afcf213cb5
This commit adds the framework to support async execution of functions. Will be used in syncing pooled resources while podmanager creation. Also, this adds periodic task support which is used to periodically sync pooled resources after particular interval. Partially-Implements blueprint add-device-orchestration Change-Id: I48f2358e4a7662898796c82d6a47aa6d947495e5
114 lines
3.2 KiB
Python
114 lines
3.2 KiB
Python
# Copyright (c) 2017 NEC, Corp.
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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 futurist
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from valence.common import exception
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LOG = logging.getLogger(__name__)
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_executor = None
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_periodics_worker = None
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def executor():
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global _executor
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if not _executor:
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_executor = futurist.GreenThreadPoolExecutor(max_workers=10)
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return _executor
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def start_periodic_worker(callables):
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"""Starts periodic execution of function passed in callables
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To enable this:
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1. Pass callables in following format
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[(func, (arg1, arg2), {}),
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(func2, (arg1, arg2), {}),]
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2. Decorate func as follow:
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@periodics.periodic(spacing=2, enabled=True)
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def func():
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pass
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:param callables: pass functions in this to execute periodically
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:returns: Future object
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"""
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global _periodics_worker
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_periodics_worker = futurist.periodics.PeriodicWorker(
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callables=callables,
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executor_factory=futurist.periodics.ExistingExecutor(executor()))
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task_worker = executor().submit(_periodics_worker.start)
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task_worker.add_done_callback(_handle_exceptions)
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def stop_periodic_tasks():
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"""Stops all periodic tasks and cleanup resources. """
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global _periodics_worker
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if _periodics_worker is not None:
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try:
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_periodics_worker.stop()
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_periodics_worker.wait()
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except Exception:
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LOG.exception("Exception occurred when stopping periodic workers")
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_periodics_worker = None
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if _executor and _executor.alive:
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_executor.shutdown(wait=True)
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LOG.debug("periodic tasks stopped successfully")
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def _spawn_worker(func, *args, **kwargs):
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"""Creates a greenthread to run func(*args, **kwargs).
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Spawns a greenthread if there are free slots in pool, otherwise raises
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exception. Execution control returns immediately to the caller.
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:returns: Future object.
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:raises: NoFreeWorker if worker pool is currently full.
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"""
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try:
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return executor().submit(func, *args, **kwargs)
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except futurist.RejectedSubmission:
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raise exception.ValenceException("No free worker available")
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def async(func):
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"""Start a job in new background thread.
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To start a async job, decorate the function as follows:
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Example:
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@async.async
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def test():
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pass
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"""
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def wrapper(*args, **kwargs):
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LOG.info("starting async thread for function %s", func.__name__)
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future = _spawn_worker(func, *args, **kwargs)
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future.add_done_callback(_handle_exceptions)
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return wrapper
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def _handle_exceptions(fut):
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try:
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fut.result()
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except Exception:
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msg = 'Unexpected exception in background thread'
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LOG.exception(msg)
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