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653 lines
20 KiB
653 lines
20 KiB
# orm/instrumentation.py
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# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors
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# <see AUTHORS file>
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#
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# This module is part of SQLAlchemy and is released under
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# the MIT License: https://www.opensource.org/licenses/mit-license.php
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"""Defines SQLAlchemy's system of class instrumentation.
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This module is usually not directly visible to user applications, but
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defines a large part of the ORM's interactivity.
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instrumentation.py deals with registration of end-user classes
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for state tracking. It interacts closely with state.py
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and attributes.py which establish per-instance and per-class-attribute
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instrumentation, respectively.
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The class instrumentation system can be customized on a per-class
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or global basis using the :mod:`sqlalchemy.ext.instrumentation`
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module, which provides the means to build and specify
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alternate instrumentation forms.
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.. versionchanged: 0.8
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The instrumentation extension system was moved out of the
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ORM and into the external :mod:`sqlalchemy.ext.instrumentation`
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package. When that package is imported, it installs
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itself within sqlalchemy.orm so that its more comprehensive
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resolution mechanics take effect.
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"""
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import weakref
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from . import base
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from . import collections
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from . import exc
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from . import interfaces
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from . import state
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from .. import util
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from ..util import HasMemoized
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DEL_ATTR = util.symbol("DEL_ATTR")
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class ClassManager(HasMemoized, dict):
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"""Tracks state information at the class level."""
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MANAGER_ATTR = base.DEFAULT_MANAGER_ATTR
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STATE_ATTR = base.DEFAULT_STATE_ATTR
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_state_setter = staticmethod(util.attrsetter(STATE_ATTR))
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expired_attribute_loader = None
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"previously known as deferred_scalar_loader"
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init_method = None
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factory = None
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mapper = None
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declarative_scan = None
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registry = None
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@property
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@util.deprecated(
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"1.4",
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message="The ClassManager.deferred_scalar_loader attribute is now "
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"named expired_attribute_loader",
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)
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def deferred_scalar_loader(self):
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return self.expired_attribute_loader
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@deferred_scalar_loader.setter
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@util.deprecated(
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"1.4",
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message="The ClassManager.deferred_scalar_loader attribute is now "
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"named expired_attribute_loader",
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)
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def deferred_scalar_loader(self, obj):
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self.expired_attribute_loader = obj
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def __init__(self, class_):
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self.class_ = class_
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self.info = {}
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self.new_init = None
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self.local_attrs = {}
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self.originals = {}
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self._finalized = False
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self._bases = [
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mgr
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for mgr in [
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manager_of_class(base)
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for base in self.class_.__bases__
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if isinstance(base, type)
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]
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if mgr is not None
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]
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for base_ in self._bases:
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self.update(base_)
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self.dispatch._events._new_classmanager_instance(class_, self)
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for basecls in class_.__mro__:
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mgr = manager_of_class(basecls)
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if mgr is not None:
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self.dispatch._update(mgr.dispatch)
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self.manage()
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if "__del__" in class_.__dict__:
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util.warn(
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"__del__() method on class %s will "
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"cause unreachable cycles and memory leaks, "
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"as SQLAlchemy instrumentation often creates "
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"reference cycles. Please remove this method." % class_
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)
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def _update_state(
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self,
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finalize=False,
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mapper=None,
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registry=None,
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declarative_scan=None,
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expired_attribute_loader=None,
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init_method=None,
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):
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if mapper:
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self.mapper = mapper
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if registry:
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registry._add_manager(self)
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if declarative_scan:
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self.declarative_scan = weakref.ref(declarative_scan)
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if expired_attribute_loader:
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self.expired_attribute_loader = expired_attribute_loader
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if init_method:
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assert not self._finalized, (
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"class is already instrumented, "
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"init_method %s can't be applied" % init_method
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)
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self.init_method = init_method
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if not self._finalized:
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self.original_init = (
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self.init_method
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if self.init_method is not None
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and self.class_.__init__ is object.__init__
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else self.class_.__init__
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)
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if finalize and not self._finalized:
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self._finalize()
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def _finalize(self):
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if self._finalized:
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return
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self._finalized = True
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self._instrument_init()
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_instrumentation_factory.dispatch.class_instrument(self.class_)
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def __hash__(self):
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return id(self)
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def __eq__(self, other):
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return other is self
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@property
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def is_mapped(self):
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return "mapper" in self.__dict__
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@HasMemoized.memoized_attribute
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def _all_key_set(self):
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return frozenset(self)
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@HasMemoized.memoized_attribute
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def _collection_impl_keys(self):
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return frozenset(
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[attr.key for attr in self.values() if attr.impl.collection]
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)
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@HasMemoized.memoized_attribute
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def _scalar_loader_impls(self):
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return frozenset(
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[
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attr.impl
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for attr in self.values()
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if attr.impl.accepts_scalar_loader
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]
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)
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@HasMemoized.memoized_attribute
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def _loader_impls(self):
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return frozenset([attr.impl for attr in self.values()])
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@util.memoized_property
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def mapper(self):
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# raises unless self.mapper has been assigned
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raise exc.UnmappedClassError(self.class_)
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def _all_sqla_attributes(self, exclude=None):
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"""return an iterator of all classbound attributes that are
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implement :class:`.InspectionAttr`.
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This includes :class:`.QueryableAttribute` as well as extension
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types such as :class:`.hybrid_property` and
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:class:`.AssociationProxy`.
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"""
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found = {}
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# constraints:
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# 1. yield keys in cls.__dict__ order
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# 2. if a subclass has the same key as a superclass, include that
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# key as part of the ordering of the superclass, because an
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# overridden key is usually installed by the mapper which is going
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# on a different ordering
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# 3. don't use getattr() as this fires off descriptors
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for supercls in self.class_.__mro__[0:-1]:
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inherits = supercls.__mro__[1]
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for key in supercls.__dict__:
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found.setdefault(key, supercls)
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if key in inherits.__dict__:
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continue
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val = found[key].__dict__[key]
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if (
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isinstance(val, interfaces.InspectionAttr)
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and val.is_attribute
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):
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yield key, val
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def _get_class_attr_mro(self, key, default=None):
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"""return an attribute on the class without tripping it."""
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for supercls in self.class_.__mro__:
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if key in supercls.__dict__:
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return supercls.__dict__[key]
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else:
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return default
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def _attr_has_impl(self, key):
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"""Return True if the given attribute is fully initialized.
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i.e. has an impl.
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"""
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return key in self and self[key].impl is not None
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def _subclass_manager(self, cls):
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"""Create a new ClassManager for a subclass of this ClassManager's
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class.
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This is called automatically when attributes are instrumented so that
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the attributes can be propagated to subclasses against their own
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class-local manager, without the need for mappers etc. to have already
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pre-configured managers for the full class hierarchy. Mappers
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can post-configure the auto-generated ClassManager when needed.
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"""
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return register_class(cls, finalize=False)
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def _instrument_init(self):
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self.new_init = _generate_init(self.class_, self, self.original_init)
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self.install_member("__init__", self.new_init)
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@util.memoized_property
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def _state_constructor(self):
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self.dispatch.first_init(self, self.class_)
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return state.InstanceState
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def manage(self):
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"""Mark this instance as the manager for its class."""
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setattr(self.class_, self.MANAGER_ATTR, self)
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@util.hybridmethod
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def manager_getter(self):
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return _default_manager_getter
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@util.hybridmethod
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def state_getter(self):
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"""Return a (instance) -> InstanceState callable.
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"state getter" callables should raise either KeyError or
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AttributeError if no InstanceState could be found for the
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instance.
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"""
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return _default_state_getter
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@util.hybridmethod
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def dict_getter(self):
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return _default_dict_getter
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def instrument_attribute(self, key, inst, propagated=False):
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if propagated:
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if key in self.local_attrs:
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return # don't override local attr with inherited attr
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else:
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self.local_attrs[key] = inst
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self.install_descriptor(key, inst)
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self._reset_memoizations()
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self[key] = inst
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for cls in self.class_.__subclasses__():
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manager = self._subclass_manager(cls)
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manager.instrument_attribute(key, inst, True)
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def subclass_managers(self, recursive):
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for cls in self.class_.__subclasses__():
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mgr = manager_of_class(cls)
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if mgr is not None and mgr is not self:
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yield mgr
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if recursive:
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for m in mgr.subclass_managers(True):
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yield m
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def post_configure_attribute(self, key):
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_instrumentation_factory.dispatch.attribute_instrument(
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self.class_, key, self[key]
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)
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def uninstrument_attribute(self, key, propagated=False):
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if key not in self:
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return
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if propagated:
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if key in self.local_attrs:
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return # don't get rid of local attr
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else:
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del self.local_attrs[key]
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self.uninstall_descriptor(key)
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self._reset_memoizations()
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del self[key]
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for cls in self.class_.__subclasses__():
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manager = manager_of_class(cls)
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if manager:
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manager.uninstrument_attribute(key, True)
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def unregister(self):
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"""remove all instrumentation established by this ClassManager."""
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for key in list(self.originals):
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self.uninstall_member(key)
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self.mapper = self.dispatch = self.new_init = None
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self.info.clear()
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for key in list(self):
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if key in self.local_attrs:
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self.uninstrument_attribute(key)
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if self.MANAGER_ATTR in self.class_.__dict__:
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delattr(self.class_, self.MANAGER_ATTR)
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def install_descriptor(self, key, inst):
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if key in (self.STATE_ATTR, self.MANAGER_ATTR):
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raise KeyError(
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"%r: requested attribute name conflicts with "
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"instrumentation attribute of the same name." % key
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)
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setattr(self.class_, key, inst)
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def uninstall_descriptor(self, key):
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delattr(self.class_, key)
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def install_member(self, key, implementation):
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if key in (self.STATE_ATTR, self.MANAGER_ATTR):
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raise KeyError(
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"%r: requested attribute name conflicts with "
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"instrumentation attribute of the same name." % key
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)
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self.originals.setdefault(key, self.class_.__dict__.get(key, DEL_ATTR))
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setattr(self.class_, key, implementation)
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def uninstall_member(self, key):
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original = self.originals.pop(key, None)
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if original is not DEL_ATTR:
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setattr(self.class_, key, original)
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else:
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delattr(self.class_, key)
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def instrument_collection_class(self, key, collection_class):
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return collections.prepare_instrumentation(collection_class)
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def initialize_collection(self, key, state, factory):
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user_data = factory()
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adapter = collections.CollectionAdapter(
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self.get_impl(key), state, user_data
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)
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return adapter, user_data
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def is_instrumented(self, key, search=False):
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if search:
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return key in self
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else:
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return key in self.local_attrs
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def get_impl(self, key):
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return self[key].impl
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@property
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def attributes(self):
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return iter(self.values())
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# InstanceState management
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def new_instance(self, state=None):
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instance = self.class_.__new__(self.class_)
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if state is None:
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state = self._state_constructor(instance, self)
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self._state_setter(instance, state)
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return instance
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def setup_instance(self, instance, state=None):
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if state is None:
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state = self._state_constructor(instance, self)
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self._state_setter(instance, state)
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def teardown_instance(self, instance):
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delattr(instance, self.STATE_ATTR)
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def _serialize(self, state, state_dict):
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return _SerializeManager(state, state_dict)
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def _new_state_if_none(self, instance):
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"""Install a default InstanceState if none is present.
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A private convenience method used by the __init__ decorator.
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"""
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if hasattr(instance, self.STATE_ATTR):
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return False
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elif self.class_ is not instance.__class__ and self.is_mapped:
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# this will create a new ClassManager for the
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# subclass, without a mapper. This is likely a
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# user error situation but allow the object
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# to be constructed, so that it is usable
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# in a non-ORM context at least.
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return self._subclass_manager(
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instance.__class__
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)._new_state_if_none(instance)
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else:
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state = self._state_constructor(instance, self)
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self._state_setter(instance, state)
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return state
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def has_state(self, instance):
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return hasattr(instance, self.STATE_ATTR)
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def has_parent(self, state, key, optimistic=False):
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"""TODO"""
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return self.get_impl(key).hasparent(state, optimistic=optimistic)
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def __bool__(self):
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"""All ClassManagers are non-zero regardless of attribute state."""
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return True
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__nonzero__ = __bool__
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def __repr__(self):
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return "<%s of %r at %x>" % (
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self.__class__.__name__,
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self.class_,
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id(self),
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)
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class _SerializeManager(object):
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"""Provide serialization of a :class:`.ClassManager`.
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The :class:`.InstanceState` uses ``__init__()`` on serialize
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and ``__call__()`` on deserialize.
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"""
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def __init__(self, state, d):
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self.class_ = state.class_
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manager = state.manager
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manager.dispatch.pickle(state, d)
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def __call__(self, state, inst, state_dict):
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state.manager = manager = manager_of_class(self.class_)
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if manager is None:
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raise exc.UnmappedInstanceError(
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inst,
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"Cannot deserialize object of type %r - "
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"no mapper() has "
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"been configured for this class within the current "
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"Python process!" % self.class_,
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)
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elif manager.is_mapped and not manager.mapper.configured:
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manager.mapper._check_configure()
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# setup _sa_instance_state ahead of time so that
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# unpickle events can access the object normally.
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# see [ticket:2362]
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if inst is not None:
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manager.setup_instance(inst, state)
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manager.dispatch.unpickle(state, state_dict)
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class InstrumentationFactory(object):
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"""Factory for new ClassManager instances."""
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def create_manager_for_cls(self, class_):
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assert class_ is not None
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assert manager_of_class(class_) is None
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# give a more complicated subclass
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# a chance to do what it wants here
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manager, factory = self._locate_extended_factory(class_)
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if factory is None:
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factory = ClassManager
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manager = factory(class_)
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self._check_conflicts(class_, factory)
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manager.factory = factory
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return manager
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def _locate_extended_factory(self, class_):
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"""Overridden by a subclass to do an extended lookup."""
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return None, None
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def _check_conflicts(self, class_, factory):
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"""Overridden by a subclass to test for conflicting factories."""
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return
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def unregister(self, class_):
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manager = manager_of_class(class_)
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manager.unregister()
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self.dispatch.class_uninstrument(class_)
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# this attribute is replaced by sqlalchemy.ext.instrumentation
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# when imported.
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_instrumentation_factory = InstrumentationFactory()
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# these attributes are replaced by sqlalchemy.ext.instrumentation
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# when a non-standard InstrumentationManager class is first
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# used to instrument a class.
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instance_state = _default_state_getter = base.instance_state
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instance_dict = _default_dict_getter = base.instance_dict
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manager_of_class = _default_manager_getter = base.manager_of_class
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def register_class(
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class_,
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finalize=True,
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mapper=None,
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registry=None,
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declarative_scan=None,
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expired_attribute_loader=None,
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init_method=None,
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):
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|
"""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_)
|
|
manager._update_state(
|
|
mapper=mapper,
|
|
registry=registry,
|
|
declarative_scan=declarative_scan,
|
|
expired_attribute_loader=expired_attribute_loader,
|
|
init_method=init_method,
|
|
finalize=finalize,
|
|
)
|
|
|
|
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
|
|
)
|
|
|
|
|
|
def _generate_init(class_, class_manager, original_init):
|
|
"""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.
|
|
|
|
if original_init is None:
|
|
original_init = class_.__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
|
|
|
|
if util.py2k:
|
|
func = getattr(original_init, "im_func", original_init)
|
|
func_defaults = getattr(func, "func_defaults", None)
|
|
else:
|
|
func_defaults = getattr(original_init, "__defaults__", None)
|
|
func_kw_defaults = getattr(original_init, "__kwdefaults__", None)
|
|
|
|
env = locals().copy()
|
|
env["__name__"] = __name__
|
|
exec(func_text, env)
|
|
__init__ = env["__init__"]
|
|
__init__.__doc__ = original_init.__doc__
|
|
__init__._sa_original_init = original_init
|
|
|
|
if func_defaults:
|
|
__init__.__defaults__ = func_defaults
|
|
if not util.py2k and func_kw_defaults:
|
|
__init__.__kwdefaults__ = func_kw_defaults
|
|
|
|
return __init__
|