You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
417 lines
14 KiB
Python
417 lines
14 KiB
Python
"""Extensible class instrumentation.
|
|
|
|
The :mod:`sqlalchemy.ext.instrumentation` package provides for alternate
|
|
systems of class instrumentation within the ORM. Class instrumentation
|
|
refers to how the ORM places attributes on the class which maintain
|
|
data and track changes to that data, as well as event hooks installed
|
|
on the class.
|
|
|
|
.. note::
|
|
The extension package is provided for the benefit of integration
|
|
with other object management packages, which already perform
|
|
their own instrumentation. It is not intended for general use.
|
|
|
|
For examples of how the instrumentation extension is used,
|
|
see the example :ref:`examples_instrumentation`.
|
|
|
|
"""
|
|
import weakref
|
|
|
|
from .. import util
|
|
from ..orm import attributes
|
|
from ..orm import base as orm_base
|
|
from ..orm import collections
|
|
from ..orm import exc as orm_exc
|
|
from ..orm import instrumentation as orm_instrumentation
|
|
from ..orm.instrumentation import _default_dict_getter
|
|
from ..orm.instrumentation import _default_manager_getter
|
|
from ..orm.instrumentation import _default_state_getter
|
|
from ..orm.instrumentation import ClassManager
|
|
from ..orm.instrumentation import InstrumentationFactory
|
|
|
|
|
|
INSTRUMENTATION_MANAGER = "__sa_instrumentation_manager__"
|
|
"""Attribute, elects custom instrumentation when present on a mapped class.
|
|
|
|
Allows a class to specify a slightly or wildly different technique for
|
|
tracking changes made to mapped attributes and collections.
|
|
|
|
Only one instrumentation implementation is allowed in a given object
|
|
inheritance hierarchy.
|
|
|
|
The value of this attribute must be a callable and will be passed a class
|
|
object. The callable must return one of:
|
|
|
|
- An instance of an :class:`.InstrumentationManager` or subclass
|
|
- An object implementing all or some of InstrumentationManager (TODO)
|
|
- A dictionary of callables, implementing all or some of the above (TODO)
|
|
- An instance of a :class:`.ClassManager` or subclass
|
|
|
|
This attribute is consulted by SQLAlchemy instrumentation
|
|
resolution, once the :mod:`sqlalchemy.ext.instrumentation` module
|
|
has been imported. If custom finders are installed in the global
|
|
instrumentation_finders list, they may or may not choose to honor this
|
|
attribute.
|
|
|
|
"""
|
|
|
|
|
|
def find_native_user_instrumentation_hook(cls):
|
|
"""Find user-specified instrumentation management for a class."""
|
|
return getattr(cls, INSTRUMENTATION_MANAGER, None)
|
|
|
|
|
|
instrumentation_finders = [find_native_user_instrumentation_hook]
|
|
"""An extensible sequence of callables which return instrumentation
|
|
implementations
|
|
|
|
When a class is registered, each callable will be passed a class object.
|
|
If None is returned, the
|
|
next finder in the sequence is consulted. Otherwise the return must be an
|
|
instrumentation factory that follows the same guidelines as
|
|
sqlalchemy.ext.instrumentation.INSTRUMENTATION_MANAGER.
|
|
|
|
By default, the only finder is find_native_user_instrumentation_hook, which
|
|
searches for INSTRUMENTATION_MANAGER. If all finders return None, standard
|
|
ClassManager instrumentation is used.
|
|
|
|
"""
|
|
|
|
|
|
class ExtendedInstrumentationRegistry(InstrumentationFactory):
|
|
"""Extends :class:`.InstrumentationFactory` with additional
|
|
bookkeeping, to accommodate multiple types of
|
|
class managers.
|
|
|
|
"""
|
|
|
|
_manager_finders = weakref.WeakKeyDictionary()
|
|
_state_finders = weakref.WeakKeyDictionary()
|
|
_dict_finders = weakref.WeakKeyDictionary()
|
|
_extended = False
|
|
|
|
def _locate_extended_factory(self, class_):
|
|
for finder in instrumentation_finders:
|
|
factory = finder(class_)
|
|
if factory is not None:
|
|
manager = self._extended_class_manager(class_, factory)
|
|
return manager, factory
|
|
else:
|
|
return None, None
|
|
|
|
def _check_conflicts(self, class_, factory):
|
|
existing_factories = self._collect_management_factories_for(
|
|
class_
|
|
).difference([factory])
|
|
if existing_factories:
|
|
raise TypeError(
|
|
"multiple instrumentation implementations specified "
|
|
"in %s inheritance hierarchy: %r"
|
|
% (class_.__name__, list(existing_factories))
|
|
)
|
|
|
|
def _extended_class_manager(self, class_, factory):
|
|
manager = factory(class_)
|
|
if not isinstance(manager, ClassManager):
|
|
manager = _ClassInstrumentationAdapter(class_, manager)
|
|
|
|
if factory != ClassManager and not self._extended:
|
|
# somebody invoked a custom ClassManager.
|
|
# reinstall global "getter" functions with the more
|
|
# expensive ones.
|
|
self._extended = True
|
|
_install_instrumented_lookups()
|
|
|
|
self._manager_finders[class_] = manager.manager_getter()
|
|
self._state_finders[class_] = manager.state_getter()
|
|
self._dict_finders[class_] = manager.dict_getter()
|
|
return manager
|
|
|
|
def _collect_management_factories_for(self, cls):
|
|
"""Return a collection of factories in play or specified for a
|
|
hierarchy.
|
|
|
|
Traverses the entire inheritance graph of a cls and returns a
|
|
collection of instrumentation factories for those classes. Factories
|
|
are extracted from active ClassManagers, if available, otherwise
|
|
instrumentation_finders is consulted.
|
|
|
|
"""
|
|
hierarchy = util.class_hierarchy(cls)
|
|
factories = set()
|
|
for member in hierarchy:
|
|
manager = self.manager_of_class(member)
|
|
if manager is not None:
|
|
factories.add(manager.factory)
|
|
else:
|
|
for finder in instrumentation_finders:
|
|
factory = finder(member)
|
|
if factory is not None:
|
|
break
|
|
else:
|
|
factory = None
|
|
factories.add(factory)
|
|
factories.discard(None)
|
|
return factories
|
|
|
|
def unregister(self, class_):
|
|
super(ExtendedInstrumentationRegistry, self).unregister(class_)
|
|
if class_ in self._manager_finders:
|
|
del self._manager_finders[class_]
|
|
del self._state_finders[class_]
|
|
del self._dict_finders[class_]
|
|
|
|
def manager_of_class(self, cls):
|
|
if cls is None:
|
|
return None
|
|
try:
|
|
finder = self._manager_finders.get(cls, _default_manager_getter)
|
|
except TypeError:
|
|
# due to weakref lookup on invalid object
|
|
return None
|
|
else:
|
|
return finder(cls)
|
|
|
|
def state_of(self, instance):
|
|
if instance is None:
|
|
raise AttributeError("None has no persistent state.")
|
|
return self._state_finders.get(
|
|
instance.__class__, _default_state_getter
|
|
)(instance)
|
|
|
|
def dict_of(self, instance):
|
|
if instance is None:
|
|
raise AttributeError("None has no persistent state.")
|
|
return self._dict_finders.get(
|
|
instance.__class__, _default_dict_getter
|
|
)(instance)
|
|
|
|
|
|
orm_instrumentation._instrumentation_factory = (
|
|
_instrumentation_factory
|
|
) = ExtendedInstrumentationRegistry()
|
|
orm_instrumentation.instrumentation_finders = instrumentation_finders
|
|
|
|
|
|
class InstrumentationManager(object):
|
|
"""User-defined class instrumentation extension.
|
|
|
|
:class:`.InstrumentationManager` can be subclassed in order
|
|
to change
|
|
how class instrumentation proceeds. This class exists for
|
|
the purposes of integration with other object management
|
|
frameworks which would like to entirely modify the
|
|
instrumentation methodology of the ORM, and is not intended
|
|
for regular usage. For interception of class instrumentation
|
|
events, see :class:`.InstrumentationEvents`.
|
|
|
|
The API for this class should be considered as semi-stable,
|
|
and may change slightly with new releases.
|
|
|
|
"""
|
|
|
|
# r4361 added a mandatory (cls) constructor to this interface.
|
|
# given that, perhaps class_ should be dropped from all of these
|
|
# signatures.
|
|
|
|
def __init__(self, class_):
|
|
pass
|
|
|
|
def manage(self, class_, manager):
|
|
setattr(class_, "_default_class_manager", manager)
|
|
|
|
def unregister(self, class_, manager):
|
|
delattr(class_, "_default_class_manager")
|
|
|
|
def manager_getter(self, class_):
|
|
def get(cls):
|
|
return cls._default_class_manager
|
|
|
|
return get
|
|
|
|
def instrument_attribute(self, class_, key, inst):
|
|
pass
|
|
|
|
def post_configure_attribute(self, class_, key, inst):
|
|
pass
|
|
|
|
def install_descriptor(self, class_, key, inst):
|
|
setattr(class_, key, inst)
|
|
|
|
def uninstall_descriptor(self, class_, key):
|
|
delattr(class_, key)
|
|
|
|
def install_member(self, class_, key, implementation):
|
|
setattr(class_, key, implementation)
|
|
|
|
def uninstall_member(self, class_, key):
|
|
delattr(class_, key)
|
|
|
|
def instrument_collection_class(self, class_, key, collection_class):
|
|
return collections.prepare_instrumentation(collection_class)
|
|
|
|
def get_instance_dict(self, class_, instance):
|
|
return instance.__dict__
|
|
|
|
def initialize_instance_dict(self, class_, instance):
|
|
pass
|
|
|
|
def install_state(self, class_, instance, state):
|
|
setattr(instance, "_default_state", state)
|
|
|
|
def remove_state(self, class_, instance):
|
|
delattr(instance, "_default_state")
|
|
|
|
def state_getter(self, class_):
|
|
return lambda instance: getattr(instance, "_default_state")
|
|
|
|
def dict_getter(self, class_):
|
|
return lambda inst: self.get_instance_dict(class_, inst)
|
|
|
|
|
|
class _ClassInstrumentationAdapter(ClassManager):
|
|
"""Adapts a user-defined InstrumentationManager to a ClassManager."""
|
|
|
|
def __init__(self, class_, override):
|
|
self._adapted = override
|
|
self._get_state = self._adapted.state_getter(class_)
|
|
self._get_dict = self._adapted.dict_getter(class_)
|
|
|
|
ClassManager.__init__(self, class_)
|
|
|
|
def manage(self):
|
|
self._adapted.manage(self.class_, self)
|
|
|
|
def unregister(self):
|
|
self._adapted.unregister(self.class_, self)
|
|
|
|
def manager_getter(self):
|
|
return self._adapted.manager_getter(self.class_)
|
|
|
|
def instrument_attribute(self, key, inst, propagated=False):
|
|
ClassManager.instrument_attribute(self, key, inst, propagated)
|
|
if not propagated:
|
|
self._adapted.instrument_attribute(self.class_, key, inst)
|
|
|
|
def post_configure_attribute(self, key):
|
|
super(_ClassInstrumentationAdapter, self).post_configure_attribute(key)
|
|
self._adapted.post_configure_attribute(self.class_, key, self[key])
|
|
|
|
def install_descriptor(self, key, inst):
|
|
self._adapted.install_descriptor(self.class_, key, inst)
|
|
|
|
def uninstall_descriptor(self, key):
|
|
self._adapted.uninstall_descriptor(self.class_, key)
|
|
|
|
def install_member(self, key, implementation):
|
|
self._adapted.install_member(self.class_, key, implementation)
|
|
|
|
def uninstall_member(self, key):
|
|
self._adapted.uninstall_member(self.class_, key)
|
|
|
|
def instrument_collection_class(self, key, collection_class):
|
|
return self._adapted.instrument_collection_class(
|
|
self.class_, key, collection_class
|
|
)
|
|
|
|
def initialize_collection(self, key, state, factory):
|
|
delegate = getattr(self._adapted, "initialize_collection", None)
|
|
if delegate:
|
|
return delegate(key, state, factory)
|
|
else:
|
|
return ClassManager.initialize_collection(
|
|
self, key, state, factory
|
|
)
|
|
|
|
def new_instance(self, state=None):
|
|
instance = self.class_.__new__(self.class_)
|
|
self.setup_instance(instance, state)
|
|
return instance
|
|
|
|
def _new_state_if_none(self, instance):
|
|
"""Install a default InstanceState if none is present.
|
|
|
|
A private convenience method used by the __init__ decorator.
|
|
"""
|
|
if self.has_state(instance):
|
|
return False
|
|
else:
|
|
return self.setup_instance(instance)
|
|
|
|
def setup_instance(self, instance, state=None):
|
|
self._adapted.initialize_instance_dict(self.class_, instance)
|
|
|
|
if state is None:
|
|
state = self._state_constructor(instance, self)
|
|
|
|
# the given instance is assumed to have no state
|
|
self._adapted.install_state(self.class_, instance, state)
|
|
return state
|
|
|
|
def teardown_instance(self, instance):
|
|
self._adapted.remove_state(self.class_, instance)
|
|
|
|
def has_state(self, instance):
|
|
try:
|
|
self._get_state(instance)
|
|
except orm_exc.NO_STATE:
|
|
return False
|
|
else:
|
|
return True
|
|
|
|
def state_getter(self):
|
|
return self._get_state
|
|
|
|
def dict_getter(self):
|
|
return self._get_dict
|
|
|
|
|
|
def _install_instrumented_lookups():
|
|
"""Replace global class/object management functions
|
|
with ExtendedInstrumentationRegistry implementations, which
|
|
allow multiple types of class managers to be present,
|
|
at the cost of performance.
|
|
|
|
This function is called only by ExtendedInstrumentationRegistry
|
|
and unit tests specific to this behavior.
|
|
|
|
The _reinstall_default_lookups() function can be called
|
|
after this one to re-establish the default functions.
|
|
|
|
"""
|
|
_install_lookups(
|
|
dict(
|
|
instance_state=_instrumentation_factory.state_of,
|
|
instance_dict=_instrumentation_factory.dict_of,
|
|
manager_of_class=_instrumentation_factory.manager_of_class,
|
|
)
|
|
)
|
|
|
|
|
|
def _reinstall_default_lookups():
|
|
"""Restore simplified lookups."""
|
|
_install_lookups(
|
|
dict(
|
|
instance_state=_default_state_getter,
|
|
instance_dict=_default_dict_getter,
|
|
manager_of_class=_default_manager_getter,
|
|
)
|
|
)
|
|
_instrumentation_factory._extended = False
|
|
|
|
|
|
def _install_lookups(lookups):
|
|
global instance_state, instance_dict, manager_of_class
|
|
instance_state = lookups["instance_state"]
|
|
instance_dict = lookups["instance_dict"]
|
|
manager_of_class = lookups["manager_of_class"]
|
|
orm_base.instance_state = (
|
|
attributes.instance_state
|
|
) = orm_instrumentation.instance_state = instance_state
|
|
orm_base.instance_dict = (
|
|
attributes.instance_dict
|
|
) = orm_instrumentation.instance_dict = instance_dict
|
|
orm_base.manager_of_class = (
|
|
attributes.manager_of_class
|
|
) = orm_instrumentation.manager_of_class = manager_of_class
|