465 lines
15 KiB
Python
465 lines
15 KiB
Python
# orm/instrumentation.py
|
|
# Copyright (C) 2005-2013 the SQLAlchemy authors and contributors <see AUTHORS file>
|
|
#
|
|
# This module is part of SQLAlchemy and is released under
|
|
# the MIT License: http://www.opensource.org/licenses/mit-license.php
|
|
|
|
"""Defines SQLAlchemy's system of class instrumentation.
|
|
|
|
This module is usually not directly visible to user applications, but
|
|
defines a large part of the ORM's interactivity.
|
|
|
|
instrumentation.py deals with registration of end-user classes
|
|
for state tracking. It interacts closely with state.py
|
|
and attributes.py which establish per-instance and per-class-attribute
|
|
instrumentation, respectively.
|
|
|
|
The class instrumentation system can be customized on a per-class
|
|
or global basis using the :mod:`sqlalchemy.ext.instrumentation`
|
|
module, which provides the means to build and specify
|
|
alternate instrumentation forms.
|
|
|
|
.. versionchanged: 0.8
|
|
The instrumentation extension system was moved out of the
|
|
ORM and into the external :mod:`sqlalchemy.ext.instrumentation`
|
|
package. When that package is imported, it installs
|
|
itself within sqlalchemy.orm so that its more comprehensive
|
|
resolution mechanics take effect.
|
|
|
|
"""
|
|
|
|
|
|
from . import exc, collections, events, interfaces
|
|
from operator import attrgetter
|
|
from .. import event, util
|
|
state = util.importlater("sqlalchemy.orm", "state")
|
|
|
|
|
|
class ClassManager(dict):
|
|
"""tracks state information at the class level."""
|
|
|
|
MANAGER_ATTR = '_sa_class_manager'
|
|
STATE_ATTR = '_sa_instance_state'
|
|
|
|
deferred_scalar_loader = None
|
|
|
|
original_init = object.__init__
|
|
|
|
factory = None
|
|
|
|
def __init__(self, class_):
|
|
self.class_ = class_
|
|
self.info = {}
|
|
self.new_init = None
|
|
self.local_attrs = {}
|
|
self.originals = {}
|
|
|
|
self._bases = [mgr for mgr in [
|
|
manager_of_class(base)
|
|
for base in self.class_.__bases__
|
|
if isinstance(base, type)
|
|
] if mgr is not None]
|
|
|
|
for base in self._bases:
|
|
self.update(base)
|
|
|
|
events._InstanceEventsHold.populate(class_, self)
|
|
|
|
for basecls in class_.__mro__:
|
|
mgr = manager_of_class(basecls)
|
|
if mgr is not None:
|
|
self.dispatch._update(mgr.dispatch)
|
|
self.manage()
|
|
self._instrument_init()
|
|
|
|
if '__del__' in class_.__dict__:
|
|
util.warn("__del__() method on class %s will "
|
|
"cause unreachable cycles and memory leaks, "
|
|
"as SQLAlchemy instrumentation often creates "
|
|
"reference cycles. Please remove this method." %
|
|
class_)
|
|
|
|
dispatch = event.dispatcher(events.InstanceEvents)
|
|
|
|
@property
|
|
def is_mapped(self):
|
|
return 'mapper' in self.__dict__
|
|
|
|
@util.memoized_property
|
|
def mapper(self):
|
|
# raises unless self.mapper has been assigned
|
|
raise exc.UnmappedClassError(self.class_)
|
|
|
|
def _all_sqla_attributes(self, exclude=None):
|
|
"""return an iterator of all classbound attributes that are
|
|
implement :class:`._InspectionAttr`.
|
|
|
|
This includes :class:`.QueryableAttribute` as well as extension
|
|
types such as :class:`.hybrid_property` and :class:`.AssociationProxy`.
|
|
|
|
"""
|
|
if exclude is None:
|
|
exclude = set()
|
|
for supercls in self.class_.__mro__:
|
|
for key in set(supercls.__dict__).difference(exclude):
|
|
exclude.add(key)
|
|
val = supercls.__dict__[key]
|
|
if isinstance(val, interfaces._InspectionAttr):
|
|
yield key, val
|
|
|
|
|
|
def _attr_has_impl(self, key):
|
|
"""Return True if the given attribute is fully initialized.
|
|
|
|
i.e. has an impl.
|
|
"""
|
|
|
|
return key in self and self[key].impl is not None
|
|
|
|
def _subclass_manager(self, cls):
|
|
"""Create a new ClassManager for a subclass of this ClassManager's
|
|
class.
|
|
|
|
This is called automatically when attributes are instrumented so that
|
|
the attributes can be propagated to subclasses against their own
|
|
class-local manager, without the need for mappers etc. to have already
|
|
pre-configured managers for the full class hierarchy. Mappers
|
|
can post-configure the auto-generated ClassManager when needed.
|
|
|
|
"""
|
|
manager = manager_of_class(cls)
|
|
if manager is None:
|
|
manager = _instrumentation_factory.create_manager_for_cls(cls)
|
|
return manager
|
|
|
|
def _instrument_init(self):
|
|
# TODO: self.class_.__init__ is often the already-instrumented
|
|
# __init__ from an instrumented superclass. We still need to make
|
|
# our own wrapper, but it would
|
|
# be nice to wrap the original __init__ and not our existing wrapper
|
|
# of such, since this adds method overhead.
|
|
self.original_init = self.class_.__init__
|
|
self.new_init = _generate_init(self.class_, self)
|
|
self.install_member('__init__', self.new_init)
|
|
|
|
def _uninstrument_init(self):
|
|
if self.new_init:
|
|
self.uninstall_member('__init__')
|
|
self.new_init = None
|
|
|
|
@util.memoized_property
|
|
def _state_constructor(self):
|
|
self.dispatch.first_init(self, self.class_)
|
|
return state.InstanceState
|
|
|
|
def manage(self):
|
|
"""Mark this instance as the manager for its class."""
|
|
|
|
setattr(self.class_, self.MANAGER_ATTR, self)
|
|
|
|
def dispose(self):
|
|
"""Dissasociate this manager from its class."""
|
|
|
|
delattr(self.class_, self.MANAGER_ATTR)
|
|
|
|
@util.hybridmethod
|
|
def manager_getter(self):
|
|
def manager_of_class(cls):
|
|
return cls.__dict__.get(ClassManager.MANAGER_ATTR, None)
|
|
return manager_of_class
|
|
|
|
@util.hybridmethod
|
|
def state_getter(self):
|
|
"""Return a (instance) -> InstanceState callable.
|
|
|
|
"state getter" callables should raise either KeyError or
|
|
AttributeError if no InstanceState could be found for the
|
|
instance.
|
|
"""
|
|
|
|
return attrgetter(self.STATE_ATTR)
|
|
|
|
@util.hybridmethod
|
|
def dict_getter(self):
|
|
return attrgetter('__dict__')
|
|
|
|
def instrument_attribute(self, key, inst, propagated=False):
|
|
if propagated:
|
|
if key in self.local_attrs:
|
|
return # don't override local attr with inherited attr
|
|
else:
|
|
self.local_attrs[key] = inst
|
|
self.install_descriptor(key, inst)
|
|
self[key] = inst
|
|
|
|
for cls in self.class_.__subclasses__():
|
|
manager = self._subclass_manager(cls)
|
|
manager.instrument_attribute(key, inst, True)
|
|
|
|
def subclass_managers(self, recursive):
|
|
for cls in self.class_.__subclasses__():
|
|
mgr = manager_of_class(cls)
|
|
if mgr is not None and mgr is not self:
|
|
yield mgr
|
|
if recursive:
|
|
for m in mgr.subclass_managers(True):
|
|
yield m
|
|
|
|
def post_configure_attribute(self, key):
|
|
_instrumentation_factory.dispatch.\
|
|
attribute_instrument(self.class_, key, self[key])
|
|
|
|
def uninstrument_attribute(self, key, propagated=False):
|
|
if key not in self:
|
|
return
|
|
if propagated:
|
|
if key in self.local_attrs:
|
|
return # don't get rid of local attr
|
|
else:
|
|
del self.local_attrs[key]
|
|
self.uninstall_descriptor(key)
|
|
del self[key]
|
|
for cls in self.class_.__subclasses__():
|
|
manager = manager_of_class(cls)
|
|
if manager:
|
|
manager.uninstrument_attribute(key, True)
|
|
|
|
def unregister(self):
|
|
"""remove all instrumentation established by this ClassManager."""
|
|
|
|
self._uninstrument_init()
|
|
|
|
self.mapper = self.dispatch = None
|
|
self.info.clear()
|
|
|
|
for key in list(self):
|
|
if key in self.local_attrs:
|
|
self.uninstrument_attribute(key)
|
|
|
|
def install_descriptor(self, key, inst):
|
|
if key in (self.STATE_ATTR, self.MANAGER_ATTR):
|
|
raise KeyError("%r: requested attribute name conflicts with "
|
|
"instrumentation attribute of the same name." %
|
|
key)
|
|
setattr(self.class_, key, inst)
|
|
|
|
def uninstall_descriptor(self, key):
|
|
delattr(self.class_, key)
|
|
|
|
def install_member(self, key, implementation):
|
|
if key in (self.STATE_ATTR, self.MANAGER_ATTR):
|
|
raise KeyError("%r: requested attribute name conflicts with "
|
|
"instrumentation attribute of the same name." %
|
|
key)
|
|
self.originals.setdefault(key, getattr(self.class_, key, None))
|
|
setattr(self.class_, key, implementation)
|
|
|
|
def uninstall_member(self, key):
|
|
original = self.originals.pop(key, None)
|
|
if original is not None:
|
|
setattr(self.class_, key, original)
|
|
|
|
def instrument_collection_class(self, key, collection_class):
|
|
return collections.prepare_instrumentation(collection_class)
|
|
|
|
def initialize_collection(self, key, state, factory):
|
|
user_data = factory()
|
|
adapter = collections.CollectionAdapter(
|
|
self.get_impl(key), state, user_data)
|
|
return adapter, user_data
|
|
|
|
def is_instrumented(self, key, search=False):
|
|
if search:
|
|
return key in self
|
|
else:
|
|
return key in self.local_attrs
|
|
|
|
def get_impl(self, key):
|
|
return self[key].impl
|
|
|
|
@property
|
|
def attributes(self):
|
|
return self.itervalues()
|
|
|
|
## InstanceState management
|
|
|
|
def new_instance(self, state=None):
|
|
instance = self.class_.__new__(self.class_)
|
|
setattr(instance, self.STATE_ATTR,
|
|
state or self._state_constructor(instance, self))
|
|
return instance
|
|
|
|
def setup_instance(self, instance, state=None):
|
|
setattr(instance, self.STATE_ATTR,
|
|
state or self._state_constructor(instance, self))
|
|
|
|
def teardown_instance(self, instance):
|
|
delattr(instance, self.STATE_ATTR)
|
|
|
|
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 hasattr(instance, self.STATE_ATTR):
|
|
return False
|
|
elif self.class_ is not instance.__class__ and \
|
|
self.is_mapped:
|
|
# this will create a new ClassManager for the
|
|
# subclass, without a mapper. This is likely a
|
|
# user error situation but allow the object
|
|
# to be constructed, so that it is usable
|
|
# in a non-ORM context at least.
|
|
return self._subclass_manager(instance.__class__).\
|
|
_new_state_if_none(instance)
|
|
else:
|
|
state = self._state_constructor(instance, self)
|
|
setattr(instance, self.STATE_ATTR, state)
|
|
return state
|
|
|
|
def has_state(self, instance):
|
|
return hasattr(instance, self.STATE_ATTR)
|
|
|
|
def has_parent(self, state, key, optimistic=False):
|
|
"""TODO"""
|
|
return self.get_impl(key).hasparent(state, optimistic=optimistic)
|
|
|
|
def __nonzero__(self):
|
|
"""All ClassManagers are non-zero regardless of attribute state."""
|
|
return True
|
|
|
|
def __repr__(self):
|
|
return '<%s of %r at %x>' % (
|
|
self.__class__.__name__, self.class_, id(self))
|
|
|
|
|
|
class InstrumentationFactory(object):
|
|
"""Factory for new ClassManager instances."""
|
|
|
|
dispatch = event.dispatcher(events.InstrumentationEvents)
|
|
|
|
def create_manager_for_cls(self, class_):
|
|
assert class_ is not None
|
|
assert manager_of_class(class_) is None
|
|
|
|
# give a more complicated subclass
|
|
# a chance to do what it wants here
|
|
manager, factory = self._locate_extended_factory(class_)
|
|
|
|
if factory is None:
|
|
factory = ClassManager
|
|
manager = factory(class_)
|
|
|
|
self._check_conflicts(class_, factory)
|
|
|
|
manager.factory = factory
|
|
|
|
self.dispatch.class_instrument(class_)
|
|
return manager
|
|
|
|
def _locate_extended_factory(self, class_):
|
|
"""Overridden by a subclass to do an extended lookup."""
|
|
return None, None
|
|
|
|
def _check_conflicts(self, class_, factory):
|
|
"""Overridden by a subclass to test for conflicting factories."""
|
|
return
|
|
|
|
def unregister(self, class_):
|
|
manager = manager_of_class(class_)
|
|
manager.unregister()
|
|
manager.dispose()
|
|
self.dispatch.class_uninstrument(class_)
|
|
if ClassManager.MANAGER_ATTR in class_.__dict__:
|
|
delattr(class_, ClassManager.MANAGER_ATTR)
|
|
|
|
# this attribute is replaced by sqlalchemy.ext.instrumentation
|
|
# when importred.
|
|
_instrumentation_factory = InstrumentationFactory()
|
|
|
|
|
|
def register_class(class_):
|
|
"""Register class instrumentation.
|
|
|
|
Returns the existing or newly created class manager.
|
|
|
|
"""
|
|
|
|
manager = manager_of_class(class_)
|
|
if manager is None:
|
|
manager = _instrumentation_factory.create_manager_for_cls(class_)
|
|
return manager
|
|
|
|
|
|
def unregister_class(class_):
|
|
"""Unregister class instrumentation."""
|
|
|
|
_instrumentation_factory.unregister(class_)
|
|
|
|
|
|
def is_instrumented(instance, key):
|
|
"""Return True if the given attribute on the given instance is
|
|
instrumented by the attributes package.
|
|
|
|
This function may be used regardless of instrumentation
|
|
applied directly to the class, i.e. no descriptors are required.
|
|
|
|
"""
|
|
return manager_of_class(instance.__class__).\
|
|
is_instrumented(key, search=True)
|
|
|
|
# these attributes are replaced by sqlalchemy.ext.instrumentation
|
|
# when a non-standard InstrumentationManager class is first
|
|
# used to instrument a class.
|
|
instance_state = _default_state_getter = ClassManager.state_getter()
|
|
|
|
instance_dict = _default_dict_getter = ClassManager.dict_getter()
|
|
|
|
manager_of_class = _default_manager_getter = ClassManager.manager_getter()
|
|
|
|
|
|
def _generate_init(class_, class_manager):
|
|
"""Build an __init__ decorator that triggers ClassManager events."""
|
|
|
|
# TODO: we should use the ClassManager's notion of the
|
|
# original '__init__' method, once ClassManager is fixed
|
|
# to always reference that.
|
|
original__init__ = class_.__init__
|
|
assert original__init__
|
|
|
|
# Go through some effort here and don't change the user's __init__
|
|
# calling signature, including the unlikely case that it has
|
|
# a return value.
|
|
# FIXME: need to juggle local names to avoid constructor argument
|
|
# clashes.
|
|
func_body = """\
|
|
def __init__(%(apply_pos)s):
|
|
new_state = class_manager._new_state_if_none(%(self_arg)s)
|
|
if new_state:
|
|
return new_state._initialize_instance(%(apply_kw)s)
|
|
else:
|
|
return original__init__(%(apply_kw)s)
|
|
"""
|
|
func_vars = util.format_argspec_init(original__init__, grouped=False)
|
|
func_text = func_body % func_vars
|
|
|
|
# Py3K
|
|
#func_defaults = getattr(original__init__, '__defaults__', None)
|
|
#func_kw_defaults = getattr(original__init__, '__kwdefaults__', None)
|
|
# Py2K
|
|
func = getattr(original__init__, 'im_func', original__init__)
|
|
func_defaults = getattr(func, 'func_defaults', None)
|
|
# end Py2K
|
|
|
|
env = locals().copy()
|
|
exec func_text in env
|
|
__init__ = env['__init__']
|
|
__init__.__doc__ = original__init__.__doc__
|
|
if func_defaults:
|
|
__init__.func_defaults = func_defaults
|
|
# Py3K
|
|
#if func_kw_defaults:
|
|
# __init__.__kwdefaults__ = func_kw_defaults
|
|
return __init__
|