addc286409
Instead of passing around kwargs to root WBE classes and to contained classes prefer to use explicitnamed arguments that are passed around. This makes the code more obvious as to what the intended arguments are and makes it easier for error validation when other unknown arguments are passed (as well as for docs). Also moves the docs for the worker engine to be a sub-TOC under the main engine document so that it can be more easily explored and managed/found... Change-Id: I9413fad187c330fee494f0d4536cc27d9a90f0fb
268 lines
11 KiB
Python
268 lines
11 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright (C) 2014 Yahoo! Inc. All Rights Reserved.
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#
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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 functools
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import six
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from taskflow.engines.worker_based import protocol as pr
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from taskflow.engines.worker_based import proxy
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from taskflow import logging
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from taskflow.types import failure as ft
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from taskflow.types import notifier as nt
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from taskflow.utils import misc
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LOG = logging.getLogger(__name__)
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def delayed(executor):
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"""Wraps & runs the function using a futures compatible executor."""
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def decorator(f):
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@six.wraps(f)
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def wrapper(*args, **kwargs):
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return executor.submit(f, *args, **kwargs)
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return wrapper
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return decorator
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class Server(object):
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"""Server implementation that waits for incoming tasks requests."""
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def __init__(self, topic, exchange, executor, endpoints,
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url=None, transport=None, transport_options=None,
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retry_options=None):
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type_handlers = {
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pr.NOTIFY: [
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delayed(executor)(self._process_notify),
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functools.partial(pr.Notify.validate, response=False),
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],
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pr.REQUEST: [
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delayed(executor)(self._process_request),
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pr.Request.validate,
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],
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}
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self._proxy = proxy.Proxy(topic, exchange, type_handlers,
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url=url, transport=transport,
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transport_options=transport_options,
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retry_options=retry_options)
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self._topic = topic
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self._endpoints = dict([(endpoint.name, endpoint)
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for endpoint in endpoints])
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@property
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def connection_details(self):
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return self._proxy.connection_details
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@staticmethod
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def _parse_request(task_cls, task_name, action, arguments, result=None,
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failures=None, **kwargs):
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"""Parse request before it can be further processed.
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All `failure.Failure` objects that have been converted to dict on the
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remote side will now converted back to `failure.Failure` objects.
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"""
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# These arguments will eventually be given to the task executor
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# so they need to be in a format it will accept (and using keyword
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# argument names that it accepts)...
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arguments = {
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'arguments': arguments,
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}
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if result is not None:
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data_type, data = result
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if data_type == 'failure':
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arguments['result'] = ft.Failure.from_dict(data)
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else:
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arguments['result'] = data
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if failures is not None:
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arguments['failures'] = {}
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for key, data in six.iteritems(failures):
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arguments['failures'][key] = ft.Failure.from_dict(data)
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return (task_cls, task_name, action, arguments)
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@staticmethod
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def _parse_message(message):
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"""Extracts required attributes out of the messages properties.
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This extracts the `reply_to` and the `correlation_id` properties. If
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any of these required properties are missing a `ValueError` is raised.
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"""
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properties = []
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for prop in ('reply_to', 'correlation_id'):
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try:
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properties.append(message.properties[prop])
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except KeyError:
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raise ValueError("The '%s' message property is missing" %
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prop)
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return properties
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def _reply(self, capture, reply_to, task_uuid, state=pr.FAILURE, **kwargs):
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"""Send a reply to the `reply_to` queue with the given information.
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Can capture failures to publish and if capturing will log associated
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critical errors on behalf of the caller, and then returns whether the
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publish worked out or did not.
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"""
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response = pr.Response(state, **kwargs)
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published = False
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try:
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self._proxy.publish(response, reply_to, correlation_id=task_uuid)
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published = True
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except Exception:
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if not capture:
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raise
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LOG.critical("Failed to send reply to '%s' for task '%s' with"
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" response %s", reply_to, task_uuid, response,
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exc_info=True)
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return published
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def _on_event(self, reply_to, task_uuid, event_type, details):
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"""Send out a task event notification."""
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# NOTE(harlowja): the executor that will trigger this using the
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# task notification/listener mechanism will handle logging if this
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# fails, so thats why capture is 'False' is used here.
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self._reply(False, reply_to, task_uuid, pr.EVENT,
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event_type=event_type, details=details)
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def _process_notify(self, notify, message):
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"""Process notify message and reply back."""
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LOG.debug("Started processing notify message %r", message.delivery_tag)
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try:
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reply_to = message.properties['reply_to']
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except KeyError:
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LOG.warn("The 'reply_to' message property is missing"
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" in received notify message %r", message.delivery_tag,
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exc_info=True)
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else:
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response = pr.Notify(topic=self._topic,
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tasks=self._endpoints.keys())
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try:
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self._proxy.publish(response, routing_key=reply_to)
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except Exception:
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LOG.critical("Failed to send reply to '%s' with notify"
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" response %s", reply_to, response,
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exc_info=True)
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def _process_request(self, request, message):
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"""Process request message and reply back."""
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LOG.debug("Started processing request message %r",
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message.delivery_tag)
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try:
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# NOTE(skudriashev): parse broker message first to get
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# the `reply_to` and the `task_uuid` parameters to have
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# possibility to reply back (if we can't parse, we can't respond
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# in the first place...).
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reply_to, task_uuid = self._parse_message(message)
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except ValueError:
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LOG.warn("Failed to parse request attributes from message %r",
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message.delivery_tag, exc_info=True)
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return
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else:
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# prepare reply callback
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reply_callback = functools.partial(self._reply, True, reply_to,
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task_uuid)
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# parse request to get task name, action and action arguments
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try:
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bundle = self._parse_request(**request)
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task_cls, task_name, action, arguments = bundle
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arguments['task_uuid'] = task_uuid
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except ValueError:
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with misc.capture_failure() as failure:
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LOG.warn("Failed to parse request contents from message %r",
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message.delivery_tag, exc_info=True)
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reply_callback(result=failure.to_dict())
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return
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# get task endpoint
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try:
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endpoint = self._endpoints[task_cls]
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except KeyError:
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with misc.capture_failure() as failure:
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LOG.warn("The '%s' task endpoint does not exist, unable"
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" to continue processing request message %r",
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task_cls, message.delivery_tag, exc_info=True)
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reply_callback(result=failure.to_dict())
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return
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else:
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try:
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handler = getattr(endpoint, action)
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except AttributeError:
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with misc.capture_failure() as failure:
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LOG.warn("The '%s' handler does not exist on task endpoint"
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" '%s', unable to continue processing request"
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" message %r", action, endpoint,
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message.delivery_tag, exc_info=True)
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reply_callback(result=failure.to_dict())
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return
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else:
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try:
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task = endpoint.generate(name=task_name)
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except Exception:
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with misc.capture_failure() as failure:
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LOG.warn("The '%s' task '%s' generation for request"
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" message %r failed", endpoint, action,
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message.delivery_tag, exc_info=True)
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reply_callback(result=failure.to_dict())
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return
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else:
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if not reply_callback(state=pr.RUNNING):
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return
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# associate *any* events this task emits with a proxy that will
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# emit them back to the engine... for handling at the engine side
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# of things...
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if task.notifier.can_be_registered(nt.Notifier.ANY):
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task.notifier.register(nt.Notifier.ANY,
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functools.partial(self._on_event,
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reply_to, task_uuid))
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elif isinstance(task.notifier, nt.RestrictedNotifier):
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# only proxy the allowable events then...
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for event_type in task.notifier.events_iter():
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task.notifier.register(event_type,
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functools.partial(self._on_event,
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reply_to, task_uuid))
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# perform the task action
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try:
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result = handler(task, **arguments)
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except Exception:
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with misc.capture_failure() as failure:
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LOG.warn("The '%s' endpoint '%s' execution for request"
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" message %r failed", endpoint, action,
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message.delivery_tag, exc_info=True)
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reply_callback(result=failure.to_dict())
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else:
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if isinstance(result, ft.Failure):
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reply_callback(result=result.to_dict())
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else:
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reply_callback(state=pr.SUCCESS, result=result)
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def start(self):
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"""Start processing incoming requests."""
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self._proxy.start()
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def wait(self):
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"""Wait until server is started."""
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self._proxy.wait()
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def stop(self):
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"""Stop processing incoming requests."""
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self._proxy.stop()
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