f368c5822e
* Added the `Notify` message type. Used to notify workers about executor has been started and to receive workers information back (topic and tasks list); * Implemented `WorkersCache` to interact with workers information easly; * Got rid of the engine `workers_info` parameter. Change-Id: I4a810b1ddb0b04c11d12b47afc5f9cdf77d070be
204 lines
8.1 KiB
Python
204 lines
8.1 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 logging
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import threading
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from kombu import exceptions as kombu_exc
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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.utils import async_utils
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from taskflow.utils import misc
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LOG = logging.getLogger(__name__)
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class WorkerTaskExecutor(executor.TaskExecutorBase):
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"""Executes tasks on remote workers."""
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def __init__(self, uuid, exchange, topics, **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._workers_cache = cache.WorkersCache()
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self._proxy = proxy.Proxy(uuid, exchange, self._on_message,
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self._on_wait, **kwargs)
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self._proxy_thread = None
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self._notify_thread = None
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self._notify_event = threading.Event()
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def _make_thread(self, target):
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thread = threading.Thread(target=target)
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# NOTE(skudriashev): When the main thread is terminated unexpectedly
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# and thread is still alive - it will prevent main thread from exiting
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# unless the daemon property is set to True.
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thread.daemon = True
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return thread
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def _on_message(self, data, message):
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"""This method is called on incoming message."""
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LOG.debug("Got message: %s", data)
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try:
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# acknowledge message before processing
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message.ack()
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except kombu_exc.MessageStateError:
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LOG.exception("Failed to acknowledge AMQP message.")
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else:
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LOG.debug("AMQP message acknowledged.")
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try:
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msg_type = message.properties['type']
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except KeyError:
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LOG.warning("The 'type' message property is missing.")
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else:
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if msg_type == pr.NOTIFY:
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self._process_notify(data)
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elif msg_type == pr.RESPONSE:
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self._process_response(data, message)
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else:
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LOG.warning("Unexpected message type: %s", msg_type)
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def _process_notify(self, notify):
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"""Process notify message from remote side."""
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LOG.debug("Start processing notify message.")
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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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self._workers_cache.set(topic, tasks)
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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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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("Start processing response message.")
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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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LOG.debug("Task uuid: '%s'", task_uuid)
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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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if response.state == pr.RUNNING:
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request.set_running()
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elif response.state == pr.PROGRESS:
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request.on_progress(**response.data)
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elif response.state in (pr.FAILURE, pr.SUCCESS):
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request.set_result(**response.data)
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self._requests_cache.delete(request.uuid)
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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 `Timeout` exception is set as a request result.
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"""
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LOG.debug("Request '%r' has expired.", request)
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LOG.debug("The '%r' request has expired.", request)
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request.set_result(misc.Failure.from_exception(
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exc.Timeout("The '%r' request has expired" % request)))
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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, timeout=pr.REQUEST_TIMEOUT, **kwargs):
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"""Submit task request to workers."""
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request = pr.Request(task, task_uuid, action, arguments,
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progress_callback, timeout, **kwargs)
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self._requests_cache.set(request.uuid, request)
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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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self._publish_request(request, topic)
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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("Sending request: %s" % request)
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try:
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self._proxy.publish(msg=request,
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routing_key=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.exception("Failed to submit the '%s' request." %
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request)
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self._requests_cache.delete(request.uuid)
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request.set_result(failure)
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else:
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request.set_pending()
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def _notify_topics(self):
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"""Cyclically publish notify message to each topic."""
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LOG.debug("Notify thread started.")
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while not self._notify_event.is_set():
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for topic in self._topics:
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self._proxy.publish(pr.Notify(), topic, reply_to=self._uuid)
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self._notify_event.wait(pr.NOTIFY_PERIOD)
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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 start(self):
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"""Start proxy thread."""
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if self._proxy_thread is None:
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self._proxy_thread = self._make_thread(self._proxy.start)
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self._proxy_thread.start()
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self._proxy.wait()
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self._notify_thread = self._make_thread(self._notify_topics)
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self._notify_thread.start()
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def stop(self):
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"""Stop proxy, so its thread would be gracefully terminated."""
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if self._proxy_thread is not None:
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if self._proxy_thread.is_alive():
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self._notify_event.set()
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self._notify_thread.join()
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self._proxy.stop()
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self._proxy_thread.join()
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self._notify_thread = None
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self._proxy_thread = None
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