class Target(object):
dispatch = event.dispatcher(TargetEvents)
class TargetOne(object):
dispatch = event.dispatcher(TargetEventsOne)
class TargetTwo(object):
dispatch = event.dispatcher(TargetEventsTwo)
class InstrumentationRegistry(object):
"""Private instrumentation registration singleton.
All classes are routed through this registry
when first instrumented, however the InstrumentationRegistry
is not actually needed unless custom ClassManagers are in use.
"""
_manager_finders = weakref.WeakKeyDictionary()
_state_finders = util.WeakIdentityMapping()
_dict_finders = util.WeakIdentityMapping()
_extended = False
dispatch = event.dispatcher(events.InstrumentationEvents)
def create_manager_for_cls(self, class_, **kw):
assert class_ is not None
assert manager_of_class(class_) is None
for finder in instrumentation_finders:
factory = finder(class_)
if factory is not None:
break
else:
factory = ClassManager
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)))
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_lookup_strategy(self)
manager.factory = factory
self._manager_finders[class_] = manager.manager_getter()
self._state_finders[class_] = manager.state_getter()
self._dict_finders[class_] = manager.dict_getter()
self.dispatch.class_instrument(class_)
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 = 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 manager_of_class(self, cls):
# this is only called when alternate instrumentation
# has been established
if cls is None:
return None
try:
finder = self._manager_finders[cls]
except KeyError:
return None
else:
return finder(cls)
def state_of(self, instance):
# this is only called when alternate instrumentation
# has been established
if instance is None:
raise AttributeError("None has no persistent state.")
try:
return self._state_finders[instance.__class__](instance)
except KeyError:
raise AttributeError("%r is not instrumented" %
instance.__class__)
def dict_of(self, instance):
# this is only called when alternate instrumentation
# has been established
if instance is None:
raise AttributeError("None has no persistent state.")
try:
return self._dict_finders[instance.__class__](instance)
except KeyError:
raise AttributeError("%r is not instrumented" %
instance.__class__)
def unregister(self, class_):
if class_ in self._manager_finders:
manager = self.manager_of_class(class_)
self.dispatch.class_uninstrument(class_)
manager.unregister()
manager.dispose()
del self._manager_finders[class_]
del self._state_finders[class_]
del self._dict_finders[class_]
if ClassManager.MANAGER_ATTR in class_.__dict__:
delattr(class_, ClassManager.MANAGER_ATTR)
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__
def __init__(self, class_):
self.class_ = class_
self.factory = None # where we came from, for inheritance bookkeeping
self.info = {}
self.new_init = None
self.mutable_attributes = set()
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)
self.manage()
self._instrument_init()
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 _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 = _create_manager_for_cls(cls, _source=self)
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_)
if self.mutable_attributes:
return state.MutableAttrInstanceState
else:
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)
def manager_getter(self):
return attrgetter(self.MANAGER_ATTR)
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_registry.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]
if key in self.mutable_attributes:
self.mutable_attributes.remove(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 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)
def dict_getter(self):
return attrgetter('__dict__')
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 BaseTarget:
dispatch = event.dispatcher(TargetEvents)
class MyClassManager(instrumentation.ClassManager):
dispatch = event.dispatcher(MyEvents)
class TargetTwo:
dispatch = event.dispatcher(TargetEventsTwo)
class TargetOne:
dispatch = event.dispatcher(TargetEventsOne)
class T1:
dispatch = event.dispatcher(E1)
class QueryableAttribute(interfaces.PropComparator):
"""Base class for class-bound attributes. """
def __init__(self, class_, key, impl=None,
comparator=None, parententity=None):
self.class_ = class_
self.key = key
self.impl = impl
self.comparator = comparator
self.parententity = parententity
manager = manager_of_class(class_)
# manager is None in the case of AliasedClass
if manager:
# propagate existing event listeners from
# immediate superclass
for base in manager._bases:
if key in base:
self.dispatch._update(base[key].dispatch)
dispatch = event.dispatcher(events.AttributeEvents)
dispatch.dispatch_cls._active_history = False
@util.memoized_property
def _supports_population(self):
return self.impl.supports_population
def get_history(self, instance, passive=PASSIVE_OFF):
return self.impl.get_history(instance_state(instance),
instance_dict(instance), passive)
def __selectable__(self):
# TODO: conditionally attach this method based on clause_element ?
return self
def __clause_element__(self):
return self.comparator.__clause_element__()
def label(self, name):
return self.__clause_element__().label(name)
def operate(self, op, *other, **kwargs):
return op(self.comparator, *other, **kwargs)
def reverse_operate(self, op, other, **kwargs):
return op(other, self.comparator, **kwargs)
def hasparent(self, state, optimistic=False):
return self.impl.hasparent(state, optimistic=optimistic)
def __getattr__(self, key):
try:
return getattr(self.comparator, key)
except AttributeError:
raise AttributeError(
'Neither %r object nor %r object has an attribute %r' % (
type(self).__name__,
type(self.comparator).__name__,
key)
)
def __str__(self):
return "%s.%s" % (self.class_.__name__, self.key)
@util.memoized_property
def property(self):
return self.comparator.property
class Pool(log.Identified):
"""Abstract base class for connection pools."""
def __init__(self,
creator, recycle=-1, echo=None,
use_threadlocal=False,
logging_name=None,
reset_on_return=True,
listeners=None,
events=None,
_dispatch=None):
"""
Construct a Pool.
:param creator: a callable function that returns a DB-API
connection object. The function will be called with
parameters.
:param recycle: If set to non -1, number of seconds between
connection recycling, which means upon checkout, if this
timeout is surpassed the connection will be closed and
replaced with a newly opened connection. Defaults to -1.
:param logging_name: String identifier which will be used within
the "name" field of logging records generated within the
"sqlalchemy.pool" logger. Defaults to a hexstring of the object's
id.
:param echo: If True, connections being pulled and retrieved
from the pool will be logged to the standard output, as well
as pool sizing information. Echoing can also be achieved by
enabling logging for the "sqlalchemy.pool"
namespace. Defaults to False.
:param use_threadlocal: If set to True, repeated calls to
:meth:`connect` within the same application thread will be
guaranteed to return the same connection object, if one has
already been retrieved from the pool and has not been
returned yet. Offers a slight performance advantage at the
cost of individual transactions by default. The
:meth:`unique_connection` method is provided to bypass the
threadlocal behavior installed into :meth:`connect`.
:param reset_on_return: If true, reset the database state of
connections returned to the pool. This is typically a
ROLLBACK to release locks and transaction resources.
Disable at your own peril. Defaults to True.
:param events: a list of 2-tuples, each of the form
``(callable, target)`` which will be passed to event.listen()
upon construction. Provided here so that event listeners
can be assigned via ``create_engine`` before dialect-level
listeners are applied.
:param listeners: Deprecated. A list of
:class:`~sqlalchemy.interfaces.PoolListener`-like objects or
dictionaries of callables that receive events when DB-API
connections are created, checked out and checked in to the
pool. This has been superseded by
:func:`~sqlalchemy.event.listen`.
"""
if logging_name:
self.logging_name = self._orig_logging_name = logging_name
else:
self._orig_logging_name = None
log.instance_logger(self, echoflag=echo)
self._threadconns = threading.local()
self._creator = creator
self._recycle = recycle
self._use_threadlocal = use_threadlocal
if reset_on_return in ('rollback', True, reset_rollback):
self._reset_on_return = reset_rollback
elif reset_on_return in (None, False, reset_none):
self._reset_on_return = reset_none
elif reset_on_return in ('commit', reset_commit):
self._reset_on_return = reset_commit
else:
raise exc.ArgumentError(
"Invalid value for 'reset_on_return': %r"
% reset_on_return)
self.echo = echo
if _dispatch:
self.dispatch._update(_dispatch, only_propagate=False)
if events:
for fn, target in events:
event.listen(self, target, fn)
if listeners:
util.warn_deprecated(
"The 'listeners' argument to Pool (and "
"create_engine()) is deprecated. Use event.listen().")
for l in listeners:
self.add_listener(l)
dispatch = event.dispatcher(events.PoolEvents)
@util.deprecated(2.7, "Pool.add_listener is deprecated. Use event.listen()")
def add_listener(self, listener):
"""Add a :class:`.PoolListener`-like object to this pool.
``listener`` may be an object that implements some or all of
PoolListener, or a dictionary of callables containing implementations
of some or all of the named methods in PoolListener.
"""
interfaces.PoolListener._adapt_listener(self, listener)
def unique_connection(self):
"""Produce a DBAPI connection that is not referenced by any
thread-local context.
This method is different from :meth:`.Pool.connect` only if the
``use_threadlocal`` flag has been set to ``True``.
"""
return _ConnectionFairy(self).checkout()
def _create_connection(self):
"""Called by subclasses to create a new ConnectionRecord."""
return _ConnectionRecord(self)
def recreate(self):
"""Return a new :class:`.Pool`, of the same class as this one
and configured with identical creation arguments.
This method is used in conjunection with :meth:`dispose`
to close out an entire :class:`.Pool` and create a new one in
its place.
"""
raise NotImplementedError()
def dispose(self):
"""Dispose of this pool.
This method leaves the possibility of checked-out connections
remaining open, as it only affects connections that are
idle in the pool.
See also the :meth:`Pool.recreate` method.
"""
raise NotImplementedError()
def _replace(self):
"""Dispose + recreate this pool.
Subclasses may employ special logic to
move threads waiting on this pool to the
new one.
"""
self.dispose()
return self.recreate()
def connect(self):
"""Return a DBAPI connection from the pool.
The connection is instrumented such that when its
``close()`` method is called, the connection will be returned to
the pool.
"""
if not self._use_threadlocal:
return _ConnectionFairy(self).checkout()
try:
rec = self._threadconns.current()
if rec:
return rec.checkout()
except AttributeError:
pass
agent = _ConnectionFairy(self)
self._threadconns.current = weakref.ref(agent)
return agent.checkout()
def _return_conn(self, record):
"""Given a _ConnectionRecord, return it to the :class:`.Pool`.
This method is called when an instrumented DBAPI connection
has its ``close()`` method called.
"""
if self._use_threadlocal:
try:
del self._threadconns.current
except AttributeError:
pass
self._do_return_conn(record)
def _do_get(self):
"""Implementation for :meth:`get`, supplied by subclasses."""
raise NotImplementedError()
def _do_return_conn(self, conn):
"""Implementation for :meth:`return_conn`, supplied by subclasses."""
raise NotImplementedError()
def status(self):
raise NotImplementedError()
