262 lines
7.6 KiB
Python
262 lines
7.6 KiB
Python
# event/registry.py
|
|
# Copyright (C) 2005-2016 the SQLAlchemy authors and contributors
|
|
# <see AUTHORS file>
|
|
#
|
|
# This module is part of SQLAlchemy and is released under
|
|
# the MIT License: http://www.opensource.org/licenses/mit-license.php
|
|
|
|
"""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 weakref
|
|
import collections
|
|
import types
|
|
from .. import exc, 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)
|
|
key = old_listener_to_key[listen_ref]
|
|
dispatch_reg = _key_to_collection[key]
|
|
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)
|
|
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)
|
|
|
|
if once:
|
|
self.with_wrapper(
|
|
util.only_once(self._listen_fn)).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):
|
|
|
|
target, identifier, fn = \
|
|
self.dispatch_target, self.identifier, self._listen_fn
|
|
|
|
dispatch_collection = getattr(target.dispatch, identifier)
|
|
|
|
if insert:
|
|
dispatch_collection.\
|
|
for_modify(target.dispatch).insert(self, propagate)
|
|
else:
|
|
dispatch_collection.\
|
|
for_modify(target.dispatch).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
|