id (set in the __id__ attribute of the class) or a local
id passed as the sole argument when instantiating SettingsObjects.
For SettingsObject subclasses which are meant to be used exclusively with a
local id, the class attribute __id__ should be left to the value None; if
__init__ is defined, it would have to accept exactly one argument, id and
the subclass MUST call the parent's __init__ after it's done doing its own
initialization of the instance (SettingsObject.__init__ needs to be
executed last, after the instance is completely initialized).
The local id takes precedence over the one specified as a class attribute.
Note: __init__ and __new__ will be called not only when a new object is
created (i.e. there weren't any settings saved in the configuration), but
also when the object is retrieved from the configuration.
"""
__group__ = None
__id__ = None
def __new__(cls, id=None):
id = id or cls.__id__
if id is None:
raise ValueError("id is required for instantiating %s" % cls.__name__)
if not isinstance(id, basestring):
raise TypeError("id needs to be a string instance")
configuration = ConfigurationManager()
instance = SettingsState.__new__(cls)
instance.__id__ = id
try:
data = configuration.get(instance.__key__)
except ObjectNotFoundError:
pass
else:
instance.__setstate__(data)
return instance
def __init__(self, id=None):
notification_center = NotificationCenter()
notification_center.post_notification('CFGSettingsObjectWasCreated', sender=self, data=TimestampedNotificationData())
@property
def __key__(self):
if isinstance(self.__class__.__id__, SettingsObjectID):
id_key = PersistentKey(self.__id__)
else:
id_key = unicode(self.__id__)
if self.__group__ is not None:
return [self.__group__, id_key]
else:
return [id_key]
@property
def __oldkey__(self):
if isinstance(self.__class__.__id__, SettingsObjectID):
id_key = PersistentKey(self.__class__.__id__.get_old(self))
else:
id_key = unicode(self.__id__)
if self.__group__ is not None:
return [self.__group__, id_key]
else:
return [id_key]
@run_in_thread('file-io')
def save(self):
"""
Use the ConfigurationManager to store the object under its id in the
specified group or top-level otherwise, depending on whether group is
None.
This method will also post a CFGSettingsObjectDidChange notification,
regardless of whether the settings have been saved to persistent storage
or not. If the save does fail, a CFGManagerSaveFailed notification is
posted as well.
"""
configuration = ConfigurationManager()
notification_center = NotificationCenter()
oldkey = self.__oldkey__ # save this here as get_modified will reset it
id_descriptor = self.__class__.__id__ if isinstance(self.__class__.__id__, SettingsObjectID) else None
modified_id = id_descriptor.get_modified(self) if id_descriptor else None
modified_settings = self.get_modified()
if id_descriptor:
try:
configuration.get(oldkey)
except ObjectNotFoundError:
save_required = True
else:
save_required = False
else:
save_required = False
if not modified_id and not modified_settings and not save_required:
return
if save_required:
configuration.update(self.__key__, self.__getstate__())
else:
if modified_id:
configuration.rename(oldkey, self.__key__)
if modified_settings:
configuration.update(self.__key__, self.__getstate__())
modified_data = modified_settings or {}
if modified_id:
modified_data['__id__'] = modified_id
if modified_data:
notification_center.post_notification('CFGSettingsObjectDidChange', sender=self, data=TimestampedNotificationData(modified=modified_data))
try:
configuration.save()
except Exception, e:
log.err()
notification_center.post_notification('CFGManagerSaveFailed', sender=configuration, data=TimestampedNotificationData(object=self, operation='save', modified=modified_settings, exception=e))
@run_in_thread('file-io')
def delete(self):
"""
Remove this object from the persistent configuration.
"""
if self.__id__ is self.__class__.__id__:
raise TypeError("cannot delete %s instance with default id" % self.__class__.__name__)
configuration = ConfigurationManager()
notification_center = NotificationCenter()
configuration.delete(self.__oldkey__) # we need the key that wasn't yet saved
notification_center.post_notification('CFGSettingsObjectWasDeleted', sender=self, data=TimestampedNotificationData())
try:
configuration.save()
except Exception, e:
log.err()
notification_center.post_notification('CFGManagerSaveFailed', sender=configuration, data=TimestampedNotificationData(object=self, operation='delete', exception=e))
def clone(self, new_id):
"""
Create a copy of this object and all its sub settings.
"""
raise NotImplementedError
@classmethod
def register_extension(cls, extension):
"""
Register an extension of this SettingsObject. All Settings and
SettingsGroups defined in the extension will be added to this
SettingsObject, overwriting any attributes with the same name.
Other attributes in the extension are ignored.
"""
if not issubclass(extension, SettingsObjectExtension):
raise TypeError("expected subclass of SettingsObjectExtension, got %r" % (extension,))
for name in dir(extension):
attribute = getattr(extension, name, None)
if isinstance(attribute, (Setting, SettingsGroupMeta)):
setattr(cls, name, attribute)
class SettingsObjectExtension(object):
"""
Base class for extensions of SettingsObjects.
"""
def __new__(self, *args, **kwargs):
raise TypeError("SettingsObjectExtension subclasses cannot be instantiated")

File Metadata

Mime Type
text/x-python
Expires
Sat, Feb 1, 6:27 AM (1 d, 11 h)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
3488854
Default Alt Text
__init__.py (25 KB)

Event Timeline