97 lines
2.9 KiB
Python
97 lines
2.9 KiB
Python
#
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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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"""Coordination and locking utilities."""
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import inspect
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import decorator
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from oslo_concurrency import lockutils
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from oslo_log import log
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from oslo_utils import timeutils
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import six
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LOG = log.getLogger(__name__)
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def synchronized(lock_name):
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"""Synchronization decorator.
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:param str lock_name: Lock name.
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Decorating a method like so::
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@synchronized('mylock')
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def foo(self, *args):
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...
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ensures that only one process will execute the foo method at a time.
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Different methods can share the same lock::
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@synchronized('mylock')
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def foo(self, *args):
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...
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@synchronized('mylock')
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def bar(self, *args):
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...
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This way only one of either foo or bar can be executing at a time.
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Lock name can be formatted using Python format string syntax::
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@synchronized('{f_name}-{resource.id}-{snap[name]}')
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def foo(self, resource, snap):
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...
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Available field names are: decorated function parameters and
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`f_name` as a decorated function name.
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"""
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@decorator.decorator
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def _synchronized(f, *a, **k):
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if six.PY2:
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# pylint: disable=deprecated-method
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call_args = inspect.getcallargs(f, *a, **k)
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else:
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sig = inspect.signature(f).bind(*a, **k)
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sig.apply_defaults()
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call_args = sig.arguments
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call_args['f_name'] = f.__name__
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lock_format_name = lock_name.format(**call_args)
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t1 = timeutils.now()
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t2 = None
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try:
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with lockutils.lock(lock_format_name):
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t2 = timeutils.now()
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LOG.debug('Lock "%(name)s" acquired by "%(function)s" :: '
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'waited %(wait_secs)0.3fs',
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{'name': lock_format_name,
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'function': f.__name__,
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'wait_secs': (t2 - t1)})
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return f(*a, **k)
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finally:
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t3 = timeutils.now()
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if t2 is None:
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held_secs = "N/A"
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else:
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held_secs = "%0.3fs" % (t3 - t2)
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LOG.debug('Lock "%(name)s" released by "%(function)s" :: held '
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'%(held_secs)s',
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{'name': lock_format_name,
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'function': f.__name__,
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'held_secs': held_secs})
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return _synchronized
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