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Fixed #11134: signals recievers that disconnect during their processing no longer mess things up for other handlers. Thanks, Honza Kral. 

While I was at it I also cleaned up the formatting of the docstrings a bit.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10831 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Jacob Kaplan-Moss 2009-05-20 16:13:55 +00:00
parent ca365b4113
commit c935d7ffe3
2 changed files with 128 additions and 75 deletions
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175
django/dispatch/dispatcher.py
View File

@ -14,15 +14,21 @@ def _make_id(target):
return id(target)
class Signal(object):
"""Base class for all signals
"""
Base class for all signals
Internal attributes:
receivers -- { receriverkey (id) : weakref(receiver) }
receivers
{ receriverkey (id) : weakref(receiver) }
"""
def __init__(self, providing_args=None):
"""providing_args -- A list of the arguments this signal can pass along in
a send() call.
"""
Create a new signal.
providing_args
A list of the arguments this signal can pass along in a send() call.
"""
self.receivers = []
if providing_args is None:
@ -30,36 +36,39 @@ class Signal(object):
self.providing_args = set(providing_args)
def connect(self, receiver, sender=None, weak=True, dispatch_uid=None):
"""Connect receiver to sender for signal
"""
Connect receiver to sender for signal.
receiver -- a function or an instance method which is to
receive signals. Receivers must be
hashable objects.
if weak is True, then receiver must be weak-referencable
(more precisely saferef.safeRef() must be able to create
a reference to the receiver).
Arguments:
Receivers must be able to accept keyword arguments.
receiver
A function or an instance method which is to receive signals.
Receivers must be hashable objects.
If receivers have a dispatch_uid attribute, the receiver will
not be added if another receiver already exists with that
dispatch_uid.
sender -- the sender to which the receiver should respond
Must either be of type Signal, or None to receive events
from any sender.
weak -- whether to use weak references to the receiver
By default, the module will attempt to use weak
references to the receiver objects. If this parameter
is false, then strong references will be used.
if weak is True, then receiver must be weak-referencable (more
precisely saferef.safeRef() must be able to create a reference
to the receiver).
dispatch_uid -- an identifier used to uniquely identify a particular
instance of a receiver. This will usually be a string, though it
may be anything hashable.
Receivers must be able to accept keyword arguments.
returns None
If receivers have a dispatch_uid attribute, the receiver will
not be added if another receiver already exists with that
dispatch_uid.
sender
The sender to which the receiver should respond Must either be
of type Signal, or None to receive events from any sender.
weak
Whether to use weak references to the receiver By default, the
module will attempt to use weak references to the receiver
objects. If this parameter is false, then strong references will
be used.
dispatch_uid
An identifier used to uniquely identify a particular instance of
a receiver. This will usually be a string, though it may be
anything hashable.
"""
from django.conf import settings
@ -99,22 +108,27 @@ class Signal(object):
self.receivers.append((lookup_key, receiver))
def disconnect(self, receiver=None, sender=None, weak=True, dispatch_uid=None):
"""Disconnect receiver from sender for signal
receiver -- the registered receiver to disconnect. May be none if
dispatch_uid is specified.
sender -- the registered sender to disconnect
weak -- the weakref state to disconnect
dispatch_uid -- the unique identifier of the receiver to disconnect
disconnect reverses the process of connect.
If weak references are used, disconnect need not be called.
The receiver will be remove from dispatch automatically.
returns None
"""
Disconnect receiver from sender for signal.
If weak references are used, disconnect need not be called. The receiver
will be remove from dispatch automatically.
Arguments:
receiver
The registered receiver to disconnect. May be none if
dispatch_uid is specified.
sender
The registered sender to disconnect
weak
The weakref state to disconnect
dispatch_uid
the unique identifier of the receiver to disconnect
"""
if dispatch_uid:
lookup_key = (dispatch_uid, _make_id(sender))
else:
@ -127,21 +141,23 @@ class Signal(object):
break
def send(self, sender, **named):
"""Send signal from sender to all connected receivers.
"""
Send signal from sender to all connected receivers.
sender -- the sender of the signal
Either a specific object or None.
If any receiver raises an error, the error propagates back through send,
terminating the dispatch loop, so it is quite possible to not have all
receivers called if a raises an error.
Arguments:
sender
The sender of the signal Either a specific object or None.
named -- named arguments which will be passed to receivers.
named
Named arguments which will be passed to receivers.
Returns a list of tuple pairs [(receiver, response), ... ].
If any receiver raises an error, the error propagates back
through send, terminating the dispatch loop, so it is quite
possible to not have all receivers called if a raises an
error.
"""
responses = []
if not self.receivers:
return responses
@ -152,23 +168,28 @@ class Signal(object):
return responses
def send_robust(self, sender, **named):
"""Send signal from sender to all connected receivers catching errors
sender -- the sender of the signal
Can be any python object (normally one registered with
a connect if you actually want something to occur).
named -- named arguments which will be passed to receivers.
These arguments must be a subset of the argument names
defined in providing_args.
Return a list of tuple pairs [(receiver, response), ... ],
may raise DispatcherKeyError
if any receiver raises an error (specifically any subclass of Exception),
the error instance is returned as the result for that receiver.
"""
Send signal from sender to all connected receivers catching errors.
Arguments:
sender
The sender of the signal Can be any python object (normally one
registered with a connect if you actually want something to
occur).
named
Named arguments which will be passed to receivers. These
arguments must be a subset of the argument names defined in
providing_args.
Return a list of tuple pairs [(receiver, response), ... ]. May raise
DispatcherKeyError.
if any receiver raises an error (specifically any subclass of
Exception), the error instance is returned as the result for that
receiver.
"""
responses = []
if not self.receivers:
return responses
@ -185,13 +206,14 @@ class Signal(object):
return responses
def _live_receivers(self, senderkey):
"""Filter sequence of receivers to get resolved, live receivers
"""
Filter sequence of receivers to get resolved, live receivers.
This checks for weak references
and resolves them, then returning only live
receivers.
This checks for weak references and resolves them, then returning only
live receivers.
"""
none_senderkey = _make_id(None)
receivers = []
for (receiverkey, r_senderkey), receiver in self.receivers:
if r_senderkey == none_senderkey or r_senderkey == senderkey:
@ -199,12 +221,15 @@ class Signal(object):
# Dereference the weak reference.
receiver = receiver()
if receiver is not None:
yield receiver
receivers.append(receiver)
else:
yield receiver
receivers.append(receiver)
return receivers
def _remove_receiver(self, receiver):
"""Remove dead receivers from connections."""
"""
Remove dead receivers from connections.
"""
to_remove = []
for key, connected_receiver in self.receivers:

28
tests/modeltests/signals/tests.py Normal file
View File

@ -0,0 +1,28 @@
from django.db.models import signals
from django.test import TestCase
from modeltests.signals.models import Person
class MyReceiver(object):
def __init__(self, param):
self.param = param
self._run = False
def __call__(self, signal, sender, **kwargs):
self._run = True
signal.disconnect(receiver=self, sender=sender)
class SignalTests(TestCase):
def test_disconnect_in_dispatch(self):
"""
Test that signals that disconnect when being called don't mess future
dispatching.
"""
a, b = MyReceiver(1), MyReceiver(2)
signals.post_save.connect(sender=Person, receiver=a)
signals.post_save.connect(sender=Person, receiver=b)
p = Person.objects.create(first_name='John', last_name='Smith')
self.failUnless(a._run)
self.failUnless(b._run)
self.assertEqual(signals.post_save.receivers, [])