291 lines
9.6 KiB
Python
291 lines
9.6 KiB
Python
# Copyright (C) 2011-2013 OpenStack Foundation
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import concurrent.futures
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import functools
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import sys
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import threading
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import time
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import keystoneauth1.exceptions
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import six
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from six.moves import queue
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import openstack._log
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from openstack import exceptions
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_log = openstack._log.setup_logging('openstack.task_manager')
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class Task(object):
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"""Represent a remote task to be performed on an OpenStack Cloud.
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Some consumers need to inject things like rate-limiting or auditing
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around each external REST interaction. Task provides an interface
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to encapsulate each such interaction. Also, although shade itself
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operates normally in a single-threaded direct action manner, consuming
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programs may provide a multi-threaded TaskManager themselves. For that
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reason, Task uses threading events to ensure appropriate wait conditions.
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These should be a no-op in single-threaded applications.
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A consumer is expected to overload the main method.
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:param dict kw: Any args that are expected to be passed to something in
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the main payload at execution time.
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"""
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def __init__(
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self, main=None, name=None, run_async=False,
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tag=None, *args, **kwargs):
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self._exception = None
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self._traceback = None
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self._result = None
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self._response = None
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self._finished = threading.Event()
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self._main = main
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self._run_async = run_async
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self.args = args
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self.kwargs = kwargs
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self.name = name or type(self).__name__
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self.tag = tag
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def main(self):
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return self._main(*self.args, **self.kwargs)
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@property
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def run_async(self):
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return self._run_async
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def done(self, result):
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self._result = result
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self._finished.set()
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def exception(self, e, tb):
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self._exception = e
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self._traceback = tb
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self._finished.set()
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def wait(self, raw=False):
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self._finished.wait()
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if self._exception:
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six.reraise(type(self._exception), self._exception,
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self._traceback)
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return self._result
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def run(self):
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try:
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# Retry one time if we get a retriable connection failure
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try:
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self.done(self.main())
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except keystoneauth1.exceptions.RetriableConnectionFailure:
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self.done(self.main())
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except Exception as e:
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self.exception(e, sys.exc_info()[2])
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class TaskManager(object):
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def __init__(self, name, rate=None, log=_log, workers=5, **kwargs):
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self.name = name
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self._executor = None
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self._log = log
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self._workers = workers
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self.daemon = True
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self.queue = queue.Queue()
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self._running = True
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if isinstance(rate, dict):
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self._waits = {}
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for (k, v) in rate.items():
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if v:
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self._waits[k] = 1.0 / v
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else:
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if rate:
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self._waits = {None: 1.0 / rate}
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else:
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self._waits = {}
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self._thread = threading.Thread(name=name, target=self.run)
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self._thread.daemon = True
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def _get_wait(self, tag):
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return self._waits.get(tag, self._waits.get(None))
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@property
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def executor(self):
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if not self._executor:
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self._executor = concurrent.futures.ThreadPoolExecutor(
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max_workers=self._workers)
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return self._executor
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def start(self):
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self._thread.start()
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def stop(self):
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self._running = False
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self.queue.put(None)
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if self._executor:
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self._executor.shutdown()
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def join(self):
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self._thread.join()
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def run(self):
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last_ts_dict = {}
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try:
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while True:
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task = self.queue.get()
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if not task:
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if not self._running:
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break
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continue
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wait = self._get_wait(task.tag)
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if wait:
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last_ts = last_ts_dict.get(task.tag, 0)
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while True:
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delta = time.time() - last_ts
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if delta >= wait:
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break
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time.sleep(wait - delta)
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last_ts_dict[task.tag] = time.time()
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self._log.debug(
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"TaskManager {name} queue size: {size})".format(
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name=self.name,
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size=self.queue.qsize()))
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self.run_task(task)
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self.queue.task_done()
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except Exception:
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self._log.exception("TaskManager died")
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raise
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def submit_task(self, task):
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"""Submit and execute the given task.
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:param task: The task to execute.
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:param bool raw: If True, return the raw result as received from the
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underlying client call.
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This method calls task.wait() so that it only returns when the
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task is complete.
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"""
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if not self._running:
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raise exceptions.TaskManagerStopped(
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"TaskManager {name} is no longer running".format(
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name=self.name))
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self.pre_run_task(task)
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start = time.time()
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self.queue.put(task)
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ret = task.wait()
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end = time.time()
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dt = end - start
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self.post_run_task(dt, task)
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return ret
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def submit_function(
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self, method, name=None, run_async=False, tag=None,
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*args, **kwargs):
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""" Allows submitting an arbitrary method for work.
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:param method: Callable to run in the TaskManager.
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:param str name: Name to use for the generated Task object.
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:param bool run_async: Whether to run this task async or not.
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:param str tag: Named rate-limiting context for the task.
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:param args: positional arguments to pass to the method when it runs.
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:param kwargs: keyword arguments to pass to the method when it runs.
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"""
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if run_async:
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payload = functools.partial(
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self.executor.submit, method, *args, **kwargs)
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task = Task(
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main=payload, name=name,
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run_async=run_async,
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tag=tag)
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else:
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task = Task(
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main=method, name=name,
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tag=tag,
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*args, **kwargs)
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return self.submit_task(task)
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def submit_function_async(self, method, name=None, *args, **kwargs):
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""" Allows submitting an arbitrary method for async work scheduling.
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:param method: Callable to run in the TaskManager.
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:param str name: Name to use for the generated Task object.
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:param args: positional arguments to pass to the method when it runs.
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:param kwargs: keyword arguments to pass to the method when it runs.
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"""
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return self.submit_function(
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method, name=name, run_async=True, *args, **kwargs)
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def pre_run_task(self, task):
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'''Callback when task enters the task queue
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:param task: the task
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Intended to be overridden by child classes to track task
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progress.
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'''
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self._log.debug(
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"Manager %s running task %s", self.name, task.name)
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def run_task(self, task):
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# Never call task.wait() in the run_task call stack because we
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# might be running in another thread. The exception-shifting
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# code is designed so that caller of submit_task (which may be
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# in a different thread than this run_task) gets the
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# exception.
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#
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# Note all threads go through the threadpool, so this is an
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# async call. submit_task will wait() for the final result.
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task.run()
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def post_run_task(self, elapsed_time, task):
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'''Callback at task completion
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:param float elapsed_time: time in seconds between task entering
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queue and finishing
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:param task: the task
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This function is intended to be overridden by child classes to
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monitor task runtimes.
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'''
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self._log.debug(
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"Manager %s ran task %s in %ss",
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self.name, task.name, elapsed_time)
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def wait_for_futures(futures, raise_on_error=True, log=_log):
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'''Collect results or failures from a list of running future tasks.'''
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results = []
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retries = []
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# Check on each result as its thread finishes
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for completed in concurrent.futures.as_completed(futures):
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try:
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result = completed.result()
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exceptions.raise_from_response(result)
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results.append(result)
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except (keystoneauth1.exceptions.RetriableConnectionFailure,
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exceptions.HttpException) as e:
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log.exception(
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"Exception processing async task: {e}".format(e=str(e)))
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if raise_on_error:
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raise
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# If we get an exception, put the result into a list so we
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# can try again
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retries.append(completed.result())
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return results, retries
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