diff options
Diffstat (limited to 'lib/sqlalchemy/event')
| -rw-r--r-- | lib/sqlalchemy/event/__init__.py | 17 | ||||
| -rw-r--r-- | lib/sqlalchemy/event/api.py | 219 | ||||
| -rw-r--r-- | lib/sqlalchemy/event/attr.py | 468 | ||||
| -rw-r--r-- | lib/sqlalchemy/event/base.py | 345 | ||||
| -rw-r--r-- | lib/sqlalchemy/event/legacy.py | 185 | ||||
| -rw-r--r-- | lib/sqlalchemy/event/registry.py | 297 |
6 files changed, 1531 insertions, 0 deletions
diff --git a/lib/sqlalchemy/event/__init__.py b/lib/sqlalchemy/event/__init__.py new file mode 100644 index 0000000..a89bea8 --- /dev/null +++ b/lib/sqlalchemy/event/__init__.py @@ -0,0 +1,17 @@ +# event/__init__.py +# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors +# <see AUTHORS file> +# +# This module is part of SQLAlchemy and is released under +# the MIT License: https://www.opensource.org/licenses/mit-license.php + +from .api import CANCEL +from .api import contains +from .api import listen +from .api import listens_for +from .api import NO_RETVAL +from .api import remove +from .attr import RefCollection +from .base import dispatcher +from .base import Events +from .legacy import _legacy_signature diff --git a/lib/sqlalchemy/event/api.py b/lib/sqlalchemy/event/api.py new file mode 100644 index 0000000..ce44f57 --- /dev/null +++ b/lib/sqlalchemy/event/api.py @@ -0,0 +1,219 @@ +# event/api.py +# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors +# <see AUTHORS file> +# +# This module is part of SQLAlchemy and is released under +# the MIT License: https://www.opensource.org/licenses/mit-license.php + +"""Public API functions for the event system. + +""" +from __future__ import absolute_import + +from .base import _registrars +from .registry import _EventKey +from .. import exc +from .. import util + + +CANCEL = util.symbol("CANCEL") +NO_RETVAL = util.symbol("NO_RETVAL") + + +def _event_key(target, identifier, fn): + for evt_cls in _registrars[identifier]: + tgt = evt_cls._accept_with(target) + if tgt is not None: + return _EventKey(target, identifier, fn, tgt) + else: + raise exc.InvalidRequestError( + "No such event '%s' for target '%s'" % (identifier, target) + ) + + +def listen(target, identifier, fn, *args, **kw): + """Register a listener function for the given target. + + The :func:`.listen` function is part of the primary interface for the + SQLAlchemy event system, documented at :ref:`event_toplevel`. + + e.g.:: + + from sqlalchemy import event + from sqlalchemy.schema import UniqueConstraint + + def unique_constraint_name(const, table): + const.name = "uq_%s_%s" % ( + table.name, + list(const.columns)[0].name + ) + event.listen( + UniqueConstraint, + "after_parent_attach", + unique_constraint_name) + + :param bool insert: The default behavior for event handlers is to append + the decorated user defined function to an internal list of registered + event listeners upon discovery. If a user registers a function with + ``insert=True``, SQLAlchemy will insert (prepend) the function to the + internal list upon discovery. This feature is not typically used or + recommended by the SQLAlchemy maintainers, but is provided to ensure + certain user defined functions can run before others, such as when + :ref:`Changing the sql_mode in MySQL <mysql_sql_mode>`. + + :param bool named: When using named argument passing, the names listed in + the function argument specification will be used as keys in the + dictionary. + See :ref:`event_named_argument_styles`. + + :param bool once: Private/Internal API usage. Deprecated. This parameter + would provide that an event function would run only once per given + target. It does not however imply automatic de-registration of the + listener function; associating an arbitrarily high number of listeners + without explicitly removing them will cause memory to grow unbounded even + if ``once=True`` is specified. + + :param bool propagate: The ``propagate`` kwarg is available when working + with ORM instrumentation and mapping events. + See :class:`_ormevent.MapperEvents` and + :meth:`_ormevent.MapperEvents.before_mapper_configured` for examples. + + :param bool retval: This flag applies only to specific event listeners, + each of which includes documentation explaining when it should be used. + By default, no listener ever requires a return value. + However, some listeners do support special behaviors for return values, + and include in their documentation that the ``retval=True`` flag is + necessary for a return value to be processed. + + Event listener suites that make use of :paramref:`_event.listen.retval` + include :class:`_events.ConnectionEvents` and + :class:`_ormevent.AttributeEvents`. + + .. note:: + + The :func:`.listen` function cannot be called at the same time + that the target event is being run. This has implications + for thread safety, and also means an event cannot be added + from inside the listener function for itself. The list of + events to be run are present inside of a mutable collection + that can't be changed during iteration. + + Event registration and removal is not intended to be a "high + velocity" operation; it is a configurational operation. For + systems that need to quickly associate and deassociate with + events at high scale, use a mutable structure that is handled + from inside of a single listener. + + .. seealso:: + + :func:`.listens_for` + + :func:`.remove` + + """ + + _event_key(target, identifier, fn).listen(*args, **kw) + + +def listens_for(target, identifier, *args, **kw): + """Decorate a function as a listener for the given target + identifier. + + The :func:`.listens_for` decorator is part of the primary interface for the + SQLAlchemy event system, documented at :ref:`event_toplevel`. + + This function generally shares the same kwargs as :func:`.listens`. + + e.g.:: + + from sqlalchemy import event + from sqlalchemy.schema import UniqueConstraint + + @event.listens_for(UniqueConstraint, "after_parent_attach") + def unique_constraint_name(const, table): + const.name = "uq_%s_%s" % ( + table.name, + list(const.columns)[0].name + ) + + A given function can also be invoked for only the first invocation + of the event using the ``once`` argument:: + + @event.listens_for(Mapper, "before_configure", once=True) + def on_config(): + do_config() + + + .. warning:: The ``once`` argument does not imply automatic de-registration + of the listener function after it has been invoked a first time; a + listener entry will remain associated with the target object. + Associating an arbitrarily high number of listeners without explicitly + removing them will cause memory to grow unbounded even if ``once=True`` + is specified. + + .. seealso:: + + :func:`.listen` - general description of event listening + + """ + + def decorate(fn): + listen(target, identifier, fn, *args, **kw) + return fn + + return decorate + + +def remove(target, identifier, fn): + """Remove an event listener. + + The arguments here should match exactly those which were sent to + :func:`.listen`; all the event registration which proceeded as a result + of this call will be reverted by calling :func:`.remove` with the same + arguments. + + e.g.:: + + # if a function was registered like this... + @event.listens_for(SomeMappedClass, "before_insert", propagate=True) + def my_listener_function(*arg): + pass + + # ... it's removed like this + event.remove(SomeMappedClass, "before_insert", my_listener_function) + + Above, the listener function associated with ``SomeMappedClass`` was also + propagated to subclasses of ``SomeMappedClass``; the :func:`.remove` + function will revert all of these operations. + + .. note:: + + The :func:`.remove` function cannot be called at the same time + that the target event is being run. This has implications + for thread safety, and also means an event cannot be removed + from inside the listener function for itself. The list of + events to be run are present inside of a mutable collection + that can't be changed during iteration. + + Event registration and removal is not intended to be a "high + velocity" operation; it is a configurational operation. For + systems that need to quickly associate and deassociate with + events at high scale, use a mutable structure that is handled + from inside of a single listener. + + .. versionchanged:: 1.0.0 - a ``collections.deque()`` object is now + used as the container for the list of events, which explicitly + disallows collection mutation while the collection is being + iterated. + + .. seealso:: + + :func:`.listen` + + """ + _event_key(target, identifier, fn).remove() + + +def contains(target, identifier, fn): + """Return True if the given target/ident/fn is set up to listen.""" + + return _event_key(target, identifier, fn).contains() diff --git a/lib/sqlalchemy/event/attr.py b/lib/sqlalchemy/event/attr.py new file mode 100644 index 0000000..0d16165 --- /dev/null +++ b/lib/sqlalchemy/event/attr.py @@ -0,0 +1,468 @@ +# event/attr.py +# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors +# <see AUTHORS file> +# +# This module is part of SQLAlchemy and is released under +# the MIT License: https://www.opensource.org/licenses/mit-license.php + +"""Attribute implementation for _Dispatch classes. + +The various listener targets for a particular event class are represented +as attributes, which refer to collections of listeners to be fired off. +These collections can exist at the class level as well as at the instance +level. An event is fired off using code like this:: + + some_object.dispatch.first_connect(arg1, arg2) + +Above, ``some_object.dispatch`` would be an instance of ``_Dispatch`` and +``first_connect`` is typically an instance of ``_ListenerCollection`` +if event listeners are present, or ``_EmptyListener`` if none are present. + +The attribute mechanics here spend effort trying to ensure listener functions +are available with a minimum of function call overhead, that unnecessary +objects aren't created (i.e. many empty per-instance listener collections), +as well as that everything is garbage collectable when owning references are +lost. Other features such as "propagation" of listener functions across +many ``_Dispatch`` instances, "joining" of multiple ``_Dispatch`` instances, +as well as support for subclass propagation (e.g. events assigned to +``Pool`` vs. ``QueuePool``) are all implemented here. + +""" + +from __future__ import absolute_import +from __future__ import with_statement + +import collections +from itertools import chain +import weakref + +from . import legacy +from . import registry +from .. import exc +from .. import util +from ..util import threading +from ..util.concurrency import AsyncAdaptedLock + + +class RefCollection(util.MemoizedSlots): + __slots__ = ("ref",) + + def _memoized_attr_ref(self): + return weakref.ref(self, registry._collection_gced) + + +class _empty_collection(object): + def append(self, element): + pass + + def extend(self, other): + pass + + def remove(self, element): + pass + + def __iter__(self): + return iter([]) + + def clear(self): + pass + + +class _ClsLevelDispatch(RefCollection): + """Class-level events on :class:`._Dispatch` classes.""" + + __slots__ = ( + "clsname", + "name", + "arg_names", + "has_kw", + "legacy_signatures", + "_clslevel", + "__weakref__", + ) + + def __init__(self, parent_dispatch_cls, fn): + self.name = fn.__name__ + self.clsname = parent_dispatch_cls.__name__ + argspec = util.inspect_getfullargspec(fn) + self.arg_names = argspec.args[1:] + self.has_kw = bool(argspec.varkw) + self.legacy_signatures = list( + reversed( + sorted( + getattr(fn, "_legacy_signatures", []), key=lambda s: s[0] + ) + ) + ) + fn.__doc__ = legacy._augment_fn_docs(self, parent_dispatch_cls, fn) + + self._clslevel = weakref.WeakKeyDictionary() + + def _adjust_fn_spec(self, fn, named): + if named: + fn = self._wrap_fn_for_kw(fn) + if self.legacy_signatures: + try: + argspec = util.get_callable_argspec(fn, no_self=True) + except TypeError: + pass + else: + fn = legacy._wrap_fn_for_legacy(self, fn, argspec) + return fn + + def _wrap_fn_for_kw(self, fn): + def wrap_kw(*args, **kw): + argdict = dict(zip(self.arg_names, args)) + argdict.update(kw) + return fn(**argdict) + + return wrap_kw + + def insert(self, event_key, propagate): + target = event_key.dispatch_target + assert isinstance( + target, type + ), "Class-level Event targets must be classes." + if not getattr(target, "_sa_propagate_class_events", True): + raise exc.InvalidRequestError( + "Can't assign an event directly to the %s class" % target + ) + + for cls in util.walk_subclasses(target): + if cls is not target and cls not in self._clslevel: + self.update_subclass(cls) + else: + if cls not in self._clslevel: + self._assign_cls_collection(cls) + self._clslevel[cls].appendleft(event_key._listen_fn) + registry._stored_in_collection(event_key, self) + + def append(self, event_key, propagate): + target = event_key.dispatch_target + assert isinstance( + target, type + ), "Class-level Event targets must be classes." + if not getattr(target, "_sa_propagate_class_events", True): + raise exc.InvalidRequestError( + "Can't assign an event directly to the %s class" % target + ) + for cls in util.walk_subclasses(target): + if cls is not target and cls not in self._clslevel: + self.update_subclass(cls) + else: + if cls not in self._clslevel: + self._assign_cls_collection(cls) + self._clslevel[cls].append(event_key._listen_fn) + registry._stored_in_collection(event_key, self) + + def _assign_cls_collection(self, target): + if getattr(target, "_sa_propagate_class_events", True): + self._clslevel[target] = collections.deque() + else: + self._clslevel[target] = _empty_collection() + + def update_subclass(self, target): + if target not in self._clslevel: + self._assign_cls_collection(target) + clslevel = self._clslevel[target] + for cls in target.__mro__[1:]: + if cls in self._clslevel: + clslevel.extend( + [fn for fn in self._clslevel[cls] if fn not in clslevel] + ) + + def remove(self, event_key): + target = event_key.dispatch_target + for cls in util.walk_subclasses(target): + if cls in self._clslevel: + self._clslevel[cls].remove(event_key._listen_fn) + registry._removed_from_collection(event_key, self) + + def clear(self): + """Clear all class level listeners""" + + to_clear = set() + for dispatcher in self._clslevel.values(): + to_clear.update(dispatcher) + dispatcher.clear() + registry._clear(self, to_clear) + + def for_modify(self, obj): + """Return an event collection which can be modified. + + For _ClsLevelDispatch at the class level of + a dispatcher, this returns self. + + """ + return self + + +class _InstanceLevelDispatch(RefCollection): + __slots__ = () + + def _adjust_fn_spec(self, fn, named): + return self.parent._adjust_fn_spec(fn, named) + + +class _EmptyListener(_InstanceLevelDispatch): + """Serves as a proxy interface to the events + served by a _ClsLevelDispatch, when there are no + instance-level events present. + + Is replaced by _ListenerCollection when instance-level + events are added. + + """ + + propagate = frozenset() + listeners = () + + __slots__ = "parent", "parent_listeners", "name" + + def __init__(self, parent, target_cls): + if target_cls not in parent._clslevel: + parent.update_subclass(target_cls) + self.parent = parent # _ClsLevelDispatch + self.parent_listeners = parent._clslevel[target_cls] + self.name = parent.name + + def for_modify(self, obj): + """Return an event collection which can be modified. + + For _EmptyListener at the instance level of + a dispatcher, this generates a new + _ListenerCollection, applies it to the instance, + and returns it. + + """ + result = _ListenerCollection(self.parent, obj._instance_cls) + if getattr(obj, self.name) is self: + setattr(obj, self.name, result) + else: + assert isinstance(getattr(obj, self.name), _JoinedListener) + return result + + def _needs_modify(self, *args, **kw): + raise NotImplementedError("need to call for_modify()") + + exec_once = ( + exec_once_unless_exception + ) = insert = append = remove = clear = _needs_modify + + def __call__(self, *args, **kw): + """Execute this event.""" + + for fn in self.parent_listeners: + fn(*args, **kw) + + def __len__(self): + return len(self.parent_listeners) + + def __iter__(self): + return iter(self.parent_listeners) + + def __bool__(self): + return bool(self.parent_listeners) + + __nonzero__ = __bool__ + + +class _CompoundListener(_InstanceLevelDispatch): + __slots__ = "_exec_once_mutex", "_exec_once", "_exec_w_sync_once" + + def _set_asyncio(self): + self._exec_once_mutex = AsyncAdaptedLock() + + def _memoized_attr__exec_once_mutex(self): + return threading.Lock() + + def _exec_once_impl(self, retry_on_exception, *args, **kw): + with self._exec_once_mutex: + if not self._exec_once: + try: + self(*args, **kw) + exception = False + except: + exception = True + raise + finally: + if not exception or not retry_on_exception: + self._exec_once = True + + def exec_once(self, *args, **kw): + """Execute this event, but only if it has not been + executed already for this collection.""" + + if not self._exec_once: + self._exec_once_impl(False, *args, **kw) + + def exec_once_unless_exception(self, *args, **kw): + """Execute this event, but only if it has not been + executed already for this collection, or was called + by a previous exec_once_unless_exception call and + raised an exception. + + If exec_once was already called, then this method will never run + the callable regardless of whether it raised or not. + + .. versionadded:: 1.3.8 + + """ + if not self._exec_once: + self._exec_once_impl(True, *args, **kw) + + def _exec_w_sync_on_first_run(self, *args, **kw): + """Execute this event, and use a mutex if it has not been + executed already for this collection, or was called + by a previous _exec_w_sync_on_first_run call and + raised an exception. + + If _exec_w_sync_on_first_run was already called and didn't raise an + exception, then a mutex is not used. + + .. versionadded:: 1.4.11 + + """ + if not self._exec_w_sync_once: + with self._exec_once_mutex: + try: + self(*args, **kw) + except: + raise + else: + self._exec_w_sync_once = True + else: + self(*args, **kw) + + def __call__(self, *args, **kw): + """Execute this event.""" + + for fn in self.parent_listeners: + fn(*args, **kw) + for fn in self.listeners: + fn(*args, **kw) + + def __len__(self): + return len(self.parent_listeners) + len(self.listeners) + + def __iter__(self): + return chain(self.parent_listeners, self.listeners) + + def __bool__(self): + return bool(self.listeners or self.parent_listeners) + + __nonzero__ = __bool__ + + +class _ListenerCollection(_CompoundListener): + """Instance-level attributes on instances of :class:`._Dispatch`. + + Represents a collection of listeners. + + As of 0.7.9, _ListenerCollection is only first + created via the _EmptyListener.for_modify() method. + + """ + + __slots__ = ( + "parent_listeners", + "parent", + "name", + "listeners", + "propagate", + "__weakref__", + ) + + def __init__(self, parent, target_cls): + if target_cls not in parent._clslevel: + parent.update_subclass(target_cls) + self._exec_once = False + self._exec_w_sync_once = False + self.parent_listeners = parent._clslevel[target_cls] + self.parent = parent + self.name = parent.name + self.listeners = collections.deque() + self.propagate = set() + + def for_modify(self, obj): + """Return an event collection which can be modified. + + For _ListenerCollection at the instance level of + a dispatcher, this returns self. + + """ + return self + + def _update(self, other, only_propagate=True): + """Populate from the listeners in another :class:`_Dispatch` + object.""" + + existing_listeners = self.listeners + existing_listener_set = set(existing_listeners) + self.propagate.update(other.propagate) + other_listeners = [ + l + for l in other.listeners + if l not in existing_listener_set + and not only_propagate + or l in self.propagate + ] + + existing_listeners.extend(other_listeners) + + to_associate = other.propagate.union(other_listeners) + registry._stored_in_collection_multi(self, other, to_associate) + + def insert(self, event_key, propagate): + if event_key.prepend_to_list(self, self.listeners): + if propagate: + self.propagate.add(event_key._listen_fn) + + def append(self, event_key, propagate): + if event_key.append_to_list(self, self.listeners): + if propagate: + self.propagate.add(event_key._listen_fn) + + def remove(self, event_key): + self.listeners.remove(event_key._listen_fn) + self.propagate.discard(event_key._listen_fn) + registry._removed_from_collection(event_key, self) + + def clear(self): + registry._clear(self, self.listeners) + self.propagate.clear() + self.listeners.clear() + + +class _JoinedListener(_CompoundListener): + __slots__ = "parent", "name", "local", "parent_listeners" + + def __init__(self, parent, name, local): + self._exec_once = False + self.parent = parent + self.name = name + self.local = local + self.parent_listeners = self.local + + @property + def listeners(self): + return getattr(self.parent, self.name) + + def _adjust_fn_spec(self, fn, named): + return self.local._adjust_fn_spec(fn, named) + + def for_modify(self, obj): + self.local = self.parent_listeners = self.local.for_modify(obj) + return self + + def insert(self, event_key, propagate): + self.local.insert(event_key, propagate) + + def append(self, event_key, propagate): + self.local.append(event_key, propagate) + + def remove(self, event_key): + self.local.remove(event_key) + + def clear(self): + raise NotImplementedError() diff --git a/lib/sqlalchemy/event/base.py b/lib/sqlalchemy/event/base.py new file mode 100644 index 0000000..510e16b --- /dev/null +++ b/lib/sqlalchemy/event/base.py @@ -0,0 +1,345 @@ +# event/base.py +# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors +# <see AUTHORS file> +# +# This module is part of SQLAlchemy and is released under +# the MIT License: https://www.opensource.org/licenses/mit-license.php + +"""Base implementation classes. + +The public-facing ``Events`` serves as the base class for an event interface; +its public attributes represent different kinds of events. These attributes +are mirrored onto a ``_Dispatch`` class, which serves as a container for +collections of listener functions. These collections are represented both +at the class level of a particular ``_Dispatch`` class as well as within +instances of ``_Dispatch``. + +""" +from __future__ import absolute_import + +import weakref + +from .attr import _ClsLevelDispatch +from .attr import _EmptyListener +from .attr import _JoinedListener +from .. import util + + +_registrars = util.defaultdict(list) + + +def _is_event_name(name): + # _sa_event prefix is special to support internal-only event names. + # most event names are just plain method names that aren't + # underscored. + + return ( + not name.startswith("_") and name != "dispatch" + ) or name.startswith("_sa_event") + + +class _UnpickleDispatch(object): + """Serializable callable that re-generates an instance of + :class:`_Dispatch` given a particular :class:`.Events` subclass. + + """ + + def __call__(self, _instance_cls): + for cls in _instance_cls.__mro__: + if "dispatch" in cls.__dict__: + return cls.__dict__["dispatch"].dispatch._for_class( + _instance_cls + ) + else: + raise AttributeError("No class with a 'dispatch' member present.") + + +class _Dispatch(object): + """Mirror the event listening definitions of an Events class with + listener collections. + + Classes which define a "dispatch" member will return a + non-instantiated :class:`._Dispatch` subclass when the member + is accessed at the class level. When the "dispatch" member is + accessed at the instance level of its owner, an instance + of the :class:`._Dispatch` class is returned. + + A :class:`._Dispatch` class is generated for each :class:`.Events` + class defined, by the :func:`._create_dispatcher_class` function. + The original :class:`.Events` classes remain untouched. + This decouples the construction of :class:`.Events` subclasses from + the implementation used by the event internals, and allows + inspecting tools like Sphinx to work in an unsurprising + way against the public API. + + """ + + # In one ORM edge case, an attribute is added to _Dispatch, + # so __dict__ is used in just that case and potentially others. + __slots__ = "_parent", "_instance_cls", "__dict__", "_empty_listeners" + + _empty_listener_reg = weakref.WeakKeyDictionary() + + def __init__(self, parent, instance_cls=None): + self._parent = parent + self._instance_cls = instance_cls + + if instance_cls: + try: + self._empty_listeners = self._empty_listener_reg[instance_cls] + except KeyError: + self._empty_listeners = self._empty_listener_reg[ + instance_cls + ] = { + ls.name: _EmptyListener(ls, instance_cls) + for ls in parent._event_descriptors + } + else: + self._empty_listeners = {} + + def __getattr__(self, name): + # Assign EmptyListeners as attributes on demand + # to reduce startup time for new dispatch objects. + try: + ls = self._empty_listeners[name] + except KeyError: + raise AttributeError(name) + else: + setattr(self, ls.name, ls) + return ls + + @property + def _event_descriptors(self): + for k in self._event_names: + # Yield _ClsLevelDispatch related + # to relevant event name. + yield getattr(self, k) + + @property + def _listen(self): + return self._events._listen + + def _for_class(self, instance_cls): + return self.__class__(self, instance_cls) + + def _for_instance(self, instance): + instance_cls = instance.__class__ + return self._for_class(instance_cls) + + def _join(self, other): + """Create a 'join' of this :class:`._Dispatch` and another. + + This new dispatcher will dispatch events to both + :class:`._Dispatch` objects. + + """ + if "_joined_dispatch_cls" not in self.__class__.__dict__: + cls = type( + "Joined%s" % self.__class__.__name__, + (_JoinedDispatcher,), + {"__slots__": self._event_names}, + ) + + self.__class__._joined_dispatch_cls = cls + return self._joined_dispatch_cls(self, other) + + def __reduce__(self): + return _UnpickleDispatch(), (self._instance_cls,) + + def _update(self, other, only_propagate=True): + """Populate from the listeners in another :class:`_Dispatch` + object.""" + for ls in other._event_descriptors: + if isinstance(ls, _EmptyListener): + continue + getattr(self, ls.name).for_modify(self)._update( + ls, only_propagate=only_propagate + ) + + def _clear(self): + for ls in self._event_descriptors: + ls.for_modify(self).clear() + + +class _EventMeta(type): + """Intercept new Event subclasses and create + associated _Dispatch classes.""" + + def __init__(cls, classname, bases, dict_): + _create_dispatcher_class(cls, classname, bases, dict_) + type.__init__(cls, classname, bases, dict_) + + +def _create_dispatcher_class(cls, classname, bases, dict_): + """Create a :class:`._Dispatch` class corresponding to an + :class:`.Events` class.""" + + # there's all kinds of ways to do this, + # i.e. make a Dispatch class that shares the '_listen' method + # of the Event class, this is the straight monkeypatch. + if hasattr(cls, "dispatch"): + dispatch_base = cls.dispatch.__class__ + else: + dispatch_base = _Dispatch + + event_names = [k for k in dict_ if _is_event_name(k)] + dispatch_cls = type( + "%sDispatch" % classname, (dispatch_base,), {"__slots__": event_names} + ) + + dispatch_cls._event_names = event_names + + dispatch_inst = cls._set_dispatch(cls, dispatch_cls) + for k in dispatch_cls._event_names: + setattr(dispatch_inst, k, _ClsLevelDispatch(cls, dict_[k])) + _registrars[k].append(cls) + + for super_ in dispatch_cls.__bases__: + if issubclass(super_, _Dispatch) and super_ is not _Dispatch: + for ls in super_._events.dispatch._event_descriptors: + setattr(dispatch_inst, ls.name, ls) + dispatch_cls._event_names.append(ls.name) + + if getattr(cls, "_dispatch_target", None): + the_cls = cls._dispatch_target + if ( + hasattr(the_cls, "__slots__") + and "_slots_dispatch" in the_cls.__slots__ + ): + cls._dispatch_target.dispatch = slots_dispatcher(cls) + else: + cls._dispatch_target.dispatch = dispatcher(cls) + + +def _remove_dispatcher(cls): + for k in cls.dispatch._event_names: + _registrars[k].remove(cls) + if not _registrars[k]: + del _registrars[k] + + +class Events(util.with_metaclass(_EventMeta, object)): + """Define event listening functions for a particular target type.""" + + @staticmethod + def _set_dispatch(cls, dispatch_cls): + # This allows an Events subclass to define additional utility + # methods made available to the target via + # "self.dispatch._events.<utilitymethod>" + # @staticmethod to allow easy "super" calls while in a metaclass + # constructor. + cls.dispatch = dispatch_cls(None) + dispatch_cls._events = cls + return cls.dispatch + + @classmethod + def _accept_with(cls, target): + def dispatch_is(*types): + return all(isinstance(target.dispatch, t) for t in types) + + def dispatch_parent_is(t): + return isinstance(target.dispatch.parent, t) + + # Mapper, ClassManager, Session override this to + # also accept classes, scoped_sessions, sessionmakers, etc. + if hasattr(target, "dispatch"): + if ( + dispatch_is(cls.dispatch.__class__) + or dispatch_is(type, cls.dispatch.__class__) + or ( + dispatch_is(_JoinedDispatcher) + and dispatch_parent_is(cls.dispatch.__class__) + ) + ): + return target + + @classmethod + def _listen( + cls, + event_key, + propagate=False, + insert=False, + named=False, + asyncio=False, + ): + event_key.base_listen( + propagate=propagate, insert=insert, named=named, asyncio=asyncio + ) + + @classmethod + def _remove(cls, event_key): + event_key.remove() + + @classmethod + def _clear(cls): + cls.dispatch._clear() + + +class _JoinedDispatcher(object): + """Represent a connection between two _Dispatch objects.""" + + __slots__ = "local", "parent", "_instance_cls" + + def __init__(self, local, parent): + self.local = local + self.parent = parent + self._instance_cls = self.local._instance_cls + + def __getattr__(self, name): + # Assign _JoinedListeners as attributes on demand + # to reduce startup time for new dispatch objects. + ls = getattr(self.local, name) + jl = _JoinedListener(self.parent, ls.name, ls) + setattr(self, ls.name, jl) + return jl + + @property + def _listen(self): + return self.parent._listen + + @property + def _events(self): + return self.parent._events + + +class dispatcher(object): + """Descriptor used by target classes to + deliver the _Dispatch class at the class level + and produce new _Dispatch instances for target + instances. + + """ + + def __init__(self, events): + self.dispatch = events.dispatch + self.events = events + + def __get__(self, obj, cls): + if obj is None: + return self.dispatch + + disp = self.dispatch._for_instance(obj) + try: + obj.__dict__["dispatch"] = disp + except AttributeError as ae: + util.raise_( + TypeError( + "target %r doesn't have __dict__, should it be " + "defining _slots_dispatch?" % (obj,) + ), + replace_context=ae, + ) + return disp + + +class slots_dispatcher(dispatcher): + def __get__(self, obj, cls): + if obj is None: + return self.dispatch + + if hasattr(obj, "_slots_dispatch"): + return obj._slots_dispatch + + disp = self.dispatch._for_instance(obj) + obj._slots_dispatch = disp + return disp diff --git a/lib/sqlalchemy/event/legacy.py b/lib/sqlalchemy/event/legacy.py new file mode 100644 index 0000000..d9f6ce5 --- /dev/null +++ b/lib/sqlalchemy/event/legacy.py @@ -0,0 +1,185 @@ +# event/legacy.py +# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors +# <see AUTHORS file> +# +# This module is part of SQLAlchemy and is released under +# the MIT License: https://www.opensource.org/licenses/mit-license.php + +"""Routines to handle adaption of legacy call signatures, +generation of deprecation notes and docstrings. + +""" + +from .. import util + + +def _legacy_signature(since, argnames, converter=None): + def leg(fn): + if not hasattr(fn, "_legacy_signatures"): + fn._legacy_signatures = [] + fn._legacy_signatures.append((since, argnames, converter)) + return fn + + return leg + + +def _wrap_fn_for_legacy(dispatch_collection, fn, argspec): + for since, argnames, conv in dispatch_collection.legacy_signatures: + if argnames[-1] == "**kw": + has_kw = True + argnames = argnames[0:-1] + else: + has_kw = False + + if len(argnames) == len(argspec.args) and has_kw is bool( + argspec.varkw + ): + + formatted_def = "def %s(%s%s)" % ( + dispatch_collection.name, + ", ".join(dispatch_collection.arg_names), + ", **kw" if has_kw else "", + ) + warning_txt = ( + 'The argument signature for the "%s.%s" event listener ' + "has changed as of version %s, and conversion for " + "the old argument signature will be removed in a " + 'future release. The new signature is "%s"' + % ( + dispatch_collection.clsname, + dispatch_collection.name, + since, + formatted_def, + ) + ) + + if conv: + assert not has_kw + + def wrap_leg(*args): + util.warn_deprecated(warning_txt, version=since) + return fn(*conv(*args)) + + else: + + def wrap_leg(*args, **kw): + util.warn_deprecated(warning_txt, version=since) + argdict = dict(zip(dispatch_collection.arg_names, args)) + args = [argdict[name] for name in argnames] + if has_kw: + return fn(*args, **kw) + else: + return fn(*args) + + return wrap_leg + else: + return fn + + +def _indent(text, indent): + return "\n".join(indent + line for line in text.split("\n")) + + +def _standard_listen_example(dispatch_collection, sample_target, fn): + example_kw_arg = _indent( + "\n".join( + "%(arg)s = kw['%(arg)s']" % {"arg": arg} + for arg in dispatch_collection.arg_names[0:2] + ), + " ", + ) + if dispatch_collection.legacy_signatures: + current_since = max( + since + for since, args, conv in dispatch_collection.legacy_signatures + ) + else: + current_since = None + text = ( + "from sqlalchemy import event\n\n\n" + "@event.listens_for(%(sample_target)s, '%(event_name)s')\n" + "def receive_%(event_name)s(" + "%(named_event_arguments)s%(has_kw_arguments)s):\n" + " \"listen for the '%(event_name)s' event\"\n" + "\n # ... (event handling logic) ...\n" + ) + + text %= { + "current_since": " (arguments as of %s)" % current_since + if current_since + else "", + "event_name": fn.__name__, + "has_kw_arguments": ", **kw" if dispatch_collection.has_kw else "", + "named_event_arguments": ", ".join(dispatch_collection.arg_names), + "example_kw_arg": example_kw_arg, + "sample_target": sample_target, + } + return text + + +def _legacy_listen_examples(dispatch_collection, sample_target, fn): + text = "" + for since, args, conv in dispatch_collection.legacy_signatures: + text += ( + "\n# DEPRECATED calling style (pre-%(since)s, " + "will be removed in a future release)\n" + "@event.listens_for(%(sample_target)s, '%(event_name)s')\n" + "def receive_%(event_name)s(" + "%(named_event_arguments)s%(has_kw_arguments)s):\n" + " \"listen for the '%(event_name)s' event\"\n" + "\n # ... (event handling logic) ...\n" + % { + "since": since, + "event_name": fn.__name__, + "has_kw_arguments": " **kw" + if dispatch_collection.has_kw + else "", + "named_event_arguments": ", ".join(args), + "sample_target": sample_target, + } + ) + return text + + +def _version_signature_changes(parent_dispatch_cls, dispatch_collection): + since, args, conv = dispatch_collection.legacy_signatures[0] + return ( + "\n.. deprecated:: %(since)s\n" + " The :class:`.%(clsname)s.%(event_name)s` event now accepts the \n" + " arguments ``%(named_event_arguments)s%(has_kw_arguments)s``.\n" + " Support for listener functions which accept the previous \n" + ' argument signature(s) listed above as "deprecated" will be \n' + " removed in a future release." + % { + "since": since, + "clsname": parent_dispatch_cls.__name__, + "event_name": dispatch_collection.name, + "named_event_arguments": ", ".join(dispatch_collection.arg_names), + "has_kw_arguments": ", **kw" if dispatch_collection.has_kw else "", + } + ) + + +def _augment_fn_docs(dispatch_collection, parent_dispatch_cls, fn): + header = ( + ".. container:: event_signatures\n\n" + " Example argument forms::\n" + "\n" + ) + + sample_target = getattr(parent_dispatch_cls, "_target_class_doc", "obj") + text = header + _indent( + _standard_listen_example(dispatch_collection, sample_target, fn), + " " * 8, + ) + if dispatch_collection.legacy_signatures: + text += _indent( + _legacy_listen_examples(dispatch_collection, sample_target, fn), + " " * 8, + ) + + text += _version_signature_changes( + parent_dispatch_cls, dispatch_collection + ) + + return util.inject_docstring_text(fn.__doc__, text, 1) diff --git a/lib/sqlalchemy/event/registry.py b/lib/sqlalchemy/event/registry.py new file mode 100644 index 0000000..ac143c4 --- /dev/null +++ b/lib/sqlalchemy/event/registry.py @@ -0,0 +1,297 @@ +# event/registry.py +# Copyright (C) 2005-2022 the SQLAlchemy authors and contributors +# <see AUTHORS file> +# +# This module is part of SQLAlchemy and is released under +# the MIT License: https://www.opensource.org/licenses/mit-license.php + +"""Provides managed registration services on behalf of :func:`.listen` +arguments. + +By "managed registration", we mean that event listening functions and +other objects can be added to various collections in such a way that their +membership in all those collections can be revoked at once, based on +an equivalent :class:`._EventKey`. + +""" + +from __future__ import absolute_import + +import collections +import types +import weakref + +from .. import exc +from .. import util + + +_key_to_collection = collections.defaultdict(dict) +""" +Given an original listen() argument, can locate all +listener collections and the listener fn contained + +(target, identifier, fn) -> { + ref(listenercollection) -> ref(listener_fn) + ref(listenercollection) -> ref(listener_fn) + ref(listenercollection) -> ref(listener_fn) + } +""" + +_collection_to_key = collections.defaultdict(dict) +""" +Given a _ListenerCollection or _ClsLevelListener, can locate +all the original listen() arguments and the listener fn contained + +ref(listenercollection) -> { + ref(listener_fn) -> (target, identifier, fn), + ref(listener_fn) -> (target, identifier, fn), + ref(listener_fn) -> (target, identifier, fn), + } +""" + + +def _collection_gced(ref): + # defaultdict, so can't get a KeyError + if not _collection_to_key or ref not in _collection_to_key: + return + listener_to_key = _collection_to_key.pop(ref) + for key in listener_to_key.values(): + if key in _key_to_collection: + # defaultdict, so can't get a KeyError + dispatch_reg = _key_to_collection[key] + dispatch_reg.pop(ref) + if not dispatch_reg: + _key_to_collection.pop(key) + + +def _stored_in_collection(event_key, owner): + key = event_key._key + + dispatch_reg = _key_to_collection[key] + + owner_ref = owner.ref + listen_ref = weakref.ref(event_key._listen_fn) + + if owner_ref in dispatch_reg: + return False + + dispatch_reg[owner_ref] = listen_ref + + listener_to_key = _collection_to_key[owner_ref] + listener_to_key[listen_ref] = key + + return True + + +def _removed_from_collection(event_key, owner): + key = event_key._key + + dispatch_reg = _key_to_collection[key] + + listen_ref = weakref.ref(event_key._listen_fn) + + owner_ref = owner.ref + dispatch_reg.pop(owner_ref, None) + if not dispatch_reg: + del _key_to_collection[key] + + if owner_ref in _collection_to_key: + listener_to_key = _collection_to_key[owner_ref] + listener_to_key.pop(listen_ref) + + +def _stored_in_collection_multi(newowner, oldowner, elements): + if not elements: + return + + oldowner = oldowner.ref + newowner = newowner.ref + + old_listener_to_key = _collection_to_key[oldowner] + new_listener_to_key = _collection_to_key[newowner] + + for listen_fn in elements: + listen_ref = weakref.ref(listen_fn) + try: + key = old_listener_to_key[listen_ref] + except KeyError: + # can occur during interpreter shutdown. + # see #6740 + continue + + try: + dispatch_reg = _key_to_collection[key] + except KeyError: + continue + + if newowner in dispatch_reg: + assert dispatch_reg[newowner] == listen_ref + else: + dispatch_reg[newowner] = listen_ref + + new_listener_to_key[listen_ref] = key + + +def _clear(owner, elements): + if not elements: + return + + owner = owner.ref + listener_to_key = _collection_to_key[owner] + for listen_fn in elements: + listen_ref = weakref.ref(listen_fn) + key = listener_to_key[listen_ref] + dispatch_reg = _key_to_collection[key] + dispatch_reg.pop(owner, None) + + if not dispatch_reg: + del _key_to_collection[key] + + +class _EventKey(object): + """Represent :func:`.listen` arguments.""" + + __slots__ = ( + "target", + "identifier", + "fn", + "fn_key", + "fn_wrap", + "dispatch_target", + ) + + def __init__(self, target, identifier, fn, dispatch_target, _fn_wrap=None): + self.target = target + self.identifier = identifier + self.fn = fn + if isinstance(fn, types.MethodType): + self.fn_key = id(fn.__func__), id(fn.__self__) + else: + self.fn_key = id(fn) + self.fn_wrap = _fn_wrap + self.dispatch_target = dispatch_target + + @property + def _key(self): + return (id(self.target), self.identifier, self.fn_key) + + def with_wrapper(self, fn_wrap): + if fn_wrap is self._listen_fn: + return self + else: + return _EventKey( + self.target, + self.identifier, + self.fn, + self.dispatch_target, + _fn_wrap=fn_wrap, + ) + + def with_dispatch_target(self, dispatch_target): + if dispatch_target is self.dispatch_target: + return self + else: + return _EventKey( + self.target, + self.identifier, + self.fn, + dispatch_target, + _fn_wrap=self.fn_wrap, + ) + + def listen(self, *args, **kw): + once = kw.pop("once", False) + once_unless_exception = kw.pop("_once_unless_exception", False) + named = kw.pop("named", False) + + target, identifier, fn = ( + self.dispatch_target, + self.identifier, + self._listen_fn, + ) + + dispatch_collection = getattr(target.dispatch, identifier) + + adjusted_fn = dispatch_collection._adjust_fn_spec(fn, named) + + self = self.with_wrapper(adjusted_fn) + + stub_function = getattr( + self.dispatch_target.dispatch._events, self.identifier + ) + if hasattr(stub_function, "_sa_warn"): + stub_function._sa_warn() + + if once or once_unless_exception: + self.with_wrapper( + util.only_once( + self._listen_fn, retry_on_exception=once_unless_exception + ) + ).listen(*args, **kw) + else: + self.dispatch_target.dispatch._listen(self, *args, **kw) + + def remove(self): + key = self._key + + if key not in _key_to_collection: + raise exc.InvalidRequestError( + "No listeners found for event %s / %r / %s " + % (self.target, self.identifier, self.fn) + ) + + dispatch_reg = _key_to_collection.pop(key) + + for collection_ref, listener_ref in dispatch_reg.items(): + collection = collection_ref() + listener_fn = listener_ref() + if collection is not None and listener_fn is not None: + collection.remove(self.with_wrapper(listener_fn)) + + def contains(self): + """Return True if this event key is registered to listen.""" + return self._key in _key_to_collection + + def base_listen( + self, + propagate=False, + insert=False, + named=False, + retval=None, + asyncio=False, + ): + + target, identifier = self.dispatch_target, self.identifier + + dispatch_collection = getattr(target.dispatch, identifier) + + for_modify = dispatch_collection.for_modify(target.dispatch) + if asyncio: + for_modify._set_asyncio() + + if insert: + for_modify.insert(self, propagate) + else: + for_modify.append(self, propagate) + + @property + def _listen_fn(self): + return self.fn_wrap or self.fn + + def append_to_list(self, owner, list_): + if _stored_in_collection(self, owner): + list_.append(self._listen_fn) + return True + else: + return False + + def remove_from_list(self, owner, list_): + _removed_from_collection(self, owner) + list_.remove(self._listen_fn) + + def prepend_to_list(self, owner, list_): + if _stored_in_collection(self, owner): + list_.appendleft(self._listen_fn) + return True + else: + return False |