openstack
/
neutron
Code Issues Proposed changes

remove and shim callbacks 

The callback modules have been available in neutron-lib since commit [1]
and are ready for consumption.

As the callback registry is implemented with a singleton manager
instance, sync complications can arise ensuring all consumers switch to
lib's implementation at the same time. Therefore this consumption has
been broken down:
1) Shim neutron's callbacks using lib's callback system and remove
existing neutron internals related to callbacks (devref, UTs, etc.).
2) Switch all neutron's callback imports over to neutron-lib's.
3) Have all sub-projects using callbacks move their imports over to use
neutron-lib's callbacks implementation.
4) Remove the callback shims in neutron-lib once sub-projects are moved
over to lib's callbacks.
5) Follow-on patches moving our existing uses of callbacks to the new
event payload model provided by neutron-lib.callback.events

This patch implements #1 from above, shimming neutron's callbacks and
removing devref + UTs. Rather than shimming using debtcollector, this
patch leaves callback constants as-is, and simply references the lib
class/function in its respective neutron callback module. This allows
consumers to test callback types without changing code. For example,
an except block block like that below continues to work even though
the raised exception now lives in lib::

try:
     neutron_cb_registry.notify(...)
except neutron_cb_exceptions.CallbackFailure:
     handle_exception()

In addition this patch contains minor UT updates to support the shim
approach.

NeutronLibImpact

[1] fea8bb64ba7ff52632c2bd3e3298eaedf623ee4f

Change-Id: Ib6baee2aaeb044aaba42a97b35900d75dd43021f
This commit is contained in:
Boden R 2017-04-24 08:59:51 -06:00
parent c204bff612
commit d79798389e
12 changed files with 31 additions and 1102 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

441
doc/source/devref/callbacks.rst
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@ -1,441 +0,0 @@
..
Licensed under the Apache License, Version 2.0 (the "License"); you may
not use this file except in compliance with the License. You may obtain
a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
License for the specific language governing permissions and limitations
under the License.
Convention for heading levels in Neutron devref:
======= Heading 0 (reserved for the title in a document)
------- Heading 1
~~~~~~~ Heading 2
+++++++ Heading 3
''''''' Heading 4
(Avoid deeper levels because they do not render well.)
Neutron Callback System
=======================
In Neutron, core and service components may need to cooperate during the
execution of certain operations, or they may need to react upon the occurrence
of certain events. For instance, when a Neutron resource is associated to
multiple services, the components in charge of these services may need to play
an active role in determining what the right state of the resource needs to be.
The cooperation may be achieved by making each object aware of each other, but
this leads to tight coupling, or alternatively it can be achieved by using a
callback-based system, where the same objects are allowed to cooperate in a
loose manner.
This is particularly important since the spin off of the advanced services like
VPN, Firewall and Load Balancer, where each service's codebase lives independently
from the core and from one another. This means that the tight coupling is no longer
a practical solution for object cooperation. In addition to this, if more services
are developed independently, there is no viable integration between them and the
Neutron core. A callback system, and its registry, tries to address these issues.
In object-oriented software systems, method invocation is also known as message
passing: an object passes a message to another object, and it may or may not expect
a message back. This point-to-point interaction can take place between the parties
directly involved in the communication, or it can happen via an intermediary. The
intermediary is then in charge of keeping track of who is interested in the messages
and in delivering the messages forth and back, when required. As mentioned earlier,
the use of an intermediary has the benefit of decoupling the parties involved
in the communications, as now they only need to know about the intermediary; the
other benefit is that the use of an intermediary opens up the possibility of
multiple party communication: more than one object can express interest in
receiving the same message, and the same message can be delivered to more than
one object. To this aim, the intermediary is the entity that exists throughout
the system lifecycle, as it needs to be able to track whose interest is associated
to what message.
In a design for a system that enables callback-based communication, the following
aspects need to be taken into account:
* how to become consumer of messages (i.e. how to be on the receiving end of the message);
* how to become producer of messages (i.e. how to be on the sending end of the message);
* how to consume/produce messages selectively;
Translate and narrow this down to Neutron needs, and this means the design of a callback
system where messages are about lifecycle events (e.g. before creation, before
deletion, etc.) of Neutron resources (e.g. networks, routers, ports, etc.), where the
various parties can express interest in knowing when these events for a specific
resources take place.
Rather than keeping the conversation abstract, let us delve into some examples, that would
help understand better some of the principles behind the provided mechanism.
Subscribing to events
---------------------
Imagine that you have entity A, B, and C that have some common business over router creation.
A wants to tell B and C that the router has been created and that they need to get on and
do whatever they are supposed to do. In a callback-less world this would work like so:
::
# A is done creating the resource
# A gets hold of the references of B and C
# A calls B
# A calls C
B->my_random_method_for_knowing_about_router_created()
C->my_random_very_difficult_to_remember_method_about_router_created()
If B and/or C change, things become sour. In a callback-based world, things become a lot
more uniform and straightforward:
::
# B and C ask I to be notified when A is done creating the resource
# ...
# A is done creating the resource
# A gets hold of the reference to the intermediary I
# A calls I
I->notify()
Since B and C will have expressed interest in knowing about A's business, 'I' will
deliver the messages to B and C. If B and C changes, A and 'I' do not need to change.
In practical terms this scenario would be translated in the code below:
::
from neutron.callbacks import events
from neutron.callbacks import resources
from neutron.callbacks import registry
def callback1(resource, event, trigger, **kwargs):
print('Callback1 called by trigger: ', trigger)
print('kwargs: ', kwargs)
def callback2(resource, event, trigger, **kwargs):
print('Callback2 called by trigger: ', trigger)
print('kwargs: ', kwargs)
# B and C express interest with I
registry.subscribe(callback1, resources.ROUTER, events.BEFORE_CREATE)
registry.subscribe(callback2, resources.ROUTER, events.BEFORE_CREATE)
print('Subscribed')
# A notifies
def do_notify():
kwargs = {'foo': 'bar'}
registry.notify(resources.ROUTER, events.BEFORE_CREATE, do_notify, **kwargs)
print('Notifying...')
do_notify()
The output is:
::
> Subscribed
> Notifying...
> Callback2 called by trigger: <function do_notify at 0x7f2a5d663410>
> kwargs: {'foo': 'bar'}
> Callback1 called by trigger: <function do_notify at 0x7f2a5d663410>
> kwargs: {'foo': 'bar'}
Thanks to the intermediary existence throughout the life of the system, A, B, and C
are flexible to evolve their internals, dynamics, and lifecycles.
Subscribing and aborting events
-------------------------------
Interestingly in Neutron, certain events may need to be forbidden from happening due to the
nature of the resources involved. To this aim, the callback-based mechanism has been designed
to support a use case where, when callbacks subscribe to specific events, the action that
results from it, may lead to the propagation of a message back to the sender, so that it itself
can be alerted and stop the execution of the activity that led to the message dispatch in the
first place.
The typical example is where a resource, like a router, is used by one or more high-level
service(s), like a VPN or a Firewall, and actions like interface removal or router destruction
cannot not take place, because the resource is shared.
To address this scenario, special events are introduced, 'BEFORE_*' events, to which callbacks
can subscribe and have the opportunity to 'abort', by raising an exception when notified.
Since multiple callbacks may express an interest in the same event for a particular resource,
and since callbacks are executed independently from one another, this may lead to situations
where notifications that occurred before the exception must be aborted. To this aim, when an
exception occurs during the notification process, an abort_* event is propagated immediately
after. It is up to the callback developer to determine whether subscribing to an abort
notification is required in order to revert the actions performed during the initial execution
of the callback (when the BEFORE_* event was fired). Exceptions caused by callbacks registered
to abort events are ignored. The snippet below shows this in action:
::
from neutron.callbacks import events
from neutron.callbacks import exceptions
from neutron.callbacks import resources
from neutron.callbacks import registry
def callback1(resource, event, trigger, **kwargs):
raise Exception('I am failing!')
def callback2(resource, event, trigger, **kwargs):
print('Callback2 called by %s on event %s' % (trigger, event))
registry.subscribe(callback1, resources.ROUTER, events.BEFORE_CREATE)
registry.subscribe(callback2, resources.ROUTER, events.BEFORE_CREATE)
registry.subscribe(callback2, resources.ROUTER, events.ABORT_CREATE)
print('Subscribed')
def do_notify():
kwargs = {'foo': 'bar'}
registry.notify(resources.ROUTER, events.BEFORE_CREATE, do_notify, **kwargs)
print('Notifying...')
try:
do_notify()
except exceptions.CallbackFailure as e:
print('Error: ', e)
The output is:
::
> Subscribed
> Notifying...
> Callback2 called by <function do_notify at 0x7f3194c7f410> on event before_create
> Callback2 called by <function do_notify at 0x7f3194c7f410> on event abort_create
> Error: Callback __main__.callback1 failed with "I am failing!"
In this case, upon the notification of the BEFORE_CREATE event, Callback1 triggers an exception
that can be used to stop the action from taking place in do_notify(). On the other end, Callback2
will be executing twice, once for dealing with the BEFORE_CREATE event, and once to undo the
actions during the ABORT_CREATE event. It is worth noting that it is not mandatory to have
the same callback register to both BEFORE_* and the respective ABORT_* event; as a matter of
fact, it is best to make use of different callbacks to keep the two logic separate.
As we can see from the last example, exception which is triggered in some callback will be
recorded, and it will not prevent the other remaining callbacks execution. Exception triggered in
callback of BEFORE_XXX will make notify process generate an ABORT_XXX event and call the related
callback, while exception from PRECOMMIT_XXX will not generate ABORT_XXX event. But both of them
will finally raise a unified CallbackFailure exception to the outside. For the exception triggered
from other events, like AFTER_XXX and ABORT_XXX there will no exception raised to the outside.
Unsubscribing to events
-----------------------
There are a few options to unsubscribe registered callbacks:
* clear(): it unsubscribes all subscribed callbacks: this can be useful especially when
winding down the system, and notifications shall no longer be triggered.
* unsubscribe(): it selectively unsubscribes a callback for a specific resource's event.
Say callback C has subscribed to event A for resource R, any notification of event A
for resource R will no longer be handed over to C, after the unsubscribe() invocation.
* unsubscribe_by_resource(): say that callback C has subscribed to event A, B, and C for
resource R, any notification of events related to resource R will no longer be handed
over to C, after the unsubscribe_by_resource() invocation.
* unsubscribe_all(): say that callback C has subscribed to events A, B for resource R1,
and events C, D for resource R2, any notification of events pertaining resources R1 and
R2 will no longer be handed over to C, after the unsubscribe_all() invocation.
The snippet below shows these concepts in action:
::
from neutron.callbacks import events
from neutron.callbacks import exceptions
from neutron.callbacks import resources
from neutron.callbacks import registry
def callback1(resource, event, trigger, **kwargs):
print('Callback1 called by %s on event %s for resource %s' % (trigger, event, resource))
def callback2(resource, event, trigger, **kwargs):
print('Callback2 called by %s on event %s for resource %s' % (trigger, event, resource))
registry.subscribe(callback1, resources.ROUTER, events.BEFORE_READ)
registry.subscribe(callback1, resources.ROUTER, events.BEFORE_CREATE)
registry.subscribe(callback1, resources.ROUTER, events.AFTER_DELETE)
registry.subscribe(callback1, resources.PORT, events.BEFORE_UPDATE)
registry.subscribe(callback2, resources.ROUTER_GATEWAY, events.BEFORE_UPDATE)
print('Subscribed')
def do_notify():
print('Notifying...')
kwargs = {'foo': 'bar'}
registry.notify(resources.ROUTER, events.BEFORE_READ, do_notify, **kwargs)
registry.notify(resources.ROUTER, events.BEFORE_CREATE, do_notify, **kwargs)
registry.notify(resources.ROUTER, events.AFTER_DELETE, do_notify, **kwargs)
registry.notify(resources.PORT, events.BEFORE_UPDATE, do_notify, **kwargs)
registry.notify(resources.ROUTER_GATEWAY, events.BEFORE_UPDATE, do_notify, **kwargs)
do_notify()
registry.unsubscribe(callback1, resources.ROUTER, events.BEFORE_READ)
do_notify()
registry.unsubscribe_by_resource(callback1, resources.PORT)
do_notify()
registry.unsubscribe_all(callback1)
do_notify()
registry.clear()
do_notify()
The output is:
::
Subscribed
Notifying...
Callback1 called by <function do_notify at 0x7f062c8f67d0> on event before_read for resource router
Callback1 called by <function do_notify at 0x7f062c8f67d0> on event before_create for resource router
Callback1 called by <function do_notify at 0x7f062c8f67d0> on event after_delete for resource router
Callback1 called by <function do_notify at 0x7f062c8f67d0> on event before_update for resource port
Callback2 called by <function do_notify at 0x7f062c8f67d0> on event before_update for resource router_gateway
Notifying...
Callback1 called by <function do_notify at 0x7f062c8f67d0> on event before_create for resource router
Callback1 called by <function do_notify at 0x7f062c8f67d0> on event after_delete for resource router
Callback1 called by <function do_notify at 0x7f062c8f67d0> on event before_update for resource port
Callback2 called by <function do_notify at 0x7f062c8f67d0> on event before_update for resource router_gateway
Notifying...
Callback1 called by <function do_notify at 0x7f062c8f67d0> on event before_create for resource router
Callback1 called by <function do_notify at 0x7f062c8f67d0> on event after_delete for resource router
Callback2 called by <function do_notify at 0x7f062c8f67d0> on event before_update for resource router_gateway
Notifying...
Callback2 called by <function do_notify at 0x7f062c8f67d0> on event before_update for resource router_gateway
Notifying...
FAQ
---
Are callbacks a mechanism for remote or local communication (intra vs inter-process)?
Callbacks as described in this document are a local communication mechanism that
allows multiple entities in the same process space to communicate with one another.
For Neutron specific remote (IPC) mechanisms, you can see read more in
:doc:`RPC API <rpc_api>` or :doc:`Messaging callbacks <rpc_callbacks>`.
Can I use the callbacks registry to subscribe and notify non-core resources and events?
Short answer is yes. The callbacks module defines literals for what are considered core Neutron
resources and events. However, the ability to subscribe/notify is not limited to these as you
can use your own defined resources and/or events. Just make sure you use string literals, as
typos are common, and the registry does not provide any runtime validation. Therefore, make
sure you test your code!
What is the relationship between Callbacks and Taskflow?
There is no overlap between Callbacks and Taskflow or mutual exclusion; as matter of fact they
can be combined; You could have a callback that goes on and trigger a taskflow. It is a nice
way of separating implementation from abstraction, because you can keep the callback in place
and change Taskflow with something else.
Is there any ordering guarantee during notifications?
No, the ordering in which callbacks are notified is completely arbitrary by design: callbacks
should know nothing about each other, and ordering should not matter; a callback will always be
notified and its outcome should always be the same regardless as to in which order is it
notified. Priorities can be a future extension, if a use case arises that require enforced
ordering.
How is the notifying object expected to interact with the subscribing objects?
The ``notify`` method implements a one-way communication paradigm: the notifier sends a message
without expecting a response back (in other words it fires and forget). However, due to the nature
of Python, the payload can be mutated by the subscribing objects, and this can lead to unexpected
behavior of your code, if you assume that this is the intentional design. Bear in mind, that
passing-by-value using deepcopy was not chosen for efficiency reasons. Having said that, if you
intend for the notifier object to expect a response, then the notifier itself would need to act
as a subscriber.
Is the registry thread-safe?
Short answer is no: it is not safe to make mutations while callbacks are being called (more
details as to why can be found `here <https://hg.python.org/releasing/2.7.9/file/753a8f457ddc/Objects/dictobject.c#l937>`_).
A mutation could happen if a 'subscribe'/'unsubscribe' operation interleaves with the execution
of the notify loop. Albeit there is a possibility that things may end up in a bad state, the
registry works correctly under the assumption that subscriptions happen at the very beginning
of the life of the process and that the unsubscriptions (if any) take place at the very end.
In this case, chances that things do go badly may be pretty slim. Making the registry
thread-safe will be considered as a future improvement.
What kind of operation I can add into callback?
For callback function of PRECOMMIT_XXX events, we can't use blocking functions or a function
that would take a long time, like communicating to SDN controller over network.
Callbacks for PRECOMMIT events are meant to execute DB operations in a transaction context. The
errors that occur will be taken care by the context manager.
What kind of function can be a callback?
Anything you fancy: lambdas, 'closures', class, object or module methods. For instance:
::
from neutron.callbacks import events
from neutron.callbacks import resources
from neutron.callbacks import registry
def callback1(resource, event, trigger, **kwargs):
print('module callback')
class MyCallback(object):
def callback2(self, resource, event, trigger, **kwargs):
print('object callback')
@classmethod
def callback3(cls, resource, event, trigger, **kwargs):
print('class callback')
c = MyCallback()
registry.subscribe(callback1, resources.ROUTER, events.BEFORE_CREATE)
registry.subscribe(c.callback2, resources.ROUTER, events.BEFORE_CREATE)
registry.subscribe(MyCallback.callback3, resources.ROUTER, events.BEFORE_CREATE)
def do_notify():
def nested_subscribe(resource, event, trigger, **kwargs):
print('nested callback')
registry.subscribe(nested_subscribe, resources.ROUTER, events.BEFORE_CREATE)
kwargs = {'foo': 'bar'}
registry.notify(resources.ROUTER, events.BEFORE_CREATE, do_notify, **kwargs)
print('Notifying...')
do_notify()
And the output is going to be:
::
Notifying...
module callback
object callback
class callback
nested callback

1
doc/source/devref/index.rst
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@ -70,7 +70,6 @@ Neutron Internals
ovs_vhostuser
quality_of_service
service_extensions
callbacks
dns_order
external_dns_integration
upgrade

7
doc/source/devref/rpc_callbacks.rst
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@ -26,9 +26,10 @@
Neutron Messaging Callback System
=================================
Neutron already has a :doc:`callback system <callbacks>` for
in-process resource callbacks where publishers and subscribers are able
to publish and subscribe for resource events.
Neutron already has a `callback system
<https://docs.openstack.org/developer/neutron-lib/devref/callbacks.html>`_
for in-process resource callbacks where publishers and subscribers are
able to publish and subscribe for resource events.
This system is different, and is intended to be used for inter-process
callbacks, via the messaging fanout mechanisms.

2
neutron/callbacks/events.py
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@ -10,6 +10,8 @@
# License for the specific language governing permissions and limitations
# under the License.
# NOTE(boden): This module will be removed soon; use neutron-lib callbacks
# String literals representing events associated to data store operations
BEFORE_CREATE = 'before_create'
BEFORE_READ = 'before_read'

44
neutron/callbacks/exceptions.py
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@ -10,44 +10,10 @@
# License for the specific language governing permissions and limitations
# under the License.
from neutron_lib import exceptions
from neutron_lib.callbacks import exceptions
from neutron._i18n import _
# NOTE(boden): This module will be removed soon; use neutron-lib callbacks
class Invalid(exceptions.NeutronException):
message = _("The value '%(value)s' for %(element)s is not valid.")
class CallbackFailure(exceptions.MultipleExceptions):
def __init__(self, errors):
self.errors = errors
def __str__(self):
if isinstance(self.errors, list):
return ','.join(str(error) for error in self.errors)
else:
return str(self.errors)
@property
def inner_exceptions(self):
if isinstance(self.errors, list):
return [self._unpack_if_notification_error(e) for e in self.errors]
return [self._unpack_if_notification_error(self.errors)]
@staticmethod
def _unpack_if_notification_error(exc):
if isinstance(exc, NotificationError):
return exc.error
return exc
class NotificationError(object):
def __init__(self, callback_id, error):
self.callback_id = callback_id
self.error = error
def __str__(self):
return 'Callback %s failed with "%s"' % (self.callback_id, self.error)
Invalid = exceptions.Invalid
CallbackFailure = exceptions.CallbackFailure
NotificationError = exceptions.NotificationError

164
neutron/callbacks/manager.py
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@ -10,167 +10,11 @@
# License for the specific language governing permissions and limitations
# under the License.
import collections
from neutron_lib.callbacks import manager
from oslo_log import log as logging
from oslo_utils import reflection
# NOTE(boden): This module will be removed soon; use neutron-lib callbacks
from neutron._i18n import _LE
from neutron.callbacks import events
from neutron.callbacks import exceptions
from neutron.db import api as db_api
LOG = logging.getLogger(__name__)
CallbacksManager = manager.CallbacksManager
class CallbacksManager(object):
"""A callback system that allows objects to cooperate in a loose manner."""
def __init__(self):
self.clear()
def subscribe(self, callback, resource, event):
"""Subscribe callback for a resource event.
The same callback may register for more than one event.
:param callback: the callback. It must raise or return a boolean.
:param resource: the resource. It must be a valid resource.
:param event: the event. It must be a valid event.
"""
LOG.debug("Subscribe: %(callback)s %(resource)s %(event)s",
{'callback': callback, 'resource': resource, 'event': event})
callback_id = _get_id(callback)
try:
self._callbacks[resource][event][callback_id] = callback
except KeyError:
# Initialize the registry for unknown resources and/or events
# prior to enlisting the callback.
self._callbacks[resource][event] = {}
self._callbacks[resource][event][callback_id] = callback
# We keep a copy of callbacks to speed the unsubscribe operation.
if callback_id not in self._index:
self._index[callback_id] = collections.defaultdict(set)
self._index[callback_id][resource].add(event)
def unsubscribe(self, callback, resource, event):
"""Unsubscribe callback from the registry.
:param callback: the callback.
:param resource: the resource.
:param event: the event.
"""
LOG.debug("Unsubscribe: %(callback)s %(resource)s %(event)s",
{'callback': callback, 'resource': resource, 'event': event})
callback_id = self._find(callback)
if not callback_id:
LOG.debug("Callback %s not found", callback_id)
return
if resource and event:
del self._callbacks[resource][event][callback_id]
self._index[callback_id][resource].discard(event)
if not self._index[callback_id][resource]:
del self._index[callback_id][resource]
if not self._index[callback_id]:
del self._index[callback_id]
else:
value = '%s,%s' % (resource, event)
raise exceptions.Invalid(element='resource,event', value=value)
def unsubscribe_by_resource(self, callback, resource):
"""Unsubscribe callback for any event associated to the resource.
:param callback: the callback.
:param resource: the resource.
"""
callback_id = self._find(callback)
if callback_id:
if resource in self._index[callback_id]:
for event in self._index[callback_id][resource]:
del self._callbacks[resource][event][callback_id]
del self._index[callback_id][resource]
if not self._index[callback_id]:
del self._index[callback_id]
def unsubscribe_all(self, callback):
"""Unsubscribe callback for all events and all resources.
:param callback: the callback.
"""
callback_id = self._find(callback)
if callback_id:
for resource, resource_events in self._index[callback_id].items():
for event in resource_events:
del self._callbacks[resource][event][callback_id]
del self._index[callback_id]
@db_api.reraise_as_retryrequest
def notify(self, resource, event, trigger, **kwargs):
"""Notify all subscribed callback(s).
Dispatch the resource's event to the subscribed callbacks.
:param resource: the resource.
:param event: the event.
:param trigger: the trigger. A reference to the sender of the event.
"""
errors = self._notify_loop(resource, event, trigger, **kwargs)
if errors:
if event.startswith(events.BEFORE):
abort_event = event.replace(
events.BEFORE, events.ABORT)
self._notify_loop(resource, abort_event, trigger, **kwargs)
raise exceptions.CallbackFailure(errors=errors)
if event.startswith(events.PRECOMMIT):
raise exceptions.CallbackFailure(errors=errors)
def clear(self):
"""Brings the manager to a clean slate."""
self._callbacks = collections.defaultdict(dict)
self._index = collections.defaultdict(dict)
def _notify_loop(self, resource, event, trigger, **kwargs):
"""The notification loop."""
errors = []
callbacks = list(self._callbacks[resource].get(event, {}).items())
LOG.debug("Notify callbacks %s for %s, %s",
[c[0] for c in callbacks], resource, event)
# TODO(armax): consider using a GreenPile
for callback_id, callback in callbacks:
try:
callback(resource, event, trigger, **kwargs)
except Exception as e:
abortable_event = (
event.startswith(events.BEFORE) or
event.startswith(events.PRECOMMIT)
)
if not abortable_event:
LOG.exception(_LE("Error during notification for "
"%(callback)s %(resource)s, %(event)s"),
{'callback': callback_id,
'resource': resource, 'event': event})
else:
LOG.debug("Callback %(callback)s raised %(error)s",
{'callback': callback_id, 'error': e})
errors.append(exceptions.NotificationError(callback_id, e))
return errors
def _find(self, callback):
"""Return the callback_id if found, None otherwise."""
callback_id = _get_id(callback)
return callback_id if callback_id in self._index else None
def _get_id(callback):
"""Return a unique identifier for the callback."""
# TODO(armax): consider using something other than names
# https://www.python.org/dev/peps/pep-3155/, but this
# might be okay for now.
parts = (reflection.get_callable_name(callback),
str(hash(callback)))
return '-'.join(parts)
_get_id = manager._get_id

109
neutron/callbacks/registry.py
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@ -10,104 +10,15 @@
# License for the specific language governing permissions and limitations
# under the License.
import collections
import inspect
from neutron_lib.callbacks import registry
from neutron.callbacks import manager
# NOTE(boden): This module will be removed soon; use neutron-lib callbacks
# TODO(armax): consider adding locking
CALLBACK_MANAGER = None
# stores a dictionary keyed on function pointers with a list of
# (resource, event) tuples to subscribe to on class initialization
_REGISTERED_CLASS_METHODS = collections.defaultdict(list)
def _get_callback_manager():
global CALLBACK_MANAGER
if CALLBACK_MANAGER is None:
CALLBACK_MANAGER = manager.CallbacksManager()
return CALLBACK_MANAGER
def subscribe(callback, resource, event):
_get_callback_manager().subscribe(callback, resource, event)
def unsubscribe(callback, resource, event):
_get_callback_manager().unsubscribe(callback, resource, event)
def unsubscribe_by_resource(callback, resource):
_get_callback_manager().unsubscribe_by_resource(callback, resource)
def unsubscribe_all(callback):
_get_callback_manager().unsubscribe_all(callback)
def notify(resource, event, trigger, **kwargs):
_get_callback_manager().notify(resource, event, trigger, **kwargs)
def clear():
_get_callback_manager().clear()
def receives(resource, events):
"""Use to decorate methods on classes before initialization.
Any classes that use this must themselves be decorated with the
@has_registry_receivers decorator to setup the __new__ method to
actually register the instance methods after initialization.
"""
def decorator(f):
for e in events:
_REGISTERED_CLASS_METHODS[f].append((resource, e))
return f
return decorator
def has_registry_receivers(klass):
"""Decorator to setup __new__ method in classes to subscribe bound methods.
Any method decorated with @receives above is an unbound method on a class.
This decorator sets up the class __new__ method to subscribe the bound
method in the callback registry after object instantiation.
"""
orig_new = klass.__new__
new_inherited = '__new__' not in klass.__dict__
@staticmethod
def replacement_new(cls, *args, **kwargs):
if new_inherited:
# class didn't define __new__ so we need to call inherited __new__
super_new = super(klass, cls).__new__
if super_new is object.__new__:
# object.__new__ doesn't accept args nor kwargs
instance = super_new(cls)
else:
instance = super_new(cls, *args, **kwargs)
else:
instance = orig_new(cls, *args, **kwargs)
if getattr(instance, '_DECORATED_METHODS_SUBSCRIBED', False):
# Avoid running this logic twice for classes inheriting other
# classes with this same decorator. Only one needs to execute
# to subscribe all decorated methods.
return instance
for name, unbound_method in inspect.getmembers(cls):
if (not inspect.ismethod(unbound_method) and
not inspect.isfunction(unbound_method)):
continue
# handle py27/py34 difference
func = getattr(unbound_method, 'im_func', unbound_method)
if func not in _REGISTERED_CLASS_METHODS:
continue
for resource, event in _REGISTERED_CLASS_METHODS[func]:
# subscribe the bound method
subscribe(getattr(instance, name), resource, event)
setattr(instance, '_DECORATED_METHODS_SUBSCRIBED', True)
return instance
klass.__new__ = replacement_new
return klass
subscribe = registry.subscribe
unsubscribe = registry.unsubscribe
unsubscribe_by_resource = registry.unsubscribe_by_resource
unsubscribe_all = registry.unsubscribe_all
notify = registry.notify
clear = registry.clear
receives = registry.receives
has_registry_receivers = registry.has_registry_receivers

2
neutron/callbacks/resources.py
View File

@ -10,6 +10,8 @@
# License for the specific language governing permissions and limitations
# under the License.
# NOTE(boden): This module will be removed soon; use neutron-lib callbacks
# String literals representing core resources.
AGENT = 'agent'
FLOATING_IP = 'floatingip'

12
neutron/tests/base.py
View File

@ -43,7 +43,6 @@ from neutron.agent.linux import external_process
from neutron.api.rpc.callbacks.consumer import registry as rpc_consumer_reg
from neutron.api.rpc.callbacks.producer import registry as rpc_producer_reg
from neutron.callbacks import manager as registry_manager
from neutron.callbacks import registry
from neutron.common import config
from neutron.common import rpc as n_rpc
from neutron.db import _model_query as model_query
@ -296,7 +295,10 @@ class BaseTestCase(DietTestCase):
self.setup_rpc_mocks()
self.setup_config()
self.setup_test_registry_instance()
self._callback_manager = registry_manager.CallbacksManager()
self.useFixture(fixture.CallbackRegistryFixture(
callback_manager=self._callback_manager))
# Give a private copy of the directory to each test.
self.useFixture(fixture.PluginDirectoryFixture())
@ -364,12 +366,6 @@ class BaseTestCase(DietTestCase):
self.addCleanup(n_rpc.cleanup)
n_rpc.init(CONF)
def setup_test_registry_instance(self):
"""Give a private copy of the registry to each test."""
self._callback_manager = registry_manager.CallbacksManager()
mock.patch.object(registry, '_get_callback_manager',
return_value=self._callback_manager).start()
def setup_config(self, args=None):
"""Tests that need a non-default config can override this method."""
self.config_parse(args=args)

0
neutron/tests/unit/callbacks/__init__.py
View File

258
neutron/tests/unit/callbacks/test_manager.py
View File

@ -1,258 +0,0 @@
# Copyright 2015 OpenStack Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import mock
from oslo_db import exception as db_exc
from neutron.callbacks import events
from neutron.callbacks import exceptions
from neutron.callbacks import manager
from neutron.callbacks import resources
from neutron.tests import base
class ObjectWithCallback(object):
def __init__(self):
self.counter = 0
def callback(self, *args, **kwargs):
self.counter += 1
class GloriousObjectWithCallback(ObjectWithCallback):
pass
def callback_1(*args, **kwargs):
callback_1.counter += 1
callback_id_1 = manager._get_id(callback_1)
def callback_2(*args, **kwargs):
callback_2.counter += 1
callback_id_2 = manager._get_id(callback_2)
def callback_raise(*args, **kwargs):
raise Exception()
def callback_raise_retriable(*args, **kwargs):
raise db_exc.DBDeadlock()
class CallBacksManagerTestCase(base.BaseTestCase):
def setUp(self):
super(CallBacksManagerTestCase, self).setUp()
self.manager = manager.CallbacksManager()
callback_1.counter = 0
callback_2.counter = 0
def test_subscribe(self):
self.manager.subscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.assertIsNotNone(
self.manager._callbacks[resources.PORT][events.BEFORE_CREATE])
self.assertIn(callback_id_1, self.manager._index)
def test_subscribe_unknown(self):
self.manager.subscribe(
callback_1, 'my_resource', 'my-event')
self.assertIsNotNone(
self.manager._callbacks['my_resource']['my-event'])
self.assertIn(callback_id_1, self.manager._index)
def test_subscribe_is_idempotent(self):
self.manager.subscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.manager.subscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.assertEqual(
1,
len(self.manager._callbacks[resources.PORT][events.BEFORE_CREATE]))
callbacks = self.manager._index[callback_id_1][resources.PORT]
self.assertEqual(1, len(callbacks))
def test_subscribe_multiple_callbacks(self):
self.manager.subscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.manager.subscribe(
callback_2, resources.PORT, events.BEFORE_CREATE)
self.assertEqual(2, len(self.manager._index))
self.assertEqual(
2,
len(self.manager._callbacks[resources.PORT][events.BEFORE_CREATE]))
def test_unsubscribe_during_iteration(self):
unsub = lambda r, e, *a, **k: self.manager.unsubscribe(unsub, r, e)
self.manager.subscribe(unsub, resources.PORT,
events.BEFORE_CREATE)
self.manager.notify(resources.PORT, events.BEFORE_CREATE, mock.ANY)
self.assertNotIn(unsub, self.manager._index)
def test_unsubscribe(self):
self.manager.subscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.manager.unsubscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.assertNotIn(
callback_id_1,
self.manager._callbacks[resources.PORT][events.BEFORE_CREATE])
self.assertNotIn(callback_id_1, self.manager._index)
def test_unsubscribe_unknown_callback(self):
self.manager.subscribe(
callback_2, resources.PORT, events.BEFORE_CREATE)
self.manager.unsubscribe(callback_1, mock.ANY, mock.ANY)
self.assertEqual(1, len(self.manager._index))
def test_unsubscribe_is_idempotent(self):
self.manager.subscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.manager.unsubscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.manager.unsubscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.assertNotIn(callback_id_1, self.manager._index)
self.assertNotIn(callback_id_1,
self.manager._callbacks[resources.PORT][events.BEFORE_CREATE])
def test_unsubscribe_by_resource(self):
self.manager.subscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.manager.subscribe(
callback_1, resources.PORT, events.BEFORE_DELETE)
self.manager.subscribe(
callback_2, resources.PORT, events.BEFORE_DELETE)
self.manager.unsubscribe_by_resource(callback_1, resources.PORT)
self.assertNotIn(
callback_id_1,
self.manager._callbacks[resources.PORT][events.BEFORE_CREATE])
self.assertIn(
callback_id_2,
self.manager._callbacks[resources.PORT][events.BEFORE_DELETE])
self.assertNotIn(callback_id_1, self.manager._index)
def test_unsubscribe_all(self):
self.manager.subscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.manager.subscribe(
callback_1, resources.PORT, events.BEFORE_DELETE)
self.manager.subscribe(
callback_1, resources.ROUTER, events.BEFORE_CREATE)
self.manager.unsubscribe_all(callback_1)
self.assertNotIn(
callback_id_1,
self.manager._callbacks[resources.PORT][events.BEFORE_CREATE])
self.assertNotIn(callback_id_1, self.manager._index)
def test_notify_none(self):
self.manager.notify(resources.PORT, events.BEFORE_CREATE, mock.ANY)
self.assertEqual(0, callback_1.counter)
self.assertEqual(0, callback_2.counter)
def test_feebly_referenced_callback(self):
self.manager.subscribe(lambda *x, **y: None, resources.PORT,
events.BEFORE_CREATE)
self.manager.notify(resources.PORT, events.BEFORE_CREATE, mock.ANY)
def test_notify_with_exception(self):
with mock.patch.object(self.manager, '_notify_loop') as n:
n.return_value = ['error']
self.assertRaises(exceptions.CallbackFailure,
self.manager.notify,
mock.ANY, events.BEFORE_CREATE,
'trigger', params={'a': 1})
expected_calls = [
mock.call(mock.ANY, 'before_create',
'trigger', params={'a': 1}),
mock.call(mock.ANY, 'abort_create',
'trigger', params={'a': 1})
]
n.assert_has_calls(expected_calls)
def test_notify_handle_exception(self):
self.manager.subscribe(
callback_raise, resources.PORT, events.BEFORE_CREATE)
e = self.assertRaises(exceptions.CallbackFailure, self.manager.notify,
resources.PORT, events.BEFORE_CREATE, self)
self.assertIsInstance(e.errors[0], exceptions.NotificationError)
def test_notify_handle_retriable_exception(self):
self.manager.subscribe(
callback_raise_retriable, resources.PORT, events.BEFORE_CREATE)
self.assertRaises(db_exc.RetryRequest, self.manager.notify,
resources.PORT, events.BEFORE_CREATE, self)
def test_notify_called_once_with_no_failures(self):
with mock.patch.object(self.manager, '_notify_loop') as n:
n.return_value = False
self.manager.notify(resources.PORT, events.BEFORE_CREATE, mock.ANY)
n.assert_called_once_with(
resources.PORT, events.BEFORE_CREATE, mock.ANY)
def test__notify_loop_single_event(self):
self.manager.subscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.manager.subscribe(
callback_2, resources.PORT, events.BEFORE_CREATE)
self.manager._notify_loop(
resources.PORT, events.BEFORE_CREATE, mock.ANY)
self.assertEqual(1, callback_1.counter)
self.assertEqual(1, callback_2.counter)
def test__notify_loop_multiple_events(self):
self.manager.subscribe(
callback_1, resources.PORT, events.BEFORE_CREATE)
self.manager.subscribe(
callback_1, resources.ROUTER, events.BEFORE_DELETE)
self.manager.subscribe(
callback_2, resources.PORT, events.BEFORE_CREATE)
self.manager._notify_loop(
resources.PORT, events.BEFORE_CREATE, mock.ANY)
self.manager._notify_loop(
resources.ROUTER, events.BEFORE_DELETE, mock.ANY)
self.assertEqual(2, callback_1.counter)
self.assertEqual(1, callback_2.counter)
@mock.patch("neutron.callbacks.manager.LOG")
def test__notify_loop_skip_log_errors(self, _logger):
self.manager.subscribe(
callback_raise, resources.PORT, events.BEFORE_CREATE)
self.manager.subscribe(
callback_raise, resources.PORT, events.PRECOMMIT_CREATE)
self.manager._notify_loop(
resources.PORT, events.BEFORE_CREATE, mock.ANY)
self.manager._notify_loop(
resources.PORT, events.PRECOMMIT_CREATE, mock.ANY)
self.assertFalse(_logger.exception.call_count)
self.assertTrue(_logger.debug.call_count)
def test_object_instances_as_subscribers(self):
"""Ensures that the manager doesn't think these are equivalent."""
a = GloriousObjectWithCallback()
b = ObjectWithCallback()
c = ObjectWithCallback()
for o in (a, b, c):
self.manager.subscribe(
o.callback, resources.PORT, events.BEFORE_CREATE)
# ensure idempotency remains for a single object
self.manager.subscribe(
o.callback, resources.PORT, events.BEFORE_CREATE)
self.manager.notify(resources.PORT, events.BEFORE_CREATE, mock.ANY)
self.assertEqual(1, a.counter)
self.assertEqual(1, b.counter)
self.assertEqual(1, c.counter)

93
neutron/tests/unit/callbacks/test_registry.py
View File

@ -1,93 +0,0 @@
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import mock
from neutron.callbacks import events
from neutron.callbacks import registry
from neutron.callbacks import resources
from neutron.tests import base
@registry.has_registry_receivers
class ObjectWithDecoratedCallback(object):
def __init__(self):
self.counter = 0
@registry.receives(resources.PORT, [events.AFTER_CREATE,
events.AFTER_UPDATE])
@registry.receives(resources.NETWORK, [events.AFTER_DELETE])
def callback(self, *args, **kwargs):
self.counter += 1
class MixinWithNew(object):
def __new__(cls):
i = super(MixinWithNew, cls).__new__(cls)
i.new_called = True
return i
@registry.has_registry_receivers
class AnotherObjectWithDecoratedCallback(ObjectWithDecoratedCallback,
MixinWithNew):
def __init__(self):
super(AnotherObjectWithDecoratedCallback, self).__init__()
self.counter2 = 0
@registry.receives(resources.NETWORK, [events.AFTER_DELETE])
def callback2(self, *args, **kwargs):
self.counter2 += 1
@registry.has_registry_receivers
class CallbackClassWithParameters(object):
def __init__(self, dummy):
pass
class CallBacksManagerTestCase(base.BaseTestCase):
def test_decorated_inst_method_receives(self):
i1 = ObjectWithDecoratedCallback()
registry.notify(resources.PORT, events.BEFORE_CREATE, self)
self.assertEqual(0, i1.counter)
registry.notify(resources.PORT, events.AFTER_CREATE, self)
self.assertEqual(1, i1.counter)
registry.notify(resources.PORT, events.AFTER_UPDATE, self)
self.assertEqual(2, i1.counter)
registry.notify(resources.NETWORK, events.AFTER_UPDATE, self)
self.assertEqual(2, i1.counter)
registry.notify(resources.NETWORK, events.AFTER_DELETE, self)
self.assertEqual(3, i1.counter)
i2 = ObjectWithDecoratedCallback()
self.assertEqual(0, i2.counter)
registry.notify(resources.NETWORK, events.AFTER_DELETE, self)
self.assertEqual(4, i1.counter)
self.assertEqual(1, i2.counter)
def test_object_inheriting_others_no_double_subscribe(self):
with mock.patch.object(registry, 'subscribe') as sub:
AnotherObjectWithDecoratedCallback()
# there are 3 methods (2 in parent and one in child) and 1
# subscribes to 2 events, so we expect 4 subscribes
self.assertEqual(4, len(sub.mock_calls))
def test_new_inheritance_not_broken(self):
self.assertTrue(AnotherObjectWithDecoratedCallback().new_called)
def test_object_new_not_broken(self):
CallbackClassWithParameters('dummy')