1f4dd72e6e
Instead of having code that is some what like the notifier
code we already have, but is duplicated and is slightly different
in the task class just move the code that was in the task class (and
doing similar actions) to instead now use a notifier that is directly
contained in the task base class for internal task triggering of
internal task events.
Breaking change: alters the capabilities of the task to process
notifications itself, most actions now must go through the task
notifier property and instead use that (update_progress still exists
as a common utility method, since it's likely the most common type
of notification that will be used).
Removes the following methods from task base class (as they are
no longer needed with a notifier attribute):
- trigger (replaced with notifier.notify)
- autobind (removed, not replaced, can be created by the user
of taskflow in a simple manner, without requiring
functionality in taskflow)
- bind (replaced with notifier.register)
- unbind (replaced with notifier.unregister)
- listeners_iter (replaced with notifier.listeners_iter)
Due to this change we can now also correctly proxy back events from
remote tasks to the engine for correct proxying back to the original
task.
Fixes bug 1370766
Change-Id: Ic9dfef516d72e6e32e71dda30a1cb3522c9e0be6
300 lines
13 KiB
Python
300 lines
13 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 threading
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from oslo.utils import timeutils
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from taskflow.engines.action_engine import executor
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from taskflow.engines.worker_based import cache
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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 exceptions as exc
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from taskflow import logging
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from taskflow import task as task_atom
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from taskflow.types import timing as tt
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from taskflow.utils import async_utils
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from taskflow.utils import misc
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from taskflow.utils import reflection
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from taskflow.utils import threading_utils as tu
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LOG = logging.getLogger(__name__)
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def _is_alive(thread):
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if not thread:
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return False
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return thread.is_alive()
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class PeriodicWorker(object):
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"""Calls a set of functions when activated periodically.
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NOTE(harlowja): the provided timeout object determines the periodicity.
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"""
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def __init__(self, timeout, functors):
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self._timeout = timeout
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self._functors = []
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for f in functors:
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self._functors.append((f, reflection.get_callable_name(f)))
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def start(self):
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while not self._timeout.is_stopped():
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for (f, f_name) in self._functors:
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LOG.debug("Calling periodic function '%s'", f_name)
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try:
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f()
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except Exception:
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LOG.warn("Failed to call periodic function '%s'", f_name,
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exc_info=True)
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self._timeout.wait()
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def stop(self):
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self._timeout.interrupt()
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def reset(self):
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self._timeout.reset()
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class WorkerTaskExecutor(executor.TaskExecutor):
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"""Executes tasks on remote workers."""
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def __init__(self, uuid, exchange, topics,
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transition_timeout=pr.REQUEST_TIMEOUT, **kwargs):
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self._uuid = uuid
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self._topics = topics
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self._requests_cache = cache.RequestsCache()
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self._transition_timeout = transition_timeout
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self._workers_cache = cache.WorkersCache()
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self._workers_arrival = threading.Condition()
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handlers = {
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pr.NOTIFY: [
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self._process_notify,
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functools.partial(pr.Notify.validate, response=True),
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],
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pr.RESPONSE: [
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self._process_response,
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pr.Response.validate,
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],
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}
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self._proxy = proxy.Proxy(uuid, exchange, handlers,
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self._on_wait, **kwargs)
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self._proxy_thread = None
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self._periodic = PeriodicWorker(tt.Timeout(pr.NOTIFY_PERIOD),
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[self._notify_topics])
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self._periodic_thread = None
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def _process_notify(self, notify, message):
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"""Process notify message from remote side."""
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LOG.debug("Started processing notify message '%s'",
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message.delivery_tag)
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topic = notify['topic']
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tasks = notify['tasks']
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# Add worker info to the cache
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LOG.debug("Received that tasks %s can be processed by topic '%s'",
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tasks, topic)
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with self._workers_arrival:
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self._workers_cache[topic] = tasks
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self._workers_arrival.notify_all()
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# Publish waiting requests
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for request in self._requests_cache.get_waiting_requests(tasks):
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if request.transition_and_log_error(pr.PENDING, logger=LOG):
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self._publish_request(request, topic)
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def _process_response(self, response, message):
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"""Process response from remote side."""
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LOG.debug("Started processing response message '%s'",
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message.delivery_tag)
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try:
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task_uuid = message.properties['correlation_id']
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except KeyError:
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LOG.warning("The 'correlation_id' message property is missing")
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else:
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request = self._requests_cache.get(task_uuid)
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if request is not None:
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response = pr.Response.from_dict(response)
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LOG.debug("Response with state '%s' received for '%s'",
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response.state, request)
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if response.state == pr.RUNNING:
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request.transition_and_log_error(pr.RUNNING, logger=LOG)
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elif response.state == pr.EVENT:
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# Proxy the event + details to the task/request notifier...
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event_type = response.data['event_type']
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details = response.data['details']
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request.notifier.notify(event_type, details)
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elif response.state in (pr.FAILURE, pr.SUCCESS):
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moved = request.transition_and_log_error(response.state,
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logger=LOG)
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if moved:
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# NOTE(imelnikov): request should not be in the
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# cache when another thread can see its result and
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# schedule another request with the same uuid; so
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# we remove it, then set the result...
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del self._requests_cache[request.uuid]
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request.set_result(**response.data)
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else:
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LOG.warning("Unexpected response status: '%s'",
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response.state)
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else:
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LOG.debug("Request with id='%s' not found", task_uuid)
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@staticmethod
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def _handle_expired_request(request):
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"""Handle expired request.
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When request has expired it is removed from the requests cache and
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the `RequestTimeout` exception is set as a request result.
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"""
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if request.transition_and_log_error(pr.FAILURE, logger=LOG):
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# Raise an exception (and then catch it) so we get a nice
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# traceback that the request will get instead of it getting
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# just an exception with no traceback...
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try:
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request_age = timeutils.delta_seconds(request.created_on,
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timeutils.utcnow())
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raise exc.RequestTimeout(
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"Request '%s' has expired after waiting for %0.2f"
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" seconds for it to transition out of (%s) states"
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% (request, request_age, ", ".join(pr.WAITING_STATES)))
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except exc.RequestTimeout:
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with misc.capture_failure() as failure:
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LOG.debug(failure.exception_str)
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request.set_result(failure)
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def _on_wait(self):
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"""This function is called cyclically between draining events."""
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self._requests_cache.cleanup(self._handle_expired_request)
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def _submit_task(self, task, task_uuid, action, arguments,
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progress_callback, **kwargs):
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"""Submit task request to a worker."""
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request = pr.Request(task, task_uuid, action, arguments,
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self._transition_timeout, **kwargs)
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# Register the callback, so that we can proxy the progress correctly.
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if (progress_callback is not None and
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request.notifier.can_be_registered(
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task_atom.EVENT_UPDATE_PROGRESS)):
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request.notifier.register(task_atom.EVENT_UPDATE_PROGRESS,
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progress_callback)
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cleaner = functools.partial(request.notifier.deregister,
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task_atom.EVENT_UPDATE_PROGRESS,
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progress_callback)
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request.result.add_done_callback(lambda fut: cleaner())
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# Get task's topic and publish request if topic was found.
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topic = self._workers_cache.get_topic_by_task(request.task_cls)
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if topic is not None:
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# NOTE(skudriashev): Make sure request is set to the PENDING state
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# before putting it into the requests cache to prevent the notify
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# processing thread get list of waiting requests and publish it
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# before it is published here, so it wouldn't be published twice.
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if request.transition_and_log_error(pr.PENDING, logger=LOG):
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self._requests_cache[request.uuid] = request
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self._publish_request(request, topic)
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else:
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LOG.debug("Delaying submission of '%s', no currently known"
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" worker/s available to process it", request)
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self._requests_cache[request.uuid] = request
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return request.result
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def _publish_request(self, request, topic):
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"""Publish request to a given topic."""
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LOG.debug("Submitting execution of '%s' to topic '%s' (expecting"
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" response identified by reply_to=%s and"
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" correlation_id=%s)", request, topic, self._uuid,
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request.uuid)
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try:
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self._proxy.publish(request, topic,
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reply_to=self._uuid,
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correlation_id=request.uuid)
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except Exception:
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with misc.capture_failure() as failure:
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LOG.critical("Failed to submit '%s' (transitioning it to"
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" %s)", request, pr.FAILURE, exc_info=True)
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if request.transition_and_log_error(pr.FAILURE, logger=LOG):
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del self._requests_cache[request.uuid]
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request.set_result(failure)
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def _notify_topics(self):
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"""Cyclically called to publish notify message to each topic."""
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self._proxy.publish(pr.Notify(), self._topics, reply_to=self._uuid)
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def execute_task(self, task, task_uuid, arguments,
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progress_callback=None):
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return self._submit_task(task, task_uuid, pr.EXECUTE, arguments,
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progress_callback)
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def revert_task(self, task, task_uuid, arguments, result, failures,
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progress_callback=None):
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return self._submit_task(task, task_uuid, pr.REVERT, arguments,
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progress_callback, result=result,
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failures=failures)
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def wait_for_any(self, fs, timeout=None):
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"""Wait for futures returned by this executor to complete."""
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return async_utils.wait_for_any(fs, timeout)
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def wait_for_workers(self, workers=1, timeout=None):
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"""Waits for geq workers to notify they are ready to do work.
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NOTE(harlowja): if a timeout is provided this function will wait
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until that timeout expires, if the amount of workers does not reach
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the desired amount of workers before the timeout expires then this will
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return how many workers are still needed, otherwise it will
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return zero.
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"""
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if workers <= 0:
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raise ValueError("Worker amount must be greater than zero")
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w = None
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if timeout is not None:
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w = tt.StopWatch(timeout).start()
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with self._workers_arrival:
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while len(self._workers_cache) < workers:
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if w is not None and w.expired():
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return workers - len(self._workers_cache)
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timeout = None
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if w is not None:
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timeout = w.leftover()
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self._workers_arrival.wait(timeout)
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return 0
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def start(self):
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"""Starts proxy thread and associated topic notification thread."""
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if not _is_alive(self._proxy_thread):
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self._proxy_thread = tu.daemon_thread(self._proxy.start)
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self._proxy_thread.start()
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self._proxy.wait()
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if not _is_alive(self._periodic_thread):
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self._periodic.reset()
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self._periodic_thread = tu.daemon_thread(self._periodic.start)
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self._periodic_thread.start()
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def stop(self):
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"""Stops proxy thread and associated topic notification thread."""
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if self._periodic_thread is not None:
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self._periodic.stop()
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self._periodic_thread.join()
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self._periodic_thread = None
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if self._proxy_thread is not None:
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self._proxy.stop()
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self._proxy_thread.join()
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self._proxy_thread = None
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