104 lines
3.3 KiB
Python
104 lines
3.3 KiB
Python
#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import collections
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import functools
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import inspect
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from oslo_log import log as logging
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LOG = logging.getLogger(__name__)
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def asynchronous(function):
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"""Decorator for MessageProcessor methods to make them asynchronous.
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To use, simply call the method as usual. Instead of being executed
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immediately, it will be placed on the queue for the MessageProcessor and
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run on a future iteration of the event loop.
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"""
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arg_names = inspect.getargspec(function).args
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MessageData = collections.namedtuple(function.__name__, arg_names[1:])
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@functools.wraps(function)
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def call_or_send(processor, *args, **kwargs):
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if len(args) == 1 and not kwargs and isinstance(args[0], MessageData):
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try:
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return function(processor, **args[0]._asdict())
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except Exception as exc:
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LOG.exception('[%s] Exception in "%s": %s',
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processor.name, function.__name__, exc)
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raise
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else:
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data = inspect.getcallargs(function, processor, *args, **kwargs)
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data.pop(arg_names[0]) # lose self
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return processor.queue.send(function.__name__,
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MessageData(**data))
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call_or_send.MessageData = MessageData
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return call_or_send
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class MessageProcessor(object):
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queue = None
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def __init__(self, name):
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self.name = name
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def __call__(self):
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message = self.queue.get()
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if message is None:
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LOG.debug('[%s] No messages' % self.name)
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return False
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try:
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method = getattr(self, message.name)
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except AttributeError:
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LOG.error('[%s] Bad message name "%s"' % (self.name,
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message.name))
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raise
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else:
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LOG.info('[%s] %r' % (self.name, message.data))
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method(message.data)
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return True
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@asynchronous
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def noop(self, count=1):
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"""Insert <count> No-op operations in the message queue."""
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assert isinstance(count, int)
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if count > 1:
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self.queue.send_priority('noop',
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self.noop.MessageData(count - 1))
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@asynchronous
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def _execute(self, func):
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"""Insert a function call in the message queue.
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The function takes no arguments, so use functools.partial to curry the
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arguments before passing it here.
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"""
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func()
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def call(self, func, *args, **kwargs):
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"""Insert a function call in the message queue."""
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self._execute(functools.partial(func, *args, **kwargs))
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def clear(self):
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"""Delete all the messages from the queue."""
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self.queue.clear()
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__all__ = ['MessageProcessor', 'asynchronous']
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