17b805acaf
If multiple processes are creating/erasing different fuel-devops
environments at the same time, there can be race condition during
libvirt object creation/deletion like:
'bridge virbr3 already exists' and others.
This patch allows to use a lock file to avoid such situation:
export DEVOPS_LOCK_FILE=/run/lock/devops_lock
If the environment variable DEVOPS_LOCK_FILE is not set, then
the lock file is not used (backward compatibility to avoid any
errors caused by using the lock file by default).
Change-Id: Id28f442959594aa5d6bb5c1d15e4f0880653070d
(cherry picked from commit cce44f4784)
103 lines
3.3 KiB
Python
103 lines
3.3 KiB
Python
# Copyright 2016 Mirantis, Inc.
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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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from __future__ import unicode_literals
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from functools import wraps
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from threading import Thread
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import fasteners
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from devops import error
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from devops import logger
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from devops import settings
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def threaded(name=None, started=False, daemon=False):
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"""Make function or method threaded with passing arguments
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If decorator added not as function, name is generated from function name.
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:type name: str
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:type started: bool
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:type daemon: bool
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"""
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def real_decorator(func):
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@wraps(func)
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def wrapper(*args, **kwargs):
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"""Thread generator for function
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:rtype: Thread
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"""
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if name is None:
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func_name = 'Threaded {}'.format(func.__name__)
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else:
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func_name = name
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thread = Thread(
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target=func,
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name=func_name,
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args=args,
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kwargs=kwargs)
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if daemon:
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thread.daemon = True
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if started:
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thread.start()
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return thread
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return wrapper
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if name is not None and callable(name):
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func, name = name, None
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return real_decorator(func)
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return real_decorator
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def proc_lock(path=settings.DEVOPS_LOCK_FILE, timeout=300):
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"""Process lock based on fcntl.lockf
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Avoid race condition between different processes which
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use fuel-devops at the same time during the resources
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creation/modification/erase.
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:param path: str, path to the lock file
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:param timeout: int, timeout in second for waiting the lock file
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"""
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def real_decorator(func):
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@wraps(func)
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def wrapped(*args, **kwargs):
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acquired = False
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if path is not None:
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logger.debug('Acquiring lock file {0} for {1}'
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.format(path, func.__name__))
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lock = fasteners.InterProcessLock(path)
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acquired = lock.acquire(blocking=True,
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delay=5, timeout=timeout)
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logger.debug('Acquired the lock file {0} for {1}'
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.format(path, func.__name__))
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if not acquired:
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raise error.DevopsError(
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'Failed to aquire lock file in {0} sec'
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.format(timeout))
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try:
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result = func(*args, **kwargs)
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finally:
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if acquired:
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logger.debug('Releasing the lock file {0} for {1}'
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.format(path, func.__name__))
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lock.release()
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return result
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return wrapped
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return real_decorator
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