e720bdb8af
Instead of having an implicit state machine for a requests lifecycle move toward an explicit state model and transition set that is validated and transitioned in a more easy to understand/reason about manner. This also fixes a bug that was found due to a response validation not taking into account a transition that was found due to this stricter transition checking. Includes a few tiny related/affected commits: * Remove testing of request repr() and str() as these types of tests are not useful and we removed the repr() version of the request message as the base classes is good enough. * Raise and capture a better exception and save its associated failure object when a request has expired (this gives expired requests better failure objects and associated details). Fixes bug 1356658 Partially fixes bug 1357117 Change-Id: Ie1386cca13a2da7265e22447b4c111a0a0074201
276 lines
11 KiB
Python
276 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 logging
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import threading
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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.openstack.common import timeutils
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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.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._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("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_arrival.acquire()
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try:
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self._workers_cache[topic] = tasks
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self._workers_arrival.notify_all()
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finally:
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self._workers_arrival.release()
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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_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("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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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.transition_log_error(pr.RUNNING, logger=LOG)
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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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moved = request.transition_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_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 fail:
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LOG.debug(fail.exception_str)
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request.set_result(fail)
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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 a worker."""
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request = pr.Request(task, task_uuid, action, arguments,
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progress_callback, timeout, **kwargs)
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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_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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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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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.", request)
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if request.transition_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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self._workers_arrival.acquire()
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try:
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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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finally:
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self._workers_arrival.release()
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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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